m1 assembly specification
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Project Documentation SPEC-0007 Revision A
Advanced Technology Solar Telescope 950 N. Cherry Avenue Tucson, AZ 85719 Phone 520-318-8102 atst@nso.edu http://atst.nso.edu Fax 520-318-8500
M1 Assembly Specification
Kerry Gonzales
24 May 2010
Name Signature Date
Prepared By:
Kerry Gonzales
Sr. Opto-Mechanical
Engineer
K. Gonzales 20 May 2010
Approved By Chen Liang
Sr. Optical Engineer C. Liang 20 May 2010
Approved By :
Eric Hansen
Optical Systems
Engineer
E. Hansen 20 May 2010
Approved By: Rob Hubbard
Systems Engineer R. Hubbard 20 May 2010
Approved By: Harvey Bass
Contracts Officer H. Bass 20 May 2010
Approved By:
Thomas Rimmele
ATST Project
Scientist
T. Rimmele 21 May 2010
Released By: Jeremy Wagner
Project Manager J. Wagner 24 May 2010
M1 Assembly Specification
SPEC-0007, Revision A Page ii
REVISION SUMMARY:
1. Date: 21 May 2010 Rev: A Changes: Initial document for release.
M1 Assembly Specification
SPEC-0007, Revision A Page iii
TABLE OF CONTENTS
1. SPECIFICATIONS OVERVIEW........................................................................................ 5
1.1 SCOPE OF THE DOCUMENT ................................................................................................ 5 1.2 RELATED DOCUMENTS ...................................................................................................... 5
1.2.1 Related ATST Project Documents ............................................................................. 5 1.2.2 Interface Control Documents and Drawings ............................................................ 5 1.2.3 Verification Methods ................................................................................................. 6
2. WORK BREAKDOWN STRUCTURE .............................................................................. 8
2.1 M1 ASSEMBLY DEFINITIONS ............................................................................................. 8
3. M1 ASSEMBLY REQUIREMENTS & SPECIFICATIONS ......................................... 10
3.1 M1 MIRROR POLISHING REQUIREMENTS & SPECIFICATION ............................................ 12 3.1.1 Scope ....................................................................................................................... 12 3.1.2 M1 Polishing Definitions ........................................................................................ 13 3.1.3 Environmental Conditions ...................................................................................... 13
3.1.4 Cleaning .................................................................................................................. 14 3.1.5 Coating Removal ..................................................................................................... 14
3.1.6 Coating .................................................................................................................... 14 3.1.7 Virtual Telescope Model ......................................................................................... 15 3.1.8 Optical Surface Specifications ................................................................................ 15
3.1.9 Interface Specifications ........................................................................................... 18 3.2 M1 CELL ASSEMBLY REQUIREMENTS & SPECIFICATIONS ............................................... 19
3.3 M1 SUPPORT SYSTEM ..................................................................................................... 20
3.3.1 Overview ................................................................................................................. 20
3.3.2 M1 Support System Functional Requirements & Specifications ............................ 21 3.3.3 M1 Support System Performance Requirements & Specifications ......................... 22
3.4 M1 CELL STRUCTURE ..................................................................................................... 23 3.5 M1 THERMAL CONTROL SYSTEM .................................................................................... 23
4. M1 ASSEMBLY CONTROL SYSTEM REQUIREMENTS & SPECIFICATIONS .. 25
4.1 M1 CONTROL SYSTEM DEFINITIONS ............................................................................... 25 4.2 M1 CONTROL SYSTEM DESIGN REQUIREMENTS ............................................................. 26
4.2.1 General Assembly Requirements ............................................................................ 26
4.2.2 Specific Assembly Requirements ............................................................................. 28 4.2.3 Performance Requirements ..................................................................................... 31 4.2.4 Operational Requirements ...................................................................................... 31
4.2.5 Interface Requirements ........................................................................................... 31
5. M1 ANCILLARY EQUIPMENT....................................................................................... 33
5.1 M1 APERTURE PLATE ..................................................................................................... 33 5.2 M1 WASHING EQUIPMENT .............................................................................................. 33
5.3 M1 LIFTER ...................................................................................................................... 34 5.3.1 Overview ................................................................................................................. 34 5.3.2 M1 Lifter Functional Requirements & Specifications ............................................ 34
M1 Assembly Specification
SPEC-0007, Revision A Page iv
5.3.3 M1 Lifter Performance Requirements & Specifications ......................................... 35
5.4 M1 ASSEMBLY HANDLING CART .................................................................................... 36 5.4.1 Overview ................................................................................................................. 36 5.4.2 M1 Assembly Handling Cart Functional Requirements & Specifications.............. 36
5.4.3 M1 Assembly Handling Cart Performance Requirements & Specifications .......... 37 5.5 M1 MIRROR SHIPPING CONTAINER SPECIFICATIONS ........................................................ 37
6. GENERAL REQUIREMENTS.......................................................................................... 38
6.1 DESIGN AND ANALYSIS REQUIREMENTS & SPECIFICATIONS ........................................... 38 6.1.1 Drawings & Documents Requirements & Specifications ....................................... 38
6.1.2 Environmental Design Requirements & Specifications .......................................... 39 6.1.3 Structural Design Requirements & Specifications ................................................. 40 6.1.4 Electrical Design Requirements & Specifications .................................................. 40
6.1.5 Thermal Design Requirements & Specifications .................................................... 41 6.1.6 Reliability & Lifetime Requirements & Specifications ........................................... 42 6.1.7 Maintenance Requirements & Specifications ......................................................... 42
6.2 FABRICATION REQUIREMENTS & SPECIFICATIONS .......................................................... 42 6.2.1 Materials and Workmanship Requirements & Specifications ................................ 42
6.2.2 Stress Relieving Requirements & Specifications .................................................... 43 6.2.3 Surface Finish, Coatings, and Paint Requirements & Specifications .................... 43
6.3 METROLOGY, INSPECTIONS, & FACTORY TEST REQUIREMENTS & SPECIFICATIONS ....... 43
6.4 PACKING AND SHIPPING REQUIREMENTS & SPECIFICATIONS .......................................... 44
M1 Assembly Specification
SPEC-0007, Revision A Page 5 of 44
1. SPECIFICATIONS OVERVIEW
1.1 SCOPE OF THE DOCUMENT
This document consists of the requirements and specifications for the development, design,
analysis, procurement, fabrication, factory assembly, factory acceptance testing, disassembly,
packaging, transportation, delivery, site assembly, and site acceptance for the ATST M1
Assembly which includes the M1 Mirror, the M1 Cell Assembly, the M1 Lifter and M1
Assembly Handling Cart.
The Contractor shall be responsible for polishing the M1 Mirror and the detailed design,
analysis, fabrication, pre-assembly, factory acceptance testing, delivery, site assembly and site
testing of the M1 Assembly and all of its subsystems as specified in this document.
1.2 RELATED DOCUMENTS
1.2.1 Related ATST Project Documents
ATST DWG-00001 M1 Blank, Detail
ATST DWG-00099 M1 Mirror, Detail
SPEC-0005 Software and Controls Requirements
SPEC-0012 Glossary and Acronym List
SPEC-0014 Software Design Description
SPEC-0020 M1 Coating Procedure
SPEC-0022 ATST Common Services Users’ Manual
SPEC-0027 Coordinate System Definition
SPEC-0029 ATST Optical Prescription
SPEC-0034 Zerodur® Blank Specification
SPEC-0063 ATST Interconnects & Services Specification
SPEC-0065 Quality Assurance Requirements
1.2.2 Interface Control Documents and Drawings
It is the intent of the ATST project to integrate and interface the M1 Assembly with other major
ATST subsystems, such as the telescope mount assembly, and various high-level control
systems. Contractor shall be required to interact and work periodically with ATST Project
personnel and outside vendors that are providing these related subsystems. The purpose of these
interactions is to refine and manage required changes associated with the critical interfaces
between the M1 Assembly and these other subsystems, and to improve the overall design and
performance of the ATST.
The Contractor shall develop and implement appropriate metrology and measurement methods
that allow verification of these interfaces during factory acceptance testing. These methods shall
be developed in conjunction with ATST Project personnel and shall be subject to approval by
AURA.
M1 Assembly Specification
SPEC-0007, Revision A Page 6 of 44
The M1 Assembly shall provide interfaces for the following items that are not directly included
in this Contract. These interfaces are each specified in their respective Interface Control
Documents that are included as part of this specification:
ICD 1.1-1.2 Telescope Mount Assembly to M1 Assembly
ICD 1.2-2.3 M1 Assembly to Wavefront Correction Control System
ICD 1.2-4.4 M1 Assembly to Telescope Control System
ICD 1.2-4.5 M1 Assembly to Global Interlock System
ICD 1.2-5.0 M1 Assembly to Enclosure Interface
ICD 1.2-6.4 M1 Assembly to Coating and Cleaning Facilities
ICD 1.2-6.5 M1 Assembly to Handling Equipment
1.2.3 Verification Methods
Included in each major numbered specification listed herein this document is a requirement
verification method. These verification methods specify the minimum standards of verification
required by AURA to ensure that the individual requirements and specifications are met.
All verification activities are the responsibility of the Contractor; i.e., the Contractor shall be
solely responsible for providing any and all test equipment, analyses, inspections, and other
means necessary to verify that the specifications and requirements have been met.
Examples of verification methods include:
Design Review. Verification by design review shall mean that the Contractor
demonstrates to AURA during the appropriate design review that the equipment shall
meet the specification by way of its intrinsic layout and configuration.
Analysis. Verification by analysis shall mean that Contractor analytically demonstrates
that the design meets the specification. Such analyses may include finite element
methods, computational fluid analyses, closed form analyses, etc. All analyses shall be
provided to AURA in written report form, in both electronic (e.g., MS Word) and paper
copy format.
Inspection. Verification by inspection shall mean that the Contractor visually
demonstrates to AURA personnel that the specification has been achieved on the as-built
equipment during factory acceptance testing.
Test. Verification by test &/or measurement shall mean that Contractor empirically
demonstrates that the as-built equipment meets the specification. Testing may be required
in the factory during factory acceptance testing and/or at the Site during Site acceptance
testing.
At a minimum, the specification compliance matrix provided by Contractor as part of the Work
shall use the verification method(s) listed in each of the requirements sections below.
