Interstellar Maintenance – part 2

Introduction – Software maintenance

Following on from the recent blogs by Philipp Reiss and Robert Freeland II, I thought I would add a little of my own perspective and experience, as a deep space software engineer. Let’s remember: the only item of a spacecraft that is routinely subject to maintenance after launch is the on-board software. This can also be used to work around other system problems. For example, when the Voyager scan platform suffered a failure the on-board software was reprogrammed to roll the whole spacecraft, to achieve an equivalent scan of the camera pointing direction. Similarly following the failure of the upper stage of Hipparcos the onboard software was substantially reconfigured, firstly for fault investigation, and recovery attempts, and then subsequently for a revised mission approach. In the end this sucessfully recovered the mission from a completely different orbit. Furthermore many spacecraft have been characterised so completely when in space that progressive refinements of the software have provided ever greater operating capabilities.  This approach to software updates has now become so sophisticated that some spacecraft are launched without anything other than their basic safety and cruise phase software loaded. This allows subsequent development and refinement of the mission software post launch. (more…)