ORLANDO, Fla. — The lander came in hot — at 12,300 miles per hour — before it slowed to a stop on the surface of a large Martian plain, ending its six-month journey from Earth.
When NASA’s InSight lander stretched its legs on the Martian surface Monday afternoon shortly before 3 p.m. Eastern time, it was the eighth time in history that NASA successfully landed a probe on the Red Planet, and the first landing since 2012.
At NASA’s Jet Propulsion Laboratory control room in California, engineers jumped, wept and hugged as the data was transmitted back to Earth — on an eight-minute delay. That’s the time it takes for the radio signal to travel 91 million miles from Mars to Earth.
InSight traveled through space for more than six months, since it launched from California’s Vandenberg Air Force Base on May 5. Built primarily by Lockheed Martin Space, InSight cost the U.S. $813.8 million and France and Germany also pitched in $180 million for the lander’s investigations.
Its mission will be to study the interior of Mars for two years, analyzing the core of the planet, listening for marsquakes and burrowing 16 feet into its surface to take its temperature.
But getting there was the challenge. Landing on the Martian surface is exceedingly difficult: Only 40 percent of the missions ever sent to Mars have been successful — all of those sent by NASA. Going into Monday’s landing, the space agency was confident InSight would be able to pull off its arrival because the technology had already been tested on NASA’s Phoenix Mars Lander, which made its Martian descent in 2008.
But engineers at NASA still experienced what they call “seven minutes of terror” as the lander made its automated descent Monday afternoon.
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Coming in at six times the speed of a high-velocity bullet, and at an angle of precisely 12 degrees, the lander’s aeroshell cut through the Martian atmosphere at about 2:47 p.m. The heat shields on the aeroshell protected the lander from temperatures as high as 2,700 degrees Fahrenheit — enough to melt steel. It then deployed its parachutes to slow it down.
Once its heat shield popped off, InSight extended its three landing legs. Off came its back shell and parachute before InSight fired up its 12 descent engines, oriented itself and slowed to 5 mph before it touched down on the Martian surface.
The landing site was Elysium Planitia, a flat plain. Because the lander won’t be studying the surface of Mars, it needs to land in the safest place possible: a smooth expanse of lava fields without big hills and with few large rocks. The plain is near the equator in the northern hemisphere of the Red Planet.
It is early winter on Mars when InSight landed, with surface temperatures on Monday estimated to be 18 degrees Fahrenheit, before dropping to minus 140 degrees Fahrenheit overnight.
The lander will now stay on the planet until November 2020. It will jackhammer into the surface and extend its heat probe first to determine the Martian temperature, before staying still on the surface collecting data. The lander’s seismometer will then measure quakes on Mars and impacts from meteors. InSight will also emit radio waves that will let scientists on Earth determine how much Mars moves when it rotates, giving them a sense for the makeup of the core of the planet.
The data gleaned will help scientists better understand the makeup of Mars’ molten core and its crust. It could also help scientists understand what caused Mars, which was made from similar materials as Earth, to become a very different place from our own planet. The data could then help scientists when they are narrowing down what exoplanets to search for when looking for Earth-like worlds.
And once InSight is wrapping up its studies on Mars in 2020, NASA will be preparing to send its next rover to the Red Planet in search for signs of past microbial life.