All analyses, test results (with test error analysis) and other verification reports shall be provided
to AURA in written report form, in both electronic (e.g., MS Word or Excel) and paper copy
format. For each Test method used for acceptance testing, the Contractor shall perform a test
error analysis. All potential errors effecting the measurement shall be listed and their influence
M1 Assembly Specification
SPEC-0007, Revision A Page 7 of 44
on the test results evaluated. The required measurement value shall be adjusted so the Test shall
yield a 99% or greater certainty that the specification has been met after taking the test error
analysis into account.
M1 Assembly Specification
SPEC-0007, Revision A Page 8 of 44
2. WORK BREAKDOWN STRUCTURE
2.1 M1 ASSEMBLY DEFINITIONS
The M1 Assembly shall be comprised of the following major systems, subsystems, and
components. Specific details, requirements, and specifications of these items are specified in
more detail later in this document.
WBS 1.2 M1 Assembly
The M1 Assembly contains the M1 mirror and subsystems which controls its optical figure
and temperature over the telescope operating conditions.
WBS 1.2.1 M1 Mirror
The M1 Mirror is the primary light-collecting mirror in ATST. The M1 Mirror is
composed of low expansion glass or glass ceramic and its optical surface is polished as
an off-axis parabola.
WBS 1.2.2 M1 Cell Assembly
Assembly containing the M1 mirror, M1 support system, M1 thermal control system,
cooled aperture plate and M1 control system
WBS 1.2.2.1 M1 Support System
The M1 Support system supports the weight of M1 and maintains nominal surface
figure over operational zenith angles and thermal conditions.
WBS 1.2.2.2 M1 Cell Structure
The M1 Cell Structure is the base that supports the M1 Support System, M1 Thermal
Control System and the cleaning and washing hardware.
WBS 1.2.2.3 M1 Thermal Control System
The M1 Thermal Control system maintains the temperature of the M1 surface and
aperture plate close to ambient temperature to prevent self-induced seeing.
WBS 1.2.2.4 M1 Safety Restraint System
The M1 Safety Restraint System provides protection of M1 in the event of seismic
activity.
WBS 1.2.2.5 M1 Control System (M1CS)
The M1 Control System controls application of the active forces to M1, and controls
the thermal management system. It includes hardware to run the software. The M1CS
communicates with the Telescope Control System (TCS).
WBS 1.2.3 M1 Aperture Plate
The M1 Aperture Plate provides an aperture stop to limit the incoming optical beam and
provides active cooling within the M1 Thermal Control System.
WBS 1.2.4 M1 Washing Equipment
M1 Assembly Specification
SPEC-0007, Revision A Page 9 of 44
The M1 Washing Equipment is installed on the M1 Assembly to remove effluent during
the in-situ washing process.
WBS 1.2.5 M1 Lifter
The M1 Lifter is a steel structure with articulated beams and lifting pads used with a
crane to install and remove the M1 from the M1 Assembly, coating chamber support and
wash-cart support.
WBS 1.2.6 M1 Assembly Handling Cart
The M1 Assembly Handling Cart is a steel structure capable of lifting the M1 Assembly
for installation and removal from the Telescope Optic Support Structure. The M1
Assembly Lifting Cart will engage the M1 Assembly at the rear of the M1 cell, lower it
from the Telescope Optics Support Structure and move the M1 Assembly from the
telescope floor area to the transport area within the observatory facility.
M1 Assembly Specification
SPEC-0007, Revision A Page 10 of 44
3. M1 ASSEMBLY REQUIREMENTS & SPECIFICATIONS
1.2.0-0005 Commonality of Designs
Wherever possible, Contractor shall utilize identical equipment and designs throughout the M1
Assembly as well as the ATST facility. The purpose of doing this is to lower costs associated
with design effort, spares and maintenance.
Verification: Design Review & Inspection
Requirement Origin: Engineering
1.2.0-0010 Reliability
The lifetime of the ATST telescope is expected to be in excess of forty years. The objective of
the facility is to allow maximum telescope availability and performance for the given weather
conditions of any day of the year. The remote nature of the site puts a premium on having robust
systems that are easily repaired.
Wherever possible, all assemblies, subassemblies, components, parts, and mechanical systems
shall be designed to exceed the lifetime of the facility. Contractor shall identify any and all items
not designed to exceed this lifetime, and maintenance procedures and spares lists shall be
provided for them.
Failure modes of all critical components, including support system actuators and thermal control
system blowers and heat exchangers, shall be evaluated and the design of all systems shall be
such that failure of a single component shall result in a minimal performance reduction of the
system.
Verification: Design Review
Requirement Origin: Engineering
1.2.0-0015 Maintainability
Routine maintenance of the M1 Assembly shall cause minimum loss of observing time. The M1
Assembly shall be designed such that routine preventative maintenance will be completed in less
than four hours per month, without removal of major components from the M1 Assembly, at
night under enclosure interior lighting. Repairs of all failures arising as a result of normal
operations of the M1 Assembly shall be accomplished in no more than 8 hours by trained
personnel. Major maintenance must be accomplished within one week on at most a yearly basis.
To the extent possible, the M1 Assembly shall be designed to be maintained using standard tools
and test equipment. Any special tools or equipment required for this operation shall be designed
and furnished by the contractor, along with detailed instructions for their use.
The M1 Assembly design shall ensure that all necessary maintenance operations can be
effectively carried out without risk to personnel or hardware. Special care must be taken in the
design of any hardware that would require maintenance personnel to work around the M1 Mirror
to avoid risk to the M1 Mirror optical surface.
M1 Assembly Specification
SPEC-0007, Revision A Page 11 of 44
Critical components, such as actuator control modules, shall be replaceable at the module level to
minimize down-time. Maintenance, replacement and repair schedules will be provided for all
components of the M1 Assembly, listing frequency and type of maintenance required.
The Contractor shall provide all special tools and equipment necessary for initial set-up,
maintenance, and servicing operations required throughout the operational life of the M1
Assembly. This excludes common hand tools such as wrenches, sockets, Allen keys, etc.
Custom stands, sights and instruments necessary for initial set-up of the system, debug, and
regular maintenance shall be delivered as special tooling and equipment. Any special handling
fixtures, such as spreader bars, necessary for handling parts of the M1 Assembly shall be
deliverable. Special tools shall be marked with the part number. For ease of installation, a lifting
feature shall be provided for any removable subassembly having a mass exceeding 15 kg.
Verification: Design Review, Inspect
Requirement Origin: Engineering
1.2.0-0020 Removal for M1 recoating
For periodic re-coating of the M1, the M1 Mirror shall be capable of being easily removed from
the Telescope. The M1 Assembly shall be capable of removal from and installation to the
telescope by 4 technicians in 4 hours. The M1 Mirror shall be capable of removal from and
installation to the M1 Assembly by 4 technicians in 4 hours.
Verification: Design Review
Requirement Origin: Engineering
1.2.0-0025 Stresses
Stresses in all members shall be maintained within safe working values for all combinations of
fabrication, assembly, operation and survival conditions. Unless specified otherwise, all stresses
shall remain below the Precision Elastic Limit of the material under any combination of
Operational and Survival Conditions.
Consideration of fatigue shall be given to all structural members and connections subjected to
regular stress fluctuations over the lifetime of the facility.
Verification: Design Review
Requirement Origin: Engineering, Safety
M1 Assembly Specification
SPEC-0007, Revision A Page 12 of 44
3.1 M1 MIRROR POLISHING REQUIREMENTS & SPECIFICATION
3.1.1 Scope
This section, defines the requirements for the ATST M1 Mirror. The ATST M1 Mirror is an off-
axis paraboloid, a circular section of a larger Ø 12 meter on-axis paraboloid. The relationship of
M1 Mirror with respect to its parent optical axis and to M2 Mirror, the secondary mirror, is
shown in Figure 1 below.
Figure 1. ATST M1-M2 optical design
AT
ST
PR
ELI
MIN
AR
Y O
PT
ICA
L D
ES
IGN
8000
M1
PR
IME
FO
CU
S
OP
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AL
AX
IS
M2
GR
EG
OR
IAN
SE
CO
ND
AR
Y
M2
PA
RE
NT
VE
RT
EX
1200
(600
0)
2000
M1
PA
RE
NT
VE
RT
EX
M2
GR
EG
OR
IAN
FO
CU
S
24 J
UN
E 2
002
M1
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MIR
RO
R
4000
M1 Assembly Specification
SPEC-0007, Revision A Page 13 of 44
3.1.2 M1 Polishing Definitions
Bidirectional Reflectance Distribution Function (BRDF). BRDF is a four-dimensional
function that defines how light is reflected at an opaque surface.
Conic Constant (K). The Conic Constant is required to define the shape of the primary mirror
with the radius of curvature. The Conic Constant k is related to the surface height (Z) as a
function of primary mirror radial position (r) from the parent vertex and Radius of Curvature (R).
Figuring. Figuring is the process used to achieve the desired shape of an optical surface.
Generating. Generating, or Generation, is the first step in figuring an optical surface and rapidly
removes material using fixed-abrasive grinding.
Optical Surface. The Optical Surface of the M1 is the polished surface shown in the referenced
drawings.
Polishing. Polishing is the optical fabrication process that creates a finished surface on the
primary mirror.
M1 Mirror. The M1 Mirror is the 4 meter diameter ATST primary mirror.
M2 Mirror. The 0.65 meter diameter concave mirror in the ATST.
Paraxial Radius of Curvature (R). The Paraxial Radius of Curvature is the center radius of the
M1 parent surface, which along with the Conic Constant, is required to define the shape of the
primary mirror.
Virtual Telescope Model (VTM). VTM is a software model of the ATST optical system. The
VTM is capable of modeling comprehensive M1 surface figure errors as well as compensators
such as correctability of M1’s active axial support and focus of M2. The VTM can be used to
predict system-level image degradation contributed by M1, and it will be used to determine M1’s
compliance to requirement.
Zenith Angle. The Zenith Angle is the angle between the primary mirror parent optical axis and
the vertical axis.
3.1.3 Environmental Conditions
3.1.3.1 Operating Environment
The M1 Mirror, while operating as a part of the ATST, shall be capable of sustained and
continuous operation in complete conformance with the requirements of this specification
throughout the expected life of the observatory while being continuously subjected to any
combination of environmental conditions given in 6.1.2, under Operating Environment.
