On Monday, December 19, the InSight lander released final messages before entering total hibernation that read:
"My power's really low, so this may be the last image I can send."
"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."
The lander has been on a mission to Mars to study its deep interior. However, a build-up of dust on its solar panels has caused it to slowly lose power. Earlier this summer, the lander had so little remaining power that the mission turned off all of InSight's other science instruments to keep the seismometer running.
NASA will declare the mission over when InSight misses two consecutive communication sessions with the spacecraft orbiting Mars. According to NASA, "there will be no heroic measures to re-establish contact with InSight."
https://mars.nasa.gov/news/9321/nasa.../?site=insight