development, deployment, test & operation of a constellation of microsatellites or payloads for,...
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Development, Deployment, Test & Operation of a Constellation of
Microsatellites or Payloads for,
Two-way Communication with,
A Variety of Sensors Deployed Near or Below Surface of the Ocean
Unattended Ground Sensors
SonobuoyField
InternationalSpace Station
TacSat-X
Host Spacecraft
P-3 ASW
UAV
Space Segment for Global Autonomous Sensors
Bob McCoy ONR Code 321SP
703 696 [email protected] Ocean Data Telemetry MicroSat Link (ODTML)
Distributed Arrays of Small Instruments (DASI)Workshop 8 June 2004
Argo Profiling Floats
Operational Characteristics Surface to 2,000 m Salinity, Temperature and Pressure Argos DCS Constraints:
Repeat Transmission every 60 to 72 seconds, 10-12 hours every 10 days
Normally around 50 pressure levels (range 33 to 115)
Data 348 to 464 bytes (12 to 16 Argos messages)
$1.2 M “value-added” processing Future Requirements
On Demand transmission 500 pressure levels (4 Kb) within one hour with reduced power demands for communications
Two-way communications (not necessarily on demand) for programming $100-150K Target data telemetry cost
Over 3000 aircraft provide reports of pressure, winds and temperature during flight.
Data Assimilation for Meteorological Forecast
Argos Data Collection System (DCS) Argos Data Collection System (DCS) in the NPOESS Erain the NPOESS Era
Iridium, GlobalStar & ORBCOMM
Existing ground-to-space/ground networking (Orbcomm, Iridium) were developed for voice and data, and rely heavily on fixed infrastructure, and power-intensive transmissions at VHF frequencies
ORBCOMM/Iridium are good for large littoral buoys where transmit power is not an issue and where L-Band attenuation (wave shadowing or microorganism growth) is not an issue
Current market (~20M/yr) is sufficient to sustain current systems but is insufficient to replenish the satellite constellation
Industry focus is not on low data-rate (<10,000 b/s) customers
Existing systems are not IP-like and require extensive groundstations and satellite monitoring
Operational Expense & Operations over the ocean
Ocean Data TelemetryMicroSat Communications Relay System
• Global Data Communications “On the Move”
– Small, Mobile and Disadvantaged Platform Transceiver Terminals (PTTs)
– Laptop Computers/Transceivers
• Availability
– Robust RF Links – In Water and Under Cover
• Capacity
– Many Users in the Field
• Service
– Simultaneous Data Nets
• Assured Access
– Acknowledgement That Messages Got Through
• Interoperability
– Seamless Connectivity to Other Systems
A Global Communications System Providing
Near Real-Time Situational Awareness
Is Essentialfor the Next Generation
Ocean Observing System
Microsatellite Constellation Goals
• Demonstrate 2-Way communication with small disadvantaged sensors anywhere in the world– UHF transmission compatible with Service ARGOS, But with the
following enhancements:- Significantly higher bandwidth (4800 b/s vs <256 b/s)- 2-Way delay-tolerant communication - “IP-like” message packaging- New protocol for increased battery life & Non-GPS geolocation- Method to provide acknowledgement that command sequences were
received (ACK/NACK)- Increased signal-to-noise at the host satellite via coding, a bi-
directional software radio, similar to e-mail to forward messages to user/sensor with defined addressing schemes
- Enhanced computer speed & storage for on-board data processing- System architecture allows evolution and expansion for future
sensors - System capable of being deployed as a mix secondary payloads
aboard host space vehicles (e.g. International Space Station, DMSP, TACSAT) or low-cost micro-satellites e.g., STP (Navy PG or USNA).