M1 Assembly Specification
SPEC-0007, Revision A Page 14 of 44
3.1.3.2 Survival Environment
The M1 Mirror shall meet the requirements of 3.1.3.1 above, without damage or requirement for
repair, after being subjected to any combination of environmental conditions specified under
Survival Environment in 6.1.2 below for any duration of time during any number of occurrences
throughout the expected life of the observatory:
3.1.3.3 Transportation Environment
The M1 Mirror shall meet the requirements of Section 3.1.3.1 above, without damage or
requirement for repair, after being subjected to any combination of environmental conditions
specified below for any duration of time during any number of occurrences while packaged in a
shipping container:
Altitude: sea level to 4500m
Ambient temperature: -20 to +50 C
Relative Humidity: 0 to 100% (condensing with salt spray)
Wind speed: 0 to 70 m/s
Gravity Orientation: Optical Surface facing up
Shock and Vibration: 10.0 g in any direction
3.1.4 Cleaning
The Optical Surface of the M1 Mirror will be subject to periodic cleaning throughout the life of
the observatory. The M1 Mirror shall meet the requirements of Section 3.1.3.1 above, without
damage or requirement for repair, after being subjected to cleaning with any combination of CO2
snow, alcohol, acetone, detergents and water.
3.1.5 Coating Removal
The coating on the M1 Mirror will be subject to periodic removal and replacement throughout
the expected life of the observatories using the procedures outlined in SPEC-0020. The M1 shall
continue to comply with all the requirements of Section 3.1.3.1 above, without damage or
requirement for repair, after being subjected to any number of coating removals. Materials that
may be used without limitation are; Hydrochloric acid, Cupric Sulfate, Potassium Hydroxide,
Nitric Acid, Ceric Ammonium Nitrate, Calcium Carbonate, Potassium Ferrocyanide solutions,
and Sodium Thiosulfate solutions.
3.1.6 Coating
The Optical Surface of the M1 Mirror will be subject to regular coating throughout the life of the
observatory. The M1 shall continue to comply with the requirements of Section 3.1.3.1 above,
without damage or requirement for repair, after being subjected to any number of such re-
coatings. Materials to be used for such coatings include, without limitation, aluminum, silver,
silicon nitride, nickel chromium, silicon and hafnium oxide. Processes used during coating may
M1 Assembly Specification
SPEC-0007, Revision A Page 15 of 44
include, without limitation, evaporation or sputtering, which require vacuum environments in the
range of 10-5
microns Hg pressures. The Optical Surface may be coated while facing either up or
down.
3.1.7 Virtual Telescope Model
The Virtual Telescope Model (VTM) is a software model of the ATST Optical System in Zemax.
The VTM will model comprehensive M1 surface figure error caused by factors such as residual
polishing error, thermal induced deformation, structure-induced deformation, and gravity
induced print-though. The VTM will also model compensators such as bending of the M1
optical surface by its active axial support actuators and focus of M2. The VTM will be capable
of predicting system level image degradation contributed by M1 surface figure error after active
compensation.
3.1.8 Optical Surface Specifications
1.2.1-0005 Optical Surface Description
The theoretical M1 Mirror parent optical surface is a conic surface of revolution described by the
following equation:
Z = r2/(R(1+(1-(1+K)r
2/R
2)0.5
)) with:
R = Radius of Curvature,
K = Conic Constant, and
r = distance from the parent optical axis.
Verification: Acceptance Test
Requirement Origin: Engineering
1.2.1-0010 Paraxial Radius of Curvature
The paraxial radius of curvature of the M1 mirror shall be:
R = 16 m 15.0 mm.
Verification: Acceptance Testing
Requirement Origin: Engineering
1.2.1-0015 Conic Constant
The Conic Constant of the primary mirror shall be:
K = -1.000
Verification: Acceptance Test
Requirement Origin: Engineering
1.2.1-0020 Surface Figure Accuracy
The Optical Surface of the M1 Mirror shall depart from the theoretical shape by less than 25 nm
RMS after the following compensations have been applied: removal of tip tilt and piston errors
M1 Assembly Specification
SPEC-0007, Revision A Page 16 of 44
and active adjustment of M1 axial actuator support forces. A maximum correction force of 30 N
is allowed for correction of surface figure errors of all spatial frequencies due to polishing.
Verification: Acceptance Test, The vendor will verify that the Optical Surface complies with the
surface figure accuracy by performing full aperture interferometry. The spatial resolution of the
phase map shall be a minimum of 500 by 500 pixels. The vendor will additionally verify the
surface figure accuracy via a second method. This second method shall be independent of the
primary interferometric test and is intended to exclude possible systemic errors in the primary
test method. This second method is preferably non-interferometric in nature.
The Optical Surface specifications shall apply over a 4000 mm diameter projected onto the
Optical Surface of M1Mirror, parallel to the optical axis of the parent parabola. It is important
to note that the optical surface is not perpendicular to the incoming solar beam, but tilted at an
angle of approximately 14°; this tilt causes the projected Ø 4000 mm clear aperture to become
an elliptical footprint when projected onto the M1 Mirror.
Requirement Origin: Engineering
1.2.1-0021 Surface Figure Accuracy, Higher Spatial Frequency Error
The Optical Surface of the M1 Mirror shall depart from the theoretical shape by less than 8 nm
RMS total, for higher spatial frequency error with spatial period from 1mm to 100mm, after the
following compensations have been applied: removal of tip tilt and piston errors and active
adjustment of M1 axial actuator support forces. A maximum correction force of 30 N is allowed
for correction of surface figure errors of all spatial frequencies due to polishing.
Verification: Acceptance Test, The vendor will verify that the Optical Surface complies with the
surface figure accuracy for higher spatial frequency error by performing Sub-aperture
interferometry. Sub-aperture interferometer measurements shall concentrate particularly at
support locations and M1 edges.
Requirement Origin: Engineering
1.2.1-0025 Aspherical Surface Slide
The aspherical surface profile of the M1 mirror shall coincide with the optical axis of the M1
parent mirror to within 2 mm.
Verification: Acceptance Test
Requirement Origin: Engineering
1.2.1-0030 Encircled Energy
The M1 mirror, while supported on the M1 Cell Assembly shall be such that the calculated
Encircled Energy (EE) concentration using the VTM, after removal of tip tilt and piston errors,
and applying active adjustment of the M1 axial actuator support forces, shall degrade, compared
to an ideal telescope, by less than:
M1 Assembly Specification
SPEC-0007, Revision A Page 17 of 44
Wavelength: 1600 nm 50% EE Degradation Diameter < .020 arcsec
This Encircled Energy specification shall be met over the full range of operational gravity
orientations and potential temperature distributions within the M1 Cell Assembly as well as
vibrations due to the M1 Thermal Control System. A maximum correction force of 30 N is
allowed for correction of support system errors. A maximum correction force of 30 N is allowed
for correction of thermal control system induced errors.
Verification: Acceptance Test (this test is expected to be performed at a single elevation angle at
or near Zenith Pointing), Analysis (Analysis will be required to estimate and remove error
contributions present in normal operation but not present in optical testing from the overall
requirement to derive the required optical test result)
Requirement Origin: Engineering
1.2.1-0040 Optional Horizon Pointing Testing
As an option, the M1 Mirror Surface Figure Accuracy and Encircled Energy shall be tested at a
Horizontal Pointing angle of approximately 75 degrees (with the M1 approximately vertical).
Verification: Optional Factory Test During this approximately horizon pointing test, the M1
Mirror shall be supported during testing on the M1 Cell Assembly.
Requirement Origin: Engineering
1.2.1-0045 Surface Imperfections
The Contractor shall use its best efforts to minimize the number of surface imperfections in the
Optical Surface. Within the Optical Surface, no surface imperfections of surface area larger than
5.0 square millimeters shall be allowed, and a maximum of 200.0 square millimeters shall be
allowed for the summation of all defective areas within the Optical Surface. No subsurface
damage shall be allowed to remain in any surface imperfection. Cracked material shall be
removed by a combination of grinding and etching.
Verification: Acceptance Test
Requirement Origin: Engineering
1.2.1-0050 Surface Roughness
As a requirement, the Optical Surface shall be polished to less than 20 Angstroms RMS surface
roughness.
As a goal, the Optical Surface shall be polished to less than 10 Angstroms RMS surface
roughness.
Verification: Acceptance Test of minimally 20 arbitrary locations, chosen by AURA, distributed
over the entire Optical Surface and covers a total area > 0.01% of the Optical Surface.
Requirement Origin: Engineering
M1 Assembly Specification
SPEC-0007, Revision A Page 18 of 44
1.2.1-0055 Surface Scatter
The Optical Surface shall yield a Bidirectional Reflectance Distribution Function (BRDF) of less
than 1.0 sr-1
at 0.002 radians from the specular direction.
Verification: Acceptance Test of 20 arbitrary locations, chosen by AURA, distributed over the
entire Optical Surface. This test shall be conducted with AURA representative present.
Requirement Origin: Engineering
1.2.1-0060 Local Decenter and Rotation of the Optical Surface
The position accuracy of the Optical Surface relative to the M1 Mirror support interface features
(mounting hardware) shall be less than 2 mm in X-Y decenter and less than 2.0 arc minutes in
rotation about the Z axis.
Verification: Acceptance Test
Requirement Origin: Engineering
3.1.9 Interface Specifications
1.2.1-0085 Configuration
The Vendor shall Generate, Figure and Polish the M1 Blank ensuring that the finished Optical
Surface be contained entirely within the “critical zone” of the M1 Blank as defined in ATST
DWG-00001.
Verification: Design Review & Inspection
Requirement Origin: Engineering
1.2.1-0090 M1 Mirror Support Interface Hardware
The M1 Mirror shall consist of all actuator attachment hardware bonded to the M1 Mirror. All
hardware bonded to the M1 Mirror shall be provided as part of the M1 Support System so as to
be compatible with the axial and lateral support actuator designs of that subsystem. The Vendor
shall select adhesive, bond joint design and install the M1 Mirror lateral and axial support
interface pads as defined on drawing ATST-DWG-00099. The bonded lateral and axial support
interfaces shall be suitable for safe operation of the finished M1 Mirror while being subjected to
any combination of the Operating and Survival Conditions listed in Section 2 above while
installed in the ATST as well as Coating and Cleaning processes.
Verification: Design Review
Requirement Origin: Engineering
1.2.1-0095 M1 Mirror Stresses
The M1 Mirror shall not incur stresses exceeding 0.7 MPa through any interface hardware.
Special attention should be given to the interface hardware design to minimize stresses imparted
to the substrate.
