The Curiosity rover is truly
an interplanetary swiss army knife—
equipped with a slew of onboard instruments
for investigating the Red Planet.
The primary mission was two years,
so we're into a couple extended missions now,
yeah, we don't know exactly how long it'll keep going.
We never know, can't predict that,
Things are still going great on the mission.
We're discovering new rock units every day,
so we hope for several more years to come.
The rover has been slowly meandering around Mars
ever since it landed in 2012,
using specialized instruments to examine the surface,
perform experiments, and even find time to take a selfie
These instruments have lead to some
historic discoveries - in 2015,
atmospheric readings from the rover suggested
that Mars at one point experienced
a “vigorous” loss of atmosphere,
causing its ancient oceans to evaporate.
And last year, Curiosity detected organic matter
in sediment samples taken from Gale Crater.
Since 2012, the rover has been traversing
the 154 km Gale crater,
and has recently begun its ascent of Mt sharp.
Scientists want to know whether Gale Crater
was once completely filled with sediment -
did it disappear over time due to erosion
or was the crater never filled at all?
Gale Crater, that the rover is exploring in,
is 5 kilometers deep,
Mount Sharp is a 5-kilometer
tall mountain inside of that crater
one of the things that happens as you bury sediments
on the Earth or any other planet
is that you increasingly compact those sediments
and lose the porosity and those sediments
will get denser and denser and denser
as you bury them to greater depths.
The key to answering this question lies in gravimetry -
the precise measurement of gravitational fields.
These fields are correlated with
density variations in the crust.
Unfortunately, the rover wasn't equipped
with instruments designed
to detect these changes.
To get around this, researchers re-calibrated
Curiosity’s accelerometers,
instruments normally used for navigation,
to measure the changes in gravitational acceleration
as the rover climbs the base of Mount Sharp.
I kinda realized one day that gravity is just
an acceleration and we have accelerometers
onboard and got curious about how good those
accelerometers were and slowly began to figure
out a calibration for that data, to the point
where we had a precision that was meaningful
for understanding the geology at the landing site.
After 5 years of measurements,
scientists were able to determine
the density of Gale Crater’s sedimentary rocks
well, in this case one of the interesting things is that
the density was surprisingly low,
even for sedimentary rocks, which tend to be
lower density than, say, a lava.
the surprisingly low density tells us that
these sediments were likely never buried to
the full depth of Gale Crater,
which would be 5 kilometers
As the mission rolls on,
researchers would like to use
Curiosity’s accelerometers for another purpose:
to measure Mars’ seismic signals
in the hopes of detecting a Marsquake.
What we kind of show is that they're not great
seismometers, and so we would need either
a pretty large earthquake
or a pretty nearby earthquake to detect it,
at least in the measurements
that we're currently making.
And while its unlikely that Curiosity will detect
a MarsQuake, the InSight lander is
designed to just that.
Researcher’s would also like solve the mystery
of how Mt. Sharp came to be.
Yes, so Mount Sharp continues to be a puzzle.
We don't know, especially for the upper layers
of the mountain, how that formed.
The whole thing is a stack of layers
and the layers are all tilted outwards, so it's almost
like a haystack in the middle of this 5km deep crater.
So especially for those upper units,
they may have formed as a free-standing haystack
rather than having filled the crater entirely.
But that's just a theory, so we'll have to
get up there and figure it out.