NASA’s Lunar Reconnaissance Orbiter (LRO) and India’s Chandrayaan-1 carried out a joint experiment Aug. 20 that could yield additional information about the possible existence of ice in a permanently shadowed crater near the Moon’s north pole, the Indian Space Research Organisation(ISRO) said in a press release.

For the experiment, Chandrayaan-1 and LRO maneuvered within 30 kilometers of each other before aiming their synthetic aperture radar instruments at Erlanger Crater. During the four minute operation, LRO picked up the radar signals Chandrayaan-1 bounded off the bottom of the crater. The resulting so-called bistatic imagery is expected to help researchers determine whether the Moon’s permanently shadowed craters harbor water ice put their by comet impacts.

“Comparing the signal that bounces straight back to Chandrayaan-1 with the signal that bounces at a slight angle to LRO provides unique information about the lunar surface,” ISRO said in a press release.