26 ASTRONOMY • OCTOBER 2019
mole needs to move deeper to make
higher-quality heat-f low measurements.
Meanwhile, TWINS has been generat-
ing outstanding daily Mars weather
reports. It discovered a small dust storm
starting around sol 42 and has detected
dozens of smaller atmospheric distur-
bances passing over the lander every sol.
The instrument’s pressure sensors
have observed many of the same
infrasound-producing small-scale atmo-
spheric vortices that the seismometer has
detected. Most of these atmospheric vor-
tices have not produced visible dust dev-
ils in camera images, however, indicating
that a whole new class of atmospheric
disturbances — “dustless devils” —
apparently exists, and InSight’s instru-
ments will be able to study them for
the first time.
Scientists have even taken simultane-
ous weather measurements and images
when Mars’ larger moon, Phobos,
eclipses the Sun. The moon’s shadowproduces tiny drops in temperature and
light levels during these events, which
last less than 30 seconds.
And, of course, the lander and IDA
cameras continue their imaging to moni-
tor the instruments as well as to under-
stand the geologic context of the Elysium
site. The rocky rims of several small, dis-
tant impact craters dot the landscape, and
dusty material fills smaller nearby craters
that scientists have dubbed hollows. The
team got the pretty f lat and rock-free site
they were hoping for — rocks cover less
than 4 percent of the surface.
Even though InSight carries no min-
eralogy or geochemistry instruments, the
images alone are consistent with a bed-
rock surface of volcanic origin fractured
and pulverized to depths of many tens to
hundreds of meters by eons of countless
impacts. This material is probably basal-
tic, like most of Mars and the typical
lava f lows seen in Hawaii and Iceland.
Geologically, InSight’s landing site in
Elysium Planitia turns out to have a lot
in common not only with the Spirit rov-
er’s landing site in Gusev Crater but also
with the Phoenix mission’s landing site
in the high-latitude northern plains.A legacy in the making
Although InSight’s full payload became
operational only a few months ago, theThe spacecraft’s robotic arm deployed the Heat Flow and Physical Properties
Package (HP^3 ) on February 12. Scientists designed this probe to measure how
much heat currently escapes from the Red Planet’s interior, as a way to learn
more about its early evolution.
On June 28, InSight’s robotic arm moved the HP^3 instrument’s support structure
(far left) to give scientists a better look at its digging tool, informally known as
the “mole,” to see why it couldn’t burrow deeper. Controllers lifted the structure
in three small steps to make sure they didn’t pull the mole out of the soil.The multiple footprints seen around the HP^3 instrument’s support structure reveal that it was moving slightly
as the instrument attempted to hammer its “mole” into Mars’ subsurface. Scientists think soil properties or a
rock are preventing the mole from going deeper, and are working on ways to get it operating.