When it comes to “repairs in space”, the Hubble space telescope can confidently be described as a trendsetter. Started on April 24, 1990, an error in the main mirror soon became apparent. In 1993 the first successful repair mission took place in earth orbit at a height of over 600 kilometers. Four more were to follow and thus enable a mission time of around 30 years. The space agencies in China, Japan, Europe and the USA are now working intensively on service satellites that are supposed to carry out maintenance work much higher in geostationary orbit – 35,786 kilometers above the Earth’s equator. The aim is to extend the service life of weather, television and communications satellites from currently 15 years by around five years.
A few weeks ago the Shanghai Academy of Spaceflight Technology (SAST) their concept for maintenance satellites on the Zhuhai Airshow before. Equipped with numerous sensors and cameras and supported by an intelligent navigation system, the repair satellite should be able to dock as autonomously as possible with older satellites in geostationary orbit. Robotic arms with multiple axes of rotation could then repair minor damage, replace solar panels or even install a module with additional fuel. This means that the satellites, which often cost several hundred million euros, could serve for a few years longer. Only then will they – as already practiced today – use the last remaining fuel to get 200 to 300 kilometers higher into a “cemetery orbit”. This last maneuver is necessary to free the limited space in geostationary orbit for new satellites.
The US company Northrop Grumman has already gained initial experience with such service missions. With two “Mission Extension Vehicles”, supported by infrared cameras and lidar scanners, it was possible to dock onto Intelsat satellites.
A second generation of such maintenance satellites – “Mission Robotic Vehicle” – is under development. These should not only carry out repairs with robotic arms, but also replace individual components on expensive communication and television satellites and install compact modules to extend the operating time – “Mission Extension Pods”. A first start of a robot satellite is planned for next year, Mission Extension Pods should be able to be used from 2024. The European Space Agency ESA is also pursuing similar concepts. But it is still unclear how far these projects have progressed and when the first starts can be expected.
Overall, the trend towards such maintenance missions to extend operating times is to be welcomed. Not least to counter the growing problem of space debris. But in the end it will be a purely economic decision. Only with further experience will you learn how many satellites can be serviced by a single service satellite and in what period of time. The costs for the service robots must also be set in relation to the satellites to be serviced. And after completion of the possible maintenance work, the service satellite itself can also be expected to retire in a higher cemetery orbit.