Tilting on the Moon

What a “save” landing for a commercial company

(Credit: NASA)

For the first time in more than 50 years America is back on the Moon. This isn’t a NASA spacecraft. It is the first time a private company has put a lander on the lunar surface. But Odysseus will go silent a couple days early. The last transmission from the lander is expected Tuesday morning. That is five days after what was called a “soft landing."

The Intuitive Machines (IM) spacecraft did not “stick the landing.” The Houston company’s lander tilted onto its side. The company’s CEO thinks Odysseus came in a bit “hot” and leaning forward. That may have dragged a landing foot on the Moon’s surface, causing Odysseus to tip onto its side with the top of the vehicle potentially resting on a rock.

Odysseus during its descent to the moon. (Credit: Intuitive Machines)

SOFT LANDING?

The “soft-landing” language may be a contract requirement for the commercial companies landing on the Moon for NASA on your tax dollar. Each mission must meet specific milestones. NASA pays for the ride to get the scientific data being sent back to Earth. The data and photos will help tell NASA a bit more about the environment of the Moon’s south pole.

Intuitive Machines CEO Steve Altemus explains how Odysseus may have ended up on its side. (Credit: NASA)

NASA wants to send astronauts to that area because it’s believed there is ice in shaded areas of craters. Ice can be used to make water for drinking, oxygen for breathing, and hydrogen for fuel. 

WHAT A SAVE

I have a feeling that years from now, astronauts will visit Odysseus in one of their rovers and will likely remember what the group of engineers from this small company accomplished in the past several days. The IM team faced the reality that they were a couple hours away from losing the entire mission. Saving Odysseus is quite the story.

Picture on left taken by a NASA Moon observer showing Odysseus on the surface of the moon. IM says the spacecraft landed 1.5 KM from its intended target. (Credit: NASA)

Flight controllers were concerned once Odysseus was in lunar orbit. Something was a bit off. The orbit was more like an oval rather than a circle. That unusual orbit led to actions that ended up saving the spacecraft and the mission.

The engineers decided to raise the orbit by firing Odysseus’ 3D printed engine. After the burn they wanted to know exactly how high the lander was flying above the surface of the Moon. The IM team decided to use their landing range finding lasers to “ping” the surface for an altitude reading. Those lasers bounce light off the surface and the return beam allow computers to determine the distance. 

Odysseus with the NASA experiment known as NDL. The NASA box is on the lander just below the NASA logo in this artist’s rendering. (Credit: Intuitive Machines)

But when the IM flight controllers tried to fire the range finders, the lasers didn’t work- no light heading to the surface and back. This critical navigation system was dead because of a mistake made on Earth before the launch of the lunar lander.

A MISTAKE ON EARTH

The team realized that a safety switch inside the range finder unit used to keep the lasers from going off and possibly blinding a worker was the problem. That switch must be physically flipped before launch to enable the lasers. There was no software workaround. The all-important lasers could not be used for guidance to land Odysseus. 

Intuitive Machine employees celebrate the landing of their spacecraft on the surface of the Moon. (Credit: Raquel Natalicchio/Houston Chronicle via AP)

Intuitive Machines CEO Tim Altemus walked into the control room and told the mission director, Tim Crain (the two are co-founders of IM) that they would have to land without lasers. “His face got absolutely white because it was like a punch in the stomach that we were going to lose the mission."

Facing the possibility of failure, the IM team searched for a solution to save the spacecraft and its commercial and six NASA payloads. It is one of those payloads that ended up saving the landing.

THE NASA EXPERIMENT

One of the NASA experiments is a new laser navigation system the agency was testing on this landing for use in future spacecraft.

The NASA box that saved the mission for Intuitive Machines. The Navigation Doppler Lidar experiment was plugged into Odysseus’s computers. (Credit: NASA)

Dr. Tim Crain, who serves as IM’s top technology officer, came up with an idea. What if they routed the NASA experimental lasers into the spacecraft’s computer and use it to land on the Moon? That became the plan. Time was critical because the orbit was not stable. The team decided to make one more orbit of the Moon to allow engineers time to write a software patch, upload it, and reboot the navigation system.

A MONTH IN TWO HOURS

Less than two hours later, the upload was done, and the landing sequence was started with the NASA laser experiment providing critical data.

“In normal spacecraft development this is the kind of thing that would have taken a month… Our team basically did that in an hour and a half. And it worked,” Crain told reporters.

Odysseus prior to launch. (Credit: Intuitive Machines)

While Odysseus was traveling a little fast and leaning to one side as it was landing, it did arrive on the lunar surface even if it wasn’t standing up as planned. The patch, the use of the NASA experiment with the clock ticking, had saved the mission.

“It was the finest pieces of engineering I’ve ever had a chance to be affiliated with,” Crain said with what appeared to be a bit of emotion.

As Crain said, his team will be telling the story of this “save” for the rest of their lives. Long after Odysseus goes silent, in a matter of hours.

Intuitive Machines CEO Steve Altemus and Dr. Tim Crain discuss the decision to use a NASA experiment to land Odysseus near the south pole of the Moon. (Credit: NASA)