1. The Drag and Atmospheric Neutral Density Explorer (DANDE) Body Mounted Solar Arrays for a Low Cost Nanosatellite Kyle D. Kemble Colorado Space Grant Annual Research Symposium April 17, 2010 Boulder, Colorado

2. 2 March 21, 2016 The University Nanosat Program University Nanosat – The National Championships of Spacecraft Design – 2 year program now in its sixth iteration –Competition to build satellites –10 out of 30 university proposals selected based on Air Force Relevance –UN5 WINNER: January 2009, Flight to Orbit Additional funding I&T at Kirtland AFB CU Nanosat Entry –Has involved a core team of more than 60 graduate and undergraduate students SERB –Received ranking for 2009 Round!

3. 3 March 21, 2016 Introduction to DANDE Mission Statement Explore the spatial and temporal variability of the neutral thermosphere at altitudes of 350 - 200 km, and investigate how wind and density variability translate to drag forces on satellites. D RAG and A TMOSPHERIC N EUTRAL D ENSITY E XPLORER

4. 4 March 21, 2016 Satellite Drag Satellite drag measurements suffer from errors caused by Unknown acceleration contribution from in- track winds coefficient of drag accuracy DANDE is designed to address these issues and provide acceleration, composition, and wind measurements simultaneously along with a well determined drag coefficient at ~350 km CHAllenging Minisatellite Payload Starshine I

5. 5 March 21, 2016 Operational Importance of Drag The density of the atmosphere in this region varies greatly (300% to 800%*) due to space weather and not yet understood coupled processes. * Forbes et. Al. “Thermosphere density response to the 20-21 November 2003 solar and geomagnetic storm from CHAMP and GRACE accelerometer data”, Journal of Geophysical Research, Vol. 111, June 2006 410 km 390 km 370 km 350 km 330 km 1999 20002001 reboost decay X5 flare 7/14/2000 ISS drops 10km in several days E. Semones et.al. WRMISS 10 http://www.oma.be/WRMISS/workshops/tenth/pdf/ex02_semones.pdf

6. 6 March 21, 2016 Dual Instrument Approach Accelerometer Subsystem As the spacecraft rotates, it modulates the drag signal to a known frequency. The unique accelerometer subsystem takes advantage of this by filtering the noise from unwanted frequencies and processing the data onboard from all accelerometers. This provides the sub-μg precision required for drag measurements. Wind and Temperature Spectrometer This instrument was invented by Dr. Fred Herrero at NASA Goddard and implemented for the DANDE platform by students at CU with NASA support. It is capable of measuring the wind direction and magnitude, atmospheric temperature, as well as the O:N 2 ratio. 1/3 Hz drag signal Frequency [Hz] Measured Energy Spectrum

7. 7 March 21, 2016 How Measurements are Made Identifying all components of the constituents of the drag equation. With a near-spherical shape, an a-priori physical drag coefficient may be calculated and a physical density can be obtained from the measurements atmosphere ρ - density V A FDFD CDCD VWVW accelerometers WTS sensor a priori knowledge tracking a priori knowledge a priori knowledge comparison solution measured a priori solution solved

8. 8 March 21, 2016 DANDE Project Benefits “I am interested in studying the many areas of density variations which we currently have little or no knowledge about... ” -Bruce Bowman Air Force Space Command DANDE will measure density, composition, and wind along its orbit : : as DANDE

9. 9 March 21, 2016 Inside of DANDE Battery Box (x2) Mass Trim System (x8) 3-axis Magnetometer Wind & Temperature Spectrometer EGSE connector Stiffeners (x4) Lightband Adapter Bracket Ball & Tube Nutation Dampener (x2) Subsystem Boxes (CDH,COM,EPS) Horizon Crossing Indicator (x2) Solar Panel (x96) Accelerometers (x6) Separation Mechanism(x2) Kinematic Mounts (x4) Receive Patch Antenna Whip Transmit Antenna (x2) Torque Rods (x2)

10. 10 March 21, 2016 Electrical Design + Contact Ge Substrate Bottom Cell: Ge Tunnel Junction Middle Cell: GaAs Tunnel Junction Top Cell: GaInP 2 - ContactQuartz 0.3μm to 1.8μm Triple Junction Cells – 3 Peak Wavelengths –Operates at a higher efficiency compared to cheaper silicon Design Environment: Terrestrial –No expensive radiation hardened coating

11. 11 March 21, 2016 Electrical Design Panel: 8 Cell Strings –20V Open Circuit –Too low of a current for proper operation Array: 116 Strings –20V Open Circuit –1.4A Short Circuit (Half of the Array illuminated) Ground Testing –Max on Orbit Power 25W

12. 12 March 21, 2016 Structural Design Panel Assembly –Solar Cell, Solder, Epoxy, PCB –Mechanical & Electrical Connection Mounting Scheme –Delrin Substrate –Modular

13. 13 March 21, 2016 Structural Design Ball Aerospace Qual Vibe Test –Solar Panel Simulator Present –Spin Cast Hemispheres –Solar Cells mounted to CubeSat

14. 14 March 21, 2016 Thermal Design Orbit Envelope Determination –Minimum Science Requirements –Communications Limitations –Component Limitations –Radiation Environment

15. 15 March 21, 2016 Thermal Design Maximum Temperature: 54’C –Voltage Drop 50% Solar Panel Considerations: –CTE Mis-match –Power Output

16. 16 March 21, 2016 D rag and A tmospheric N eutral D ensity E xplorer Colorado Space Grant Consortium & CU Aerospace Engineering Sciences