InSight Surface Operations, 26 Nov 2018- 21 Dec 2022 Options

[stevesliva]

https://presse.cnes.fr/en/world-first-frenc...tects-marsquake

[alan]

https://twitter.com/NASAInSight/status/1120768743284469760

[rhr]

It's the big one! Well, in a manner of speaking...

Translation of:
https://www.seis-insight.eu/fr/actualites/469-quake-sol128

Insight detects the first earthquake on Mars

7 april 2019, during sol 128, the two detectors in the seismometer SEIS in
Insight detected the first seismic tremor on mars, more than 40 years after the
attempt by NASA's mythical Viking landers.

Since the wind and thermal sheild was emplaced 2 february 2019, which
dramatically reduced environmental noise, the seismometer SEIS on Insight has
been listening daily for activity on the red planet. Although the instrument
immediately presented researchers with a continual and very weak noise,
originating from both noise sources in the lander and the constant action of
the atmosphere on the surface, seismologists hoped above all to be able to pick
out the signature of seismic events from the data received every day from
Elysium Planitia. And now it has been done: during sol 128 the first
earthquake, weak but originating from mars, was detected by SEIS.

On the trail of Viking

Before Insight, the only seismometer capable of detecting earthquakes on mars
was that of the lander Viking 2, which landed 3 september 1976 on the desolate
and pebbly expanse of Utopia Planitia. Unlike the seismometer of Viking 1, of
which the movable part was never able to be unlocked, the instrument was
functional, but unfortunately it was rendered ineffective by the action of wind
on the landing site, especially during the day. This was due to the fact that,
unlike SEIS, Viking did not put its seismometer on the ground or use a wind
sheild.

All in all, over a period of 560 mars days (called sols), or 19 months from
1976 to 1978, the data returned by Viking 2's seismometer was mainly useful to
meteorologists. In all of the recorded data only 1 candidate event of
potentially seismic origin was detected on sol 80. Unfortunately no data was
colected by the weather station that sol, preventing validation of the event:
seismologists couldn't be certain that the sequence of vibrations was really of
seismic origin and not just wind. To prevent this from happening again,
Insight was equipped with an environmental station more capable than that of
Viking (temperature, wind speed and direction, ultra-sensitive barometer, and
magnetometer), and which is expected to function continually through the end of
the mission.

The sol 128 signal

Looking back, it's a good bet that none of the geophysicists who worked on
Viking could imagine that a period of 40 years would elapse before the
signature of an earthquake would finally be dected on the red planet. And yet
that's how it happened. After 1976 none of the succesful landers carried
seismometers, while numerous geophysical missions were canceled. Reaching the
martian surface 26 november 2018 and deploying SEIS with its robotic arm 19
december last, Insight has opened a new chapter in mars exploration, and has
put the previously neglected science of planetary seismology back on the map.

The event observed by Insight on sol 128 was of very weak amplitude, and
corresponds to a tiny displacement of the martian surface. The jolt was so
tenuous that it's not possible to localize its epicenter, the location of its
source on the globe of mars. By a domino effect, not knowing this makes the
analysis of the data very uncertain, and does not allow the event to be placed
on a scale of magnitude. It is also not possible to identify the physical
mechanism of the ground movement. It could be a micro-tremor from a more or
less great depth, probably in the crust, originating in stress from the cooling
and contraction of the planet, or it could be a meteorite impact.

Although seismologists working on Insight will continue to study the sol 128
event for many years to come, one interesting observation has already been
made: many fundamental characteristics of the event, such as its duration, its
form, and the distribution of energy in different frequencies, leads one to
think that the red planet, from a seismological point of view, is more like the
moon than the earth.

Mars seismology: a common thread with the moon

Unlike mars, the moon's first seismometers were placed not by a landed robot
but by the hands of astronauts during the Apollo missions. The first station,
set up by the crew of Apollo 11 in july 1969 on the sea of tranquility, only
worked for a month or so, but was quickly replaced by a network of more
sophisticated instruments set up by Apollo missions 12 14 15 and 16 in
different regions of the lunar near side. The last instrument was the
gravimeter from Apollo 17, later used as a seismometer.

As is often the case in planetary science, the moon quickly perplexed
seismologists, in as much as the data collected was very different from the
terrestrial data they had handled before. When the first lunar earthquakes
were recorded they were not initially recognized as such by scientists.
Crashing many heavy objects into the surface of the moon (like Saturn V third
stages or lunar modules) to create artificial vibrations helped geophysicists
recognize lunar seismic events and understand how seismic waves propagate
through our satellite.

This is due to the fact that the lunar regolith is completely dehydrated.
Although seismic waves experience little attenuation as a result of the very
low level of water, they are none the less diffracted in all directions by
structures of all sizes. Exposed to meteoritic bombardment for billions of
years, the lunar crust, far from being homogeneous, has been completely
crushed. Reverberating incessantly through the cracked and faulted envelope,
waveforms spread out in time and become complex. Instead of recording a clear
signal over a reasonably short time, a seismometer on the moon records instead
a very diffuse and unstructured signal spread out over a long interval of time
(up to an hour).

