JPL is sending a giant ear into space to listen to the insides of Mars

The Jet Propulsion Laboratory in Pasadena is getting ready to send a landing probe to Mars for the first since the Curiosity rover arrived at the Red Planet in 2012. 

On Wednesday, the probe known as InSight landed at Vandenberg Air Force north of Santa Barbara in preparation for launch in the next few months. 

The lander, which made the trip aboard a cargo plane from Denver, will have its vital signs checked, loaded with rocket fuel and shot into space sometime between May and June.

Curiosity and other landing probes sent to Mars have been mostly concerned with the planet's exterior terrain, looking at its composition and checking for signs of water and life.
 
But InSight has a whole different focus: the planet's interior.

"In some ways it’s going to a whole new planet. I mean we explored the surface of Mars, but all we’ve ever done is scratched the surface," said Bruce Banerdt, principal investigator of the InSight mission. "And now, we’re going to explore all of the inside of Mars, which is a whole new ballgame."

Scientists are still unsure of the size or make up of the planet's core, the thickness of its crust and the composition of its layers. So, to figure out what's going on, InSight will rely on a diverse set of tools to take an internal snapshot.

An artist's impression of the InSight lander on Mars. Its seismometer on the left listens to waves running through the planet's interior, while its heat flow probe on the right monitors temperature changes 15 feet deep.

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NASA/JPL-CALTECH

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The lander will rely heavily on its seismometer, or a giant ear-like tool that'll sit on the Martian surface and listen for seismic waves as they pass through the planet's interior. 

"If you put the seismometer in Nebraska, it would sense the hum of the ocean," said Sharon Kedar, InSight seismometer investigation scientist for JPL, when discussing the sensitivity of the equipment.

The waves are created by a number of different events on Mars. Meteorite impacts, interior tidal changes and cracks forming in the planet's crust as it cools and contracts, all have their own unique wavelengths. Scientists can use them to get a clear snapshot of the inside of the planet. That's because those wavelengths are modified by the materials they come in contact with, within the planet.

Scientists are also hoping to document Marsquakes for the first time.

Another tool in InSight's arsenal is its heat flow probe, or a giant thermometer that punches its way 15 feet deep into the surface. It'll monitor the increase in temperature as it descends, information that scientists will use to study thermal energy flow within Mars. From that, they'll extrapolate the planet's thermal history -- a peek into how it came together as the universe formed.

They'll also monitor the planet's wobble as it spins, which'll allow them to estimate the size and composition of its possibly molten core.

"The inside of Mars is really a vault that's storing all of this evidence from the early solar system," said Banerdt. "So, by going and mapping out the inside of Mars, we're really kind of going back in time, like a time machine, to the earliest stages of the solar system formation so that we can actually understand how our planet got here."

The InSight mission was supposed to take off in 2016, but was postponed after a leak in the seismometer vacuum system was discovered. Because of that, the mission team missed its launch window and had to wait another 26 months, or until Mars is at its closest point once again. The lander is expected to arrive in November.