[meteorite-list] ESA's New Camera Follows Disintegration of a Comet (Schwassmann-Wachmann 3)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri May 19 12:47:24 2006
Message-ID: <200605191645.JAA11201_at_zagami.jpl.nasa.gov>

http://www.esa.int/esaCP/SEMN1C9ATME_index_0.html

ESA's new camera follows disintegration of a comet
European Space Agency
19 May 2006

The continuing disintegration of Comet 73P/Schwassmann-Wachmann 3 has
allowed ESA scientists to see into the interior of the comet. Using a
revolutionary camera attached to the ESA Optical Ground Station on
Tenerife, they have followed the detailed twists and turns of various
comet fragments.
 
The superconducting camera, SCAM, is an ultra fast photon counting
camera, developed by ESA. It is cooled to just 300 thousandths of a
degree above absolute zero. This enables its sensitive electronic
detectors, known as superconducting tunnel detectors, to register almost
every single photon of light that falls into it. As such, it is the
perfect instrument with which to detect fast and faint changes in the
fragments of the comet.

Comet 73P/Schwassmann-Wachmann 3 is a short-period comet that approaches
the Sun every 5.4 years. Two apparitions ago, in 1996, the comet nucleus
split into five pieces (Fragments A, B, C, D, E) of which 3 (B, C, E)
were still visible at its 2001 return.
 
When it approached the Sun again this year, seven fragments were
initially observed, indicating that the comet was breaking apart again.
Indeed, as astronomers watched, further fragments broke off. Fragment B
alone produced at least seven new pieces. At present, about 40 fragments
are visible, most of which are likely to be very small and with
irregular and short-lived activity.

SCAM was attached to the one-metre ESA Optical Ground Station telescope
on 7 May 2006, when the disintegrating comet was observed . Every few
microseconds, the camera reads out the number of photons that have
touched it and their colour. Using the unprecedented accuracy of the
camera, ESA scientists charted the evolution of the dust and gas
envelopes associated with each fragment for two hours. Now they must
analyse the results.

In particular they will be looking for differences in the size and shape
of the fragments and also any colour differences between them that might
indicate compositional differences. Other studies are made possible by
SCAM's unrivalled time resolution. Outbursts and activity from each
fragment can be traced down to changes that occur on a timescale of one
minute. In addition, as the dust and gas particles released from the
fragments move with velocities between 0.5 and 1 kilometres per second,
the observations will allow the interaction of the gas and dust flow to
be studied for the two fragments closest to one another.

Comet 73P/Schwassmann-Wachmann 3 is one of the comets that was
considered as a potential target for ESA's Rosetta mission. In 1995 even
before its initial splitting, it was abandoned in favour of comet
46P/Wirtanen. After the launch delay of 2003, ESA decided not to
re-select 73P/Schwassmann-Wachmann 3 as the replacement Rosetta target,
because of the comet's volatile behaviour. In 2014, Rosetta will
rendezvous and land on the Jupiter-family comet 67P/Churyumov-Gerasimenko.

 
 
For more information:
 
Rita Schulz, ESA - for questions on the comet
Email: Rita.Schulz _at_ esa.int

Didier Martin, ESA - for questions on the SCAM camera
Email: Didier.Martin _at_ esa.int

Christian Erd, ESA - for questions on the OGS optical station
Email: Christian.Erd _at_ esa.int
Received on Fri 19 May 2006 12:45:17 PM PDT