More info on the last minute update that took place while in orbit.... definitely not something you want to see happen and someone, somewhere feels like crap right now:
Fortunately, the only payload mounted on the side of the lander now facing the surface is a static payload: an artwork provided by artist Jeff Koons. Other commercial and NASA payloads are operating, and many of them collected data during the flight to the moon and during the descent to the surface.
One of those NASA payloads may have saved the mission. Engineers were able to use data from the Navigation Doppler Lidar instrument developed at NASA’s Langley Research Center to replace laser rangefinders on the lander that were not working.
Controllers discovered the problem with the lander’s laser rangefinders after going into orbit around the moon Feb. 21 and deciding to use them to more precisely measure the lander’s orbit, which was more elliptical than intended. The lasers, though, did not work, and engineers determined that a physical switch — a safety measure on the ground because the lasers are not eye-safe — was not flipped before launch.
“It was like a punch in the stomach. We were going to lose the mission,” Altemus recalled. Crain then found it would be possible to take the data from two lasers in the NASA instrument and incorporate them into the lander’s navigation system.
“In normal software development for a spacecraft, this is the kind of thing that would have taken a month,” Crain said. “Our team basically did that in an hour and a half.”
That process also provided a greater validation of the NASA payload than originally expected. “The technology performed flawlessly,” said Prasun Desai, NASA deputy associate administrator for space technology. “It acquired range and velocity data well above the required five-kilometer altitude as it was descending.”
He noted the goal of flying the payload was to achieve a technology readiness level (TRL) of 6 on a 1-to-9 scale, validating a prototype of the technology in a relevant environment. With its use on the landing, “we were able to get an operational system now, TRL 9. It’s ready to be used from now on.”
Altemus added it was “fortuitous” that Nova-C was in an elliptical orbit that prompted engineers to activate the laser rangefinder earlier than expected and thus discovered the problem. “That was fortunate and a bit of luck for us.”
In normal operations, Crain said, the laser rangefinders would not have been activated until after the lander began its powered descent to the surface. “We would have probably been five minutes to landing before we realized those lasers weren’t working,” he said.