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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
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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
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Over 3000 aircraft provide reports of pressure, winds and temperature during flight.
Data Assimilation for Meteorological Forecast
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Argos Data Collection System (DCS) Argos Data Collection System (DCS) in the NPOESS Erain the NPOESS Era
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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
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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
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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).
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Multiple Access With Collision Avoidanceby Invitation (MACA-BI) Network Protocol
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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)
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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)
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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
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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
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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
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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
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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
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• 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
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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
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6-8 Hrs Revisit time
Sp
InternationalSpace Station
Tac-Sat n
Near Term2 Planes
Ultimate goal6 Satellites in 3 Planes
2.5 Hr revisit
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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