|
Class: Technology. Type: Communications. Destination: Low Earth Orbit. Nation: USA. Agency: Orbcomm. Manufacturer: Orbcomm. Small satellite bus, specially designed for multiple launch by Pegasus or Taurus family launch vehicles. Notably used for the Orbcomm LEO network for global communications and related spacecraft. Orbital's MicroStar was a commercially-produced spacecraft bus designed for multiple launch by Orbital's Pegasus or Taurus launch vehicles. MicroStar supported payloads up to 68 kg and provides a three to five-year mission life. The baseline bus was comprised of three rings stacked together vertically -- a core ring housing all primary spacecraft bus systems and a payload support module consisting of two rings and a payload mounting shelf. Payloads requiring different depths could be accommodated by using fewer rings, or by creating a custom ring. The open avionics architecture, stackable mechanical design and scalable spacecraft design maximize payload performance and flexibility.
Using a production line approach for assembly and testing, Orbital delivered over 38 MicroStar spacecraft, including 26 ORBCOMM satellites launched in 10 months in 1995-1996. This approach provided cost and schedule advantages through the use of mature designs, familiar manufacturing and test equipment, dedicated and experienced personnel, and established vendor sources. The production line remained in place to support ORBCOMM spares and individual MicroStar missions such as T1 and MUBLCOM. NASA's QuikTOMS spacecraft also took advantage of this production line.
Customers could purchase the MicroStar spacecraft alone, or as part of a turn-key service that includes operations and data delivery as well. For the OrbView-1 and OrbView-2 programs, Orbital provided end-to-end payload services. The company produced the satellite bus, integrated two payloads, and launched the satellite on Pegasus. Orbital conducted mission operations from its own ground station delivering data to principal investigators via direct downlink and the Internet.
H
The MicroStar platform was originally developed to support the ORBCOMM wireless data communications system, which provided real-time, mobile, two-way data and messaging communications services worldwide. The first three MicroStar units, ORBCOMM FM-1&-2 and the OrbView-1 remote sensing satellite, were launched on a single Pegasus in April 1995.
Core Technical Specifications
- Bus Dry Mass: 58.6 kg
- Payload Mass Capability: 68.0 kg
- Redundancy: Single string
- Orbit: 700-1,000 km, all inclinations
- Launch Vehicle Compatibility: Pegasus, Taurus, SELVS I and II
- Typical Mission Lifetime: 3-5 years
- Delivery: 24 Months ARO
- Bus Dimensions (Diameter x Height): 104 x 16.5 cm
- Payload Support Module Dimensions (Diameter x Height): 104 x 33 cm
- Construction: AlBeMet/Al Honeycomb
- Shape: Dual-faced cylinder
- Power Subsystem: Payload Power: 50 W orbit average; Bus Voltage: 14 VDC unreg, 28 V reg; Solar Arrays: 2 GaAs; Batteries: 10 A-hr NiH2 CPVs
- Attitude Control Subsystem: Stability Mode 3-axis; Pointing Capabilities: Control . ± 0.6°; Knowledge. < 1°; Rate/Stability <0.01°/sec
- Command & Data Handling Subsystem: Flight Processor 68302; Rad Tolerant 15 K rad; Data Storage Capacity 3 MB; Interface Architecture . RS-422/RS-485; S-Band Uplink/Downlink Rates 2 Kbps/2 Mbps
Options
- Custom structural ring configuration for flexible payload accommodations
- Increased power (up to 270W BOL) provided by second set of solar arrays for certain orbit/payload combinations
- 1553/1773 payload data interface to accommodate existing high-level interfaces
- Reduced pointing accuracy function (10° accuracy per axis) for missions requiring less precision
- Payload data storage enhancement (256 MB of storage)
- Propellant capacity of 26 kg hydrazine with 4 thrusters of 0.9 N each for orbit maintenance
- Mission operations and data delivery for two years
Typical orbit: 663 km circular orbit, 69.3 deg inclination. Mass: 43 kg (94 lb). Associated Launch Vehicle: Pegasus, Pegasus XL, Taurus.
