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 Space Technology
Research Vehicle STRV-1a and STRV-1b
Launched on Ariane flight V64 on the 17th of June 1994, the two 52kg micro-satellites built by the UK defence
Research Agency (DRA) at Farnborough U.K., and are to evaluate new technologies in the
harsh environment of a GTO orbit. The spacecraft are cubical in shape, with 450mm sides.
Experiments are carried from the Ballistic Missile Defence Organisation (BMDO), the
European Space Agency (ESA), DRA, and various Universities.
The GTO orbit is particularly harsh in terms of radiation. It has a 300km perigee, and
36000km height apogee, is inclined at 7 degrees, and has a 10h35m period. The orbit
crosses the Van Allen Belts each orbit with a maximum of ionising radiation seen in near
Earth orbit, suffers electrostatic charges close to apogee, and atomic oxygen erosion at
perigee. Payloads test advanced structural materials, new radiation hardened computers,
sensors, solar cells and micro-electronics. Further demonstrations are the use of ADA
software a restricted memory environment, vibration suppression on a cryogenic cooler,
measurement and elimination of electrostatic charge, measurement of atomic oxygen erosion,
measurement of cosmic rays and total received dose, and improved battery charging
techniques. The mission life-time is expected to be one year.
The dual redundant power system employs GaAs solar cells, a 28V power distribution bus,
and uses NiCd batteries. The average power available from the panels is about 31W (before
regulation). Bus requirements are approximately 19W, making 12W available to the payloads.
Attitude determination is achieved via V-slit sun and Earth sensors, and analogue sun
sensors with hemispherical field of view. Attitude control is achieved via magnetorquers,
and a Xenon cold gas thruster system.
The On Board Data Handling System perform the nominal telemetry and telecommand
functions. It uses a Plessey MIL-STD-1750 microprocessor employing radiation tolerant
Silicon On Saphire (SOS) technology. The ESA CCSDS packet telemetry and telecommand is
implemented using custom chip-sets. The redundant system weighs 2.5kg, requires 6W of
power, supports 128kBytes of SOS RAM, 64kBytes of radiation tolerant ROM, and 4kBytes of
SOS boot PROM. Software for the On-Board Computer is primarily written in ADA.
The Radio Frequency systems conform to the CCSDS standards as far as required by the
project, and the enhancement of the security aspects were part of an experiment. Dual
redundant transmitters and receivers are employed at S-band. The uplink data rate is
125bps, and the downlink rate is 1kbps, with a power of 1W into an omni-directional
sleeved dipole antenna.
STRV (Space Technology Research Vehicles) are experimental satellites procured for the
UK Ministry of Defence by the Defence Research Agency (DRA) at Farnborough.
scientific involvement by the Universities of Southampton and Kent, and MSSL. The UK
civilian scientific involvement on STRV 1A was as follows:
The University of Southampton provided an experiment to view Atomic Oxygen Effects
around the Earth
MSSL built a Cold
Ion Detector (CID), to monitor the activity of ions as the spacecraft passes through the
Earth's radiation belts.
Specifications
- Mass 50-53kg
- Volume 450 x 450 x 450mm
- Structure Carbon/Peek thermoplastic skinned aluminium honycomb panels
- Power GaAs body mounted panels, 31 to 33W (BOL)
- Power storage 46Whr (16 NiCd cells)
- Attitude control Spin stabilised at 5rpm, magnetorquer control
- Primary computer MIL-STD-1750 (SOS)
- Primary RAM 128kBytes SOS RAM
- Primary ROM 64kBytes SOS ROM, 4kBytes SOS boot PROM
- Communications ESA TM/TC CCSDS standard, S-band packet TM at 1kbps
Bus
 On-Board Data Handling (DRA) - Structure and Thermal design (DRA)
- Power system and Batteries (SSTL)
Payloads
- STRV-1a
- Xenon Plasma Charge Neutraliser(DRA)
- Cold Ion Detector
(DRA/MSSL)
- Surface Charge Detector (DRA/SIL)
- Langmuir Probe (DRA)
- Cosmic Ray & Dosimetry monitor (DRA/UKAEA)
- Battery Recharge (ESA-ESTEC)
- Radiation Dose Rate Sensor (DRA/MMS)
- Atomic Oxygen Effects (DRA/U.of Soton)
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- STRV-1b
- Cryo-coller/Vibration Suppression (BMDO/JPL)
- Infra-red Detectors (BMDO/JPL)
- SEU/radiation monitor (BMDO/JPL)
- Neural Network Microprocessors (BMDO/JPL)
- Radiation Environment Monitor (ESA-ESTEC/PSI)
- Solar Cell Technology (DRA/SSTL)
During their planned operational life, the STRV satellites were operated from the DRA
Lasham groundstation in the UK, using a 12m tracking dish. Later the satellite control was
turned over to the University of Colorado.
Follow on mission are planned. STRV-1c and 1d are due
for launch in 1999 on the ARIANE-5 ASAP.
References
| [1] |
The Space Technology Research Vehicles
STRV-1a and 1-b Mission update, N.Wells, Space Dept. DRA, Farnborough, U.K. |
| [2] |
The Space Technology Research Vehicles
STRV-1a and 1-b first results, N.Wells, Presented at the 8th annual AIAA/Utah Stae
University Conference on Small Satellites, 19 Aug - 1 Sept 1994. |
| [3] |
CCSDS Communications Standards on STRV,
S.Foley, Jounal of the British Interplanetary Society, Vol 51 No 10 October 1998, ISSN
0007-0904X |
[SSHP 1994][STRV at DERA][STRV at LASP, UoC][SSHP
future missions: STRV 1c and 1d]
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