Touchdown: lunar landings and load cells

Published On: January 31 2024

The team behind Japan’s latest moon mission must have breathed a sigh of relief when after a week of inactivity, their SLIM lunar lander had sufficient battery to restart itself.

The JAXA team suspected the issue arose when one of the the SLIM lander’s twin boosters failed just before landing. As a result, it landed on its side, with its solar panels pointing in the wrong direction. One of the mini rovers it released just before landing was able to take an image of the lander almost upside down on the slope of Shioli Crater. Only when the sun position changed did the panels receive sufficient light to recharge the batteries and resume operation.

As an article in Space News explains:

“The SLIM landing was intended to occur in two steps. First with landing thrusters down, then a smaller thruster firing to tip the spacecraft onto its side. SLIM is then cushioned by five crushable, 3D-printed aluminum lattice landing legs.”

(We’d bet that those crushable legs were tested to destruction using load cells at some point!)

 

The Eagle hasn’t landed

It’s not the first time a lunar landing has failed. It has been estimated that over half of lunar landings fail, including some very recent attempts:

  • Luna-25 crashed into the moon in August 2023, ending Russia’s first Moon lander mission in 47 years.
  • The Astrobotic and NASA lander peregrine was set to be the first U.S. mission to soft-land on the moon since Apollo 17. However, a fuel leak meant the lander was returned to earth and burned up on re-entry.

According to CBS News:

“A private lunar lander has never safely reached the moon’s surface — though other companies have tried. In 2019, a spacecraft built by Israel-based company SpaceIL smashed into the moon during a landing attempt. And again in 2023, Japan-based company Ispace lost control of its lander as it careened toward the moon’s surface.”

And it’s not just the moon that is an issue. In 2014, the European Rosetta mission sent the Philae lander to land on Comet 67P. The lander bounced off the surface.

 

Why do lunar landings fail?

According to an article in National Geographic:

“The engineering challenge of a lunar landing is trickier than docking with the space station … There’s no atmosphere to help slow down the spacecraft using parachutes, the pull of gravity increases speed on the way down, and much of the surface is strewn with boulders. Even in the sunlight, the shadows and glare can befuddle landing cameras and sensors.”

 

And the success stories

One of the most successful planetary exploration missions to date is NASA’s Mars Curiosity Rover. This has now notched up over 4,000 days on the red planet and continues to explore further afield from its landing site. We’ve written about its load cells before and you can check the latest mission updates here.

The Indian Chandrayaan-3 also touched down in August 2023 around 600km from the lunar South Pole. Its predecessor, Chandrayaan-2 , crashed on the lunar surface in 2019.According to the ISRO website the lander’s sensors include:

  • Laser Inertial Referencing and Accelerometer Package (LIRAP)
  • Ka-Band Altimeter (KaRA)
  • Lander Position Detection Camera (LPDC)
  • LHDAC (Lander Hazard Detection & Avoidance Camera)
  • Laser Altimeter (LASA)
  • Laser Doppler Velocimeter (LDV)
  • Lander Horizontal Velocity Camera (LHVC)
  • Micro Star sensor
  • Inclinometer & Touchdown sensors

You can check out more details and construction diagrams here.

 

Need load cells for your next space mission?

Or in fact any mission, project or adventure! We can design and manufacture specific load cells to your exact requirements. or browse our online store for a wide range of “off the shelf” load cells.