Verification: Design Review, Analysis
Requirement Origin: Engineering
M1 Assembly Specification
SPEC-0007, Revision A Page 19 of 44
1.2.1-0100 Alignment Targets
The Vendor shall design and install alignment target registration features on the M1 Mirror to
accurately locate the Optical Surface for the purpose of installation and alignment using a laser
tracker measurement system (i.e. FARO or API laser tracker systems). The location of the targets
are defined on the drawing ATST-DWG-00099. The location of these targets relative to the best
fit theoretical optical surface shall be delivered as part of acceptance test documentation. The
accuracy in position of these targets shall be within 100 microns of their reported position
relative to the measured Optical Surface geometry.
Verification: Design Review & Factory Test
Requirement Origin: Engineering
3.2 M1 CELL ASSEMBLY REQUIREMENTS & SPECIFICATIONS
1.2.2-0005 Scope
The general requirements of the M1 Cell Assembly are as follows:
Accurately support, locate and maintain position of the M1 within the required tolerance
over the full range of operational conditions.
Maintain the M1 optical surface figure within the required tolerance over the full
operational range of the telescope.
Maintain the M1 optical surface temperature within the required tolerance over the full
range of operational conditions.
Provide active optics correction capability using the M1 axial actuators for control of the
M1 surface figure.
Allow straightforward removal of the M1 from the M1 Assembly for periodic re-coating
of M1.
Allow removal of the M1 Assembly from the Telescope Mount Assembly
Allow in-situ cleaning and washing of the M1 reflective surface.
Provide earthquake protection of the M1 in the event of seismic shock.
Verification: Design Review
Requirement Origin: Engineering
1.2.2-0010 Performance Modeling
Many individual factors contribute to the final optical performance of the ATST M1 Assembly.
A detailed and balanced error budget shall be generated that lists the individual contributions to
M1 Assembly contributions to overall telescope wavefront error, and these errors shall be
combined in an appropriate manner to demonstrate the M1 Assembly meets the Encircled
Energy specification (1.2.1-0030) under all operating conditions.
Verification: Design Review, Analysis
Requirement Origin: Engineering
M1 Assembly Specification
SPEC-0007, Revision A Page 20 of 44
1.2.2-0015 Electronic Heat Sources
It is essential to avoid heat sources on or near the telescope, which could thermally disturb the
M1 or the air in the optical path. All heat sources larger than 10 W located on or near the M1
Cell Assembly, including control electronics, shall be insulated in an enclosure and actively
cooled. The maximum total heat input into the local environment from the M1 Cell Assembly
shall be no greater than 30 W.
Verification: Design Review
Requirement Origin: Engineering
1.2.2-0020 Thermal Mass
The M1 Cell Assembly constitutes a large thermal mass in the system. It is essential that the
temperature of the external surfaces be controlled to avoid “seeing” disruptions in the optical
path. The external surfaces of the M1 Cell Assembly shall remain within ±2ºC of the ambient
temperature at all times.
Verification: Design Review & Factory Test. At a minimum the Factory Acceptance Test will be
performed at one (1) ambient temperature condition for all M1 Assembly operational modes.
Requirement Origin: Engineering
3.3 M1 SUPPORT SYSTEM
3.3.1 Overview
1.2.2.1-0005 Scope
The M1 Support System shall contain 120 axial support actuators arranged in five circular rings.
Support pads at the upper end of each actuator are bonded to the back of the M1 Mirror; these
support pads shall be made of a material that closely matches the M1 Blank thermal properties
and shall have a connection joint between the actuator rod and support pad for assembly and
disassembly of the axial support system. The axial supports shall attach to the rear surface of the
M1 cell and shall be easily removed for servicing and removal of the M1 Mirror for recoating.
Axial support forces shall be adjustable to control the M1 Mirror optical surface figure.
The M1 Support System shall contain 24 lateral supports arranged at intervals around the outside
diameter of the M1 Mirror and attached to the M1 cell structure. Support pads at the end of each
actuator shall be bonded to the outside diameter of the M1 Mirror; these support pads shall be
made of a material that closely matches the M1 Blank thermal properties and shall have a
connection joint between the actuator rod and support pad for assembly.
The M1 Support System shall control the position of the M1 Mirror in six degrees of freedom
and control the M1 Mirror optical surface figure at the direction of the M1 Control System.
Verification: Design Review
Requirement Origin: Engineering
M1 Assembly Specification
SPEC-0007, Revision A Page 21 of 44
1.2.2.1-0010 Basic Requirements
The M1 support system shall accurately support, locate and maintain the position of the M1
Mirror within the required tolerance over the full operational range of the telescope. It shall also
maintain the M1 Mirror optical surface figure within the required tolerances.
The M1 Support System shall be insensitive to thermal distortions and flexure of the M1 Cell
Structure. Changes in shape of the M1 Cell Structure shall not cause the position and surface
figure requirements of the M1 Assembly to be exceeded under operational conditions.
Verification: Design Review & Inspection
Requirement Origin: Safety, Engineering, Science Requirements
3.3.2 M1 Support System Functional Requirements & Specifications
1.2.2.1-0015 Seismic Safety
The M1 Support System shall ensure that the M1 Mirror survives the seismic conditions of this
specification without damage by providing passive restraint.
Verification: Design Review, Analysis
Requirement Origin: Engineering
1.2.2.1-0020 Actuator Failure Condition
Safety of the M1 Mirror is a critical requirement of the M1 Support System; the actuator designs
shall limit the maximum force that can be applied. No failure, or combination of failures, is
allowed that can damage the M1 Mirror or impart a local stress of greater than 0.7 MPa in the
M1 Mirror.
(As a goal, actuator failure would result in a fixed minimum force applied to the M1 Mirror
leading to the ability for correction of the resulting optical surface error by adjusting the forces
applied to adjacent actuators.)
Verification: Design Review & Factory Test
Requirement Origin: Engineering
1.2.2.1-0025 Actuator Replacement Capability
Each M1 Support System actuator shall be capable of removal and installation from the M1
Assembly by 1 technician in less than 2 hours.
Verification: Design Review & Factory Test
Requirement Origin: Safety
1.2.2.1-0030 Hysteresis
The operational requirements of the M1 Assembly demand that support forces will vary from
positive to negative and back again over a day tracking the sun. The design of the axial and
lateral support system shall minimize hysteresis and dead-zone effects due to this force direction
change.
M1 Assembly Specification
SPEC-0007, Revision A Page 22 of 44
Verification: Design Review
Requirement Origin: Engineering
3.3.3 M1 Support System Performance Requirements & Specifications
1.2.2.1-0035 M1 Figure Adjustment
The M1 Support System shall be able to accurately adjust the M1 Mirror optical surface figure
by applying arbitrary orientation Zernike correction terms to correct for telescope errors external
to the M1 Assembly. The minimum actuator force available for these corrections shall be 75 N
above or below the nominal support force. Specific corrections with the ranges and tolerances
specified below shall be demonstrated:
Term Absolute Minimum
Adjustment (microns RMS)
Residual error (nm RMS)
Astigmatism 10 30
Coma 1 36
Spherical 1 56
Trefoil 1 17
Quatrefoil 1 26
All motions shall be smooth, free of vibration and precisely controlled. The figure correction
shall be accomplished and stable within five (5) seconds of receiving the command.
Verification: Design Review, Factory Test. M1 Zernike correction terms shall be tested using
full aperture interferometry.
Requirement Origin: Science Requirement Flow-down
1.2.2.1-0045 M1 Figure Stability
The M1 Support System shall stably maintain any commanded optical surface figure of the M1
Mirror, with RMS figure change at a rate of less than 10 nm RMS over any 10 minute period, for
any combination of static or changing operational conditions.
Verification: Design Review & Factory Test. M1 Figure Stability shall be tested using full
aperture interferometry.
Requirement Origin: Science Requirement Flow-down
1.2.2.1-0050 M1 Mirror Position
The M1 Support System shall be able to define and adjust the M1 Mirror position with the
ranges and tolerances specified below:
Motion: Range: Repeatability:
De-center motion (X or Y) ± 500 μm ± 2 μm
Piston (Z) motion ± 1000 μm ± 2 μm
M1 Assembly Specification
SPEC-0007, Revision A Page 23 of 44
Tip-tilt motion (about X or Y) ± 50 arc seconds ± 0.5 arc seconds
Z axis rotation ± 15 arc minutes ± 2 arc seconds
All motions shall be smooth, free of vibration and precisely controlled. These specifications
include the effects of the M1 Cell Structure and the M1 Support System. The position correction
shall be accomplished and stable within sixty (60) seconds of receiving the command.
Verification: Design Review & Factory Test
Requirement Origin: Engineering
1.2.2.1-0055 M1 Support Stiffness
The M1 Mirror axial supports shall have a minimum stiffness of 20 N/micron. The M1 Mirror
lateral supports shall have a minimum stiffness of 40 N/micron.
Verification: Design Review & Factory Test
Requirement Origin: Science Requirement Flow-down
3.4 M1 CELL STRUCTURE
1.2.2.2-0005 Scope
The M1 Cell Structure is a structural steel weldment that interfaces to the Telescope Mount
Assembly and all of the M1 Assembly subsystems. It provides a mounting surface and load
reaction for all of the axial and lateral support actuators. It houses the M1 thermal control system
hardware and also provides a mounting location for sensors, facility interface panel(s), M1
Assembly Handling Cart and the M1 Lifter.
Verification: Design Review
Requirement Origin: Engineering
1.2.2.2-0010 Basic Requirements
The M1 Cell Structure shall be designed to provide high resonant frequencies relative to all
excitation sources and minimum deflection with changing gravitational loading. The M1 Cell
Structure shall have minimum thermal mass and heat capacity consistent with the required
mechanical performance. The M1 Cell Structure shall provide adequate access for maintenance
and service of the support actuators and thermal control system hardware contained within the
M1 Cell Structure.
Verification: Design Review & Inspection
Requirement Origin: Safety, Engineering
3.5 M1 THERMAL CONTROL SYSTEM
1.2.2.3-0005 Scope
The M1 Thermal Control System controls the optical surface temperature of the M1 Mirror. It
consists of all equipment required to monitor and control the optical surface temperature.
Verification: Design Review
M1 Assembly Specification
SPEC-0007, Revision A Page 24 of 44
Requirement Origin: Engineering
1.2.2.3-0010 Basic Requirements
The M1 Thermal Control System shall provide cooling to the M1 Mirror, minimizing convective
heat transfer to the ambient air from any surface that may contribute to local seeing effects. The
temperature control shall be done in such a way as to allow all other requirements of the M1 Cell
Assembly to be met while the Thermal Control System is operating under any combination of
operational environmental conditions.
