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Setback for Israeli lunar lander as computer glitch prevents scheduled maneuver

Will malfunctions thwart first Israeli mission to the Moon?

A hitch in computer systems Monday evening caused an Israeli lunar spacecraft to miss a scheduled adjustment in its trajectory en route to the moon, engineers reported on Tuesday.

The maneuver by the Beresheet craft was postponed after the space vehicle’s on-board computer executed an independent restart. As a result, the craft automatically canceled an engine burn scheduled to keep it on track for an April lunar landing.

“At the moment we are not very worried. Of course it isn’t nice, but we are still optimistic,” said SpaceIL CEO Dr. Ido Anteby.

Engineers on Tuesday were still examining the data to figure out what happened. Opher Doron, the general manager of the Space Division at Israel Aerospace Industries, said that the engineers had not encountered a similar problem during simulations.

The spacecraft is still set to land on the Moon on April 11, as engineers built in a number of buffer days in case of delays, said Doron.

Beresheet is headed to the moon through a roundabout path that helps the tiny spacecraft, about the size of a car, save on fuel. The spacecraft will circle Earth six or seven times in a series of growing ellipses before jumping into the moon’s orbit on April 4.

The setback came a day after Beresheet successfully completed its first maneuver by firing its engine while tens of thousands of miles away from Earth. The first maneuver was at the furthest point in the first ellipse, nudging the spacecraft toward a second, larger ellipse.

The second maneuver, set for late Monday night, was scheduled to take place at the closest point to earth along the first ellipse, just 600 kilometers (370 miles) above the northern hemisphere.

Engineers are only in contact with the spacecraft for about half an hour every four hours, but Anteby said all the communication windows are working as expected. “We know we are going to lose communication, and then we’re just waiting and waiting and waiting for it to come back, and it doesn’t always come back at exactly the same moment you expect,” he said. “And then suddenly you get the communication back, and this time we saw that the maneuver wasn’t completed.”

Following the successful launch of Beresheet into space early Friday morning, the team in the control room began looking into a small problem with its star navigation system. The navigation system allows the spacecraft, which is spinning in space, to figure out its orientation. Understanding the orientation is crucial for a number of operations, including ensuring that the onboard engines that direct the spacecraft to the correct trajectory are activated in the right direction. Anteby said on Tuesday that engineers were checking to see if the involuntary reset was a side effect of the issues with the star navigation system.

Aviv Priel, an engineer who is part of the team that controls the spacecraft’s maneuvers, said the team had discussed whether to put off the planned maneuvers while trying to understand more about the star navigation issue.

Priel said the team believes glare from the sun on the the spacecraft’s sensors is making it more difficult than expected for the spacecraft to orient itself according to the position of the stars. However, he added that the issue only happens at certain angles, and the team thus far is able to manipulate the spacecraft to obtain a full reading.

“The thing with the star tracker is it brought a lot of uncertainties with the first maneuver,” said Priel, referring to the successful maneuver on Sunday. “At some points, we weren’t sure if we should put it off. But we overcame it, we implemented it, and it was beautiful to see. During the [first] maneuver we had online communication — not immediately, with about a two-second delay, but we saw it almost real time.

“It was very exciting to see the main engine turn on and the measurements and the star navigation system working,” he said. “It was exciting and breathtaking as well.”

When Ofer Doron, a senior official at Israel Aerospace Industries, was asked Tuesday morning if the malfunction which occurred onboard the Beresheet spacecraft Monday night would endanger the mission to the Moon, he said the issue was still under examination.

“We still don’t know, we’re studying the issue. At the moment I am not terribly worried,” said Doron, adding that “the more we understand what caused the malfunction, the more we’ll know how to prevent it from happening again.”

“Basically, the whole thing happened when there was no communication,” with the spacecraft, Doron continued.

SpaceIL, the private company behind the launch, is still confident that Beresheet will complete its lunar landing on schedule, reaching the moon’s surface on April 11th.

SpaceIL CEO Dr. Ido Antebi said that at least for now, it does not appear that the malfunction will prevent the spacecraft from landing on the Moon on schedule.

“If we succeed in fixing the malfunction within a day or two, there’s no reason why the glitch should force a change in the date of arrival at the Moon.”


Image: A computer simulation shows the route that the Beresheet spacecraft will take the Moon, with a series of larger ellipses around the Earth until it reaches an orbit around the Moon. (courtesy SpaceIL)

Sources: The Times of Israel & Israel National News (Arutz Sheva)