Multiple Access With Collision Avoidanceby Invitation (MACA-BI) Network Protocol
GeoLocation Determination via Doppler Shift
• Spacecraft (S/C) Avionics Measure Doppler Shift on Uplink Carrier Frequency As S/C Approaches and Moves Away From Location of PTT
• At Point of Inflection of Doppler Curve (i.e., Rx vs. Tx Frequencies Are Equal), PTT Position Is Perpendicular to S/C Ground Track
– Slope of Curve at Inflection Point Determines Distance From PTT to S/C Ground Track
• Location Errors of ~125m to 3000m (i.e, PTT Local Oscillator Stability, Number of Samples, and S/C Ephemeris Errors)
Doppler Shift Metrology
Sources of Location
• Location Errors Are Greatest When PTT Is ~170 km of the S/C Ground Track or More Than 2,700 km From S/C Ground Track
• Other Factors:
– PTT Oscillator Stability – Mean PTT Short Term Frequency Stability <4x10E-5 (20 Minutes)
– Mean PTT Frequency Must Not Vary > 24 Hz Between Multiple Passes (Two Overpasses)
– PTT Altitude Creates Errors Due to Changes in Assumed Altitude (Sea Level)
- Coupled in the “Across-Track” Coordinate of the Fix With Little Effect on the “Along-Track” Coordinates
Spacecraft Requirements
• Location Determination Requires Ephemeris Within 300m (“Along-Track”) and 250m (“Across-Track”)
• Location Determination Requires >5 Doppler Measurements w/ >420 sec Interval Between First and Last Measurements w/ 240 sec Separation (Minimum Accuracy)
ODTML Key Performance Parameters Data Exfiltration, All Floats Floats to be serviced 3,000 Global float population (assumed) In view 600 Assume 20% in view per 24-hour day Data per float per SBIR announcement 50,000 bits per day total, daily float data collected 30.0 Mbits # in-view orbits per day (single satellite) 13.0 Single grd station, high latitude, LEO Total, downlinked data bits per in-view pass 2.3 Mbits
Data Exfiltration, Single Satellite Total data bits per orbit w/ single grd station 2.3 Mbits Data overhead @ 15% 0.3 Mbits Total, data downlink per pass 2.7 Mbits Data encoding (symbol rate) 5.3 Assumed factor of two (K=7, R=1/2) Downlink time (1/2 of mid-latitude pass) 180.0 sec Downlink rate 29.5 kbit/sec
Data Exfiltration from Single Float Data per float 50,000 bits per day Data overhead @ 15% 7,500 bits per day Total, data per float 57,500 bits per day Data encoding (symbol rate) 115,000 Assumed factor of two (K=7, R=1/2) Data exfiltration rate 4,800 b/sec Data exfiltration time 24 sec XMT power out 0.50 watt Total XMT power (eff = 15%) 3.33 watts XMT power consumed 80 watt-seconds (joule) Joules per data bit 0.0014 < 0.1 Joule/bit (rqmt from SBIR N02-062)
Communications RelayPayload Breadboard
DC-DC Converters3.3V, 5V, ±12V 24VDC Input
Motor Drive Interfaces(0 Populated)
Linear Regulators2.5V, ±5V Analog
Expansion Interface(0 Populated)
Expansion Interfaces0 Populated)
ExpansionInterface
(0 Populated) RS232 Interface RS422 Interface
LVDS Interface
EEPROM
PROM
XILINXVirtex400 FPGA
Local SRAM
Shared SRAM
Configurator1553 InterfaceDiscrete I/O
ExpansionInterface
MCU RS232
Actel54SXnn FPGA
ODTML MicroSat Configuration
Simple Design and Interfaces Enable Ease of
Development and Integration
Payload Minimum Resources Available:
• ~25 Watts Orbital Average Power (OAP) - Basic
• ~5 kg Mass (Basic)
• 0.3m x 0.75m x 0.8m Size
• 350 b/s Average Payload Stored Data + 100 b/s Payload Housekeeping Stored Data
Thermally Stable With Constant Dark
and Sun Sides
ODTML Payload Provides
Uplink/Downlink Communications
Body Mounted GaAs Solar Arrays:
• Allows Common Satellite Design for All Orbit Planes
• Minimizes Body Drag Perturbations on Gravity Gradient (G-G) Stabilizing Torques
• Improves Reliability
• Reduces Cost and Simplifies Integration
Communications Relay Transceiver
Communications Relay Processor
Hydrazine Propulsion System
Magnetic Torque Rods
Three Axis Magnetometer
Spacecraft Avionics (Includes 3 Micro Gyros)
Lithium Ion Battery
Spacecraft Structure
Heritage LightBand Separation
Low Cost Communications GatewayUses Same Electronics Suite As Buoy
System Characteristics
• UHF Eggbeater Antenna
– Omni-Directional
– Circular Polarization (RHCP)
• Communications Relay Payload Repackaged for Ground Environment Plus High Power Amplifier (HPA)
• Laptop Interface (Portable Ops) OR PC-Based Mail Server and Remote Intelligent Monitoring System (RIMS) for Fixed Gateway
Potential Launch Opportunities
Low-cost launch opportunities:
• Alternate Launch Vehicles
– EELV Secondary Launch
- 4 tons excess for each DMSP
launch
– SpaceEx Falcon - TacSat follow-on
• University MicroSat Designs
– CubeSat
– ASTRID/MUNIN
– USNA PC Sat
Cubesat
EELV
SpaceEx Falcon
CubeSat
ChipSat
MUNIN
PC Sat
TacSat-1 Program ElementsNavy Highlights
• GROUND STATION: Blossom Point MD
– Navy Facility
– With VMOC (Virtual Mission Operations Center) for SIPRNET Tasking & Data Dissemination
• MICROSATELLITE:
– 1 yr Life, 110kg, 186W
– 40in dia. x 20in high
– 500km, 64º inc.