The M1 Thermal Control System shall be designed so that the failure of one component such as
a blower or heat exchanger shall result in a minimal performance reduction of the system.
Critical components of the M1 Thermal Control System shall be monitored during operation and
any change in their health status shall be directed to the telescope control system.
The M1 Thermal Control System shall provide, at a minimum (TBR), six (6) additional thermal
sensor inputs that can be populated by AURA after acceptance of the system. The M1 Control
System shall have the ability to read and convey the data from these additional inputs to the TCS
as required.
Verification: Design Review
Requirement Origin: Engineering
1.2.2.3-0015 Temperature Range
The M1 Thermal Control System shall be capable of maintaining the surface temperature of the
M1 Mirror within 2ºC of the temperature of the surrounding ambient air during any and all
operating conditions.
Verification: Design Review, Analysis
Requirement Origin: Engineering, Science Requirement Flow-down
1.2.2.3-0020 Temperature Response
The optical surface shall be capable of an average temperature change of 5° C in 8500 seconds
with uniformity of ±0.5° C. This temperature change shall be accomplished using liquid coolant
at 15° C cooler than the ambient air. The initial blank temperature shall be at ambient
temperature and be uniform over the entire mirror to within ±0.5° C.
Verification: Design Review & Factory Test
Requirement Origin: Science Requirement Flow-down
1.2.2.3-0025 Temperature Uniformity
The M1 Thermal Control System shall provide cooling to the M1 Mirror in such a way as to
maintain temperature uniformity of any point of the M1 Mirror optical surface within ±0.5° C
under any combination of operational conditions.
Verification: Design Review & Analysis
Requirement Origin: Science Requirement Flow-down
M1 Assembly Specification
SPEC-0007, Revision A Page 25 of 44
1.2.2.3-0030 Vibration
The M1 Thermal Control System shall not create vibrations that degrade telescope imaging
performance. Any M1 Mirror optical acceptance testing results using the M1 Cell Assembly
shall include any and all vibration effects from the M1 Thermal Control System.
Verification: Design Review & Factory Test
Requirement Origin: Science Requirement Flow-down
1.2.2.3-0035 System Safety
The M1 Thermal Control System shall include all necessary hardware to detect fault conditions
within the M1 Assembly as described in ICD 1.2/4.5 and transmit them to the GIS, including but
not limited to leak detection, over temperature conditions, flow and pressure loss etc.
The M1 Thermal Control System shall be capable of responding to all GIS commands as
described in ICD 1.2/4.5, including but not limited to being depowered separately from the
remainder of the M1 Assembly when commanded by the GIS.
Verification: Design Review & Inspection
Requirement Origin: Engineering
4. M1 ASSEMBLY CONTROL SYSTEM REQUIREMENTS & SPECIFICATIONS
4.1 M1 CONTROL SYSTEM DEFINITIONS
The following definitions are used throughout this section.
Controller. A controller is a computing component that executes software to close servo loops,
read external sensors, and interface with higher level software.
Engineering User Interface. The engineering user interface is a graphical user interface (GUI)
that provides control and status information to a user for a particular subsystem. An engineering
user interface may be instantiated on a remote computer via a network connection. More than
one engineering user interface may be open.
Index Position. The index position is a specific location within the range of travel of a
mechanism. It has a unique sensor or marker to identify it to a mechanism controller.
Interlock. An interlock is a hardwired connection between two systems or mechanisms that
provides time-critical safety information.
Interlock Condition. An interlock condition exists if a system or mechanism raises an interlock
connection because it has detected a possible safety conflict.
Interlock Override. An interlock override is a manually set condition to inform a system to
ignore a particular interlock condition.
M1 Assembly Specification
SPEC-0007, Revision A Page 26 of 44
Observatory Control System (OCS). The OCS is the highest level software system,
responsible for coordinating observations and providing system services.
Telescope Control System (TCS). The TCS is responsible for control of all telescope
subsystems.
Wavefront Correction Control System (WCCS). The Wavefront Correction Control System
is responsible for determining and transmitting corrective values for observed errors in the
wavefront delivered by the telescope.
4.2 M1 CONTROL SYSTEM DESIGN REQUIREMENTS
The M1 Control System (M1CS) is one element of the M1 Assembly, along with the M1 Mirror,
M1 Cell Structure, M1 Thermal Control System, and others.
From a software systems point of view, the M1 Control System (M1CS) is a subsystem of the
ATST Telescope Control System (TCS). While the TCS is responsible for the overall operation
of the telescope, it delegates responsibility for the operation of the M1 Assembly to the M1CS.
The M1CS is required to accept input demands from the TCS and apply them to its own internal
components. Additionally the M1CS is responsible for all internal operations, i.e., those
activities that are wholly performed inside the M1 Assembly or are initiated by the M1CS.
Commands to the M1CS are sent through the ATST Common Services, defined in the ATST
Common Services User’s Manual (SPEC-0022-1).
4.2.1 General Assembly Requirements
The M1CS has a number of general requirements placed upon the entire system, but not
necessarily applicable to specific subassemblies. These requirements define the basic functional
and performance requirements of the M1CS as they apply to the M1 Assembly. Additional
requirements placed upon the software define operational and interface requirements. Finally,
there are a set of general requirements for software standards, documentation, and testing.
1.2.2.5-0001 Control
The M1CS shall control all actuators, sensors, and other mechanical and optical components
associated with the M1 Assembly. No other system or controller shall operate these components
without using the M1CS to control them. Control of the M1CS shall be through the approved
TCS/M1CS interface (ICD 1.2/4.4).
Verification: Design Review & Inspection
Source: Software Concepts
1.2.2.5-0005 Status
The M1CS shall maintain and provide status information on all actuators, sensors, and other
components associated with the M1 Assembly. Status information shall include position, rate,
forces, temperatures, wavefront correction input and any other information required to determine
the condition of the M1 Assembly, the M1CS, and its components. Status information shall be
M1 Assembly Specification
SPEC-0007, Revision A Page 27 of 44
updated at rates necessary to perform both manual and automatic control processes as specified
herein. Status information shall be made available to requesting systems through the TCS-to-M1
Assembly interface (ICD 1.2/4.4).
In general, status information is pertinent and expected to be sent from the M1CS if it contains
any information on the current condition of the hardware and software within the M1 Assembly
and is useful for diagnostics, operating control loops, or possibly indicative of errors or problems
within the M1 Assembly. The information found in the M1CS status reports is defined by the
TCS to M1 Assembly Interface Control Document. This information shall be inserted, modified,
and reviewed as part of the design process.
Verification: Design Review & Inspection
Source: Software Concepts
1.2.2.5-0010 Default state
The default state of any equipment shall be an inert, non-moving, non-powered condition.
Equipment within the M1 Assembly shall take this state on an interlock condition, initialization,
shutdown, or when demanded through the software interface.
Verification: Design Review & Inspection
Source: Software Concepts, Engineering, Safety
1.2.2.5-0015 Restart
The M1CS shall perform all requests sent through its interface without need of reboot or re-
initialization, unless the request demands such an operation.
Verification: Design Review & Inspection
Source: Software Concepts, Engineering
1.2.2.5-0020 Health
The M1CS shall be able to determine if the current state of the M1 Assembly is within
operational specifications. The M1CS shall report this current state as its “health”. The health
shall be determined and reported at least every three seconds through the ATST Common
Services health reporting mechanism, as specified by SPEC-0022-1.
Verification: Design Review & Inspection
Source: Software Concepts, Operational Concepts
1.2.2.5-0025 Logging
The M1CS shall log pertinent data to the ATST facility log mechanism. Pertinent data shall
include state changes, configuration changes, errors, alarms and warnings, and any other
information that may assist in reconstructing the operation of the M1CS. The M1CS logging
level shall be user selectable for the depth of information, per the ATST logging facility
definitions of logging levels, as specified by SPEC-0022-1.
Verification: Design Review & Inspection
M1 Assembly Specification
SPEC-0007, Revision A Page 28 of 44
Source: Software Concepts, Operational Concepts
1.2.2.5-0030 Availability
The M1CS shall always be available to accept or reject commands. It shall not block any
command request while processing another command request.
This requirement prevents the M1CS from processing a command in only one thread, essentially
blocking subsequent commands until the first one is completed. This behavior is necessary to
effect commands such as stop and pause after an initial start command; otherwise it would be
difficult to stop an ongoing operation.
Verification: Design Review & Inspection
Source: Software Concepts
1.2.2.5-0035 Persistence of data
Static information required by the M1CS to operate shall be recoverable after a restart or reboot.
This information may include, but is not limited to, zero points, lookup tables, and configuration
parameters. Dynamic information, such as current position and state, may be reset or recovered
after initialization. Static information shall be stored through the ATST Common Services
mechanism for default configuration storage.
Verification: Design Review & Inspection
Source: Software Concepts, Engineering
4.2.2 Specific Assembly Requirements
1.2.2.5-0100 Control of the axial and lateral support actuators
The M1CS shall control the operation of the M1 Support System. The M1CS shall define the
position of the axial and lateral support actuators and maintain that position under all operating
conditions per specification.
The M1CS is the sole controller of mirror support and resulting mirror figure during normal
operations. It is the responsibility of the M1CS to provide accurate and responsive values to the
actuators to keep the mirror position within specification, in all defined operating modes (open
loop, closed loop) and at all mirror elevation angles.
Verification: Factory Test
Source: Software Concepts, Engineering
1.2.2.5-0105 Open-loop correction
The M1CS shall perform open-loop correction of the M1 Mirror figure for the current zenith
angle, temperature, temperature gradient, or any other variable operating condition that
influences M1 Mirror figure. The correction forces shall be predetermined and applied as
necessary to maintain the M1 Mirror figure. The M1CS shall be commanded to enable or disable
the open loop-correction. The current zenith angle shall be used to determine the corrective
forces for each axial and lateral actuator, along with any other information (i.e., temperature,
azimuth angle, etc.) needed to maintain M1 Mirror figure.
