Intuitive Machines has completed its investigation into the landing incident of its second lunar rover, Athena, which capsized shortly after landing near the south pole of the Moon 6 March 2024 year. The main reason is a combination of three technical and navigational problems, which led to a loss of vertical position.
Firstly, during the final descent stage, the Athena laser altimeter (altitude sensor) was prone to signal interference, which distorted the height indicators. This deprived the device of the ability to accurately determine the distance to the surface of the Moon.
The second problem was the difficult light conditions in the landing area. Near the South Pole, the Sun illuminates the surface at a low angle, forming long shadows. This made it difficult for the navigation system to work, which focused on visual landmarks.
The third factor is the limitation of Athena's optical navigation. She used images from NASA's Lunar Reconnaissance Orbiter, collected from a height 100 km. However, these pictures were not taken into account, how the craters look from a lower altitude under the specific lighting of the south pole.
Due to the overturning, Athena's solar panels could not get enough power, and the device was declared lost the very next day after landing.
Athena performed the IM-2 mission as part of the CLPS program (Commercial Lunar Payload Services) from NASA, aimed at delivering scientific instruments to the Moon by private landers. As part of the Athena mission, it was supposed to deliver the Grace hopper and Lunar Outpost Lunar Outpost's MAPP rover to the surface of the Moon, however, both failed to separate due to a botched landing.
This is the second incident involving Intuitive Machines: IM-1's previous Odysseus mission in February 2024 year also ended with overturning after landing, although the device worked on the surface for seven Earth days.
The company stated, which is making major technical changes to the design of its next lander for the IM-3 mission in 2026 year. They include:
installation of altimeters with different operating principles, which undergo more stringent tests;
sensors to determine speed regardless of lighting;
extended crater database for better navigation;
using images from IM-2 to train machine learning algorithms.
Intuitive Machines hopes, that the accumulated experience will help them successfully implement future lunar missions - soft landing, keep the vertical position and start working immediately.