The lander is expected to arrive near the Gruithuisen domes. The two volcanic mountains Mons Gruithuisen Gamma (left) and Mons Gruithuisen Delta (right; image mosaic from four images acquired by the Lunar Reconnaissance Orbiter Camera 2009-2011, image width approx. 55 kilometres) are of volcanic origin. Volcanism was not uncommon on the Moon; it mainly formed the extensive dark plains that are clearly visible from Earth. These were formed from thin basaltic lava. However, the Gruithuisen domes must have been formed from a more viscous, barely flowable lava, which on Earth is produced by the addition of water – but which does not exist on the Moon. Scientists are hoping to gain new insights into the history of the formation of the domes.