In a recent development, we have gained insights into why the private Athena lunar lander toppled over on the Moon earlier this year. Operated by the Houston-based company Intuitive Machines, Athena marked its landing near the lunar south pole on March 6, but unfortunately, it fell onto its side shortly after touching down. This unfortunate incident rendered Athena's solar panels ineffective in harnessing adequate sunlight, leading to the probe being declared inoperable the following day.
More than two months after the incident, Intuitive Machines conducted a thorough autopsy of the Athena lander, identifying three critical issues that combined to cause the anomaly. The first issue was related to interference with the readings from Athena's laser altimeter, a vital instrument responsible for gauging the lander's distance from the lunar surface. Steve Altemus, CEO of Intuitive Machines, explained during an earnings call on May 13 that signal noise and distortion in the final descent phase prevented accurate altitude readings from being obtained.
The second factor contributing to the mishap was the challenging lighting conditions present in Athena's landing zone, located approximately 100 miles (160 kilometers) from the lunar south pole. Altemus noted that the unique topography and low-angle sunlight created long shadows and dim lighting, which severely impacted the precision capabilities of the landing system.
Lastly, Athena's compromised ability to recognize craters in the landing area played a significant role in its downfall. The lander's optical navigation system relied on images collected by NASA's Lunar Reconnaissance Orbiter (LRO) from an altitude of 62 miles (100 kilometers). However, this imagery did not accurately reflect how craters appeared at lower altitudes under the specific lighting conditions encountered while approaching the landing site.
The IM-2 mission was part of NASA's Commercial Lunar Payload Services (CLPS) program, aimed at deploying agency science equipment on private robotic moon landers. The mission's primary objective was to collect cost-efficient data to support NASA's Artemis program, which focuses on crewed lunar exploration. Athena was equipped with various NASA science instruments and additional payloads, including Intuitive Machines' hopping spacecraft, Grace, and the MAPP rover developed by Lunar Outpost from Colorado. Unfortunately, Athena's fall prevented these two spacecraft from successfully deploying onto the lunar surface.
The IM-2 mission followed the successful IM-1 mission, which saw Intuitive Machines' Odysseus spacecraft land on the Moon in February 2024. However, like Athena, Odysseus also tipped over after landing due to damage sustained to its landing legs. Despite this setback, Odysseus managed to operate on the lunar surface for seven Earth days before communication was lost.
Intuitive Machines is committed to ensuring that its next lunar lander, set to launch on the IM-3 mission in 2026, will remain upright during its descent. The company is implementing various improvements based on the lessons learned from both IM-1 and IM-2 missions. Altemus highlighted that they have added dissimilar and redundant altimeters to the sensor suite, which are undergoing more rigorous testing than ever before. Additionally, they have incorporated a lighting-independent sensor for measuring surface velocity and expanded the onboard terrain crater database to enhance navigation across the lunar surface.
Furthermore, the team is utilizing detailed south pole imagery captured during IM-2 to feed machine-learning algorithms, thereby improving navigation and crater-tracking capabilities for future missions. Altemus confidently stated, "Moving forward, we will succeed. Land softly, land upright, land ready to operate."
