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 8699mccoyr@onr.navy.mil 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, chapmanj@pxi.com

Contact