CAPE CANAVERAL, Fla. — It all comes down to the final six minutes of a six-month journey to Mars.

NASA’s Insight spacecraft will enter the Martian atmosphere at supersonic speed, then hit the brakes to get to a soft, safe landing on the alien red plains.

After micromanaging every step of the way, flight controllers will be powerless over what happens at the end of the road Monday, nearly 100 million miles away. The communication lag between Mars and Earth is eight minutes.

“By the time we hear anything, the whole thing is already done,” said project manager Tom Hoffman of NASA’s Jet Propulsion Laboratory. “Either it happened or it hasn’t happened.”

Any small last-minute adjustments must be completed 1 ½ hours before touchdown, said Rob Grover, lead engineer for the landing team.

“All of our efforts to make sure we’re successful all happen in the years before,” he explained.

A brief rundown of Insight’s do-or-die entry, descent and landing:

Insight will come in like a 12,300-mph arrow, piercing the top of the Martian atmosphere.