CLOUDS ON MARS, GO FIGURE. While our taxpayer bucks are on Mars checking out those noises, NASA.org also provided a beautiful view of clouds on Mars. Click here. |
The spacecraft's exquisitely sensitive seismometer, called
the Seismic Experiment for Interior Structure (SEIS), can pick up vibrations as
subtle as a breeze. The instrument was provided by the French space agency,
Centre National d'Études Spatiales (CNES), and its partners.
SEIS was designed to listen for marsquakes. Scientists want
to study how the seismic waves of these quakes move through the planet's
interior, revealing the deep inner structure of Mars for the first time.
But after the seismometer was set down by InSight's robotic
arm, Mars seemed shy. It didn't produce its first rumbling until this past
April, and this first quake turned out to be an odd duck. It had a surprisingly
high-frequency seismic signal compared to what the science team has heard since
then. Out of more than 100 events detected to date, about 21 are strongly considered
to be quakes. The remainder could be quakes as well, but the science team
hasn't ruled out other causes.
Quakes
Put on headphones to listen to two of the more
representative quakes SEIS has detected. These occurred on May 22, 2019 (the
173rd Martian day, or sol, of the mission) and July 25, 2019 (Sol 235). Far
below the human range of hearing, these sonifications from SEIS had to be
speeded up and slightly processed to be audible through headphones. Both were
recorded by the "very broad band sensors" on SEIS, which are more
sensitive at lower frequencies than its short period sensors.
The Sol 173 quake [click here] is about a magnitude 3.7; the
Sol 235 quake is about a magnitude 3.3. Click here.
Each quake is a subtle rumble. The Sol 235 quake becomes
particularly bass-heavy toward the end of the event. Both suggest that the
Martian crust is like a mix of the Earth's crust and the Moon's. Cracks in
Earth's crust seal over time as water fills them with new minerals. This
enables sound waves to continue uninterrupted as they pass through old
fractures. Drier crusts like the Moon's remain fractured after impacts,
scattering sound waves for tens of minutes rather than allowing them to travel
in a straight line. Mars, with its cratered surface, is slightly more
Moon-like, with seismic waves ringing for a minute or so, whereas quakes on
Earth can come and go in seconds.
Mechanical Sounds and
Wind Gusts
SEIS has no trouble identifying quiet quakes, but its
sensitive ear means scientists have lots of other noises to filter out. Over
time, the team has learned to recognize the different sounds. And while some
are trickier than others to spot, they all have made InSight's presence on Mars
feel more real to those working with the spacecraft.
"It's been exciting, especially in the beginning,
hearing the first vibrations from the lander," said Constantinos
Charalambous, an InSight science team member at Imperial College London who
works with the SP sensors. "You're imagining what's really happening on
Mars as InSight sits on the open landscape."
Charalambous and Nobuaki Fuji of Institut de Physique du
Globe de Paris provided the audio samples for this story, including the one below,
which is also best heard with headphones and captures the array of sounds
they're hearing.
On March 6, 2019, a camera on InSight's robotic arm was
scanning the surface in front of the lander. Each movement of the arm produces
what to SEIS is a piercing noise.
Wind gusts can also create noise. The team is always on the
hunt for quakes, but they've found the twilight hours are one of the best times
to do so. During the day, sunlight warms the air and creates more wind
interference than at night.
Evening is also when peculiar sounds that the InSight team
has nicknamed "dinks and donks" become more prevalent. The team knows
they're coming from delicate parts within the seismometer expanding and
contracting against one another and thinks heat loss may be the factor, similar
to how a car engine "ticks" after it's turned off and begins cooling.
You can hear a number of these dinks and donks in this next
set of sounds, recorded just after sundown on July 16, 2019 (Sol 226). Listen
carefully and you can also pick out an eerie whistling that the team thinks may
be caused by interference in the seismometer's electronics.
What does it sound like to you? A hall full of grandfather
clocks? A Martian jazz ensemble? Click here.
About InSight
JPL manages InSight for NASA's Science Mission Directorate.
InSight is part of NASA's Discovery Program, managed by the agency's Marshall
Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver
built the InSight spacecraft, including its cruise stage and lander, and
supports spacecraft operations for the mission.
A number of European partners, including France's Centre
National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), are
supporting the InSight mission. CNES provided the Seismic Experiment for
Interior Structure (SEIS) instrument to NASA, with the principal investigator
at IPGP (Institut de Physique du Globe de Paris). Significant contributions for
SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS)
in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in
Switzerland; Imperial College London and Oxford University in the United
Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package
(HP3) instrument, with significant contributions from the Space Research Center
(CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain's Centro
de Astrobiología (CAB) supplied the temperature and wind sensors.
WHILE WE’RE ON MARS.
NASA's InSight used its Instrument Context Camera (ICC)
beneath the lander's deck to image these drifting clouds at sunset. This series
of images was taken on April 25, 2019, the 145th Martian day, or sol, of the
mission, starting at around 6:30 p.m. Mars local time.
NASA MARS CLOUD VIDEO: Click here.
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