5 Space Technology “Paving the Way for Future Micro-Satellite Missions” 1 NASA’s Space Technology 5 Mission NSF workshop on Small Satellite Missions for Space Weather and Atmospheric Research J.A. Slavin NASA GSFC May , 2007

2 Pathfinder for Magnetospheric Constellation

3 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.

4 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 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

5 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 (30 o C, 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

6 ST5 Mission Profile Launched March 22, 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 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"

7 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

8 ST-5 Field-aligned Current Observations “Slow” “Typical” “Rapid” Rate of Field-Aligned Current Sheet Change (10 s – 10 min)

9 ST5 Observations of Magnetization of Earth’s Crust – 2/2 First Micro-spacecraft Gradiometer Measurements Green: SC094 Observations Red: Comprehensive model (CM4) Model Prediction Along-Track Gradient of the Crustal Magnetic Field 2006 Day 091 Start UT: 0200

10 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%

11 Summary Remarks Space 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)

12 Technology Transfer Space Technology 5 Technology Symposium was held on September 13, 2006 (CD Proceedings is ITAR Controlled – please contact Candace Carlisle 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.

13 Thank You!