You may have heard that on Friday, August 22, the European Space Agency
(ESA) launched two new Galileo satellites aboard a Soyuz ST rocket out of French Guiana. At first they thought all was well, but later, as data emerged, they found the orbits to be out of the plane, too low and fairly eccentric. The details on the orbit insertion anomaly can be found in the Arianespace press release
. Using the details from the press release, I did some analysis to see how the new orbit might affect the navigation accuracy for the Initial Operational Configuration (IOC) and their Final Operational Configuration (FOC). It isn’t as bad as I would have thought, especially in the FOC case. There are higher maximum navigation errors in a few spots, but nothing critical, and there appears to be no major effects over the EU. Since they’ll have 30 satellites in the FOC system, leaving them out completely may be an option too.
Note that this analysis looks only at navigation accuracy from a coverage perspective. There will probably be additional errors and issues with the Galileo orbit propagation models and clock states for these two satellites because of the elliptical orbit. Those effects are not taken into account here.
You can download a scenario from the STK Data Federate
(username: anonymous) and explore the both constellations, the new orbits of the satellites and the maximum navigation error for a day of both the IOC and the FOC. A license for STK Coverage
is needed to see the maximum navigation error. You can get a demo license for STK Coverage
by visiting agi.com/eval