NASA tackling mysteries of Mars’ deepest interior
Mission will probe Red Planet’s history, geophysical activity
NASA’s Mars InSight spacecraft, scheduled to launch on Saturday, is headed to one of the most boring places on the Red Planet.
Its landing spot will be Elysium Planitia, an idyllically named expanse that will most likely be flat as far as the spacecraft’s eyes can see — no mountains in the distance, probably not even many large rocks nearby.
“We picked something as close to a 100-kilometer-long parking lot as we could find anywhere,” said Bruce Banerdt, the mission’s principal investigator.
He said that one of his colleagues described it as “Kansas without the corn.”
Which is exactly what the scientists want.
InSight — the name is a compression of the mission’s full name, Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport — is in many ways a diversion from “follow the water,” the mantra that has kept NASA focused on the possibility that the sun’s fourth planet may have once been hospitable for life.
This mission will instead probe the mysteries of Mars’ deep interior and help answer geophysical questions about the planet’s structure, composition and how it formed.
Since there was not much interest in what InSight will find at the surface, a safe — that is, flat — landing spot was selected.
Mars is, like Earth, largely rock. But it is considerably smaller — half as wide as Earth and one-ninth the mass. A cubic foot of Mars weighs, on average, 245 pounds, making it almost 30 percent less dense than Earth. (Because Mars is smaller, the gravity is weaker, and the center is not squeezed as tightly.)
It was only in 2003 that scientists, delving into tiny variations in Mars’ gravitational pull on one of NASA’s orbiting spacecraft, concluded that the core must still be at least partly molten.
Many other details remain unknown. How often does the ground shake with marsquakes? Just how big is the core? How thick is the crust? How much heat is flowing out?
“We know some, but we don’t know a lot,” Banerdt said. The new mission aims to provide “foundational information of the planet’s history and its activity,” he added. “I’m looking forward to making the first map of the inside of the planet.”
The 1,380-pound spacecraft is currently sitting on top of an Atlas 5 rocket at Vandenberg Air Force Base in California. Launch is scheduled at 4:05 a.m. local time on Saturday.
Tagging along for the ride is Mars Cube One — two briefcasesize satellites that are to test communications technologies for relaying signals from InSight to Earth. This will be the first time such small satellites, known as CubeSats, have been sent on an interplanetary journey.
If weather or other issues prevent a Saturday launch, NASA has additional opportunities over the next five weeks to get InSight off the ground before Mars and Earth move too far out of alignment. Even if the launch slips, InSight’s arrival date at Mars remains the same: Nov. 26.
After landing, InSight will take a few months to deploy two instruments: a dome-shaped package containing seismometers and a heat probe that will hammer itself about 16 feet into the Martian soil.
The $814 million mission hinges on detecting something that has never been definitively detected before: marsquakes.
That is not for lack of trying. NASA’s two Viking landers in the 1970s carried seismometers. Only the one aboard Viking 2 was successfully deployed. But it was mounted on the spacecraft, and not placed on the ground, so it ended up measuring the buffeting of wind gusts rather than marsquakes.
Scientists are confident that temblors course around and through the planet. The planet is cooling and shrinking, and its crust most likely occasionally cracks, setting off a marsquake up to magnitude 6.0 or maybe even 7.0.
Similar rumblings are known to occur on Earth’s moon, which is smaller than Mars. Moonquakes were recorded by seismometers placed on the surface by NASA astronauts during the Apollo moon landings.