Finnish satellite testing system to ESA

VTT Technical Research Centre of Finland has designed and constructed a satellite testing system called > '> RF Suitcase> '> for the Herschel / Planck mission of the European Space Agency (ESA). The purpose of the RF (Radio Frequency) Suitcase is to demonstrate the RF compatibility between spacecraft and ground stations prior to launch and to test the uplink and downlink functional and performance characteristics.

Among others, the values of several tens of configuration parameters for the ground stations are determined, such that each ground station can immediately communicate with the two satellites, once they are released from the launcher. The RF Suitcase also simulates the basic characteristics of the telecommand and telemetry data of the spacecraft and thus for a ground-station operator it will seem like he or she would be communicating with a real satellite.

VTT is commissioned by the French company Alcatel Alenia Space to design and construct this satellite testing system for Herschel and Planck satellites to be delivered to ESA.

The RF parts of the RF Suitcase operating in X-band are engineering models that are similar to actual flight hardware. A set of programmable RF attenuators are used to simulate the propagation losses between the spacecraft and ground stations over a distance of about 1.5 million km. These RF parts together with Telecommand and Telemetry Simulator are integrated into a single transportable cabinet. Furthermore, the cabinet includes a user-friendly control and monitoring subsystem that enables local and remote operation of the RF suitcase.

The satellite testing system is traditionally called RF Suitcase, because it should be able to travel to test-locations, where it is too risky or too expensive to ship a real satellite. The unit, which is approximately 175 cm high and weight over 200 kg, has wheels to make it easy to move. The unit was transported to Turin in a specially constructed transportation container for first tests in spring 2006.

The system was then delivered to ESA for a test campaign at the satellite control centre (ESOC) in Darmstadt, Germany. The final tests at Herschel-frequency are foreseen in summer 2007. Prior to the launch of the real satellites, which is scheduled for mid 2008, the RF Suitcase will be used in various complementary tests to demonstrate that communications between ground stations and the satellites will function.

The Herschel satellite is an astronomical telescope sensitive to infrared radiation. Its main purpose is to investigate the history of how planets, stars and galaxies formed from cold gas and dust clouds and to study how they continue to form in our own and other galaxies. Planck will look back at the dawn of time, close to the Big Bang, by observing the most ancient radiation in the Universe, known as the 'cosmic microwave background'. Together, Herschel and Planck form the largest scientific deep-space mission ever undertaken in Europe. Both satellites will be launched on board Ariane 5 from French Guiana in mid 2008.

VTT has previously delivered RF Suitcases to ESA for the Soho and Cluster satellites.