This Echo is READ ONLY !   NO Un-Authorized Messages Please!
 ~~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1\13 UK - Plasma Probe Scientists Ready For Rosetta Blast-Off
Part 1 of 2

For Immedidate Use

Plasma probe scientists ready for Rosetta blast-off
Imperial College of Science, Technology and Medicine
United Kingdom
January 13, 2003

Scientists who built and will control the instruments to investigate 
plasma changes around a comet describe their contribution to the ten 
year long mission at a pre-launch press briefing in London today 
(Monday 13 January).

While the actual launch date for the European Space Agency's Rosetta 
mission has yet to be confirmed, the scientists, engineers and 
technicians behind the plasma-detecting instruments on board the 
spacecraft are all ready to begin the journey to comet Wirtanen they 
hope will return a rich scientific bounty.

"We're not very familiar with plasma here on Earth, but it does exist 
all around us, for example, in fluorescent lights or the flame of a 
match. It's simply a gas which has become electrically charged," says 
Chris Carr, spokesman for the Rosetta Plasma Consortium instruments, 
based at Imperial College London.

"Outside the confines of our atmosphere on earth, the vacuum of space 
is filled with a very, very dilute plasma - maybe only a thousand 
atoms in each litre of space."

The Rosetta Plasma Consortium has built highly sensitive instruments 
capable of detecting and measuring the properties of this diffuse 
plasma.

The sensors will be switched on well before the cameras are able to 
see any activity on the surface of the comet, making it likely that 
plasma instruments will be one of the first to detect the telltale 
signature of the comet.

The Plasma Consortium's chief interest is to learn how the solar wind 
- a stream of plasma that flows out from the Sun and fills the Solar 
System - interacts with the comet itself.

"A lot of the gas which comes off the comet is actually turned into 
plasma by the action of the strong ultra-violet light from the Sun," 
explains Mr Carr.

"So there is a source of plasma pushing outwards from the comet which 
meets the solar wind head on, producing a 'bubble' of comet plasma in 
a sea of solar wind."

The plasma instruments will study the structure of this bubble, which
measures about a million kilometres wide, and compares with a nucleus 
size of the comet of just one kilometre.

"One of the things we're really excited about is that we will be 
monitoring the comet over a long period of time, so we will be able to 
watch as the comet activity goes from nothing to a really strong 
outflow of material," says Mr Carr.

The plasma instruments weigh just over 7kg, and because Rosetta is far 
out in deep space, with very little sunlight shining on the solar 
panels, have been designed to consume less than a quarter of the power 
of a single light bulb.

The plasma investigation will be carried out by a group of five 
instruments built by space researchers from Sweden, Germany, France, 
USA and the UK.

Scientists at Imperial College London built the Plasma Interface Unit 
- the 'nervous system' - that links up the five ultra-sensitive 
plasma-detecting probes aboard Rosetta (See notes to editors).

Assuming a successful Rosetta launch before the end of January 2003, 
theirs will be the first scientific instrument to be turned on at the
'commissioning' stage due to take place from February at the European 
Space Agency operations centre in Darmstadt, Germany.

The PIU itself weighs about 3kg and is the size of two shoe boxes on 
top of each other, and has been the focus of a number of technical 
innovations.

"Developing this unit, the 'nervous system' for the plasma 
instruments, was a constant balancing act between miniaturisation to 
save space and weight and maintaining its reliability to give 
continuous operation in space for ten years," says Dr Chris Lee, 
Rosetta Plasma Consortium Operations Manager, based at Imperial 
College London.

For example, the walls of the box were machined down from sheets of
aluminium 2.54 centimetres (an inch) thick to just 0.3mm in places - a
machining task that required a new technical innovation from Ray 
Swain, head of the Department of Physics workshops, as standard 
techniques left the metal warped.

Scientists from Imperial's Space and Atmospheric Physics Group have
extensive experience in building and operating plasma instruments 
aboard space missions including those that have flown on the Cluster 
mission around Earth, the Cassini mission to Saturn, the Double Star 
mission around Earth and the Ulysses mission to the Sun.

The Imperial team behind the PIU was recently promoted from 
Co-Investigator to Principal Investigator status.

                                     ###

For more information and pictures please contact:

Chris Carr
Rosetta Plasma Consortium spokesman
Department of Physics
Imperial College London
Tel: 44-207-594-7765
E-mail: c.m.carr{at}imperial.ac.uk

Dr Chris Lee
Rosetta Plasma Consortium Operations Manager
Department of Physics
Imperial College London
Tel: 44-207-594-7762
E-mail: c.g.y.lee{at}imperial.ac.uk

Tom Miller
Imperial College London Press Office
Tel: 44-207-594-6704
Mobile: 44-780-388-6248
E-mail: t.miller{at}imperial.ac.uk

Notes to editors:

Chris Carr will be speaking at the UK media briefing for the Rosetta 
mission on Monday 13 January, 1.30pm at the Royal Society, London. 
Further details from Julia Maddock at the Particle Physics and 
Astronomy Research Council.  Tel: 44-179-344-2094 Email: 
julia.maddock{at}pparc.ac.uk

(continued)

---