Rosetta and the Leonids
Very few comets have been observed at close quarters by spacecraft,
so most of what we know about these primitive planetary building
blocks comes from ground observations.
by studying comet dust that enters Earth's atmosphere and creates
the shooting stars, scientists can learn a lot about these mysterious
cosmic snowballs. This information can then be used to predict what
spacecraft will encounter when it arrives at Comet Wirtanen in 2011.
"Our studies of the Leonids should tell us about the porosity
of the particles that cause the Leonid shower," said Koschny.
"This will help us to calculate the density of their parent comet,
Tempel-Tuttle, and to improve our understanding of comets in general."
In addition, by examining the composition of the meteors (looking at
their chemical makeup by studying their chemical fingerprints) scientists
can speculate on what the comet will be like close-up. Studying the density
and intensity of the Leonids helps in understanding how the comet behaves.
This is an important factor in selecting the landing site for the Rosetta
"When Rosetta becomes the first spacecraft to go into orbit
around the nucleus of Comet Wirtanen and to release a lander onto
its surface, we want to have a good idea about what to expect,"
said Koschny. "Our observations of the dust from Tempel-Tuttle,
which is similar in many ways to Wirtanen, should be a great help."
As part of their Australian adventure the team will also be testing
a prototype instrument called the Mutual Impedance probe (or MI
for short). But, rather than looking at the skys, the MI probe focuses
firmly on the ground. The dry conditions are an ideal testing ground
for the probe, which is similar to the SESAME instrument currently
being developed for Rosetta. Both of these instruments have been
developed to examine the surface layers of an object, a comet or
planet for example, by measuring the electrical properties of these
objects. By studying these electrical signals, scientists can learn
about the composition of the surface layers, and may even discover
the presence of water. The results of these tests will help the
Rosetta team better understand the data which will come from Rosetta.