M1 Assembly Specification
SPEC-0007, Revision A Page 29 of 44
At a minimum, the M1CS shall keep open-loop correction tables for the following sets of mirror
natural mode coefficients (mm1..20):
Static +
(mm1 .. mm20) * cos(el) +
(mm1 .. mm20) * sin(el) +
(mm1 .. mm20) * (T – T0) +
(mm1 .. mm20) * (dT/dz) +
(mm1.. mm20)* solar flux +
(mm1.. mm20)* TBD,
Where Static defines the non-changing set of actuator force values to correct for static errors
such as polishing or support position errors. The variable correction is supplied by coefficients
which are scaled; cos(el) and sin(el) define the cosine and sine accumulative error due to
changing elevation angle el; (T - T0) defines the cumulative error due to the difference in the
current temperature of the optical surface (T) and the nominal temperature (T0); and dT/dz
defines the temperature gradient (dT) through the mirror perpendicular to the optical surface (dz).
The Contractor shall define the static force values and additional open-loop correction tables for
other parameters if they are necessary to maintain the optical performance specification.
Verification: Factory Test
Source: Engineering
1.2.2.5-0110 Closed-loop correction
The M1CS shall be capable of closed-loop correction of the M1 Mirror figure. The M1CS shall
use information from the ATST Wavefront Correction Control System (WCCS) and any
necessary look up table values to calculate and apply the appropriate force adjustments for each
axial support actuator to provide closed-loop figure correction. The M1CS shall be commanded
to enable or disable the closed-loop correction through the TCS interface.
If the open-loop mode operation is enabled after operating in closed-loop mode, the last closed-
loop demands applied will be used to calculate a zero point offset (difference between closed
loop and LUT demand) which will be added to all LUT position and or figure demands.
While closed loop correction is enabled, if updates from the WCCS are not received within a
user definable period between 10 seconds and 10 minutes, actuator forces shall be updated by the
M1CS based on the last available closed-loop support force set with open-loop look up table
(LUT) adjustments made to compensate for changes in telescope position, temperature, etc.
Verification: Factory Test
Source: Engineering
M1 Assembly Specification
SPEC-0007, Revision A Page 30 of 44
1.2.2.5-0112 WCCS controlled closed-loop correction
The M1CS shall be capable of closed-loop correction of the M1 Mirror figure using only
information from the WCCS to calculate and apply the appropriate force adjustments for each
axial support actuator to provide closed-loop figure correction. The M1CS shall be commanded
to enable or disable this WCCS controlled closed-loop correction through the TCS interface.
Verification: Factory Test
Source: Engineering
1.2.2.5-0115 Control of the M1 Thermal Control System
The M1CS shall control the operation of the M1 mirror thermal control system. Control shall
include the ability to enable and disable the M1 mirror thermal control system, maintain optical
surface temperatures within specification relative to ambient air temperature, create a
temperature profile within the M1 that is based upon the projected ambient temperature of the
next day’s observations (as provided by the TCS), and read and report all temperatures and other
sensors involved in the operation of the M1 thermal control system.
Verification: Design Review, Factory Test
Source: Operational Concepts, Engineering
1.2.2.5-0120 Observing Mode: Thermal Control System
The M1CS shall execute closed-loop control of the thermal control system by reading
temperature sensors and applying an appropriate response with the blowers, coolant control
valves, and other thermal equipment. The control loop shall maintain the optical surface mirror
temperature equal to that of the ambient environment within specification.
While in the Observing Mode the M1CS interface shall have the following control options:
Closed-loop control using measured temperatures to maintain the system at ambient
temperature.
Open-loop control that provides maximum cooling at all times.
Open-loop control that can apply any combination of tabulated cooling data (for example
based on diurnal cycles, telescope position, etc.) that is populated by the user at anytime.
No-Control (Off) setting that provides no thermal control.
Verification: Factory Test
Source: Operational Concepts, Engineering
1.2.2.5-0125 Preconditioning Mode: Thermal Control System
The M1CS shall execute thermal control of the M1 Mirror to prepare it for Observing Mode. The
M1CS shall create temperature set points based on the time until observations are scheduled to
begin and the ambient temperature expected at the start of observations which will be supplied
by the TCS, or based on data from the previous dawn stored by the M1CS.
While in the Preconditioning Mode the M1CS interface shall have the following control option:
Fixed duration preconditioning prior to set start time.
M1 Assembly Specification
SPEC-0007, Revision A Page 31 of 44
Verification: Factory Test
Source: Operational Concepts, Engineering
1.2.2.5-0130 Loss of an actuator
The M1CS shall be able to operate with removed or disabled actuators, under the condition the
removed or disabled actuators shall apply no force to the M1 mirror. The M1CS shall have the
capability to adjust forces on other actuators to minimize the performance degradation due to the
loss of a single actuator.
Verification: Test
Source: Engineering
4.2.3 Performance Requirements
1.2.2.5-0200 Update mirror forces at rates between 0.1 and 1 Hz
The M1CS shall continuously update the forces on the M1 Mirror at a rate between 0.1 Hz and 1
Hz. The rate shall be externally controllable through the public interface with the TCS.
Verification: Factory Test
Source: Science Requirements
4.2.4 Operational Requirements
1.2.2.5-0300 Engineering user interface
The M1CS shall provide a Graphical User Interface (GUI) that controls all required functionality
of the M1 Assembly. This engineering user interface shall use the same interfaces specified for
the TCS (ICD 1.2/4.4) and WCCS (ICD 1.2/2.3).
Verification: Inspection, Factory Test
Source: Operational Concepts, Engineering
1.2.2.5-0305 Time
The M1CS shall use International Atomic Time (TAI) in all calculations. It shall use TAI in all
data distribution.
Verification: Inspection
Source: Engineering
4.2.5 Interface Requirements
1.2.2.5-0400 Common Services Framework
The M1CS shall provide a software interface that conforms to the ATST interface for the
Common Services Framework (SPEC-0022). The Common Services Framework interface shall
be controlled by the ATST; the M1CS shall use the interface defined by the ATST.
Description: The Common Services Framework defines three levels of component interface: (a)
the containers and container managers the M1CS components shall operate within, (b) the
M1 Assembly Specification
SPEC-0007, Revision A Page 32 of 44
controller model the M1CS components shall implement, and (c) the services the M1CS shall
employ to interact with the ATST software system.
Verification: Design Review
Source: Software Concepts
1.2.2.5-0405 Telescope Control System
The M1CS shall accept and act upon commands and configurations from the ATST Telescope
Control System (TCS) for all operational and engineering activities. The commands,
configurations, and events shall be defined in the interface control document ICD 1.2/4.4.
Description: The TCS commands the M1CS to perform in a specified wavefront mode, such as
closed-loop wavefront correction, or a particular thermal mode, such as closed loop thermal
correction. The TCS also requires the M1CS to broadcast status events at regular intervals or
upon state changes. In addition, the engineering GUI uses the same interface to perform the
above activities and additional ones as necessary for testing, diagnosis, and performance
monitoring.
Verification: Design Review
Source: Software Concepts
1.2.2.5-0410 Wavefront Correction Control System
The M1CS shall accept and act upon wavefront correction information from the ATST
Wavefront Correction Control System (WCCS). The wavefront correction information format,
type, and rate are specified in the interface control document ICD 1.2/2.3.
Description: Wavefront information is broadcast by the WCCS to all subscribed listeners. The
M1CS shall be one of the subscribed listeners and shall act upon the information sent by the
WCCS to correct its mirror figure.
Verification: Design Review
Source: Science Requirements, Software Concepts
1.2.2.5-0415 Interlock
The M1CS shall respond to a global interlock signal by placing itself and its subsystems in a
safe, default state. The default state shall prevent the M1CS from moving any mechanisms or
equipment while the interlock condition exists. The M1CS shall reject commands while the
global interlock signal is active. The action currently underway when the interlock condition
occurred should be aborted.
The M1CS shall respond to the release of a global interlock signal by accepting new commands.
The M1CS shall not exit the default state until commanded by the TCS or the engineering user
interface.
M1 Assembly Specification
SPEC-0007, Revision A Page 33 of 44
Description: The M1CS needs to listen for broadcasted interlock conditions and place itself in a
safe state when it detects an interlock condition. Upon the release of the interlock condition the
M1CS needs to be able to resume processing commands and performing actions.
The broadcast interlock condition is not the same as the hardware GIS interlock used by the
mechanical systems in the M1 Assembly. It is a software event sent by the Observatory Control
System when it determines that a hardware interlock is ongoing and may impact operations. It
shall not be used for personnel or equipment safety reasons.
Verification: Design Review
Source: Safety, Engineering
5. M1 ANCILLARY EQUIPMENT
5.1 M1 APERTURE PLATE
1.2.3-0005 Scope
The M1 Aperture Plate is a continuous ring that defines the clear aperture of the M1, the entrance
aperture of the ATST.
Verification: Design Review
Requirement Origin: Engineering
1.2.3-0010 Basic Requirements
The M1 Aperture Plate shall be located immediately in front of the M1 Mirror optical surface,
and will define the 4 meter circular clear aperture of the incoming optical path as viewed along
the optical axis of the telescope. The M1 Aperture Plate shall have a thickness no greater than 75
mm. The sunward facing surface of the M1 Aperture Plate shall be illuminated by direct
sunlight. The absorbing surface shall be painted black with an average solar absorption of greater
than 95%. The temperature of the M1 Aperture Plate shall be maintained at ambient temperature
within a range of +/-1° C.
Verification: Design Review & Inspection
Requirement Origin: Engineering, Science Requirements
5.2 M1 WASHING EQUIPMENT
1.2.4-0005 Scope
The M1 Washing Equipment consists of equipment used to collect and remove the effluent
accumulated at the lower edge of the M1 Mirror during the in-situ washing process.
Verification: Design Review & Inspect
Requirement Origin: Engineering
1.2.4-0010 Basic Requirements
The M1 Mirror will be washed in-situ periodically at a near horizon pointing position. The
mirror surface will be washed using a liquid soap solution and rinsed with distilled water. The
M1 Assembly Specification
SPEC-0007, Revision A Page 34 of 44
M1 Washing Equipment shall include equipment around the lower half of the M1 Mirror to
contain the liquid effluent and prevent its damaging M1 Cell Assembly components. Features in
the design will be provided to verify that no leakage has occurred past any seal during the
washing process.
Verification: Design Review
Requirement Origin: Engineering
1.2.4-0015 Maintainability
M1 Aperture Plate removal or relocation and any M1 Washing Equipment installation required
in preparation for in-situ washing shall be capable of being accomplished within one hour by
four technicians
Verification: Design Review & Inspection
Requirement Origin: Engineering
5.3 M1 LIFTER
5.3.1 Overview
1.2.5-0005 Scope
The M1 Lifter is a steel structure with articulated beams and lifting pads used with a crane to
install and remove the M1 Mirror from the M1 Assembly, coating chamber and wash-cart.
