SPHERES

Payload Systems Inc

ISS Flight Preparation & Hardware Status

08 July 2002

Steve Sell (sell@payload.com)

Stephanie Chen (chen@payload.com)

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Agenda

• Payload Systems activities

• Mission description and logistics

• Integration activities

• Hardware build status

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Payload Systems Activities

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Payload Systems Activities

• Design and construct SPHERES flight hardware– Spheres– Beacons– Laptop hardware

• Conduct NASA International Space Station integration activities– Safety review process– Develop experiment procedures– Conduct crew training– Create Graphical User Interface (GUI)– Conduct training of ISS crews

• Conduct hardware analyses and testing– Safety verification analysis– Flight certification testing

• Vibration• EMI acoustic

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Mission Description and Logistics

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Major Components

SPHERES Satellites

Laptop Assembly

Ultrasound Beacon

(5 Total)

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Hardware Components

• SPHERES consists of three “satellites”, eight inches in diameter

– Each satellite is self-contained with power (AA batteries), propulsion (CO2 gas), computers, and navigation equipment

– The satellites communicate with each other and an ISS laptop through a low-power wireless (RF) link

• Five ultrasound beacons located in the SPHERES work envelope act as a navigation system

– Each beacon is self-contained and uses two AA batteries

– A single beacon is approximately the size of a pager

– Operational volume is 6’ x 6’ x 6’ (up to 10’ x 10’ x 10’ is possible)

PADS beacon

Satellite

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SPHERES Satellite

+ Z

- Y

- XUltrasonic receivers

CO2 tank

Adjustable regulator

Pressure gauge

Thruster

Satellite body axes

Diameter 8 in (0.2 m)

Mass 7.85 lb (3.56 kg)

Thrust(single thruster)

<1 oz (0.2 N)

CO2 Capacity 6 oz (170g)

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Operational Configurations

• Mode 1: Single satellite operations– Long term station-keeping– Minimum propellant maneuvers

through pre-determined profiles• Isolated multidimensional rotation,

multidimensional translation• Combined rotation & translation

• Modes 2 and 3: Multiple satellite operations (two or three satellites)– Docking– Topological orientations

• Independent control• Collision avoidance• Hierarchical control (leader-follower)• Distributed control (consensus)

Example configurations on the KC-135

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Satellites perform formation flying maneuver

Uplink protocols to OPS LAN prior to SPHERES ops

Each satellite calculates position from PADS

beacons

Appropriate thrusters fire

Transfer protocol/commandsvia wireless link to satellites

Data continuously downloaded to laptop

Downlink experiment data to ground after SPHERES ops

Control loop

ISS Laptop

ISS Laptop

Typical Test Session

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Typical Crew Operations

Load tanks & battery packs

into satellites

Upload protocols from laptop to

satellites

Run protocols from laptop

Unstow equipment

Satellites out of gas / power?

Setup test area(position US beacons)

NO

YESTest session over?

YES

NO

Take down and stow equipment

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SPHERES GUI (Sample)

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Mission Logistics

• SPHERES manifested on ISS for two increments– Ascent flight ISS-12A.1 (STS-116, June 2003), – Resupply flight ISS-13A (STS-117, September 2003) for replacement of

consumables– Descent flight ISS-15A (STS-119, January 2004)

• Operation Time– Allocated 20 hours operation time (nominally spread over twelve sessions)

• Initial stowage requirements– Three SPHERES satellites– Five US beacons– Laptop transmitter– Consumables (CO2 tanks and battery packs)– Spares TBD

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Stowage Allocation

• SPHERES is allotted 1.83 Middeck Locker Equivalents (MLEs) over ascent and resupply flights– 1.5 MLE total on ascent flight– 0.33 MLE total on one resupply flight

• Stowage allocated in Cargo Transfer Bags in the SpaceHab Module– Possible to be stowed in any locker location

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Consumables

• Two approaches were taken to determine consumable estimates: top-down (fixed stowage constraint) and bottom-up (fixed operation hours)

