Big test coming up for tiny satellites trailing Mars lander

FILE - This illustration made available by NASA in March 2018 shows the twin Mars Cube One project (MarCO) spacecrafts flying over Mars with Earth and...
FILE - In this undated photo made available by NASA in March 2018, engineer Joel Steinkraus uses sunlight to test the solar arrays on one of the Mars ...

FILE - This illustration made available by NASA in March 2018 shows the twin Mars Cube One project (MarCO) spacecrafts flying over Mars with Earth and...

FILE - In this undated photo made available by NASA in March 2018, engineer Joel Steinkraus uses sunlight to test the solar arrays on one of the Mars ...

CAPE CANAVERAL, Fla. (AP) — A pair of tiny experimental satellites trailing NASA's InSight spacecraft all the way to Mars face their biggest test yet.

Their mission is to broadcast immediate news of InSight's plunge through the Martian atmosphere on Monday.

The twin CubeSats will pass within a few thousand miles (kilometers) of Mars as the lander attempts its dicey touchdown. They're named WALL-E and EVE after the main characters in the 2008 animated movie.

If they manage to relay InSight's radio signals to ground controllers nearly 100 million miles (160 million kilometers) away, the world will know within minutes whether the spacecraft landed safely.