Why Did Israel’s Lander Crash on the Moon Yesterday?

We don’t know the exact details yet, but they told us which part failed first, leading to the crash. Crashing a spacecraft on the Moon was not part of the plan for Israel, but the historic Beresheet lander did reach and orbit that familiar heavenly body. It did so taking the longest route of any craft ever to reach the Moon’s surface, four million miles. The craft sent these two images before the failed landing:

Image from 13.7 miles above the Moon’s surface.
Last image before crash, April 11, 2019

The problem is described by the team so far as a chain of events that disrupted the main engine during descent to the Moon’s surface.

The craft, named Beresheet (translated: in the beginning), was slated to touch down on the surface of the Moon at approximately 3:25 PM PST, but communications with the vessel were lost upon impact. 

Via TheNextWeb

… “Preliminary data supplied by the engineering teams of SpaceIL and Israel Aerospace Industries (IAI) suggests a technical glitch in one of Beresheet’s components triggered the chain of events yesterday that caused the main engine of the spacecraft to malfunction,” the Mission explained, in a statement released Friday. “Without the main engine working properly, it was impossible to stop Beresheet’s velocity. Beresheet overcame the issue by restarting the engine. However, by that time, its velocity was too high to slow down and the landing could not be completed as planned.”

More at FoxNews

Crash debris from the uncrewed Israeli lander Beresheet will permanently occupy the lunar surface after SpaceIL’s effort to land on the moon failed Thursday (April 11). It was a disappointment for the program and a setback for the private Israeli company’s efforts to join the small community of organizations that have successfully landed on Earth’s nearest neighbor.

Via link

Communications were lost with the spacecraft just 150 meters (!!!) above the surface

Via Buzz Aldrin Twitter

Preliminary technical information collected by the teams shows that the first technical issue occurred at 14 km above the Moon. At 150 meters when the connection with #Beresheet was lost, it was moving at 500 km/h, making a collision inevitable.

Via TeamSpaceIL Twitter

“If at first you don’t succeed, try try again,” Netanyahu said. He vowed to put an Israeli spacecraft on the moon “intact” in the next two years.

About 20 minutes before the scheduled landing, engine firings slowed Beresheet’s descent. Engineers watched in silence as the craft glided toward a free-fall.

But then viewing screens showed the engine misfiring and the velocity surging as it headed toward the lunar surface. Radio signals from the spacecraft abruptly cut off.

Scientists, who were giddy with excitement only seconds earlier, were visibly distraught, and celebrations at viewing centers across the country were dashed.

Via JournalGazette

There was initially a failure in an inertial measurement unit and this lead to an unplanned shutdown of the engines.


It’s been reported, based on information from the livestream, that an Inertial Measurement Unit failed and the team was unable to reset the component due to a repeated loss of communications with the JPL network. The entire spacecraft was reset to restore communications and control, but this appears to have come too late. By the time connectivity was restored, the spacecraft was moving too quickly to be fully braked before impacting the lunar surface.

Via ExtremeTech

What is an inertial measurement unit?

Inertial Measurement Units (IMUs) [are] self-contained system[s] that [measure] linear and angular motion usually with a triad of gyroscopes and triad of accelerometers

Via Xsens

… an electronic device that measures and reports a body’s specific force, angular rate, and sometimes the magnetic field surroundings the body, using a combination of accelerometers and gyroscopes, sometimes also magnetometers. IMUs are typically used to maneuver aircraft, including unmanned aerial vehicles (UAVs), among many others, and spacecraft, including satellites and landers. 

Via Wikipedia

It was really a comparatively inexpensive project, so some malfunction is not so unexpected if you consider the budget.

The project cost a measly $100 million. By comparison the Apollo Program would have figured at around $80 billion by today’s rates. 

A nice mission for the next craft would be to land, pick up the bits of the older crashed craft and bring them home… but I suspect that won’t happen any time soon.


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