Nature: Despite wrong orbit satellites could still aid scientists
On 22nd August, the European Space Agency (ESA) launched the first two fully operational satellites of the Galileo global navigation system — but after a successful lift-off, tracking data showed that the satellites were in the wrong orbit. Investigations into why the fault occurred and whether the satellites can be moved are still underway. What is already clear, however, is that there will be no easy fix. The satellites don’t have enough fuel to move themselves and it may require a separate satellite mission to move them into place.
Fortunately, the satellites could still be of use even in their current location. Their orbit is so misshapen that its mathematical parameters are incompatible with Galileo’s standardized data format, making them unusable for commercial purposes, but the situation is more hopeful for many scientists wanting to use Galileo data in their research. Richard Langley, a GNSS expert at the University of New Brunswick in Fredericton, Canada told Nature that researchers track such navigation probes independently with a global network of dozens of ground stations, and combine that information with the timing data transmitted by the satellites themselves.
“With Galileo’s timing data and the independent ground-tracking information on the satellites’ orbits, scientists should be able to measure changes in the position of points on the ground much smaller than the one-metre margin of error for standard navigation-system receivers. This level of precision is good enough to detect millimetres of movement in tectonic plates, for example.”
Read the full story here