Leaving home to catch a comet (Forwarded)

ESA Science News
http://sci.esa.int

30 December 2003

Leaving home to catch a comet

ESA's comet chaser Rosetta will soon be heading towards its new target, known as
Comet 67P/Churyumov-Gerasimenko. With its launch now planned for 26 February
2004, Rosetta will be one of the most ambitious scientific missions ever
launched by Europe.

One year ago, scientists around the world were eagerly awaiting the start of
Rosetta's historic mission to orbit and land on a small comet called
46P/Wirtanen. Then, following a mishap with an Ariane 5 launch vehicle, the
mission was put on hold and scientists began to search for other comets that
would be within Rosetta's range.

Following an analysis of available objects, ESA decided to send Rosetta to
another regular visitor to our Solar System, Comet 67P/Churyumov-Gerasimenko.

Under the revised flight plan, the spacecraft will now make one fly-by of Mars
and three fly-bys of Earth on its way to the comet. This journey will also
enable Rosetta to make two excursions into the main asteroid belt before its
comet rendezvous.

At present, scientists are still discussing the amount of extra science that
will be done during the 10-year trek to Churyumov-Gerasimenko. Some observations
of Mars will be possible, and there is likely to be at least one opportunity to
study an asteroid at close quarters.

A number of possible asteroids have already been identified as candidates for
study, but the final selection will be made after launch, once the mission team
has determined how much surplus fuel is available on the spacecraft.

However, the most exciting phase of Rosetta's 11-year mission will come when it
meets Churyumov-Gerasimenko in August 2014.

From an orbit of just a few kilometres, its cameras will be able to map the
entire pockmarked surface of the icy nucleus at high resolution and search for
suitable landing sites.

Once a safe landing site has been selected, the Rosetta lander will separate
from the orbiter and slowly descend to the surface. If all goes according to
plan, the lander will anchor itself to the icy crust and begin a detailed survey
of its surroundings.

The lander will return close-up pictures of the comet's nucleus, drill into the
dark organic crust, and sample the primordial ices and gases. Meanwhile, the
orbiter will continue to monitor the dramatic changes in the nucleus that take
place as it approaches the Sun. Because Rosetta will escort the comet around the
Sun, beyond its closest approach, we will also see the changes as it leaves the Sun.

Rosetta will provide new insights into such fundamental mysteries as the
formation of Earth's oceans and the origin of life. It may even help the human
race to survive, giving us vital clues about how to respond should we ever find
a comet on a collision course with the Earth.

This remarkable voyage of exploration will come to a close in December 2015, six
months after the comet swings back out to the colder regions beyond Jupiter.

More about ...

* Rosetta overview
http://www.esa.int/export/esaSC/120389_index_0_m.html

Related articles

* New destination for Rosetta, Europe's comet chaser
http://www.esa.int/esaSC/SEMLSFS1VED_exploring_0.html
* Landing on a cosmic iceberg
http://www.esa.int/esaSC/SEM6N12A6BD_exploring_0.html
* Why is our comet mission called 'Rosetta'?
http://www.esa.int/esaSC/SEM0J00P4HD_index_0.html
* The challenge of landing on alien worlds
http://www.esa.int/esaSC/SEMSTPWO4HD_index_0.html
* Accidental space scientist: An interview with Gerhard Schwehm
http://www.esa.int/esaSC/SEMFM2XLDMD_index_0_iv.html
* Here for the duration: An interview with Kristin Wirth
http://www.esa.int/esaSC/SEMGMB374OD_index_0_iv.html

IMAGE CAPTIONS:

[Image 1:
http://www.esa.int/export/esaSC/SEME..._index_1.html]
Rosetta leaves home to catch a comet.

Credits: ESA

[Image 2:
http://www.esa.int/export/esaSC/SEME...html#subhead1]
Relative sizes of Otawara, Siwa and other known asteroids.
On the outward leg of its 11-year trek to a comet, Rosetta will make two
excursions into the main asteroid belt that lies between the orbits of Mars and
Jupiter. On each visit, Rosetta will send back the first detailed pictures of
and scientific data on some asteroids.

Credits: AOES Medialab/NASA/ JPL, JHU/ APL

[Image 3:
http://www.esa.int/export/esaSC/SEME...html#subhead3]
Rosetta will drop a lander onto a comet for the first time. This artist's
impression shows the Rosetta lander anchored to the comet’s surface, it will
work for a minimum mission target of 65 hours, but its operations may continue
for many months.

The lander structure consists of a baseplate, an instrument platform, and a
polygonal sandwich construction, all made of carbon fibre. Some of the
instruments and subsystems are beneath a hood, which is covered with solar
cells. An antenna transmits data from the surface to Earth via the Orbiter. The
lander carries nine experiments, with a total mass of about 21 kilograms. It
also carries a drilling system to take samples of subsurface material.

Credits: ESA/AOES Medialab