A computer model to protect space missions from comets

A computer model to protect space missions from comets Washington: A computer model that can locate
the `active regions` on a comet`s surface and help protect
space probes from possible damages caused by dust emitted from
these regions has been developed by scientists.



The model, developed by the scientists from the Max
Planck Institute for Solar System Research (MPS) in Germany,
uses only that information which is available from Earth.
It adopts an indirect approach -- taking into
consideration the 3-D shape of the comets -- to localise the
active regions.



"Pictures taken from Earth show the comet and its jets as
a 2-D projection in which where exactly the dust particles and
gases originate from cannot be well identified," said Hermann
Bohnhardt from the MPS.



Pointing out that until now, "computer programs trying to
find the active regions assumed the comet as a sphere or
ellipsoid", Jean-Baptiste Vincent from MPS said: "Since in
reality comets often have quite bizarre shapes, for many
applications this approach is not good enough."



The team therefore took the standard approach and
developed a program based on the entire rotation period of a
comet during which the changes in its luminance allow its true
form to be calculated.
In the next step, the researchers fed this program with
assumptions on where the active regions might be located. They
also made an "educated guess" related to the physical
properties of the dust particles like size and initial
velocity upon emission from the nucleus.



Based on the data, the computer simulation delivered an
image. The team then compared this image with the actual one
obtained through a telescope and refined it step by step until
simulation and the actual image agreed.



The method has passed its first test and the scientists
believe they could successfully apply it to the comet Tempel 1
that was the destination of NASA`s Deep Impact Mission in
2005.



"Even though ever since this mission we know where
Tempel1`s active regions are, we pretended not to," said
Vincent.



Now the researchers intend to calculate the active
regions of the comet Churyumov-Gerasimenko, the rendezvous
target for ESA`s Rosetta mission on which the Rosetta lander
Philae will touch down in late 2014.



The mission, to which MPS contributed many scientific
instruments, has been on route to its destination beyond the
orbit of Mars and the asteroid belt since 2004.



In the crucial phase of the mission, the new method could
help to determine a safe route for Rosetta through the
cometary coma and may even help find a suitable landing site.



PTI