4mcpMission 4M transmitted its final message on November 11, 2014, with its primary lithium battery completely depleted after 438 hours of continuous operation—approximately four times the design lifespan for the extreme cold of space.
The 4M mission was a tribute to Manfred Fruchs, founder of LuxSpace's parent company, OHB Group, who died in April 2014 at the age of 75. The mission was attached to the Chinese Long March rocket, which launched in October 2014 carrying the Chang'e 5-T1 spacecraft, testing technology for a future lunar sample return mission.
LuxSpace's mission aimed to increase public interest in space exploration, and the 14 kg of useful signals transmitted continuously throughout the spaceflight were tracked by amateur radio operators worldwide. Prizes were offered to more than 75 people who received the signals. Another objective was to promote LuxSpace's microsatellite approach to space missions in general.
Data collected by amateur radio operators would help demonstrate and develop a crowd-based approach to spacecraft tracking and navigation. Additionally, 4M was equipped with a small dosimeter that recorded radiation levels during the mini-probe's mission, especially as it passed through the Van Allen belt. This data will aid in the design of radiation shielding for future lunar missions.
The 4M space probe's electronic payload required approximately 4.5 watts of power. This was supplied by a battery consisting of 28 super-robust Saft LSH20 HTS primary lithium cells. The LSH20 HTS is designed to provide high energy in a compact, lightweight, and robust package, ensuring reliable power for demanding applications in spaceflight. Secondary power, to extend the mission's lifespan, was provided by solar panels working in conjunction with a rechargeable MPS lithium-ion (Li-ion) battery.
"We are delighted that Saft's lithium batteries played a vital role in the success of this groundbreaking project, which heralds a new era in the development of low-cost microsatellite missions," said Yannick Borthomieu, Product Manager for Satellites and Launches at the Saft Group. "Together with the Philae Lander, the 4M probe is an important benchmark demonstrating how our super-robust LSH20 HTS cells can easily meet the demands of even the most challenging space missions."
Upon returning from the Moon, the 4M probe entered a highly elliptical orbit around Earth for a period of 14 days. Depending on the solar panel illumination, 4M may occasionally wake up and re-establish transmissions.

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