Thanks to MagellanTV for sponsoring today’s video. Insight has been on Mars for over two years now,
and has reached the end of its original two year mission. However, scientists are so pleased with
its success so far that NASA has agreed to extend the mission for another two years,
until December 2022. But what has Insight achieved in its time on Mars to lead to this extension?
And what challenges might it face as it goes beyond its expected lifetime in the coming two
years on the red planet? I’m Alex McColgan, and you’re watching Astrum. Together in this video
we will find out what Insight has discovered, relive the highs and lows of Insight’s time on
Mars since we last checked in, and learn what the future holds for this incredible lander.
By the end of this video, I hope I earn your like and subscription!
If you watched my last video on this subject, you’ll remember that the primary mission of
Insight was to discover more about the formation of Mars by uncovering data
about its internal formation and processes. To do this, it came equipped with a seismometer
(called SEIS) to help it detect seismic activity like earthquakes or meteor impacts,
and a Heat Probe and Physical Properties instrument (HP³, or “Mole”) which was to
dig down 5 metres into Mars’ surface to take the temperature of the red planet at different depths.
However, there was a problem. When the Mole was first deployed, it wouldn’t dig. The mole was
not designed with a drill, as this would have been too heavy to carry on the journey, and
would have needed a large cradle to stabilise it. Instead, scientists designed it to make its way
into the surface of the planet using an internal hammering system. This would be lighter, and more
compact. However, the mole only got a few inches into the dry soil of mars before getting stuck.
It would hammer, but wasn’t going any deeper. Had it hit a rock? Scientists had
chosen the landing site especially because there were few large rocks in the area,
and the mole had been designed in such a way that it should have been able to go around small rocks.
The team took their time to think through what might be causing the problem, doing their best to
create a replica of the situation on Earth using data from Insight’s cameras. This wasn’t a perfect
process, as it’s impossible to perfectly mimic the lower gravitational conditions of Mars on Earth
even with replicas made from scaled down lighter materials,
but by October 2019 they had figured out that the likely problem was a lack of friction. They
took photos of the hole with the mole partially backed out, and saw that the soil in this spot
was different from what they’d been expecting. The Mole had been designed with loose soil in mind,
the kind that would fall in around the mole as it dug and provide it with the friction it needed to
dig deeper. However, although the surface you see here certainly appears loose and dusty, only a few
inches deeper the scientists realised there was a layer of a cemented soil known as duricrust.
The particles of duricrust stick together more tightly, which meant they weren’t falling into
the hole the mole was creating, and weren’t providing the friction necessary to dig deeper.
Scientists hadn’t realised that this type of soil was here when they picked the site for landing.
But what were the scientists going to do about it? While Insight is equipped with a robotic arm,
the top of the mole was not designed to be grabbed by this arm, so they couldn’t just
move it to another position. And as you can see here there is a delicate cable designed to relay
data from the mole back to Insight, which could be damaged if they just pushed down on the top
of the mole with the arm. So, the first plan was to place the arm next to the digging mole,
pinning the mole in place. Perhaps this would provide the friction necessary to get it started.
However, this proved to be not enough. Next, the team tried to scoop soil into the hole the mole
had created. This also proved unsuccessful. Finally, in October 2020, a full year later,
scientists tried to push the top of the mole with the robotic arm.
Although this did cause the mole to successfully completely bury itself, the hopes that this
raised were soon dashed when the team realised the mole would not go any deeper on its own.
By January 14, 2021, the team had given up on the mole altogether, although they still felt they’d
learned valuable information for future missions, about the nature of Martian soils. Fortunately,
Insight’s other scientific equipment was working much more effectively.
SEIS, the seismometer, was doing a much better job in providing a glimpse into Mars’s inner workings.
SEIS has been listening to the sounds of Mars for over two years now, and has detected over
500 different seismic events. Mars does not have tectonic plates like Earth does,
but it does have volcanic regions that produce earthquakes from time to time.
SEIS can pick up vibrations from these earthquakes, which gives it a clearer idea of
the makeup of the planet’s mantle and inner core. Scientists have learned 3 interesting things from
all this data. First, Mars tends to have frequent, but small, earthquakes, none more powerful than
magnitude 3.7. Scientists are surprised that they’ve detected nothing more powerful given
how frequently smaller earthquakes are happening, and are still piecing together why this might be.
Perhaps Mars is more static than was expected? Or perhaps we simply haven’t been lucky enough
to witness a big one? It’s too early to tell for certain. Second, the wind hides earthquakes.
Because SEIS is so sensitive, it can hear the vibrations caused by the wind,
and sometimes this masks the vibrations of small earthquakes, like static on a radio. During the
windier parts of Mars’ yearly cycle, the number of earthquakes appears to go down, but this is likely
just because SEIS isn’t detecting them. Scientists are currently planning to use the mechanical arm
to bury parts of the seismometer, as this might reduce the interference from the wind.
Finally, and strangely, these earthquakes are missing surface waves. All earthquakes
create waves. Two of the main types – Primary waves and Secondary waves – travel through the
mantle. However, normally there are also “surface waves” that run along the surface
of the planet crust, and for some reason these have never been detected on Mars.
Scientists are still not quite sure why, but wonder if this is evidence of extensive
fracturing of the upper 10 kilometres of Mars’ crust, which might be diffusing the waves. To
find out more, we will have to wait and see. Insight has a difficult task ahead of it.
Over the two years it’s been here, dust has built up on its two solar panels.
Scientists had hoped that dust devils would blow away this wind in “cleaning events”,
but so far this hasn’t happened. In February 2021, Insight was only collecting 27% of the power it
would have been collecting had the dust not been there, and this is potentially a big problem.
Martian temperatures can drop from 0 degrees Celsius during the day to as low as -100 degrees
Celsius during the night-time. Without on board heaters, these temperature swings could really
damage Insight’s on-board circuitry. Scientists have a delicate juggling act on their hands.
They must decide where to send Insight’s dwindling power reserves – to the arm, to the SEIS reader,
the radio, or the vital heaters that keep Insight alive. And with Mars entering its winter period,
as well as “aphelion” – the time in Mars’ year when it’s furthest from the sun – they have
decided to settle Insight down to hibernate, using its precious power mostly on keeping its circuitry
safe and warm. However, scientists are hopeful that come July, as Mars gets closer to the Sun
again, Insight can bring its other equipment back online, and the science can continue.
The data collected by InSight has very real implications for us. Knowing the inner
workings of Mars help us compare that to how Earth operates, which can give us a more complete view
of how all the terrestrial planets formed. Another planet of particular interest is Venus,
and how we believe it went from a potential habitable planet to becoming inhospitable.
There’s a great episode in the “Cosmic Journeys” series on MagellanTV where they deep dive into
what happened to our sister planet. MagellanTV is a subscription streaming platform which you
can use on pretty much any device, dedicated to the best documentaries on science and technology,
with a whole host of fascinating space videos. If you wanted to check out the Venus: Death of
a Planet video I just mentioned or if you want to check out their huge library for yourself, use can
use my link in the description to get a one-month free trial, I highly recommend giving it a go!
So there we have it, a recap of everything Insight has done and achieved since the last video. If you
missed that video, you can check it out here. Be sure to like and subscribe for more space videos.
And a big thanks to my patrons and members. If you want to support the channel and have your
name added to this list, check the links in the description. All the best, and see you next time.