Housekeeping Telemetry Compression: When, How and Why Bother?

Compression of science data for space missions is an established technique whereas data compression of housekeeping telemetry is rare. This paper questions this state of affairs and we investigate the potential advantages and disadvantages of the latter. Using real data from the ROSETTA spacecraft we describe a set of experiments demonstrating that massive compression of housekeeping data can be achieved using standard off the shelf products. We then use these experiments to describe a pre-processing technique that enables a very simple algorithm to obtain similar performances, thus showing that implementation can be relatively straightforward. On average, compression factors often were achievable using standard software and compression factors of seven using very simple software. We then address the issue of risk and demonstrate how a combination of compression and mitigation techniques can be used to reduce mission risk rather than increase it. Given these results the paper attempts to shift the focus on each new mission to ask itself ldquoHow can we afford not to compress our housekeeping data?".