Verification: Design Review
Requirement Origin: Engineering
1.2.5-0010 Basic Requirements
The M1 Lifter shall safely and accurately install the M1 Mirror on the M1 Cell Assembly
supports, coating chamber supports and wash-cart supports. The M1 Lifter shall be capable of
being stored on a horizontal surface while holding the M1 Mirror. During use, stresses within
the M1 Lifter and M1 Mirror shall be within safe limits. The M1 Lifter shall incorporate a cover
to protect the M1 Mirror from falling objects while it is in use.
Verification: Design Review
Requirement Origin: Safety, Engineering
5.3.2 M1 Lifter Functional Requirements & Specifications
1.2.5-0015 Protective Cover
The M1 Lifter shall incorporate a protective cover, shielding the M1 Mirror from damage due to
dropped items weighing up to 1 Kg from heights of 10 meters.
Verification: Design Review, Factory Test
Requirement Origin: Engineering
M1 Assembly Specification
SPEC-0007, Revision A Page 35 of 44
1.2.5-0020 Handling Safety
The M1 Lifter shall incorporate alignment guides that preclude possible damage to the M1
Mirror due to mishandling of the M1 Lifter while being lowered over the M1 Mirror.
Verification: Design Review
Requirement Origin: Safety, Engineering
1.2.5-0025 Storage
The M1 Lifter shall be capable of being stored on the M1 Handling Cart.
Verification: Design Review
Requirement Origin: Engineering
1.2.5-0030 Maintainability
The M1 Lifter shall be capable of being configured into a state ready to lift the M1 Mirror by
three technicians within ten minutes from the time it is lowered onto the M1 Cell Assembly.
Verification: Design Review & Factory Test
Requirement Origin: Engineering
5.3.3 M1 Lifter Performance Requirements & Specifications
1.2.5-0035 M1 Stress Levels
Safety of the M1 substrate is critical to the operation of the M1 Lifter; the design shall include a
mechanism that limits the maximum force that can be applied. No failure, or combination of
failures, shall be allowed that can damage the M1 Mirror or impart a local stress of greater than
0.7 MPa in the M1 Mirror.
Verification: Design Review, Analysis
Requirement Origin: Safety, Engineering
1.2.5-0040 Safety Factors
Safety of the M1 Mirror substrate is critical to the operation of the M1 Support System; the
design shall use a minimum safety factor of 4 for all components. The load rating shall be
stenciled on the M1 Lifter and visible from 10 meters.
Verification: Design Review, Analysis
Requirement Origin: Safety, Engineering
1.2.5-0045 Repeatability
The M1 Lifter shall be capable of reinstallation of the M1, after the repeated lifting operations
required by the coating process, to within an accuracy that allows reconnection to the M1 Cell
Assembly actuators without the need to adjust actuator positions.
Verification: Design Review & Factory Test
Requirement Origin: Engineering
M1 Assembly Specification
SPEC-0007, Revision A Page 36 of 44
5.4 M1 ASSEMBLY HANDLING CART
5.4.1 Overview
1.2.6-0005 Scope
The M1 Assembly Handling Cart is a self propelled steel structure capable of lifting and
transporting the M1 Assembly as needed by integration, coating and maintenance procedures
through the observatory facility.
Verification: Design Review
Requirement Origin: Engineering
1.2.6-0010 Basic Requirements
The M1 Assembly Handling Cart will engage the M1 Assembly at the bottom of the M1 Cell,
lower the M1 Assembly from the telescope, and move the M1 Assembly from the observing
floor to the receiving area within the observatory facility.
Verification: Design Review & Inspection
Requirement Origin: Safety, Engineering
5.4.2 M1 Assembly Handling Cart Functional Requirements & Specifications
1.2.6-0015 Lifting Capacity
The M1 Assembly Handling Cart shall be capable of lifting and lowering the M1 Assembly for
installation and removal from the telescope. The lifting capacity of the M1 Assembly Handling
Cart shall be a minimum of two times its expected nominal load. The raise and lower speed shall
be adjustable between 1 and 5 mm/s.
Verification: Design Review & Factory Test
Requirement Origin: Engineering
1.2.6-0020 Transport Capacity
The M1 Assembly Handling Cart shall be capable of transporting the M1 Assembly up a two
percent grade over an even surface containing concrete expansion joints, 25 mm wide gaps
between floor surfaces and 5 mm height changes in self propelled operation. The transport speed
shall be adjustable between 10 and 100 mm/s in both the forward and reverse directions. The M1
Assembly Handling Cart shall be steer-able with a minimum turning radius of 4 meters measured
at the centerline of the M1 Assembly Handling Cart. The M1 Handling Cart shall utilize wheels
with rubber tires for transport.
Verification: Design Review & Factory Test
Requirement Origin: Engineering
1.2.6-0025 M1 Accessibility
The M1 Assembly Handling Cart shall allow access to all M1 Assembly components for
disassembly and reassembly of the M1 Support System required by the recoating process. All
disassembly and reassembly procedures shall be possible with the M1 Assembly on the M1
Assembly Handling Cart.
M1 Assembly Specification
SPEC-0007, Revision A Page 37 of 44
Verification: Design Review
Requirement Origin: Engineering
1.2.6-0030 Control
The M1 Assembly Handling Cart shall be manually controlled using a hand paddle with a 5
meter cable. Guides that allow precise location of the M1 Assembly Handling Cart with respect
to fixed posts and rails that are installed in the facility floor shall be incorporated in the design
and supplied with the Handling Cart hardware.
Verification: Design Review
Requirement Origin: Engineering
1.2.6-0035 Power Source
The M1 Assembly Handling Cart shall be capable of being connected to the facility power
sources specified in the relevant ICD while traveling between the telescope and transport area.
The M1 Assembly Handling Cart is required to be able to be disconnected from power while
carrying the M1 Assembly to transit in an elevator. Brakes shall be automatically applied in the
event of a power loss.
Verification: Design Review
Requirement Origin: Engineering
5.4.3 M1 Assembly Handling Cart Performance Requirements & Specifications
1.2.6-0035 Seismic Loading and Safety Factors
Safety of the M1 substrate is critical to the operation of the M1 Assembly Handling Cart; the
design shall use a minimum safety factor of 4.0 for all components. The load rating shall be
stenciled on the M1 Assembly Handling Cart and visible from 10 meters.
Verification: Design Review & Analysis
Requirement Origin: Safety, Engineering
5.5 M1 MIRROR SHIPPING CONTAINER SPECIFICATIONS
1.2.1-0055 General
The Vendor shall design, fabricate and deliver a reusable shipping container that is suitable for
safely transporting the M1 Blank and coated M1 Mirror while being subjected to any
combination of the Transportation Conditions listed in Section 2 above.
Verification: Design Review & Inspection
Requirement Origin: Engineering
1.2.1-0060 Envelope
The size of the shipping container shall not exceed an envelope five (5) meters square on a side
and two (2) meters in height.
M1 Assembly Specification
SPEC-0007, Revision A Page 38 of 44
Verification: Design Review & Inspection
Requirement Origin: Engineering
1.2.1-0065 Lifter Compatibility
The design of the shipping container shall allow use of a lifting fixture to remove and install the
M1 Mirror that attaches to the M1 Mirror at six (6) places equally spaced around the outer
diameter of the M1 Mirror as shown in ICD 1.2/6.5.
Verification: Design Review & Inspection
Requirement Origin: Engineering
6. GENERAL REQUIREMENTS
6.1 DESIGN AND ANALYSIS REQUIREMENTS & SPECIFICATIONS
To the extent possible, subsystems that are off the shelf or previously designed, built, and tested
by Contractor or by AURA should be used to minimize cost and to optimize the ability to
maintain and procure spare parts. Design of components should be achieved using the most
efficient and effective manufacturing processes to simplify all components and ensure the lowest
cost and highest reliability without sacrificing performance.
Wherever possible, the M1 Assembly subsystems shall be organized into modules for ease of
mounting/dismounting and servicing. Written instructions for the removal, installation, servicing,
alignment, and adjustment shall be provided by Contractor for all subsystems.
Contractor shall supply all mechanical and electronic hardware associated with each mechanical
system, and shall provide all necessary amplifiers, wiring, utility routing, hangers, cable trays,
and connections to the appropriate control system to operate the systems. Design of all utility
routing shall be subject to approval by AURA.
Unless stated otherwise, all requirements and specifications stated in this General Requirements
& Specifications shall be subject to verification via design review and inspection.
6.1.1 Drawings & Documents Requirements & Specifications
All detail design drawings shall conform to AMSE Y14.5M-2009.
All detail design drawings shall be in System International (metric) units with Imperial (inch)
secondary units shown in parentheses as required. All analyses shall be performed in the System
International system (metric).
All detail design drawings shall be generated in (or transferable to) the latest commercially-
available version of SolidWorks. These drawings, along with printed hard copies, shall be
provided to AURA upon completion of the Work.
M1 Assembly Specification
SPEC-0007, Revision A Page 39 of 44
All computer aided design (CAD) 3d solid models of the M1 ASSEMBLY shall be provided to
AURA in the latest commercially-available version of SolidWorks format upon completion of
the Work.
Four sets of manuals shall be prepared, containing all information related to maintenance and
operation of the pertinent M1 Assembly, so that the information in the Manuals will be adequate
to enable ATST project personnel to perform the full range of expected operating and regular
maintenance functions related to the M1 Assembly without the need to seek information from a
source other than the manuals.
The manuals shall have the maintenance and operating information organized into suitable sets
of manageable size, which shall be bound into individual binders properly identified on both the
front and spine of each binder, which is indexed (thumb-tabbed) and includes pocket folders for
folded sheet information. The Manuals shall also be supplied in electronic form.
Such information shall include, but not limited to, all information related to normal operations
and procedures, emergency operations and procedures, normal maintenance and procedures,
emergency maintenance and procedures, spare parts, warranties, wiring diagrams, inspection
procedures, performance curves, shop drawings, product data, and similar applicable
information. The maintenance tasks to be covered in the Manuals include, but are not limited to:
Removal and reinstallation for recoating the M1 Mirror,
Cleaning and washing of M1 Mirror,
Replacement and calibration of position, pressure or temperature sensor equipment as
well as axial and lateral actuators, and thermal control system components,
Adjustment and tuning of PID parameters for actuator and temperature control loops,
Troubleshooting system failures
6.1.2 Environmental Design Requirements & Specifications
The ATST observatory Site is located at an elevation of approximately 3050 meters (10,000
feet).