• CO2 tanks– Part of the SPHERES mission investigates

ways to minimize propellant usage– This means that no exact number of tanks

can be determined for total operations– Initial estimate is 94 tanks

• Batteries– Current estimate is 88 battery packs

Replacement CO2 tanks and battery packs

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ISS Equipment

• Workstation

– SPHERES will use Payload Equipment Restraint System (PERS) as a temporary workstation

– H-Strap interfaces with seat track provide two sides of velcro

• Attach laptop restraint for configurable laptop station

• Belly bag can be used to contain extra hardware (satellites) during test session

H-StrapLaptop Restraint Belly Bag

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ISS Lapto

p

Handrail clamp

ISS Equipment

• Laptop– SPHERES GUI runs protocols from

laptop • Protocols uplinked to OPS LAN but no

connection is required during testing

– Data stored on laptop until downlinked to ground following test session

• US beacons will attach to seat-track interfaces and/or handrail clamps– Locations will be entered into laptop prior

to operations

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Operational Scenarios

Envisioned operations in ISS Node 1 Envisioned operations in US Lab

• SPHERES will operate in United States Operational Segments (USOS) only

• Ideal test area is 6’ x 6’ x 6’– Most likely will operate in 5’ x 5’ x 10’, given ISS Node configuration

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Integration Activities

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Integration Status & Milestones

• Status– Completed Phase II Safety Review Feb 2002

– Payload Integration Agreement baselined June 2002

– Preliminary draft of crew procedures submitted June 2002

– First test of positioning system in ISS node mockup conducted June 2002

• Upcoming milestones– KC test of engineering Sphere scheduled July 2002

– October 2002 – EMI and Vibe testing

– November 2002 – Payload Training Dry Run

– November 14, 2002 – Phase III Safety Review

– December 2002 – Training Session 1

– January 31, 2003 – Flight hardware delivery to JSC

– June 5, 2003 – Launch on STS-116, 12A.1 to ISS

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Hardware Build Status

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Flight Hardware Status

• First unit build is 95% complete: all components are in-house– All structural components completed and assembled– All avionics components completed and assembled– All pressurized components installed– Not all tubing and wiring has been routed– Shell is prototype

• Anticipated 100% complete build in 1-2 weeks

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Structural Frame

• Aluminum structure – Six laser cut rings– Six sheet metal

brackets – Twelve cross members– Provides stiffness and

mounting points for satellite components

Laser cut rings

Cross members

Metal bracket

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Structure

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Electronics Board Locations

• Electronics are divided into two assemblies– PADS and computing

• Signal processing

• Computing

– Propulsion and power• Thruster valve control

• Power distribution

PADS and computation boards

Propulsion and power boards

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Assembly - Avionics

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Structural Assembly Stage One

• Electronics assemblies– Electronics are assembled inside a partial structure and wired– Avionics can be tested on the bench top

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Structural Assembly Stage One

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Structural Assembly Stage Two

• Remaining sheet metal brackets are attached– Battery packs and regulator/tank assembly can then be

installed

Mounting brackets

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Structural Assembly Stage Two

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Structural Assembly Stage Three

• Propulsion system tubing is routed– Tubing is assembled prior to final structural element placing

– Manifolds distribute gas from CO2 tank to twelve thruster nozzles

Tubing manifolds Thrusters

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Structural Assembly Stage Three

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Full Assembly• Satellite is fully functional without shell

Aluminum frame

CO2 tank

Thruster

Pressure gauge

Battery pack

Ultrasonic receiver

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Full Assembly

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External Shell Structure

• Two part shell assembly– Constructed of polycarbonate

– Secured with four fasteners per side– Hinged door for battery access– Cut-outs for thrusters and sensors

Attachmentscrew

Polycarbonate half shell

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Schedule Milestones

• July 29 - August 3, 2002 – KC-135 Flights

• October 2002 – EMI and Vibe testing

• November 2002 – Payload Training Dry Run

• November 14, 2002 – Phase III Safety Review

• December 2002 – Training Session 1

• January 31, 2003 – Flight hardware delivery to JSC

• June 5, 2003 – Launch on STS-116, 12A.1 to ISS