by Kristiina Kämäräinen
VTT Information Technology has delivered the Cluster RF-Suitcase to the European Space Operation Centre (ESOC) in Darmstadt, Germany at the end of 1994. The purpose of the Suitcase is to test the RF compatibility between ground stations and spacecraft and to test the uplink and downlink functional characteristics.
The CLUSTER RF-Suitcase belongs to the Cluster mission, where four identical spacecraft will be launched into large, elliptic polar orbits around the earth on the early test flight of Ariane 5 at the end of 1995. The four spacecraft will detect how particles from the Sun interact with the earth's magnetic field. Each spacecraft carries eleven scientific instruments which observe the magnetic and electrical interactions between the earth and the sun. ESOC operates the four spacecraft via two ground stations. At ESOC the Suitcase simulates the telecommand and telemetry systems of the spacecraft. The telemetry system is that part of the spacecraft which gathers the scientific data from the instruments and forwards it to the ground stations.
The telecommand system controls the operation of the spacecraft and the scientific instruments according to the commands received from the ground stations. The Suitcase contains spacecraft engineering models: RFDU (RF distribution unit), HPA (high power amplifier), S-band transponder, CDMU (central data management unit) and RTU (remote terminal unit). The control system of the Suitcase is implemented using an industrial PC, which controls the Suitcase in addition to the ground stations. Using a MS-Windows based graphical user interface the operator can generate telecommands and telemetry stimuli data and observe the telecommands received from the ground stations and the telemetry data from the Suitcase. The Suitcase doesn't contain the scientific instruments, therefore the scientific simulation data is generated by hardware and software developed by VTT.
DORNIER has the main responsibility of the CLUSTER program. ALCATEL ESPACE is the subcontractor to DORNIER and VTT is the subcontractor to ALCATEL ESPACE. The development of the Suitcase is mainly financed by ESA. The rest of the financing comes from TEKES and VTT.
VTT Information Technology delivered a similar test equipment to SAAB ERICSSON SPACE at the end of April 1994. This Suitcase belongs to the SOHO mission of ESA.
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