Israel’s Beresheet lunar lander imagery taken before crash landing on April 11.
Credit: SpaceIL and Israel Aerospace Industries (IAI)

A preliminary investigation of what caused Israel’s Beresheet crash landing on the Moon April 11 has found it appears that a “manual command” was entered into the spacecraft’s computer.

“This led to a chain reaction in the spacecraft, during which the main engine switched off, which prevented it from activating further,” according to a SpaceIL and Israel Aerospace Industries (IAI) statement.

Teams continue to investigate further, in order to understand the full picture of what occurred during the mission, the statement explains. “In the coming weeks, final results of the investigation will be released.”

Lunar Reconnaissance Orbiter (LRO).
Credit: NASA/GSFC

LRO lookout

Meanwhile, Researchers are on the lookout for a NASA piggyback experiment that could have survived the destructive April 11 crash landing of Israel’s lunar lander, Beresheet.

There will be repeat attempts to target the crash site by NASA’s Lunar Reconnaissance Orbiter (LRO).

Crash landing survivor? NASA Goddard Space Flight Center/MIT Laser Retro-reflector Array (LRA) for Lunar Landers.
Credit: SpaceIL/Courtesy Xiaoli Sun/GSFC

Along with high-power camera sweeps, LRO will be using an onboard Lunar Orbiter Laser Altimeter (LOLA), trying to detect a NASA-provided laser retro-reflector array in the Beresheet wreckage zone.

Called the NASA Goddard Space Flight Center/MIT Laser Retro-reflector Array (LRA) for Lunar Landers, the ball-shaped device was located on the top side of the Israeli lander.

Laser beaming

The size of a computer mouse, LRA is composed of eight mirrors made of quartz cube corners that are set into a dome-shaped aluminum frame. That array is lightweight, radiation-hardened and long-lived.

NASA experiment after installation (the array is mounted on the top of the spacecraft, lower left, at about 7 o’clock position).
Credit: SpaceIL/Courtesy Xiaoli Sun/GSFC

From the high-flying LRO, laser beams generated by LOLA would strike the device and then are backscattered from the lunar surface. For each laser beam, LOLA measures its time of flight, or range.

Overhead passes

While there will be many attempts to target the wreckage, LRO is only directly over the site twice per month, and one of those will be in darkness (not an issue for the laser), explains Massachusetts Institute of Technology’s David Smith, the principal investigator for LOLA and an emeritus researcher at NASA Goddard in Greenbelt, Maryland.

“But the site can be viewed on several passes around the ‘overhead’ pass by looking off to the side or forward or backward. This requires the spacecraft to slew or roll to see the target,” Smith adds. “That’s a decision that LRO makes to ensure there are no issues with regard to constraints on pointing close to the sun or star cameras being able to see the stars (and not the lunar surface),” he said, so the process requires requests for slew and role magnitudes and directions to the LRO project for a specific observation time.

Integrated on Israeli lunar lander, a NASA scientific payload consisting of a small Lunar Retroreflector Array (LRA).
Credit: NASA/Goddard Space Flight Center

Pointing requests

This is normal procedure, Smith said, but typically there’s need to submit pointing requests about a week in advance. That allows the LRO project to check on pointing abilities (there are limits) of LRO and on thermal effects and spacecraft solar array pointing for charging the batteries.

“It may take 10 to 15 minutes for the spacecraft to turn to the desired direction and another 15 minutes to return to its normal nadir mode for just a few seconds of observations,” Smith told Inside Outer Space.

The Israeli lunar spacecraft weighed only 1,322 pounds, or 600 kilograms.
Credit: Eliran Avital

“I am sure the project will start to attempt observations as soon as possible,” Smith said. LRO’s camera system and the laser are co-boresighted, “so when the camera slews to take an image the laser altimeter automatically goes with it and will attempt to make a range observation at the same time.”

At a speed of over 3,300 miles per hour (1.5 kilometers per second), the whole LRO observation period is over in a few seconds, Smith said.

Last image from failed Beresheet lunar lander, at a distance of 9 miles (15 kilometers) from the surface of the Moon.
Credit: SpaceIL and Israel Aerospace Industries (IAI)

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