Odysseus lands on US moon for first time in more than 50 years


For the first time in more than half a century, a US-made spacecraft has made a soft landing on the Moon.

There was much drama and much intrigue Thursday evening when Intuitive Machines attempted to land its Odysseus spacecraft in a small crater not far from the moon's south pole. About 20 minutes after touchdown, NASA announced success, but some questions remained about the health of the lander and its orientation. Why? Because when Odysseus was calling home, his signal was weak.

But after what the spacecraft and its developer, Houston-based Intuitive Machines, did Thursday, it was a miracle that Odysseus made it through.

lose your way

The landing attempt was delayed by about two hours because mission controllers had to hastily send a last-minute software patch to the lander while it was still in orbit around the Moon. Patching the software of your spacecraft shortly before its most important mission is the last thing a vehicle operator wants to do. But the intuitive machines were frustrated.

Earlier on Thursday, the company realized that its navigation lasers and cameras were not working. These rangefinders are essential for two functions during landing: terrain-relative navigation and threat-relative navigation. These two modes help the flight computer on Odysseus to accurately determine where it is during descent – ​​by snapping lots of images and comparing them to known lunar topography – and to find a safe landing site. Help identify hazards, such as boulders.

Without these rangefinders, Odysseus was going to land facing the moon. Fortunately, the mission carried a lot of science payload. As part of its commercial lunar program, NASA is paying approximately $118 million for the delivery of six scientific payloads to the lunar surface.

One of these payloads was the Navigation Doppler Lidar Experiment, a 15-kilogram package containing three small cameras. With this NDL payload, NASA tried to test technologies that could be used to improve navigation systems in future landing attempts on the Moon.

Odysseus's only chance was that he could somehow tap into two of the three cameras of the NDL experiment and use one for terrain-relative navigation and the other for threat-relative navigation. So the software was hastily written and sent to the lander. This was some true MacGyver material. But will it work?

a new house

The Odysseus lander began descent from a circular orbit 57 miles (92 kilometers) above the moon's surface, one hour and 13 minutes before its planned landing time. On this timeline, 11 minutes before touchdown, the lander began a powered descent using its main engine powered by liquid oxygen and methane. During these final, critical minutes, Odysseus's instantaneous terrain-relative navigation cameras scanned the surface for hazards, such as boulders, to ensure a safe landing site.

After touchdown, mission controllers knew it might take a minute or two for a good signal to come back from the lander, which was transmitting signals back to large satellite dishes on Earth. First one, then two, and then five minutes passed in an uneasy silence in the Intuitive Machines mission control room. Nothing.

Finally, after 10 minutes, mission director Tim Crain reported that the lander was sending a light signal to Earth.

“We're not dead yet,” said Crane, the company's co-founder.