Microstar Chronology
- 1999 May 18 - MUBLCOM - Launch Site: Vandenberg. Launch Vehicle: Pegasus XL. Perigee: 770 km (470 mi). Apogee: 775 km (481 mi). Inclination: 97.70 deg.
After deploying the TERRIERS satellite, the conical Payload Adapter Fitting (1998-26E) was jettisoned at 05:21 GMT, leaving the disk-shaped MUBLCOM satellite attached to the Pegasus XL PRIMEX HAPS-Lite stage. The second HAPS burn at 05:22 GMT raised apogee to 775 km, followed by a third, apogee burn at 06:10 GMT which circularised the orbit. MUBLCOM was deployed to a 769 km x 776 km x 97.7 degree orbit. The final HAPS burn then placed the depleted HAPS stage in a lower 388 km x 722 km x 97.1 degree disposal orbit. MUBLCOM (Multiple beam Beyond Line-of-sight Communications) was an experimental satellite funded by DARPA and managed by the US Army's Communications-Electronics Command (CECOM) at Ft Monmouth, New Jersey. It was built by Orbital Sciences using the Microstar (Orbcomm type) bus and carries a payload testing hand-held radio satellite communications for the armed forces. Six years later MUBLCOM was the target for the DART Autonomous Rendezvous Technology mission. On April 16, 2005, DART closed within 100 m of MUBLCOM satellite, then evidently began a series of out-of-control maneuvers resulting in an in-space collission and MUBLCOM being bumped into a 3 to 5 km higher orbit. DART was deorbited while MUBLCOM, still functioned, continued on in space.
- 2006 April 15 - Formosat 3F - Launch Site: Vandenberg. Launch Vehicle: Minotaur. Mass: 70 kg (154 lb). Perigee: 497 km (308 mi). Apogee: 542 km (336 mi). Inclination: 72.00 deg. Period: 95.00 min.
- 2006 April 15 - Formosat 3E - Launch Site: Vandenberg. Launch Vehicle: Minotaur. Mass: 70 kg (154 lb). Perigee: 496 km (308 mi). Apogee: 538 km (334 mi). Inclination: 72.00 deg. Period: 95.00 min.
- 2006 April 15 - Formosat 3D - Launch Site: Vandenberg. Launch Vehicle: Minotaur. Mass: 70 kg (154 lb). Perigee: 496 km (308 mi). Apogee: 538 km (334 mi). Inclination: 72.00 deg. Period: 95.00 min.
- 2006 April 15 - Formosat 3C - Launch Site: Vandenberg. Launch Vehicle: Minotaur. Mass: 70 kg (154 lb). Perigee: 567 km (352 mi). Apogee: 681 km (423 mi). Inclination: 72.00 deg. Period: 97.20 min.
- 2006 April 15 - Formosat 3A - Launch Site: Vandenberg. Launch Vehicle: Minotaur. Mass: 70 kg (154 lb). Perigee: 496 km (308 mi). Apogee: 538 km (334 mi). Inclination: 72.00 deg. Period: 95.00 min.
FORMOSAT-3 consisted of six small 62 kg Orbcomm-type satellites with GPS receivers which were to measure atmospheric conditions by studying the effect of the atmosphere on GPS satellite signals passing through it. The satellites, also known as COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate), would eventually be positioned in equally spaced orbit planes
at around 800 km altitude.
- 2006 April 15 - Formosat 3B - Launch Site: Vandenberg. Launch Vehicle: Minotaur. Mass: 70 kg (154 lb). Perigee: 500 km (310 mi). Apogee: 541 km (336 mi). Inclination: 72.00 deg. Period: 95.00 min.
Bibliography and Further Reading - McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Essential internet newsletter recording worldwide weekly space events. Accessed at: http://www.planet4589.org/jsr.html.
- NASA GSFC Orbital Parameters, .
- McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.
|