Science

NASA lander survives harrowing descent to surface of Mars

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Twelve thrusters slowed InSight to the surface of Mars.

JPL-Caltech/NASA

Update: NASA’s InSight spacecraft survived its descent through the thin atmosphere of Mars and successfully landed on the planet’s surface today. Although hurdles remain to achieve operating status, the lander is well positioned to begin to take Mars’s heartbeat in the next few months.

“It was intense, and you could feel the emotion,” says NASA Administrator Jim Bridenstine in Washington, D.C.

NASA was able to quickly confirm the landing thanks to a flawless performance by two tiny satellites that accompanied the lander. These CubeSats caught and relayed InSight’s signal to Earth, along with a bonus: a first picture of the terrain where the lander will place its two instruments.

Although the picture is obscured by motes of dust on the camera, the terrain looks promising, says Rob Manning, chief engineer at the Jet Propulsion Laboratory (JPL) here. “It looks like there’s not a lot of rocks in the field of view.” A confirming “beep” of health, sent directly from InSight followed, soon after the CubeSat relay. Now, the agency must wait 5 hours for confirmation that the lander’s solar panels have been deployed.

Here is our story from earlier today:

PASADENA, CALIFORNIA—A boring spot on Mars is about to get real interesting. Later today, at 11:54 a.m. PST, NASA’s $814 million InSight spacecraft will attempt to land on a flat lava plain near the martian equator. The mission will be NASA’s first landing on the Red Planet since the Curiosity rover in 2012.

“I’m really confident, personally, that we’re going to land safely,” says Bruce Banerdt, the mission’s principal investigator here at JPL. “Doesn’t mean I’m not nervous.”

The size of an SUV, InSight is designed to explore the martian interior by sensing “marsquakes.” It has spent the past 6 months uneventfully cruising through space, making occasional tweaks to its trajectory. That calm will break at 11:41 a.m., when the spacecraft pivots and presents its heat shield to the atmosphere. At 11:47 a.m., the spacecraft will begin its screaming plunge toward the surface; friction will send temperatures on the heat shield soaring to 1500°C.

The descent will take just over 6 minutes, less than the “7 minutes of terror” made famous by the Curiosity rover. (And also less than the 8 minutes it takes for communication to reach Earth from Mars; all times in this story reflect the arrival of InSight’s signal.) Based on NASA’s Phoenix spacecraft, which landed in 2008, InSight uses retrorockets to slow the craft directly, rather than a “sky crane” to lower itself like Curiosity. But InSight is heavier than Phoenix, and its landing site is 1.5 kilometers higher, which means there is less atmosphere to slow the spacecraft. This meant reinforcing InSight’s heat shield and parachute suspension lines.

After deploying the parachute, InSight will discard its heat shield and extend three legs. A belly-mounted radar will begin to sense the approaching ground. After detaching from the parachute, 12 thrusters will slow the lander’s descent to just over 2 meters per second before it touches down.

If all goes as hoped, NASA will catch word of a safe landing thanks to two briefcase-size spacecraft that launched with InSight, together called Mars Cube One (MarCO). These first-ever interplanetary CubeSats sport experimental antennas that will relay InSight’s signal to Earth some 10 to 20 seconds after landing. A small fuel leak on one of the CubeSats has forced its engineers to creatively compensate, angling the spacecraft so the leak pushes in the desired trajectory, says Joel Krajewski, MarCO’s project manager at JPL. “The current trajectory is completely good.”

The MarCo satellites could also relay InSight’s first picture of its landing site. The image, which could come several hours after landing, relayed by an orbiter passing overhead, will be fuzzy—the lander’s two cameras will still have dust caps on. But it should be enough to give JPL’s scientists a good look at their landing site. “Hopefully it’ll be flat and boring,” says Tom Hoffman, the mission’s project manager at JPL.

If MarCO doesn’t do the job, NASA should still hear a “beep” directly from InSight by 12:01 p.m. Yet one of the most critical phases of the landing won’t occur until 16 minutes after touchdown, when the dust kicked up by its landing has settled and Insight unfurls its two solar panels. A status report on the panels won’t arrive until some 5 hours after landing. “Frankly, I will be a little bit nervous until I have the solar panels out,” Hoffman says. “After that, we should be in good shape.”

NASA scientists chose InSight’s landing zone, the vast and dull Elysium Planitia, because they’re interested in Mars’s interior, not its surface. Rocks on the surface could complicate placing the lander’s two primary instruments—a sensitive seismometer and a heat probe—directly on the surface with a robotic arm. It will take several months for the InSight team to choose where to place them. The process mirrors selecting a landing site, and both endeavors have been led by the same JPL scientist, Matthew Golombek. “It’s pretty simple,” he says. “We don’t want a rock underneath. We don’t want a slope that’s too steep. We don’t want underdense material for it to sink into.”

Once mission managers are ready, InSight’s robotic arm will pluck the volleyball-size seismometer from the lander’s deck and place it on the ground, with its power provided by a tether. The arm will then place a wind and heat shield on top of it like a bell jar. The station, developed by French partners, will catch rumbles of marsquakes, important for interpreting the planet’s interior. To avoid the wind vibrations that could trip up its measurements, it will be placed as far away from the lander as possible, up to the arm’s limit of some 1.5 meters away.

The heat probe, developed by German partners, will be deployed soon after. Over the course of a few weeks, it will drive a rod 5 meters into the surface with thousands of strokes of a tungsten hammer, slipping around small rocks—and hopefully not hitting large ones. The heat probe will measure how much heat is escaping from the planet, and how quickly—a clue to when it was most volcanically active. But if there’s only one ideal instrument site, the seismometer takes priority, Golombek says, as it is InSight’s primary scientific payload.

Once all this work is complete, InSight can finally get down to business, using the 50 to 100 marsquakes it might see over its 2-year primary mission to reveal the dimensions and composition of the martian interior—and, in turn, the story of its creation.

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