Odie and SLIM Asleep on the Moon

Sundown has returned to the area of the Moon where two small lunar landers — one Japanese, one American — have been collecting imagery and data. Both are powered only by solar cells, so when the Sun sets the surface and the landers literally go dark. They are not designed to survive the bitter cold 14-day lunar nights, but Japan’s SLIM beat the odds and returned to life for a few days this week. Time will tell if it can do that again and if the U.S. lander, Intuitive Machines’ Odyssesus, or Odie, will wake up later this month.

Whether or not they awaken, the landers are considered successful by their sponsors even though the landings were not without drama.

The Japan Aerospace Exploration Agency’s Smart Lander for Investigating Moon, SLIM, landed on January 19 Eastern Standard Time (EST) making Japan just the fifth country to successfully put a lander on the Moon. The Soviet Union and the United States did it in the 1960s and 1970s, China and India more recently.

SLIM lost an engine during descent and landed upside down and had to wait a few days until the Sun-angle changed to really get to work. But it sent back images and data, slept through the first lunar night, and awakened this week enough to send back another image from its navigation camera.

3/1午前3時過ぎ（日本標準時）にしおりクレータは日没を迎え、SLIMは再び休眠に入りました。厳しい温度サイクルを繰り返すことになるため故障確率は上がりますが、次回の日照（3月下旬）でもSLIMは再び運用を試行する予定です。#JAXA #SLIM #たのしむーん

2/29 23:00過ぎ 航法カメラによる周辺画像 pic.twitter.com/xutv56uSU9

— 小型月着陸実証機SLIM (@SLIM_JAXA) March 1, 2024

Unfortunately just as the Moon gets bitter cold at night, it is broiling hot in the daytime and thermal control was a problem when operations resumed this week. Even though they could get an image from the navigation camera, JAXA said the Multi Band Camera (MBC) did not work properly. SLIM is in the Shioli crater where JAXA said the Sun set today, March 1, at 3:00 am Japan Standard Time (February 29, 1:00 pm EST). They will try again to contact SLIM in late March when the Sun returns, but “the probability of failure will increase due to repeated severe temperature cycles.”

The U.S. lander, Odysseus, is owned by a private company not the government and is the first commercial lander to soft-land on the Moon. Houston-based Intuitive Machines (IM) is one of several companies building landers through Public-Private Partnerships with NASA under the Commercial Lunar Payload Services (CLPS) program. NASA purchases lunar delivery services from companies that design, build and own the landers and procure launch services. NASA expects the companies to find non-NASA customers to close the business case. Odie is carrying six payloads from NASA and six from commercial customers.

In a news conference on Wednesday, NASA and IM declared Odie a success. IM anticipated Odie’s solar cells would lose access to sunlight that evening, but the lander persevered just a bit longer, sending back an image captured on landing day, February 22.

Before its power was depleted, Odysseus completed a fitting farewell transmission. Received today, this image from February 22nd showcases the crescent Earth in the backdrop, a subtle reminder of humanity’s presence in the universe.

Goodnight, Odie. We hope to hear from you… pic.twitter.com/RwOWsH1TSz

— Intuitive Machines (@Int_Machines) February 29, 2024

Time will tell if either lander wakes up when the Sun returns. Neither the batteries nor the electronics are designed to survive -250°C (-418°F) temperatures.  These new types of lunar landers, less expensive but also less resilient, do not have radioisotope power sources like the Soviet, U.S., and Chinese lunar landers.