Rocsat 1

In the early 1990's Taiwan adopted a long-range plan for acquiring technologies related to developing and operating spacecraft. The National Space Program Office was subsequently established to oversee a 15-year program which envisioned the launch of three LEO spacecraft with foreign assistance. The multidiscipline Rocsat program will include telecommunications payloads on at least the first two missions.

Rocsat 1, initially scheduled for launch in 1998 and finally launched on 16 January 1999, was built by TRW and carries a Ka-band communications relay experiment. The communications payload was built and integrated by Taiwan's Microelectronics Technology. The 400-kg spacecraft was be placed into a low altitude, low inclination orbit (600 km, 35 degrees) by a US LLV booster. Rocsat 2, with a more capable communications payload was tentatively scheduled for launch in the year 2000. Integral Systems, Inc., of the US provides the satellite control facility for the Rocsat program.

Planning for the ROCSAT-I project began in 1992 and contracts were awarded starting in 1994. The project components include:

1. Satellite bus - A contract was signed with the American firm TRW in April 1994 for fabrication of the satellite bus. In order to achieve the goal of technology transfer, the Space Program Office sent 28 personnel to TRW to participate in planning, design, assembly and testing work over a two-year period. All team members successfully completed their training and received certificates. In the project to make satellite components in the R.O.C., four companies were selected to make the ROCSAT-1 solar array, battery, computer, remote interface and filter/diplexer. The engineering and flight assemblies were tested and certified by TRW and, after being mounted on the satellite bus, and transported to the satellite integrated testing facility located in the Hsinchu Science-Based Industrial Park. Obtaining manufacturer and component certification, and actually launching the components into space on board a satellite, were necessary preconditions for entering the international space technology market.

2. Ground system - The ROCSAT ground system (RGS) consists of: a mission operation center, mission control center, science experiment control center and a flight dynamics facility located at the National Space Program Office; two telemetry, tracking and command stations located respectively at National Central University in Chungli and at the aerospace laboratory of National Cheng Kung University in Tainan; scientific data distribution centers located at National Taiwan Ocean University in Keelung, National Central University in Chungli, and the Space Program Office in Hsinchu; a ground communication network (GCN) linking all these facilities. Besides being used for the ROCSAT-1, the RGS will be used for future satellites. The individual ground system facilities are currently in the midst of the construction, testing and acceptance phases.

3. Payload instrumentation - The three instrument packages--ocean color imager (OCI), Ionospheric Plasma and Electrodynamics Instrument (IPEI) and Experimental Communications Payload (ECP), built by contractors. Three science teams have been organized to carry out projects involving these instruments. Data and results obtained by the science teams will be shared with domestic and international scientists.

4. Integrated testing facility - The completed satellite integrated testing facility includes a large clean room, a highly-clean machine room, a machine shop, an electrical wiring shop and various laboratories and testing rooms. 5. Launch services - A contract was signed with America's Lockheed Martin Corporation to launch the ROCSAT-1 near the end of 1998 at Cape Canaveral using a LMLV-1 rocket.

Following its arrival in Taiwan in May 1997, the ROCSAT-1 spacecraft and its three payloads were subjected to integrated testing by space program personnel. It was anticipated that the satellite will be launched some time between the end of 1998 and March 1999. Scientific data collected by the satellite during the first four years after its launch will be distributed to researchers throughout the world in order to make a contribution to science.

ROCSAT-1 is a member of the TRW lightsat family, a series of small, modular satellites whose flexible design is readily tailored to mission-specific requirements. Built in three modules to allow parallel development and test, the spacecraft is compatible with a wide range of launch vehicles. The ROCSAT-1 design easily accommodates larger payloads for future low-earth orbiting spacecraft; only minor modifications are needed for geosynchronous missions.

Characteristics

TRW Lightsat

• Spacecraft and Payload: 1.10 m (44 in.) dia. x 2.02 m (79.5 in.) long
• Solar Arrays: Two wings; 1.16 x 2.46 m (46 x 97 in.)
• Weight: 401 kg (882 lb)
• Electrical Power: 450 W

Payload

• Experimental Communication Payload (ECP): Relay Ka-band telecommunications
• Ionosphere Plasma Electrodynamics Instrument (IPEI): Measure the ionization of the earthís upper atmosphere in low and middle latitudes
• Ocean Color Imager (OCI): Collect data on visible and near-infrared radiances over low latitude oceans

Design Life: 4 years

Reliability: >0.9 at two years

Launch Date: April 1998

Launch Vehicle: Small satellite launch vehicle

Orbit: 600 km (324 nmi) circular orbit, 35 degree inclination

Attitude Control

• 3-axis stabilized
• Pointing (3s)
• Control: 0.5 deg
• Knowledge: 0.1 deg
• Stability: 0.01 deg/sec

Communications

• S-band
• Uplink data rate: 2 kbps
• Downlink data rate: 1.4 mbps
• Data storage: 2 gb

Modular Design

• Payload module: hosts ECP, IPEI and OCI experiments and electronics
• Core module: provides spacecraft housekeeping functions
• Reaction control subsystem module: contains propulsion system for orbit trim capability