India became only the fourth nation in history to send a spacecraft to Mars orbit when the Mars Orbiter Mission (MOM) took up residence above the red planet. Now, eight years later, the Indian Space Research Organisation (ISRO) reports that MOM has gone offline, and it is not expected to come back. It’s sad to see MOM go, but the mission lasted much longer than its expected six to 10-month lifespan.

MOM, also known as Mangalyaan, arrived in orbit of Mars in September 2014, less than a year after it launched aboard an ISRO Polar Satellite Launch Vehicle. MOM was designed to be a technology demonstration mission, but it was still equipped to do science. It carried instruments to analyze the planet’s atmosphere, as well as a high-resolution camera. It beamed back numerous images of surface details, as well as data on the planet’s thin atmosphere and dust storms.

It’s unclear what finally caused the aging satellite to go offline, but the agency has confirmed it is not recoverable. It’s possible Mangalyaan ran through the last of its fuel — it had a limited supply of 1,880 pounds (852 kilograms) at launch. Without fuel, the spacecraft cannot control its attitude to keep the communication array pointed at Earth. There’s also some speculation that the satellite’s automated recovery system failed, causing it to change orientation and point the antenna away from Earth.

One of the full-disk images of Mars sent back by MOM.

Another possibility is that MOM ran down its battery. It relies on three solar panels to generate up to 800W of power for its lithium-ion cells. However, eclipses drain the battery, which has a limited capacity — the Mars Orbiter Mission expended a substantial amount of its fuel five years ago to shorten the duration of these periods. An ISRO official told The Hindu that it recently encountered back-to-back eclipses lasting more than seven hours. MOM was only designed to handle an eclipse duration of 100 minutes. The long eclipses may have drained the battery beyond the safe limit, causing the probe to lose contact.

Most missions to the red planet cost hundreds of millions of dollars, but India managed to launch MOM for a mere $25 million. It would have been a bargain even if it didn’t exceed the original six-month design life. Despite knowing that Mangalyaan is gone forever, the ISRO is still investigating the cause. This could give engineers something to think about as India moves toward another Mars mission and a rover in the latter half of this decade.

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