Crash stops stray pioneer

In 2011, NASA’s MESSENGER probe is the first to enter into an orbit around the innermost and smallest planet of the Solar System, Mercury.

Over a period of four years, the probe reveals that the small rocky planet has a large, partly liquid core and that cooling makes the planet slowly shrink. Based on data from the probe, scientists conclude that Mercury – as the only Solar System planet apart from Earth – is still geologically active.

In April 2015, after 11 years in space, MESSENGER runs out of power and dies in a dramatic finale. In order that MESSENGER does not end up as a stray craft with empty fuel tanks, NASA chooses to crash the probe against Mercury’s pockmarked surface.