Cape Canaveral, Fla.
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 on 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 1½ hours before touchdown, said Rob Grover, lead engineer for the landing team.
Six minutes before touchdown, InSight will come in like a 12,300-mph arrow, piercing the top of the Martian atmosphere about 77 miles above the surface. Engineers are shooting for a 12-degree angle of attack, almost parallel to the ground. Too steep, the spacecraft could burn up. Too shallow, it could bounce back into space. Atmospheric friction slows the spacecraft, but builds up heat. Its heat shield is made to withstand the 2,700 degrees Fahrenheit. Once InSight is down to seven miles, its parachute opens at a breakneck 860 mph.
Three minutes before touchdown, shortly after the white nylon chute opens with a yank, InSight ditches its heat shield and unfolds its three legs. After two minutes of descending under the parachute, the spacecraft, still supersonic, starts using radar to determine speed and altitude, from about 1½ miles up. Less than a minute remains until touchdown. With its speed now down to 134 mph, the lander dumps its back shell and parachute. It is less than a mile above the ground.
Almost immediately, InSight’s 12 descent engines start firing to further slow the lander and keep it away from the severed back shell.
InSight is aiming for a 5 mph touchdown in a plain near the equator called Elysium Planitia.
Touchdown should be around 3 p.m. on the East Coast.