After 4 years on Mars, NASA's InSight lander sends one last selfie and then falls silent

It could be the end of the red dusty line for NASA's InSight lander, which has fallen silent after four years on Mars.

The lander's power levels have been dwindling for months because of all the dust coating its solar panels. Ground controllers at California's Jet Propulsion Laboratory knew the end was near, but NASA reported that InSight unexpectedly didn't respond to communications from Earth on Sunday.

"It's assumed InSight may have reached the end of its operations," NASA said late Monday, adding that its last communication was Thursday. "It's unknown what prompted the change in its energy."