• AIRCRAFT:
– EP-3’s: 1 Fixed & 3 Mobile RORO Units; Also RJ’s (TBD #) Expected
– Implementing an Naval, ONR Cross-Mission CONOP
• LAUNCH VEHICLE: Falcon by SpaceX– New, Privately Developed– LOX-RP1 gives ~1000 lb to 500km– 60klb, 70ft by 5.5ft dia.– Navy Contract• PAYLOADS:
– CopperField-2S: Navy TENCAP
– SEI: NRL/ONR? Developed
– Visible & IR Cameras (Army NVL)
$12M
$3M
• IR Camera & UHF Radio
• SEI Hermetically Sealed Chassis (CuF-2S is Similar)
• Rubidium Clock & Low Cost Receivers (0.5-18GHz Range Used)
TacSat-1 Spacecraft Components
• Specific Emitter Identification (UYX-4) & Copperfield-2S Payload Hardware
• Spacecraft Bus & EAGE Hardware
CURRENT Technology by COMPUTER INDUSTRY
STANDARDS(3 Million Gate FPGA)
Receivers
Clock
UYX-4
Fans2 Places
IR Camera Does NOT Require Cryo-Cooling
Program Plan
• Build satellite/aircraft payload and test via aircraft flight(s) (2005)
• Orbital test using existing orbital UHF satellite (2005)
– (10kg NanoSat; half duplex mode – SpaceQuest)
• Deliver satellite payload on International Space Station (2006)
– 57º Inclination (via Space Test Program)
• Launch polar payload/satellite (2007) on TacSat-n, DMSP or STP payload of opportunity
• Test ocean to space system with realistic RF & ocean environment
– Communication links with actual Doppler
– Distance fading
– Actual environment (shadow fading - wave height)
– Operate autonomously, unattended
6-8 Hrs Revisit time
Sp
InternationalSpace Station
Tac-Sat n
Near Term2 Planes
Ultimate goal6 Satellites in 3 Planes
2.5 Hr revisit
Operational CapabilityConcept of Operation
Ocean Data Telemetry MicroSat Link (ODTML)
• Communications Relay Payload to Support an Integrated Global Ocean Observing System via MicroSat or Host Platform
• Data Infiltration and Exfiltration for Small, Mobile, and Low-Power Ocean Buoys and Sensor Transceiver Nodes
• Two-Way, Delay-Tolerant, “Internet-Like” Messaging Services on Global or Theater Basis
• Allows Users to Send Commands and Receive Telemetry From Autonomous Buoys or Distributed Sensor Nodes
• Decouples Nodes From Space Segment Allowing Evolutionary Upgrades or Expansion of Capabilities
• Higher Bandwidth, Lower Power Than Existing Service Argos> 50 Kilobits Per Node Per Day< 0.1 Joule Per Bit Transmitted
Two-Way Global Communication to ProvideNear Real-Time Awareness Is Essential
for Next Generation Ocean Observing Systems
• Phase I – Lab Demonstration Completed• Phase II – Non-Flight Engineering Unit (6/04 ONR SBIR Funds)
6/04 – 6/06 System, H/W & S/W Designs/Demos 1/06 – 12/06 Engineering Unit Build, Integration & Test1/07 – 3/07 Field Demonstrations
• Requesting Official: Dr. C. Luther, ONR, 703-696-4123• Phase II Sponsor: Dr. R. McCoy, ONR, 703-696-8699
• ONR Small Business Innovation Research (SBIR) Topic N02-062 (ODTML)
• DOD Space Exp Review Board (SERB) ONR-0301 (Ranked Experiment)
• Global Data Collection System Architecture via “Ad-Hoc Wireless Networking” and “Instant Messaging”
• “Router in the Sky” via MicroSat or Aircraft Host
Technical Approach
Enabling Technology• Flight-Proven FPGAs, Router and Cellphone
Concepts, and Low-Cost On-Orbit Commercial MicroSats (Spacequest / Aprize, Ltd)
Schedule & Budget
Praxis, Inc., 2200 Mill Road, Alexandria, VA 22314Mr. R. Jack Chapman, Principal Investigator703-837-8400, [email protected]
Contact