Two lunar landers have fallen over – but they’re still doing okay

Both of the landers currently on the surface of the moon have ended up lying on their sides, but they still appear to be functioning surprisingly well.

The Smart Lander for Investigating Moon (SLIM) launched by the Japan Aerospace Exploration Agency (JAXA) touched down on the moon on 19 January, marking a milestone for Japan as its first lunar lander. US company Intuitive Machines landed its Odysseus spacecraft – nicknamed Odie – on the lunar surface on 22 February, becoming the first private company to successfully put a spacecraft on the moon.

Despite being on its side, Odysseus’s solar panels have been functioning since it landed. However, the antenna that is supposed to point towards Earth to transmit data isn’t oriented correctly, slowing the flow of information. Odysseus has been taking data and slowly sending images back to Earth, but its solar panels will soon be bathed in the frigid darkness of lunar night.

“Once the sun sets on Odie, the batteries will attempt to keep the vehicle warm and alive, but eventually it’ll fall into a deep cold,” said mission director Tim Crain in a press conference on 23 February. “Of course, the next time the sun illuminates the solar arrays, we’ll turn our dishes to the moon, just to see if the radios and the batteries and the flight computers survive that deep cold.” Odysseus is expected to stop transmitting on 27 February, according to a post on X from Intuitive Machines.

The two landers are both near the moon’s south pole, but they are far enough away from one another that their days begin and end at different times – as the sun goes down on Odysseus, it will still be midday where SLIM is settled.

But because it was also tilted on its side when it landed, SLIM’s solar panels were not collecting any sunlight, so a few hours after its landing, its operators shut it down to preserve battery life. The hope was that if the solar panels did become illuminated as the sun moved across the sky, it could turn on again. This occurred nine days later, but only lasted for a few days before the lander was plunged into lunar night, with temperatures dropping as low as -133°C (-208°F) – far too cold for the spacecraft to continue to function.

But it appears to have survived the deep freeze. On 25 February, the official SLIM account on X posted that a signal had been received from the lander. However, the post also stated: “As it was still midday on the moon, the temperature of the communication equipment was extremely high, so communication was terminated after only a short period of time.”

As the day wanes over the SLIM lander, its operators will try once again to establish communication. If this works, it may lend some hope that the Odysseus lander could survive lunar night as well. With several other landing attempts this year failing, that hope is much needed. In all, there are 10 missions planned for the the south pole of the moon this year, and in two more years the Artemis III mission aims to return astronauts to the moon for the first time in more than 50 years.