“The models were right”: astronomers find ‘missing’ matter (www.esa.int)

After a thorough evaluation, ESA preselected the proposals of the following Challengers:...
Launched on 19 December 2013, Gaia’s fuel tank is now approaching empty – it uses about a dozen grams of cold gas per day to keep it spinning with pinpoint precision. But this is far from the end of the mission.
In brief...
As ESA’s Hera planetary defence mission flew past planet Mars it autonomously locked onto dozens of impact craters and other prominent surface features to track them over time, in a full-scale test of the self-driving technology that the spacecraft will employ to navigate around its target asteroids.