Local air pressures will be influenced by the Site altitude and by exposure of the observatory to
local weather conditions. All M1 Assembly subassemblies, parts and components shall be vented
so that changes in pressure when transporting from sea level to the observatory site shall not
cause damage or failure.
Any equipment designed to operate at normal atmospheric air pressures and incorporating air
cooling shall be de-rated for the reduced air density at the Site.
M1 Assembly Specification
SPEC-0007, Revision A Page 40 of 44
There are two separate environmental conditions that shall be used by the Contractor when
performing the Work. These are the Operating Conditions and Survival Conditions. The
following subsections describe these two conditions.
Operating Conditions
The following data represents the range of environmental conditions expected during daytime
hours when the facility will be in use. The M1 Assembly and all of its subsystems shall remain
fully operational throughout the range of conditions indicated.
Operating wind speeds: Up to 5 m/s (11 mph) from any direction.
Operating temperature range: -2 to 22C (28 to 72 F)
Temperature change rate: +/-2 ºC/hr maximum
Operating humidity range: 0 to 70 percent relative humidity
Gravity Orientation 0 to 75 telescope Zenith angle
Survival Conditions
The following data represent the extreme environmental conditions the M1 Assembly must be
able to withstand without damage, and with the ability to return to operation within all
specifications upon return to an Operating Condition. The M1 Assembly shall not be required to
operate in these Survival Conditions.
Survival air temperature range: -10 to 27 C (14 to 81 F)
E-Stop or Seismic acceleration: 2 g in any direction added to nominal conditions
Survival wind speed 0 to 20 m/s from any direction
Survival humidity range: 0 to 95 percent relative humidity
Gravity orientation 0 to 90 telescope Zenith angle
6.1.3 Structural Design Requirements & Specifications
Stresses in all members shall be maintained with safe working values for all possible
combinations of fabrication, erection, operation, and survival conditions. Unless specified
otherwise by AURA, a minimum Factor of Safety of 4.0 under any combination of operational
and environmental loading shall be used during the course of the Work.
Gravity loads, temperature effects, wind effects, and seismic loads shall be combined per an
approved standard when determining the critical cases for maximum stresses and deflections.
All mechanical and electrical components of the telescope are to be selected so as to prevent
their exciting vibration (i.e., resonances) of the telescope in any mode.
6.1.4 Electrical Design Requirements & Specifications
Power to the M1 Assembly shall be provided at each major subsystem location. All
electronic/electrical equipment must have over-current protection (thermal breakers, fuses,
lightening arresters, ground-fault interrupts, surge protection, etc.). Fuses must be easily
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SPEC-0007, Revision A Page 41 of 44
accessible for replacement. All electronic/electrical equipment must have a main line circuit
breaker or power switch, and a controlled light indicator for power status.
All electrical/electronic installations must comply with National Electrical Code where
applicable.
All electronic/electrical equipment in the M1 Assembly must have safety grounds.
The M1 Assembly and its components should minimize electromagnetic interference (EMI) with
scientific instruments and other telescope systems. Emissions and immunity to EMI must be
considered in every part of the M1 Assembly design. Electronic equipment used in the telescope
area must be EMI certified and comply with FCC regulation Part 15, Class B limit for emissions.
For equipment used in the control or computer room, Class A limit is acceptable. All electronic
equipment must be certified IEC 1000-4-2 or better for electrostatic discharge (ESD) immunity
and, IEC 1000-4-3 and IEC 1000-4-6, or better, for radio frequency interference (RFI) immunity.
Immunity to power-line disturbances (IEC 1000-4-9, IEC 1000-4-13), electrical fast transient
(IEC 1000-4-4), and surges (IEC 1000-4-5) is also desired.
All power and signal cables and leads shall be shielded.
Contractor shall define and provide electrical connectors, cabling, and tubing consistent with
high reliability operation and EMC constraints. Connectors shall be capable of being rapidly
disconnected for service of all assemblies of the M1 Assembly. Connectors shall be keyed so that
incorrect connection is not possible. Proper and appropriate strain relief shall be provided to
ensure reliability and to minimize effect of cabling loads on the M1 Assembly. Only high-quality
rough-service connectors may be used.
Power and signal cables should be shielded for low and high frequency interference. Whenever
possible, power and signal wires must be routed separately. The cabling design must avoid
ground loops. Cables and tubing shall be compatible with use with the cable wraps with
acceptable flexibility, size, weight, and life cycles considered. All cables which go through the
cable wrap systems must resist cork-screwing, and be capable of withstanding multiple reverse
bends. The jacketing material must be smooth and friction-free enough to move easily within the
cable wraps, be able to slide easily over neighboring cables, be resistant to oil and abrasion, and
remain flexible at low temperatures. The jacket material should be molded onto the conductors,
eliminating any possibility of the conductors shifting inside the cable.
All utilities shall be strain relieved at all disconnects and end points.
Shielded cables and armored fiber optic cables shall also meet the above requirements. Cables
designated for power must also meet the specifications for voltage and amperage capacities as
per the U.S. National Electric Code.
6.1.5 Thermal Design Requirements & Specifications
It is essential to minimize heat sources on or near the M1 Assembly that could thermally disturb
the air in the optical path.
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SPEC-0007, Revision A Page 42 of 44
Any and all equipment that is cooled shall be designed in such a way that external or internal
condensation does not occur.
6.1.6 Reliability & Lifetime Requirements & Specifications
The design lifetime of the ATST facility shall be 50 years. The objective of the facility is to
allow maximum high-performance telescope usage for the given weather conditions of any day
of the year. The remote nature of the site puts a premium on having robust systems that are
highly reliable and are easily and quickly repaired.
Due consideration of fatigue shall be given to all enclosure structural members and connections
subjected to stress fluctuations over the lifetime of the facility.
Wherever possible, all assemblies, subassemblies, components, parts, and mechanical systems
shall be designed to exceed the lifetime of the facility. Contractor shall identify any and all items
not designed to exceed this lifetime, and their application and use shall be subject to approval by
AURA.
Friction and wear components not expected to provide reliable performance over the design
lifetime shall be easily replaced. Servicing instructions shall include inspections of such
equipment to evaluate conditions on a periodic basis.
6.1.7 Maintenance Requirements & Specifications
The M1 Assembly shall be configured such that all necessary maintenance operations can be
easily carried out without risk to personnel or to the telescope.
The M1 Assembly shall be configured such that all maintenance requirements are minimal. All
maintenance procedures shall be approved by AURA.
6.2 FABRICATION REQUIREMENTS & SPECIFICATIONS
6.2.1 Materials and Workmanship Requirements & Specifications
All materials used in the Work shall be new and of high grade commercial quality. They shall be
sound and free from defects, both internal and external, such as cracks, laminations, inclusions,
blow holes or porosity.
Workmanship shall be of a high grade of commercial practice and adequate to achieve the
accuracies and surface finishes called for on all drawings and in the specifications.
All manufacturing processes, such as plating, welding or heat treatment, shall be specified and
performed in such a manner as to achieve the strength and properties required without
introducing any material defects such as hydrogen embrittlement, excessive grain growth, or
residual stress concentrations.
M1 Assembly Specification
SPEC-0007, Revision A Page 43 of 44
All metal edges shall be free of burrs and sharp corners. No sharp edges that might constitute a
hazard to personnel or equipment (e.g., cabling) shall remain on the finished components.
Materials used by Contractor shall be consistent with all requirements including life cycle,
reliability, and maintainability. Substitution (e.g., to obtain improved performance or reduced
cost) is subject to written approval by AURA.
6.2.2 Stress Relieving Requirements & Specifications
All welds shall be stress relieved after welding and/or prior to final machining.
Shop drawings shall include heat treatment specifications for all parts requiring treatment to
meet the performance and functional specifications required of the M1 Assembly. Temperature-
time charts and records of heating, quenching treatments, material tests, etc., shall be kept and
identified with the parts and submitted to AURA as required for approval.
All welded parts, unless specified or approved otherwise by AURA, shall be fully stress relieved
prior to final machining operations.
6.2.3 Surface Finish, Coatings, and Paint Requirements & Specifications
All exposed machined surfaces, unless specified otherwise, shall have a surface finish of 64-
microinches or better.
Surface finishes are to be approved by AURA as suiting the location and function of each
member. These finishes shall not adversely affect the functioning of the telescope, nor require
additional maintenance during the life of the telescope.
All parts of the telescope shall be finished so as to promote cleanliness of the telescope and to
avoid contamination of any mirror surface or instrument. It is of prime importance that all
protective coatings are of high quality and long life due to the high cost of recoating and the
resulting interference with telescope operation. AURA reserves the right to inspect all surface
preparation for each individual coating prior to application.
All metallic surfaces, other than mating machined surfaces, shall be painted or otherwise
permanently protected against atmospheric corrosion.
All exterior surfaces of the M1 Assembly shall be finished with a highly durable paint or an
equivalent coating approved by AURA applied per Federal Standard 595, color TBD by AURA.
All finishes shall be durable against atmospheric and sun exposure, airborne dust impact,
personnel access on and around the structure, and any other expected wear conditions.
6.3 METROLOGY, INSPECTIONS, & FACTORY TEST REQUIREMENTS & SPECIFICATIONS
All equipment and standards used in acceptance testing shall be calibrated and traceable to
established standards to ensure accuracy and integrity of testing. These tests shall be
M1 Assembly Specification
SPEC-0007, Revision A Page 44 of 44
satisfactorily performed to demonstrate compliance with the stated requirements in this
specification.
Failure to meet all acceptance test requirements to the satisfaction of AURA shall result in
rework or other corrective actions by Contractor until the requirements are met.
The final deliverable cables and hoses shall be used in all acceptance testing at Contractor’s
facility.
6.4 PACKING AND SHIPPING REQUIREMENTS & SPECIFICATIONS
Contractor shall be responsible for all aspects of shipping, including shipping arrangements,
shipping, handling, and storage costs, transportation permits, customs and port of entry fees,
taxes, and all other costs associated with transporting the M1 Assembly components from the
Contractor’s facility to the Site.
All materials and equipment for shipment shall be prepared in such a manner as to protect them
from damage in transit and storage. Special care shall be taken with electrical and electronic
components, which shall be packed with a dehumidifying agent to effectively deal with
condensation.
Proper identification of parts and adequate provision for slinging and handling of equipment
without damage shall be made.
All packaging, packing materials, slinging, and handling equipment design shall be approved by
AURA.
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