You may have heard that the NASA InSight mission will be touching down on Mars on the 26th
November.
But why all the hype for this mission?
What makes it different from the Curiosity rover that’s already on Mars right now?
Well, as it happens, there are a lot of differences!
I’m Alex McColgan, and you’re watching Astrum, and together we will go through what
makes the InSight mission so special.
If you are pretty up to date with your NASA missions, you may recognise the design of
InSight from somewhere… that is because this lander is based off the Phoenix lander
design, the NASA mission that landed near the north pole of Mars in 2008.
It’s about a meter, or 4ft high, and 6m, or 20ft long.
The reason NASA reused the design was to keep R&D costs down, as well as hopefully meaning
it has a better chance of successfully landing seeing as NASA have done it once before.
You see, Mars doesn’t have the best success rate for space agencies.
Roughly half the missions destined to go to Mars either didn’t leave the ground, or
failed once they arrived!
So, by reusing a design that worked, scientists are hoping for a successful landing on Monday.
So how do they expect this spacecraft to land?
Firstly, it will enter the atmosphere 125km up or 77mi at almost 20,000kmph, or 12,000mph.
This entry will generate a lot of heat, roughly 15,000c or 27,000f, which the heat shield
will absorb.
Once the lander has slowed down enough, the heatshield will pop of and a supersonic parachute
will deploy, further slowing InSight down.
Yes, Mars does have an atmosphere, although it is very thin compared to Earth standards.
With the speed InSight is travelling though, this parachute still makes a big difference,
although it wouldn’t be enough by itself to stop the lander smashing into the planet.
Unlike the Mars rovers which just had giant air bags to bounce on landing, this spacecraft
is using its own rockets to land.
So, InSight’s legs will spring into position, ready for landing,
once the parachute has slowed it down enough, that too will pop off,
leaving just the lander itself.
It will use its onboard rockets to carefully reach to surface.
This whole process will be over the course of about 7 minutes.
Upon impact with the surface, the rocket will have kicked up a lot of dust, which is not
very good for solar panels.
So, InSight will wait 16 mins before deploying its solar array to let dust settle.
This is what it looks like sped up in the testing environment before it launched.
On Mars, these panels will generate around 300-600 watts under normal conditions.
However, of course dust in atmosphere does affect power generation, like clouds would
on Earth, so this can be different every day.
Looking around at where they think InSight will land, you’ll notice it is really flat.
This is on purpose; a flat landing area means a better chance of landing correctly.
While this is going on, two cube sats have been following InSight to Mars, called Marco
A and B. Their mission is to relay realtime information back to Earth about whether the
landing was successful or not, and if the solar cells have deployed.
The Marco mission is a technology demonstration mission, so it doesn’t have scientific instruments,
but rather it carries different technologies.
These satellites are really small, only the size of a briefcase.
They are the first time cubesats have been sent into deep space, and no-one was sure
how well they would do, but so far they have been totally operational.
Marco will listen to UHF frequencies from InSight with the antenna on the bottom of
the spacecraft, and will transmit that data back to Earth using this bigger antenna.
The big antenna operates like a satellite dish on earth, except they designed it to
be flat so it can be space efficient.
Amazingly, these satellites can only generate 17 watts of power, yet are still able to receive
signals from the surface of Mars and transmit millions of kilometres back to Earth.
Should they not work though, all is not lost for InSight.
It can also communicate with some of the other orbits already at Mars, like the Mars Reconnaissance
Orbiter.
The only difference is that the MRO can’t relay information back in real time.
After performing their mission, the Marco cubesats will fly by Mars, unable to slow down enough to
enter orbit around Mars, and instead will forever drift around the Sun.
The Marco team will continue to communicate with the cubesats to see how long they last
past this mission.
So, assuming everything goes well, what will InSight be doing on Mars?
Although based on the same design as the Phoenix lander, its onboard scientific instruments
are quite different.
Insight’s main goals are to look for clues about the formation of Mars, and compare it
to what we know about Earth, so we can better understand the formation of terrestrial planets
generally.
The way scientists do this is through a seismometer, an instrument which will be able to detect
the vibrations caused by Marsquakes and meteor impacts.
You see, vibrations from these events travel through the mantle of the planet, and by detecting
these vibrations, that will enable us to know the size of the core, the physical characteristics
of the mantle, and the thickness of the crust on Mars.
The seismometer on Insight will actually be placed carefully with a robotic arm directly
onto the surface, and a wind shield will be placed directly over it, as the wind would
impact this instrument greatly while it is trying to detect the slightest of vibrations.
The other instrument is a highly sensitive thermometer, which will take readings from
the surface, all the way down to 4.5m or 15ft by using a little hammer to bury the instrument
down.
By extrapolating the temperatures as it goes down, scientists can predict where the mantle
must start and how hot it must be near the centre of the planet.
With a combination of the data InSight generates, scientists will better understand how the
interior of planets impact the surface environment, as it is not fully understood yet.
We can’t do this from only Earth, as Earth’s interior system has evolved a lot, whereas
Mars never really got started.
Earth has active plate tectonics and a magnetic field, but Mars not.
By taking measurements of the interior of Mars, it is almost like looking back in time
a few billion years on Earth before Earth got kicked started.
So!
Fingers crossed everything goes well on Monday.
I wish the teams involved with this project the very best of luck, as they have already
put several years’ worth of work into this project and it hasn’t even landed
yet.
Let’s see what InSight discovers for us!
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