Science & Technology

Forget Rovers: NASA's InSight Lander Will Learn About Mars By Sitting Still

Let's face it: NASA is good at generating cute Mars rovers that collect tons of scientific data. The Opportunity rover has crawled more than a marathon on Mars since landing at Meridiani Planum in 2004, exploring the rim of a huge crater and finding tons of evidence of water to boot. And in 2012, the Curiosity rover touched down in Gale Crater and found an ancient water streambed within weeks of its arrival. Today, Curiosity is making its way up a mountain (Mount Sharp) and trying to learn about the Martian climate by looking at the layers of strata.

So you'd be forgiven for thinking the Mars InSight mission — which launches no earlier than Saturday, May 5 (click here to see how you can watch it live!) — isn't as exciting, because this lander is just going to sit still on the surface. With no new vistas appearing in the camera view every few days or weeks, why bother going at all? Truth be told, InSight needs to sit quietly because it's doing something entirely different. It's trying to teach us about the insides of Mars. Here's why that's important.

This artist's concept shows the InSight lander, its sensors, cameras and instruments.
An artist's rendering of a rocket launching with the InSight spacecraft in May.

Subtle Science

The science InSight performs requires a lot of patience. For example, scientists are interested in how big the core of Mars is, and what that core is made of. That's important to help us understand rocky planets in general. The rocky planets Mercury, Venus, Earth, and Mars formed out of the same material — at least, we think they did — but they all have different environments.

Mercury is a barren planet, similar to Earth's moon. Venus is a hellish world with volcanic eruptions. Mars has a thin atmosphere that disappeared over the eons, causing flowing water on the surface to dry up. Earth, meanwhile, hosts the only life that we know of. Why are these worlds so different? Planetary scientists are trying to understand the answer, but part of it may come from the composition of the core, crust and mantle inside of each planet.

InSight will probe the Martian core through a radio science experiment. It will transmit its position to a network of NASA antennas on Earth called the Deep Space Network. But even while InSight stays still, Mars will not. Mars orbits the sun and it wobbles a bit as it does so. Scientists will measure the degree of that wobble, and from there, they can figure out what the Martian insides are made of.

InSight atop a United Launch Alliance Atlas V rocket
An engineer in the clean room at Lockheed Martin Space in Littleton, Colorado, affixes a dime-size chip onto the lander deck of NASA's InSight spacecraft. This second microchip, contains 1.6 million names submitted by the public to ride along with InSight to Mars.

Sensing Shakes and Digging Deep

But that's not the only benefit to InSight staying quiet. Scientists are really hoping to catch evidence of marsquakes. They're kind of like earthquakes, but not exactly the same thing. On Earth, quakes happen via plate tectonics: rigid plates underneath our planet's mantle shift around and create earthquakes as they slide or rub against each other. Martian quakes will likely happen due to volcanic activity or cracks in the planet's crust. InSight may even catch the vibrations after meteorites, or space rocks, slam into the surface of Mars.

It's not the first time scientists tried to find marsquakes, but the effort failed due to bad design. Back in 1976, the first NASA landers touched down on Mars: Viking 1 and Viking 2. Overall the missions were successes, lasting long past their design lifetimes. But the seismometer experiment was a bit of a bust. The device was on top of the spacecraft, and it kept swaying in the Martian wind. As you can imagine, that messed up the marsquake measurements.

InSight will also do the deepest drill dive ever on Mars, using a heat probe. The Curiosity rover also carries a drill, but it's a puny one in comparison; InSight will dig down to as far as 16 feet (5 meters) below the surface, while Curiosity's drill can only probe a couple of inches. (The aging Curiosity drill has been stubborn lately, forcing NASA to try new techniques to get it working.)

Neither Curiosity's or InSight's probes are better or worse; it's just that they have different science goals. While Curiosity is more interested in surface change and composition, InSight needs to move below the surface to a zone where the Martian seasons won't affect measurements. There, it's going to measure how much heat is coming up from the Martian interior. Heat is important for understanding volcanoes, and could help us learn how the mighty Olympus Mons and the other volcanoes in the Martian area known as the Tharsis region operated.

Directive: Explore Mars

The kicker is InSight won't be travelling to Mars by itself. In honor of the 2008 Pixar movie "Wall-E," two little CubeSats (small spacecraft) nicknamed "Wall-E" and "Eva" will travel along with it. The CubeSats will provide data on InSight's landing when it touches down on Mars on Nov. 26 in a flat zone called Elysium Planitia. If all goes well, the CubeSats will help scientists learn more about landing on Mars, which is super important because so many Mars landing missions have failed.

If you're really anxious for another American rover mission, NASA has you covered. The agency will launch its Mars 2020 rover in (as the name suggests) 2020. And this will be a far more active mission. The rover will roam the surface in search of habitable environments. It may even bury some samples for a future mission to pick up and return to Earth. The Europeans also plan to send a rover (with a drill) in 2020, as part of their larger ExoMars exploration program.

And who knows, InSight may still be operating when these rovers arrive. InSight is expected to last about two Earth years (one Martian year), but depending on funding and its design it could keep working for a little longer. Best of luck to all of these spacecraft with their missions!

NASA Mars InSight Overview

Written by Elizabeth Howell May 2, 2018