A new analysis of an unprecedented
snapshot of NASA's Phoenix Mars Lander descending to the surface of Mars has
turned up more detail, including a dark spot that is likely the spacecraft's
jettisoned heat shield.
NASA's Mars Reconnaissance Orbiter
(MRO), currently circling the red planet, took the image
of Phoenix suspended from its parachute as it fell to the Martian surface
at 7:36 p.m. ET on May 25. The orbiter used its High Resolution Imaging Science
Experiment (HiRISE) camera. The image made history as
the first ever taken of a spacecraft as it descended toward the surface of
another planet.
MRO was about 475 miles (760
kilometers) away when it pointed its camera at Phoenix. In the image, both the 30-foot-wide
(10-meter) parachute and the aeroshell protecting the
lander are clearly visible. Even the lines connecting
the parachute to the lander can be seen.
After further analyzing the image,
the HiRISE team discovered a small,
dark dot located below the lander (which appears
as a white smudge). Team members think this dot is Phoenix's heat shield, which was discarded
after the parachute was deployed. (The heat shield protected the lander from burning up when it entered Mars' atmosphere and
quickly decelerated because of friction.)
"Given the timing of the image
and of the release of the heat shield, as well as the size and the darkness of
the spot compared to any other dark spot in the vicinity, we conclude that HiRISE also captured Phoenix's heat shield in
freefall," said HiRISE principal investigator
Alfred McEwen of the University of Arizona.
The image also includes two
colored swaths recorded by red, blue-green and infrared detectors. The
color bands missed the spacecraft, but do show frost or ice in the bowl of the
relatively young 6-mile (10-km) wide impact crater unofficially called "Heimdall" that dominates the image. The frost shows up
as blue in the false-color HiRISE data and is visible
on the right wall within the crater.
Although Phoenix appears to be descending into the
crater, it (and its heat shield) actually landed 12 miles (20 km) away. The
$420 million mission is slated to run for three months and is searching for
signs of past and present habitability in the Martian soil.
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