NASA's InSight Mars lander has sent what will likely be its final communication from the Red Planet, posting a picture of its dust-covered seismometer on Twitter accompanied by a tear-jerking farewell message.
"My power's really low, so this may be the last image I can send," the message read.
"Don't worry about me though: my time here has been both productive and serene.
"If I can keep talking to my mission team, I will — but I'll be signing off here soon. Thanks for staying with me."
InSight — which stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport — landed on Mars in November 2018 tasked with studying the make-up of the planet's interior and monitoring meteorite activity.
Its landing site, on a volcanic plain near the equator known as Elysium Planitia, was chosen for its flat, featureless landscape, allowing for more accurate seismic measurements to be taken directly from the surface.
The lander achieved its primary scientific goals by the end of 2020, after which NASA extended its mission for another two years.
However, its reliance on solar power and Mars's regular dust storms meant the mission would always be a short-term affair.
The @NASAInSight Twitter account — managed by the NASA team back here on Earth — has been tweeting in the first person throughout the lander's mission, gaining more than 771,000 followers in the process.
It has become known for posting "selfies" taken using the lander's robotic arm, as well as showing off "postcards" sent by well-wishers on Earth.
Mission was always 'at Mars's mercy'
Last month NASA warned the InSight mission was almost at an end, as dust collecting on the lander's solar panels had left it operating at well below 20 per cent of its original generating capacity since midway through the year.
The space agency had turned off all of InSight's scientific instruments except its seismometer in an attempt to extend the mission, however it said InSight was unlikely to remain operational for more than "a few more weeks".
"We're at Mars's mercy. Weather on Mars is not rain and snow; weather on Mars is dust and wind," said the mission's principal investigator, Bruce Banerdt of NASA's Jet Propulsion Laboratory.
"We'll keep making science measurements as long as we can."
NASA said it would declare the mission over when InSight missed two consecutive communication sessions with the Mars Relay Network, five spacecraft currently orbiting the planet.
NASA's Deep Space Network will listen in for a time after that, however the space agency said there would be "no heroic measures" to re-establish contact with the lander.
Once the mission is over, Foresight, a full-size engineering model of InSight kept on Earth to allow scientists to practice deploying scientific instruments, will be crated and placed in storage "with loving care", Dr Banerdt said.
"It's been a great tool, a great companion for us this whole mission," he said.
