In July 2018, a stable body of liquid water was found on Mars using a radar instrument on board the European Space Agency's Mars Express orbiter. For this, they have used Mars Advanced Radar for Subsurface and lonosphere Sounding (MARSIS). Mars Express consists of two parts, the Mars Express Orbiter and Beagle 2, a lander designed to perform exobiology and geochemistry research. It is the second longest surviving, continually active spacecraft in orbit around a planet other than Earth, behind only NASA's still active 2001 Mars Odyssey.