SSTL Midisatellite Credit - NASA

Enlarged version of the basic Surrey Microsat bus.

The MicroSat-100 enhanced microsatellite platform expanded the range of SSTL's modular microsatellite to missions of 70 to 130 kg total mass, with a typical payload mass of up to 40 kg.

Whilst building extensively on the MicroSat-70 heritage, the enhanced microsatellite provided substantially greater payload power and volume to match emerging customer requirements. It included orbit station-keeping for constellation applications, and an advanced attitude control system using reaction wheels and control moment gyros for agile and precise pointing. A typical configuration (as used on three Disaster Monitoring Constellation satellites) included 2 Gbytes of on-board storage and dual-redundant 8-Mbit/sec S-band downlinks.

The MicroSat-100 structure was based on the same modular principles as the MicroSat-70. The internal module stack was mounted on larger facets providing accommodation for additional avionics, propulsion and payload subsystems. The volume above the stack was available for payloads, and was generally configured as an Earth-facing aperture.

The MicroSat-100 was proven in orbit by the AlSAT-1 mission, and further units were launched in 2003. The MicroSat-100 provided a proven baseline for customization, or an exceedingly cost-effective off-the-shelf solution for LEO remote sensing missions.

Typical orbit: 662 km circular orbit, 98 deg inclination. Basic Diameter: 0.61 m (2.00 ft). Maximum Diameter: 0.97 m (3.18 ft). Mass: 130 kg (280 lb). Payload: 40 kg (88 lb). Electric System: 0.11 average kW. Associated Launch Vehicle: Ariane 4, Kosmos 11K65M.

• 2002 November 28 - ALSAT-1 - Launch Site: Plesetsk. Launch Vehicle: Kosmos 11K65M. Mass: 80 kg (176 lb). Perigee: 681 km (423 mi). Apogee: 745 km (462 mi). Inclination: 98.20 deg. Period: 99.00 min.

  Delayed from September 12, October 29. ALSAT 1 was an Algerian imaging minisatellite. The 90-kg satellite was the first part of an international Disaster Monitoring System (DMS) for alerting natural/man-made disasters. ALSAT was built by Surrey Satellite for the CNTS (Centre National des Techniques Spatiales) in Algiers. It carriee a 32-m resolution 3-band imager, a 100 mN resistojet thruster for small orbit corrections, and a GPS receiver. The SSTL Microsat-100 class satellite was a 0.60m cube with a 6m gravity gradient boom. As well as gravity gradient stabilization, it used a momentum wheel to improve stability for imaging.

• 2003 September 27 - BNSCSat 1 (DMC-UK) - Launch Site: Plesetsk. Launch Vehicle: Kosmos 11K65M. Mass: 80 kg (176 lb). Perigee: 677 km (420 mi). Apogee: 694 km (431 mi). Inclination: 98.20 deg. Period: 98.50 min.

• 2003 September 27 - Bilsat 1 (BiltenSat, Tubitak 1, DMC-Turkey) - Launch Site: Plesetsk. Launch Vehicle: Kosmos 11K65M. Mass: 100 kg (220 lb). Perigee: 677 km (420 mi). Apogee: 695 km (431 mi). Inclination: 98.20 deg. Period: 98.50 min.

  Three disaster monitoring DMC satellites (BILSAT-1, NigeriaSat-1 and UK-DMC) were lofted in a single Kosmos launch. They joined the first DMC satellite, AlSAT-1, which was launched into a 686 km sun-synchronous low Earth orbit in November 2002, to provide a worldwide daily imaging capability. The spacecraft were 3-axis stabilised nadir-pointing. The imaging payload was a 32-metre resolution GSD multispectral wide-swath Earth imaging cameras and a12-metre GSD panchromatic camera. The Kosmos rocket delivered the satellites into orbit with a precision about an order of magnitude better than the maximum allowable - placing the satellites into orbit with a semi-major axis accurate to within 700 metres and just 300 metres from that of AlSAT-1. Bilsat 1 was built for TUBITAK-ODTU-BILTEN, the Information Technology and Electronics Research Institute of the Middle East Technical University, Ankara, Turkey

• 2003 September 27 - NigeriaSat 1 (DMC-Nigeria) - Launch Site: Plesetsk. Launch Vehicle: Kosmos 11K65M. Mass: 80 kg (176 lb). Perigee: 677 km (420 mi). Apogee: 694 km (431 mi). Inclination: 98.20 deg. Period: 98.50 min.

• 2005 October 27 - Topsat - Launch Site: Plesetsk. Launch Vehicle: Kosmos 11K65M. Mass: 108 kg (238 lb). Perigee: 682 km (423 mi). Apogee: 707 km (439 mi). Inclination: 98.20 deg. Period: 98.70 min.

  Delayed from May 18, mid-July, August 25, September 27 and 30, 2005. UK military surveillance research satellite.

• 2005 October 27 - Beijing-1 - Launch Site: Plesetsk. Launch Vehicle: Kosmos 11K65M. Mass: 140 kg (300 lb). Perigee: 682 km (423 mi). Apogee: 705 km (438 mi). Inclination: 98.20 deg. Period: 98.60 min.

  Beijing-1 carried a 31-cm focal-length cartographic telescope with a resolution of 4 meters. It was to be part of the international Disaster Monitoring Constellation. Operated by Tsinghua University for Beijing Landview Mapping Information Technology Ltd.

• 2007 March 9 - CFESat - Launch Site: Cape Canaveral. Launch Vehicle: Atlas V. Mass: 159 kg (350 lb). Perigee: 558 km (346 mi). Apogee: 563 km (349 mi). Inclination: 35.40 deg. Period: 95.90 min.

  The Cibola Flight Experiment satellites carried eight new technologies for space flight validation, including a new power supply, inflatable antennas, deployable booms, a new type of launch-vehicle separation system, and a high-density pack of AA lithium-ion batteries. Cibola's on-board field programmable gate array supercomputer processed data onboard, then beamed only the results rather than the raw data to the ground. The Cibola also had a science mission: the study of lightning, ionospheric disturbances, and other sources of radio frequency (RF) atmospheric noise.