5Space Technology

“Paving the Way for Future Micro-Satellite Missions”

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NASA’s Space Technology 5 Mission

NSF workshop on Small Satellite Missions for Space Weather and Atmospheric Research

J.A. SlavinNASA GSFCMay 15 -17, 2007

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Pathfinder for Magnetospheric Constellation

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ST5 Mission Overview• NASA New Millennium Program mission to flight-

validate new concepts and technologies

• Design and build 25 kg spacecraft:

- Design, develop, integrate, test and operate three full service spacecraft, through the use of breakthrough technologies and provide a roadmap (written report). Integrate and validate technologies.

• Research-quality spacecraft:

- Demonstrate the ability to achieve accurate, research-quality scientific measurements utilizing a constellation of 3 micro-satellites.

• Constellation Operations:

- Execute the design, development, test and operation of multiple spacecraft to act as a single constellation rather than as individual elements.

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ST-5 Spacecraft• Developed by GSFC in-house• Description

- 3 spin-stabilized (~20 rpm) micro-spacecraft- Mass 25 kg (each)- ~50 cm x 48 cm 8-sided spacecraft- Integral card cage structure (for C&DH, PSE)- Cold Gas Propulsion (10 m/s)- Intended to fly as “secondary” to GTO- Launched on Pegasus to 300 x 4500 km (105.6 deg)

• Key performance parameters- Spin axis knowledge – 0.2 deg; Control - 0.5 deg- 25 W Triple Junction Solar Array (29% Efficiency)- 5 V bus with new generation Lithium Ion Battery- X-band up/down 1 – 100 kbps- Onboard science event triggers and data storage- Magnetically Clean S/C (< 1 nT achieved)- Radiation Qualified to 100 krad

• Science & Operations demonstration- Research-grade miniature flux-gate magnetometer (UCLA)- “Lights-Out” totally autonomous operations for several weeks

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Micro-Thruster

CULPRiT

Transponder

Variable Emittance Coatings

Low Voltage Power System

ST5 New Millennium Program Technologies• Power System incorporating a Lithium-Ion Battery and

triple-junction solar cells: Provide s/c power- Battery effective Capacity = 7.5A-h

(to 6Vdc C/2 discharge)

- Solar array beginning of Life Electrical output per panel (30oC, 1 Sun Air-Mass Zero): load voltage = 10.2Vdc, current = 1.16 amps

• Microthruster: Used for attitude maintenance and Delta-V maneuvers to constellation formations

- Can be operated in pulse and continuous fire modes

- Specific impulse greater than 60 sec.

- Thrust greater than 2.1 N at 2000 psi, and greater than 0.1 N at 100 psi.

• X-Band Transponder: Provides coherent uplink and downlink

- Uplink rate 1 kbps; Downlink rate 1 kbps and 100 kbps.

- Average bit error rate (BER) of less than 1x10-5 for each downlink pass.

• Complimentary Metal Oxide Semiconductor, Ultra Low Power Logic (CULPRiT): Low-voltage CMOS technology

- Radiation and latch-up tolerant

- Used as Reed Solomon encoder

- Operating voltage of 0.5V

• Variable Emittance Thermal Coatings: Thermal control demonstration

- Range of emissivity variation 0.4 to 0.6

• Software Tools for Autonomous Ground Operations: Perform model-based constellation health and safety management and provide efficient constellation management with a high degree of automation.

Autonomous Operations

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ST5 Mission Profile• Launched March 22, 2006

- Pegasus out of Vandenberg

- Approximately 10 min after launch, ejected 3 min apart Frisbee-style

• Mission Duration: 90 days

- 7 day launch & early orbit period

- Mission completed June 20, 2006

• Orbit

- 105.6 deg inclination (full sun orbit)

- ~ 300 km perigee; ~ 4500 km apogee

- 136 minute period

• Communications: Deep Space Network, McMurdo Ground Station

• Constellation Configuration: "String of Pearls"

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Research-quality Science Demonstration

• ST5 validated the constellation concept by the measurement of important physical parameters that cannot be determined by single spacecraft

• Formation fly in pre-determined configuration over the Earth’s northern and southern auroral zones (position uncertainty < 1 km)

• Returned research-grade magnetometer measurements from a suitable platform

• Measured auroral current sheet motion and thickness, electric current density, and temporal stability using the ST-5 constellation data

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ST-5 Field-aligned Current Observations

“Slow” “Typical” “Rapid”

Rate of Field-Aligned Current Sheet Change (10 s – 10 min)

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ST5 Observations of Magnetization of Earth’s Crust – 2/2

First Micro-spacecraft Gradiometer MeasurementsGreen: SC094 Observations

Red: Comprehensive model (CM4) Model Prediction

Along-Track Gradient of the Crustal Magnetic Field

2006 Day 091Start UT: 0200

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ST5 Autonomous Operations

• Data Return Statistics

- Overall data return rate: 94.13% (94.44% ENG data, 91.93% MAG data)

• SC094: 91.74%

• SC155: 93.68%

• SC224: 94.13%

- Data return rate during AUTO OPS demonstration week: 81.31% (86.40% ENG, 76.22% MAG)

• SC094: 73.67%

• SC155: 84.34%

• SC224: 84.54%

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Summary RemarksSpace Technology 5 demonstrated the functionality of

micro-satellites for Space Weather applications.

Technical Highlights:

• Autonomous Operations Test (> 80% data recovery)

• Power Systems – 5 Volt bus

• CULPRIT Low Voltage Rad Hard Reed-Solomon Encoder

• Miniature X-Band Transponder (1 – 100 kbps)

• Propulsion (10 m/s)

• LEO Magnetic Fields Science Validation

Primary Disappointment:

• Could not obtain a secondary launch from any source within our 2 year launch window (except Ariane)

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Technology Transfer

• Space Technology 5 Technology Symposium was held on September 13, 2006 (CD Proceedings is ITAR Controlled – please contact Candace Carlisle [candace.carlisle@nasa.gov] for more information; see also nmp.nasa.gov).

• Space Technology 5 open literature articles can be found in major Aerospace Journals and Meetings Proceedings.

• Preparations are underway for Special ST-5 Section of Geophysical Research Letters.

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Thank You!