The CEO of IM invited Eric Berger into IM-1 Mission Control, clearly to try to pitch him that the mission was an “absolute success”. And after the visit, Berger agrees with him. He also learned some heretofore unrevealed information.
It turns out that Odysseus landed on the Moon without any altimetry data
Yikes. That’s incredible. No wonder the landing did not go well.Altemus [the CEO] said Tuesday that the flight computer onboard Odysseus was unable to process data from the NASA payload [the hastily patched in alternate nav system] in real time. Therefore, the last accurate altitude reading the lander received came when it was 15 kilometers above the lunar surface—and still more than 12 minutes from touchdown. That left the spacecraft, which was flying autonomously, to rely on its optical navigation cameras. By comparing imagery data frame by frame, the flight computer could determine how fast it was moving relative to the lunar surface. Knowing its initial velocity and altitude prior to initiating powered descent and using data from the inertial measurement unit (IMU) on board Odysseus, it could get a rough idea of altitude. But that only went so far.
"So we're coming down to our landing site with no altimeter," Altemus said.
And supposedly a photo is coming tomorrow taken by the lander at the moment of touchdown, just after one of the legs broke but it was still upright.Unfortunately, as it neared the lunar surface, the lander believed it was about 100 meters higher relative to the Moon than it actually was. So instead of touching down with a vertical velocity of just 1 meter per second and no lateral movement, Odysseus was coming down three times faster and with a lateral speed of 2 meters per second.
"That little geometry made us hit a little harder than we wanted to," he said.
But all was not lost. Based upon data downloaded from the spacecraft and imagery from NASA's Lunar Reconnaissance Orbiter, which flew over the landing site, Intuitive Machines has determined that the lander came down to the surface and likely skidded. This force caused one of its six landing legs to snap. Then, for a couple of seconds, the lander stood upright before toppling over due to the failed leg.