Astrobotic knew its first area mission can be rife with dangers. In any case, the corporate’s Peregrine spacecraft would try one thing by no means completed earlier than—touchdown a business spacecraft on the floor of the Moon.

Probably the most hazardous a part of the mission, really touchdown on the Moon, would occur greater than a month after Peregrine’s launch. However the robotic spacecraft by no means made it that far. Throughout Peregrine’s startup sequence after separation from its United Launch Alliance Vulcan rocket, one of many spacecraft’s propellant tanks ruptured, spewing treasured nitrogen tetroxide into area. The incident left Peregrine unable to land on the Moon, and it threatened to kill the spacecraft inside hours of liftoff.

“What a wild journey we have been simply on, not the result we have been hoping for,” mentioned John Thornton, CEO of Astrobotic.

Astrobotic’s management crew, understanding of the corporate’s headquarters in Pittsburgh, swung into motion to save lots of the spacecraft. The propellant leak abated, and engineers wrestled management of the spacecraft to level its photo voltaic arrays towards the Solar, permitting its battery to recharge. Over time, Peregrine’s scenario stabilized, though it did not have sufficient propellant remaining to try a descent to the lunar floor.

Peregrine continued on a trajectory out to 250,000 miles (400,000 kilometers) from Earth, about the identical distance because the Moon’s orbit. Astrobotic’s unique flight plan would have taken Peregrine on one lengthy elliptical loop round Earth, then the spacecraft would have reached the Moon throughout its second orbit.

On its method again towards Earth, Peregrine was on a flight path that may deliver it again into the ambiance, the place it could dissipate on reentry. That meant Astrobotic had a choice to make. With Peregrine stabilized, ought to they try an engine burn to divert the spacecraft away from Earth onto a trajectory that would deliver it to the neighborhood of the Moon? Or ought to Astrobotic maintain Peregrine in line to reenter Earth’s ambiance and keep away from the danger of sending a crippled spacecraft out to the Moon?

Making lemonade out of lemons

This was the primary time Astrobotic had flown an area mission, and its management crew had a lot to be taught. The malfunction that brought on the propellant leak seems to have been with a valve that didn’t correctly reseat through the propulsion system’s initialization sequence. This valve activated to pressurize the gasoline and oxidizer tanks with helium.

When the valve did not reseat, it despatched a “rush of helium” into the oxidizer system, Thornton mentioned. “I describe it as a rush as a result of it was very, very quick. “Inside somewhat over a minute, the strain had risen to the purpose within the oxidizer aspect that it was effectively past the proof restrict of the propulsion tank. We imagine at that time the tank ruptured and led to, sadly, a catastrophic lack of propellant … for the first mission.”

Thornton described the glum temper of Astrobotic’s crew after the propellant leak.

“We have been coming from the very best excessive of an ideal launch and got here right down to the bottom low, after we discovered that the spacecraft now not had the helium and now not had the propulsion wanted to try the Moon touchdown,” he mentioned. “What occurred subsequent, I feel, was fairly outstanding and galvanizing.”

In a press briefing Friday, Thornton outlined the obstacles Astrobotic’s controllers overcame to maintain Peregrine alive. With out a wholesome propulsion system, the spacecraft’s photo voltaic panels weren’t pointed on the Solar. With a couple of minutes to spare, one in every of Astrobotic’s engineers, John Shaffer, devised an answer to reorient the spacecraft to begin recharging its battery.

As Peregrine’s oxidizer tank misplaced strain, the leak fee slowed. At first, it appeared just like the spacecraft might need solely hours of propellant remaining. Then, Astrobotic reported on January 15 that the leak had “virtually stopped.” Mission controllers powered up the science payloads aboard the Peregrine lander, proving the devices labored and demonstrating the spacecraft might have returned knowledge from the lunar floor if it landed.

The small propulsive impulse from the leaking oxidizer drove Peregrine barely off target, placing it on a course to deliver it again into Earth’s ambiance. This arrange Astrobotic for a “very tough resolution,” Thornton mentioned.

Nudging Peregrine off its collision course with Earth would have required the spacecraft to fireside its fundamental engines, and even when that labored, the lander would have wanted to carry out extra maneuvers to get near the Moon. A touchdown was nonetheless out of the query, however Thornton mentioned there was a small probability Astrobotic might have guided Peregrine towards a flyby or influence with the Moon.

“The factor we have been weighing was, ‘Ought to we ship this again to Earth, or ought to we take the danger to function it in cislunar area and see if we will ship this out farther?'” Thornton mentioned.