FedSat: exchange launch capacity for useful science

FedSat, catalogued as Fedsat, launched from Japan on 14 December 2002. Australia’s Cooperative Research Centre for Satellite Systems brought research institutions and industry together around the mission. Its experiments included magnetic-field measurements, communications, GPS and reconfigurable computing. These payloads shared a spacecraft, but each had its own question and criteria for useful performance.

Sharing a platform can reduce duplicated equipment, yet it also creates competing demands. Instruments need electrical power, temperature control, data storage and contact time. The integration team must check that the combined requirements fit, including periods when several experiments would like to operate. Adding the individual successes of laboratory prototypes does not establish that the complete spacecraft can support them simultaneously.

The September 2002 agreement between Japan’s NASDA and Australia’s CSIRO provided launch capacity alongside ADEOS-II in exchange for magnetic-field data. The planned scientific use was to combine observations from several satellites to improve knowledge of the near-Earth environment. The agreement made data a contribution with a defined purpose, rather than an incidental by-product of a launch ride.

Combining observations requires more than putting files in one folder. Researchers need time references, positions, coordinate conventions, units and information about instrument calibration — open definition. Imagine one instrument reports a field value in nanotesla while another reports microtesla. One microtesla equals one thousand nanotesla. Without conversion, numerically similar values could represent very different physical conditions. Documentation makes exchanged data interpretable.

A reciprocal mission needs usable data

The prelaunch agreement gave a three-year target lifetime. The Australian Space Agency’s later history records operations continuing until a battery failure in 2007, after the mission launched in 2002. A target describes an intended design interval; later operating evidence tells us what occurred. Neither date alone explains how well each experiment met its objectives.

Consider an invented review with three separate rows: the bus remained operational, a communications experiment completed its tests, and a magnetic dataset was delivered in a usable format. Each row needs supporting evidence. A spacecraft can outlive its target while one payload has limited results, or operate briefly yet complete a bounded experiment. Evaluating the mission at this level gives partnerships a clearer account of what they actually received.