The way that the first seismic signal was detected on mars bore a striking
similarity to the way it happened on the moon. When it first appeared on the
control screens the event of sol 128 was originally classified as of unknown
origin. After discarding many hypotheses such as meteorological phenomena or
lander activity (like solar panel vibrations or robotic arm movements) or even
a parasitic signal from the instrument itself, seismologists at the Mars Quake
Service (MQS, a working group convened by Insight at the Ecole Polytechnique
Fédérale in Zurich) have used a series of techniques and sophisticated tools to
make the data speak, and have reached the conclusion that the sol 128 event
originated from mars, the first ever detected on the planet. And the
characteristics of the signal show that mars, like the moon, posseses
structures that strongly diffract seismic waves, and which make interpretation
of waveforms more complex than on earth.

In addition to sol 128, three other events are currently under consideration as
potential seismic events. They occurred respectively on sols 105 (14 march)
and 132 and 133 (11 and 12 april 2019). Unlike the signal of sol 128 they were
only heard by the SEIS's ultra-sensitive VBB detectors given the very small
amount of energy they contained. Although the origin of these signals remains
mysterious they are not associated with meteorological activity or currently
known noise sources.

Throughout its lifetime (july 1969 to september 1977) the Apollo lunar
seismometer network recorded 10,000 seismic events, often at a great depth
(800-1000km), but sometimes near the surface, and generally of weak magnitude
(less than 2 on the Richter scale), plus 2000 signals from meteoritic impacts.
All these events have allowed a determination of the interior structure of the
moon, a characterisation of the properties of its crust, mantle, and core, and
the proposing of hypotheses concerning its formation.

If the moon is to serve as a better guide to the analysis of data from Insight
than the earth, scientists will have to redouble their ingenuity to get mars to
reveal its secrets. The observation of the first series of events shows that
mars certainly still has seismic activity, if small, and that chances are good
that we will see larger events in the months and years to come, capable of
illuminating a good part of the interior structure of mars and revealing the
sectets of its evolution.

In planetary seismology patience is clearly a virtue, and for geophysicists
studying mars a 40-year wait has just come to an end.

[MahFL]

Hopefully the first of many .

[nprev]

Thank you VERY much for the translation, rer.

One question that occurs to me is what effect large amounts of subsurface ice may have on seismic signatures. Hopefully there will be enough events detected to at least determine qualitative differences between the overall regoliths of Mars and the Moon in this area.

[Phil Stooke]

Very useful translation, thanks! I think the Viking missions should be described as 'legendary' rather than 'mythical'. However, the new result is very exciting and hopefully only the first of many.

Phil

[PaulH51]

Clouds Anyone?
Sol 145 ICC

[atomoid]

There's a new article on the NASA site showing the clouds and sunrise/sunset pics

[fredk]

Thanks for pointing those out. It's not clear what happened with the "colour corrected" versions - perhaps they meant to say false colour.

[vikingmars]

A day on Mars with pictures taken from the InSight Instrument Context Camera (ICC).
The two small yellow Sun symbols show when sunrise and sunset take place.
Enjoy

[Deimos]

The InSight cameras are partially color blind (tritanomaly, with a short-wavelength sensitivity that is close to the mid-wavelength sensitivity). Maki et al (paywall) describe an aggressive matrix to convert InSight white-balanced images to sRGB. I suspect this is a result of that extrapolation.

[fredk]

Thanks for that reference. I can imagine that a matrix to sRGB would have to work hard to discriminate some colours. Still, the test chart images (Fig 8) seem to show that the sRGB conversion works well. Maybe being in a high S/N lab situation helps.

This makes me wonder what has been done to the public pngs. Perhaps just a white balance but no sRGB conversion? The public png colours look not bad, but I guess being in a nearly monochromatic environment helps! The flags and green and blue dots on the calibration target do look fairly desaturated, eg in this sol 10 image:

https://mars.nasa.gov/insight-raw-images/su...0004_0010M_.PNG

That's what you'd expect for an image before transforming to sRGB.

[JRehling]

Thoughts of the mole being obstructed remind me of other cases where similar impasses occurred.

Apollo 15 drilled for two purposes, the first being the very same: To put a heat-flow probe below the surface. This was much more difficult than anticipated and led to delays and eventually accepting a lesser depth than desired. Drilling for a second purpose, a deep core sample, also did not go well, and even removing the drill proved more difficult than anticipated.

The drill gear/procedures were redesigned for Apollo 16, solving the drilling problem, but a different mishap disabled the heat-flow experiment on Apollo 16.

Apollo 14 used a sampling tube plus hammer without a drill and achieved a depth of only 70 cm.

Drilling was also difficult during Apollo 17 and consumed more time budget than expected. Harrison Schmitt, who operated the drill, summarized, "Anybody who's thinking about drilling on the moon — I don't think we have those issues settled yet."

I'm also reminded of the difficulty in placing a sample of ice into the Mars' Phoenix experiment (this was never accomplished as planned) and the outstanding possibility that the Deep Space 2 penetrator probes also failed due to unanticipated difficulty in the mechanical entry of the probes into the regolith (the true cause of failure may never be known).

All told, the rate of mishaps in penetrating the surface of another world more than a few centimeters is probably nearer 100% than 0% and, in context, the difficulty with the mole is not surprising.

[mcaplinger]

Maybe being in a high S/N lab situation helps.

Signal levels in the lab are typically much lower than under solar illumination because it's hard to get sunlight in a lab.

The MER-heritage CCD has very low QE in the blue so the Bayer pattern needs a lot of boosting in the blue.

I'm not sure what issue you're actually reacting to.

[PaulH51]

Interesting Mole Update 'DLR HP3 Blog' link