Geological Chronicle
Mons Gruithuisen Gamma is a lunar dome that lies north of the crater Gruithuisen at the western edge of Mare Imbrium. Spanning a diameter of 19.65 kilometers, the structure climbs gently to a height of over 1,500 meters, with a small crater at its summit. To the east lies the similar Mons Gruithuisen Delta. Directly south of the domes, a portion of Oceanus Procellarum was named Sinus Viscositatis by the International Astronomical Union in December 2022.
In June 2025, the International Astronomical Union named a 150-meter crater Mareta near the summit of Mons Gruithuisen Gamma. The dome was selected as the destination for Peregrine Mission One, which launched on January 8, 2024, on the maiden flight of the Vulcan Centaur rocket. A leaky valve subsequently caused the mission to fail before a landing attempt could be made.
A second exploration attempt is planned under NASA's Commercial Lunar Payload Services program. Firefly Aerospace intends to use a Blue Ghost lander to deploy a rover at Gruithuisen Gamma in 2028. The lander and rover carry Lunar-VISE instruments to map local variations in geological composition and thermophysical properties.