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A snag in the computer systems Monday night missed an Israeli lunar engine a planned adjustment of its trajectory towards the moon, said engineers Tuesday.
The Beresheet aircraft maneuver was postponed after the spacecraft's on-board computer performed an independent restart. As a result, the craft automatically canceled a planned engine combustion to keep it on track for a lunar landing in April.
"For the moment, we are not very worried. Of course, it's not pleasant, but we remain optimistic, "said SpaceIL General Manager Dr. Ido Anteby.
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Tuesday engineers were still reviewing the data to understand what had happened. Opher Doron, general manager of the Space Division at Israel Aerospace Industries, said the engineers had not encountered a similar problem during the simulations.
The spacecraft is yet to land on the moon on April 11, while engineers have built several buffer days in case of delay, said Doron.
Beresheet heads to the moon through a roundabout that helps the tiny, car-sized spacecraft save fuel. The spacecraft will circle the Earth six or seven times in a series of growing ellipses before jumping into the moon's orbit on April 4.
The mishap occurred one day after Beresheet completed its first maneuver by pulling its engine tens of thousands of kilometers from the Earth. The first maneuver was at the farthest point of the first ellipse, pushing the spacecraft toward a second, larger ellipse.
The second maneuver, scheduled for Monday night, was to take place at the closest point of the Earth along the first ellipse, just 600 kilometers above the northern hemisphere.
The engineers only come into contact with the satellite for about half an hour every four hours, but Anteby said all the communication windows were working as expected. "We know that we are going to lose communication, then we wait, wait and wait for her to come back, and she does not always return exactly the same time you expect," he said. "And then, suddenly, you resume communication and this time, we saw that the maneuver was not over."
After the successful launch of Beresheet in early Friday morning space, the control room team began to look into a small problem with its star navigation system. The navigation system allows the spacecraft, which turns in space, to determine its orientation. Understanding the direction is crucial for a number of operations, especially to ensure that the onboard engines that direct the spacecraft to the right trajectory are activated in the right direction. Anteby said on Tuesday that engineers were checking whether the unintentional reset was a side effect of the problems with the star navigation system.
A computer simulation shows the route that will take the shuttle Beresheet to the moon, with a series of larger ellipses around the Earth until it reaches an orbit around the moon. (courtesy SpaceIL)
Aviv Priel, an engineer who is part of the team that controls the maneuvers of the spacecraft, said his team had discussed the desirability of postponing planned maneuvers while trying to better understand the problem of navigation by stars.
Priel added that the team thought that the glare of the sun on the spacecraft's sensors made the orientation of the spacecraft more difficult than expected, depending on the position of the stars. However, he added that the problem only occurs from certain angles and that the team is up to now able to manipulate the spacecraft to get a complete reading.
"The problem with star tracking is that it has brought a lot of uncertainty with the first maneuver," said Priel, referring to Sunday's successful maneuver. "At times, we did not know if we had to postpone it. But we overcame it, we implemented it and it was beautiful to see. During the [first] maneuver, we had an online communication – not immediately, with a delay of about two seconds, but we saw it almost in real time.
"It was very exciting to see the main engine running and the measurements and the star navigation system working," he said. "It was exciting and breathtaking too."
A SpaceX Falcon 9 rocket takes off with Israeli Lunar Lander and an Indonesian telecommunication satellite at Space Launch Complex 40, on February 21, 2019, in Cape Canaveral, Florida (AP Photo / Terry Renna)
Beresheet, which means "Genesis" in Hebrew, was lifted from Cape Canaveral on top of a Falcon 9 rocket from the private SpaceX company of entrepreneur Elon Musk.
In case of success, Beresheet will enter the story twice: as the first private sector on the Moon and the first from Israel.
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