Nigeria has sponsored or co-sponsored six satellites, of which only two are currently operational. One of them is functioning even though it has passed its expiry date, according to the director general of the National Space Research and Development Agency. The Conversation’s West Africa regional editor, Adejuwon Soyinka, asks space policy researcher Samuel Oyewole to explain what this means for the country.
What does it mean for a satellite to run out of fuel or expire?
A satellite can be said to have expired by design or operation. Like every other machine, satellites are designed with a projected expiry date or calculated life expectancy. Beyond this period the operational survival is not guaranteed by the manufacturer. The ability to keep functioning beyond the set date is driven by a combination of factors. These include the quality of its design, development and maintenance as well as a favourable host environment. A satellite can survive as long as it is supported by its hardware and software, control system and hosting orbit.
Operationally, a satellite expires when any of its critical components suffers enough damage or is degraded to the point of causing system or major sub-system failure.
A satellite is made up of different components. These include a protective box, on-board computer for receiving, processing and transmitting signals, as well as solar array panels, batteries and fuel for energy. Any problem with any of these can translate to the operational end of a satellite.
Unlike cars or aircraft, satellites don’t really need fuel for their daily orbital operation. They mostly rely on solar powered batteries. However, the fuel is relevant in supporting satellites to maintain orbital trajectory and conduct manoeuvres when required. Hence, when a satellite runs out of power it is usually switched off to avoid collision.