In 2021, Mars is set to receive new robotic inhabitants.
But until then, we have other explorers hard at work
learning what makes the Red Planet tick.
Like NASA’s InSight lander!
InSight touched down in November 2018,
and its first results were finally released this week in two Nature journals.
The results reveal a seismically active world with magnetic
and atmospheric phenomena, all begging for further investigation.
InSight lives in a sediment-filled crater in the Elysium Planitia region
a volcanic plain a bit north of where Curiosity is.
Its mission is to learn what it’s like beneath Mars’s surface.
And to do that, it brought along some really cool instruments.
For one, it has Mars’s first seismometer in forty years!
At first, that could seem like a weird thing to bring to Mars.
Because until recently, we thought the planet was geologically dead,
with not an earthquake, or... a marsquake, to be found.
But the hope was that this seismometer could at least help us learn about
other seismic activity, from things like meteorite impacts or dust devils.
And it delivered!
As of September, InSight had recorded 174 seismic events.
And at least twenty-four of them bore resemblance to minor earthquakes.
Now, Mars doesn’t have tectonic plates,
the main thing that causes earthquakes here at home,
but this suggests it still has some kind of quakes!
So, Mars isn’t dead after all!
We’re still learning how these things work, but they may be caused
by Mars’s continual cooling over the billions of years since it formed.
As it cools, it contracts, which applies stress.
And given enough time, the material under stress could break, causing a quake.
These twenty-four events happened so deep
that you and I probably couldn’t feel them from the surface.
But InSight could!
And by looking at how the vibrations travel through the planet,
it could teach us about Mars’s geology and what the planet is made of.
Besides the seismometer, InSight also has
the first magnetometer to grace the Martian surface.
Mars doesn’t have a planet-wide magnetic field anymore,
but some of the rocks deep in its crust are still magnetic.
And InSight’s instrument can detect that.
So far, it’s measured the strength of these local magnetic fields
and how they change over the course of the day.
But it’s also teaching about Mars a whole.
Given how deep these rocks appear to be buried,
scientists estimate they’re about 3.9 billion years old.
That’s slightly younger than when most scientists believe
Mars’s planet-wide magnetic field shut down,
so it could mean that field lasted a little longer than we thought!
Finally, this is all cool, but InSight is leaving us with a few mysteries, too.
Like, its atmospheric instruments found that night-time gravity waves
are more abundant than prior data suggest.
Gravity waves are regular, periodic changes in air pressure, temperature,
or wind speed, caused by changes in the air buoyancy.
And they’re entirely different from gravitational waves,
the distortions in space-time we detect when black holes collide.
But despite seeing them on Mars, we don’t really know what they mean.
InSight also found the first evidence of infrasound on Mars
sound waves with frequencies lower than what we can hear.
But again, we’re not sure what that can teach us.
So there’s a lot left to learn!
And we’re also waiting for two of InSight’s other instruments,
including its heat probe, to collect enough data to publish.
Fortunately, the mission was expected from the outset
to take twenty-four months to meet all its objectives,
so our little lander is still on track.
In related news, Mars’s two lumpy moons,
Phobos and Deimos, are scheduled to get their own visitor!
Last week, the Japanese Space Agency JAXA announced
that their Martian Moons eXploration mission, or MMX,
has entered the development phase.
That means it’s no longer just a research project:
Engineers can officially start developing hardware and software.
Mars may have two moons to Earth’s one, but they’re way smaller.
On average, Phobos is only twenty-three kilometers across,
roughly the length of a half-marathon, and Deimos is about half of that.
We’re also not sure how Mars got them.
They may have started in the asteroid belt,
then been flung towards Mars by Jupiter’s gravity.
Or they could have formed like Earth’s moon probably did:
from the debris left over after something smashed into Mars.
One way to answer this question would be to study the moons’s compositions
and see how similar they are to Mars itself.
And that’s what MMX will do!
After surveying both moons, the spacecraft will land on Phobos
and collect at least a ten-gram sample
from at least two centimeters below the surface.
Then, it will return that sample to Earth for analysis.
No one has ever gone to Phobos like this,
but sample return missions are no stranger to JAXA.
Their Hayabusa2 probe is currently on its way home
carrying a bit of the asteroid Ryugu.
But the MMX mission takes further strides by collecting more material and by
using a corer instead of a tiny cannonball to blast material off the surface.
The craft will also have to navigate another planet’s gravitational field,
rather than visit a space potato freely orbiting the Sun like Ryugu.
But it will be worth it!
Besides helping us understand where the moons came from,
studying bits of Phobos will help scientists answer questions
about the history of water in the solar system.
For instance, if the moon formed from Mars,
it could carry a record of Mars’s watery past.
Or if it formed in the asteroid belt, it could help us understand the space rocks
that may have brought Mars and Earth their water early-on.
The mission will also provide a look at how Mars has evolved in general
over billions of years.
That’s because both moons are suspected of accumulating material
kicked off the planet’s surface during meteorite impacts
bits thrown into the air fast enough to wind up in space!
MMX will even help determine how humans could visit these moons
and collect samples themselves.
Under the current timeline, MMX is looking to launch in 2024
and return before the end of the decade.
Which, conveniently, leaves us plenty of time before Phobos
is scheduled to be ripped apart by Mars’s gravity… in 30 to 50 million years.
So, we’ve got some wiggle room — and plenty to learn in the meantime.
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