[meteorite-list] Rosetta's Target Comet is Becoming Active (Comet 67P/Churyumov-Gerasimenko)
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 15 May 2014 08:25:32 -0700 (PDT)
Rosetta's Target Comet is Becoming Active
European Space Agency
15 May 2014
The target of ESA's Rosetta mission has started to reveal its true personality
as a comet, its dusty veil clearly developing over the last six weeks.
The sequence of images presented here of comet 67P/Churyumov-Gerasimenko
were taken between 27 March and 4 May, as the gap between craft and comet
closed from around 5 million km to 2 million km.
By the end of the sequence, the comet's dusty veil - the "coma" - extends
some 1300 km into space. By comparison, the nucleus is roughly only 4
km across, and cannot yet be "resolved".
The coma has developed as a result of the comet moving progressively closer
to the Sun along its 6.5 year orbit. Even though it is still more than
600 million km from the Sun - more than four times the distance between
Earth and Sun - its surface has already started to warm, causing its surface
ices to sublimate and gas to escape from its rock-ice nucleus.
Comet on 30 April
As the gas escapes, it also carries a cloud of tiny dust particles out
into space, which slowly expands to create the coma.
As the comet continues to move closer to the Sun, the warming continues
and activity rises, and pressure from the solar wind will eventually cause
some of the material to stream out into a long tail.
Rosetta and the comet will be closest to the Sun in August 2015, between
the orbits of Earth and Mars.
The onset of activity now offers scientists the opportunity to study dust
production and structures within the coma before getting much closer.
"It's beginning to look like a real comet," says Holger Sierks, principal
investigator for OSIRIS, the Optical, Spectroscopic and Infrared Remote
Imaging System, at the Max Planck Institute for Solar System Research,
"It's hard to believe that only a few months from now, Rosetta will be
deep inside this cloud of dust and en route to the origin of the comet's
In addition, tracking the periodic changes in brightness reveals the nucleus
is rotating every 12.4 hours - about 20 minutes shorter than previously
"These early observations are helping us to develop models of the comet
that will be essential to help us navigate around it once we get closer,"
says Sylvain Lodiot, ESA Rosetta spacecraft operations manager.
OSIRIS and the spacecraft's dedicated navigation cameras have been regularly
acquiring images to help determine Rosetta's exact trajectory relative
to the comet. Using this information, the spacecraft has already started
a series of manoeuvres that will slowly bring it in line with the comet
before making its rendezvous in the first week of August.
Detailed scientific observations will then help to find the best location
on the comet for the Philae lander's descent to the surface in November.
Close-up of comet on 30 April
The images shown here were taken during a six-week period that saw the
orbiter's 11 science experiments and the lander and its 10 instruments
switched back on and checked out after more than 2.5 years of hibernation.
Earlier this week, a formal review brought these commissioning activities
to a close, giving the official "go" for routine science operations.
"We have a challenging three months ahead of us as we navigate closer
to the comet, but after a 10-year journey it's great to be able to say
that our spacecraft is ready to conduct unique science at comet 67P/C-G,"
says Fred Jansen, ESA's Rosetta mission manager.
More about Rosetta
Rosetta is an ESA mission with contributions from its member states and
NASA. Rosetta's Philae lander is provided by a consortium led by DLR,
MPS, CNES and ASI. Rosetta will be the first mission in history to rendezvous
with a comet, escort it as it orbits the Sun, and deploy a lander.
Comets are time capsules containing primitive material left over from
the epoch when the Sun and its planets formed. By studying the gas, dust
and structure of the nucleus and organic materials associated with the
comet, via both remote and in-situ observations, the Rosetta mission should
become the key to unlocking the history and evolution of our Solar System,
as well as answering questions regarding the origin of Earth's water and
perhaps even life.
More about OSIRIS
The scientific imaging system was built by a consortium led by the Max
Planck Institute for Solar System Research (Germany) in collaboration
with CISAS, University of Padova (Italy), the Laboratoire d'Astrophysique
de Marseille (France), the Instituto de Astrof??sica de Andaluc??a, CSIC
(Spain), ESA's Scientific Support Office, the Instituto Nacional de T??cnica
Aeroespacial (Spain), the Universidad Polit??cnica de Madrid (Spain),
the Department of Physics and Astronomy of Uppsala University (Sweden),
and the Institute of Computer and Network Engineering of the TU Braunschweig
(Germany). OSIRIS was financially supported by the national funding agencies
of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC) and Sweden (SNSB),
and the ESA Technical Directorate.
For more information, please contact:
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer at esa.int
ESA Rosetta mission manager
Email: fred.jansen at esa.int
ESA Rosetta project scientist
Email: matthew.taylor at esa.int
ESA Rosetta spacecraft operations manager
Email: sylvain.lodiot at esa.int
OSIRIS Principal Investigator
Max Planck Institute for Solar System Research
Tel: +49 551 384 979 - 242
Email: Sierks at mps.mpg.de
Received on Thu 15 May 2014 11:25:32 AM PDT