High-resolution pictures have now been released of the Philae probe in
the act of landing on Comet 67P last Wednesday.
They were acquired by
the Narrow Angle Camera on the Rosetta satellite, which had dropped the little
robot towards the surface of the "ice mountain."
The images are
presented as a mosaic covering the half-hour or so around the "first
touchdown" - the probe then bounced to a stop about 1km away.
Philae lost battery power
on Friday and is no longer communicating with Earth.
Scientists still have
not located the craft's current resting spot.
But European Space
Agency controllers have not given up hope of hearing from the plucky robot
again - if it can somehow get enough light on to its solar panels to recharge
its systems.
Getting a precise fix
on its location, to then photograph its present predicament would provide a
better idea of whether this is likely to happen.
The new NAC images
will certainly help in this respect because they show the direction the lander
took as it bounced away.
At the weekend, Esa
presented some fascinating views of the first touchdown taken by Rosetta's
navigation cameras, but the Osiris NAC system has substantially better
resolution.
The mosaic is produced
by the Max Planck Institute for Solar System Research, which operates Osiris.
It details Philae's
descent, and the impact mark it leaves on 67P's surface. You then see the 100kg
probe heading away on its initial bounce.
It's
a trap
This rebound reached
hundreds of metres above the comet and lasted almost two hours.
When Philae came back
down, it made another small leap, which took it into a high-walled trap.
Telemetry and pictures
from the robot itself indicate this location is covered in deep shadow for most
of 67P's day.
As a consequence,
Philae receives insufficient solar power to re-boot and form a radio link to
the orbiting Rosetta spacecraft.
Esa cannot be sure the
robot will ever come back to life, but even if it does not the agency says it
is "hugely happy" with what was achieved in the 60 hours following
landing.
The probe managed to
complete more than 80% of its planned primary science campaign on the surface.
This data was pulled
off the robot just before its sagging energy reserved dropped it into sleep
mode.
Little of the results
have so far been released by the various instrument teams. The one major
exception is MUPUS.
This sensor package
from the German space agency's Institute for Planetary Research deployed a
thermometer on the end of a hammer.
It retrieved a number
of temperature profiles but broke as it tried to burrow its way into the
comet's subsurface.
Scientists say this
shows the icy material underlying 67P's dust covering to be far harder than
anyone anticipated - having the tensile strength of some rocks.
It also helps explain
why Philae bounced so high on that first touchdown.
The 4km-wide comet has
little gravity, so when key landing systems designed to hold the robot down
failed at the crucial moment - the probe would have been relying on thick,
soft, compressive layers to absorb its impact.
However much dust it
did encounter at that moment, it clearly was not enough to prevent Philae
making its giant rebound.
News Credit: BBC NEWS
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