COMM Subgroup Tomo Sugano (Primarily served as COMM personnel) Tasks –Started out by helping Relative Orbit team with differential delta-V requirement and GN2 mass –Communication Scheme of the mission –System Integration (on-board flight computer) Tomo Sugano (1/15)

Differential Drag Compensation Ballistic coefficients different between satellite and shuttle Difference in drag forces (i.e. acceleration) exists. (B-Coeff. of Shuttle) >> (B-Coeff. of Satellite) Satellite must expend Delta-V to keep up with space shuttle. Tomo Sugano (2/15)

Computations Atmospheric drag acceleration (Da): Drag acceleration difference between the two spacecraft: STS: S = 64.1 m 2, C D = 2.0, m = 104,000 kg (orbiter typical) Sat: S = m 2 (nominal), C D = 3.0 (worst case), m = 50 kg Tomo Sugano (3/15)

Computations (cont’d) Orbiter speed (assuming circular orbit) Definition of Delta-V (or specific impulse) Mass expenditure of propellant (i.e. GN2 cold gas) Tomo Sugano (4/15)

Results Using I sp = 65 sec; assume 50 kg for satellite weight Conclusions - At the typical 300 km LEO, Delta-V for 1 day mission is 1.36 m/s - Satellite will need at least 107 grams of GN2 to compensate drag - In addition to this Delta-V, we have orbit transfer Delta-V and ADCS Delta-V.  How we determined tank size. Tomo Sugano (5/18)

COMM: Overview Receive data from the space shuttle Transmit data to the space shuttle Satellite Computer Tx Rx Wireless LAN Transceiver Satellite Satellite must be able to: Space Shuttle Orbiter Receive Commands Transmit Photos Tomo Sugano (6/15)

COMM: Operational Schematic SatelliteSpace Shuttle FCS CPU Image Buffer Archival Memory LAN Tx Rx Downlink Uplink LAN RAM Data Flow Tomo Sugano (7/15) CPU

COMM: Communication Devices Local Area Network (LAN) Protocol is utilized. Satellite -A Zonet light-weight wireless LAN transceiver Space Shuttle - An integrated wireless LAN transceiver of a Panasonic Toughbook Tomo Sugano (8/15)

COMM: Zonet Wireless LAN USB Adapter Model: Zonet ZEW g USB Adapter Dimensions: 93.5 x 27.5 x 10 mm Mass: 32.0 grams Transfer Rate: 54Mbps (nominal) Uplink (Receive): 260 mW Downlink (Transmit): 350 mW Frequency: GHz ~ GHz - S-band (space approved, open band) Tomo Sugano (9/15)

COMM: Antenna Modification Zonet LAN adapter uses “Microstrip antenna.” Compact and reliable for short-distance communication. Directly attach antenna on the face of satellite Tomo Sugano (10/15)

COMM: Image Transfer Estimated size of each image: Mb Our LAN protocol and devices allow nominal 54Mbps with pier-to-pier method. Virtually no cause of appreciable noise in space between satellite and space shuttle Transfer time of each image: less than a few seconds. Image buffer need not to be large - A few GB USB jump drive recommended. Tomo Sugano (11/15)

Selection of System Integration CPU System integration is core of the FCS  Selection of flight computer CPU Arcom VIPER 400 MHz CPU found viable VIPER is suitable because of its - Light weight, 96 grams - Operable temperature range -40 C to + 85 C - Windows Embedded feature  easy to program - Computation speed, 400 MHz - Memory capacity, up to 64MB of SDRAM - 5 serial ports - USB ports enables utilization of Zonet LAN adapter & jump drive VIPER CPU board top view Tomo Sugano (12/15)

Control System Integration - Overview ADCS and Orbit Rectification Computations Execute ADCS and Orbit Rectification In-flight image capture handling Data archiving Tomo Sugano (13/15)

System Integration – Overall Scheme Flight Computer FCSCOMM Sensors POWER ADCS Output Orbit Control Output Other Outputs Tomo Sugano (14/15)

System Integration – Data Connections Star TrackerSpin WheelsGPS1ThrustersGPS2 Flight Computer FCS POWER Serial 1 Serial 2Serial 3Serial 4Serial 5 PWR Flow USB 1USB 2 Wireless LAN Archival Memory Camera Digital I/O Tomo Sugano (15/15)

Conclusion Thank you for your attention!