A few hours after a successful liftoff on United Launch Alliance’s Vulcan rocket, Astrobotic’s first commercial lunar lander ran into serious trouble. The robotic Peregrine lander, still in orbit around Earth, appears to have a propellant leak that will prevent it from reaching the Moon.

There are 20 payloads aboard the Peregrine lunar lander, including five from NASA, which is paying Astrobotic about $108 million for delivery of its science instruments to the Moon’s surface. Peregrine was the first US-owned lunar lander to launch to the Moon in more than 50 years, and Astrobotic is one of 14 companies selected by NASA to deliver the agency’s scientific instruments to the lunar surface.

This program, called Commercial Lunar Payload Services (CLPS), is aimed at flying robotic precursor missions to the Moon before NASA astronauts land on the lunar surface in the agency’s Artemis program. Astrobotic’s CLPS mission was first to the launch pad.

Propulsion anomaly

Astrobotic’s ground controllers, working out of a control center at the company’s Pittsburgh headquarters, struggled to stabilize the spacecraft throughout Monday. The problem with the lander’s propulsion system initially prevented Peregrine from maneuvering into a Sun-pointing orientation needed to recharge its battery using solar power.

In additional updates, Astrobotic said the propulsion system malfunction would probably threaten the spacecraft’s ability to soft-land on the Moon. Engineers uplinked commands for the spacecraft to perform an “improvised maneuver”  to reorient its solar panels toward the Sun. That apparently worked, at least temporarily, and Astrobotic reported Peregrine was recharging its battery.

Another statement from Astrobotic released Monday afternoon painted a bleaker picture of the status of Peregrine Mission One.

“Unfortunately, it appears the failure within the propulsion system is causing a critical loss of propellant,” the company said. “The team is working to try and stabilize this loss, but given the situation, we have prioritized maximizing the science and data we can capture. We are currently assessing what alternative mission profiles may be feasible at this time.”

Astrobotic released an image from the Peregrine lander appearing show a section of distributed multi-layer insulation on the exterior of the spacecraft.  This was the “first visual clue” aligning with telemetry data indicating a propulsion system problem, Astrobotic posted on the social media platform X.

“Nonetheless, the spacecraft’s battery is now fully charged, and we are using Peregrine’s existing power to perform as many payload and spacecraft operations as possible,” Astrobotic said.

Peregrine’s control thrusters are struggling to keep the lander from an uncontrollable tumble, Astrobotic said. If the thrusters hold up to the extra burden, Astrobotic said Monday evening that the lander could remain in a stable Sun-pointing state for about 40 more hours, based on current fuel consumption.

An unmitigated propellant leak would certainly prevent Peregrine from achieving Astrobotic’s goal of landing on the Moon. If the mission went according to plan, the Peregrine lander would complete two long phasing loops around Earth before intercepting the Moon and entering lunar orbit in late January. Then, the Peregrine spacecraft would have ignited its main engines for a powered descent to the lunar surface around February 23.

But that’s not going to happen for this mission. “At this time, the goal is to get Peregrine as close to lunar distance as we can before it loses the ability to maintain its Sun-pointing position and subsequently loses power,” Astrobotic said Monday.

The Peregrine lander’s propulsion system uses a hypergolic propellant mixture, combining hydrazine fuel and a solution of nitric oxide and nitrogen tetroxide as the oxidizer. This is a tried-and-true architecture because hydrazine and nitrogen tetroxide immediately combust upon contact with one another, meaning the propulsion system doesn’t need an ignition source.

According to Astrobotic, the spacecraft has two tanks each of fuel and oxidizer, plus a fifth tank for helium pressurant. There are five main engines and 12 smaller attitude control engines.

Sharad Bhaskaran, Astrobotic’s Peregrine mission director, told Ars before the launch that the design for the lander’s propulsion system was “fairly simple and straightforward.”

But this was Astrobotic’s first space mission, so engineers were eager to learn how the spacecraft operated in orbit. “This is about proving the technology, proving the spacecraft can operate successfully and carry out its mission,” Bhaskaran said Friday. “You can do all the testing you want on the ground, and you can do all the simulations, but once you get to space, that’s when everything gets proven.”

https://arstechnica.com/?p=1994369