Investigating an incident that occurred hundreds of
millions of miles away can be tricky. But with a little help from
NASA’s Mars Reconnaissance Orbiter, European Space Agency officials
are getting closer to figuring out exactly what happened with their
Mars lander, Schiaparelli.
A week after the site was photographed in black and white,
NASA’s orbiter passed over the site again, taking new color
photographs. The images have been pieced together, providing a view
of the entire impact site and helping to clear up some
speculations. Fragments of the lander are visible, supporting the
hypothesis that the lander crashed, while photos of the rear heat
shield suggest it burned as expected.
The images are the latest clue in the evolving mystery of what,
exactly, happened to Schiaparelli. The landing was always intended
as a test of the ESA technology, which had been developed to cope
with the unique challenges of landing on Mars. Figuring out what
went wrong will allow scientists to address the problem — which
some suggest was a software glitch — before the next ESA mission to
Mars, scheduled for 2020.
Schiaparelli was equipped with a range of high-tech hardware and
software to help it navigate the descent to the surface of the Red
Planet. A parachute and thrusters were installed to help it slow
down after entering Mars’ atmosphere.
The lander was much too far away to be controlled manually from
Earth. It takes at least 26 minutes for signals to make a round
trip, while the descent lasts just six minutes. So an advanced
computer was deployed to run the landing automatically.
But all did not go as planned. Schiaparelli lost contact with
Earth, and black and white images taken by NASA’s Mars
Reconnaissance Orbiter showed what appears to be a new crater on
the planet’s surface. ESA scientists said that the impact crater
was consistent with Schiaparelli crashing into the ground at 186
miles per hour.
The new color photos appear to corroborate that theory. The
bright white spots around the dark region identified as the crash
site appear in both sets of photos, for instance, allowing the ESA
to conclude that they are "most likely to be fragments of
Schiaparelli," rather than image "noise."
Images of the rear heat shield, meanwhile, show a pattern of
bright and dark patches. This seems to indicate that the heat
shield performed as expected: "the external layer of insulation has
burned away in some parts and not others."
The parachute appears to have shifted in the wind, the new
photos show. The Mars Reconnaissance Orbiter previously observed
something similar happening to Curiosity’s parachute, so this, too,
is as expected.
But scientists looking at the black and white photos highlighted
the location of the parachute and heatshield, saying their distance
from the new crater is consistent with both pieces being ejected
sooner in the descent than they should have been. That adds up to a
picture of confused landing software causing Schiaparelli’s
demise.
"Fundamentally there’s a software issue here between the radar
and the on-board computer system," Mark McCaughrean, a senior
science advisor at ESA, told the Associated Press. "The radar was
giving inconsistent info on where it was."
The good news is, it shouldn’t be impossible to fix.
"As it is, we have one part that works very well and one part
that didn’t work as we expected," Jorge Vago, project scientist for
ExoMars, told Nature after the earlier photos were released. "The
silver lining is that we think we have in hand the necessary
information to fix the problem." The new photos will help with
that.
The ESA said that its probe into the incident should be
completed by the end of November. An independent inquiry board has
also been initiated.