Australian telescopes to
take part in Huygens

space-probe experiment

9 Dec 2004

On 14 January, radio telescopes of CSIRO and other Australian institutions
will help pinpoint the location of the European Space Agency's Huygens probe
as it plunges through the clouds of Titan, Saturn's largest moon.

The goal is to measure the speed of the winds in Titan's atmosphere.

This experiment is being coordinated by JIVE, the Joint Institute for VLBI
in Europe. It is separate from the tracking of the probe's parent Cassini spacecraft,
which will be done by NASA’s Deep Space Communication Network, including
the Canberra Deep Space Communications Complex at Tidbinbilla, ACT.

Shortly after 9 pm AEDT the probe will start its descent through the clouds
of Titan, 1.2 billion kilometres from Earth. Using a special technique, a network
of 17 radio telescopes in Australia, the USA, China and Japan will attempt to
determine its entry point to within a kilometre.

The radio telescopes taking part in Australia are the CSIRO telescopes near
Parkes, Narrabri and Coonabarabran (all in NSW) and telescopes of the University
of Tasmania near Hobart and Ceduna (South Australia).

As it parachutes through Titan's clouds the Huygens probe will transmit data
to the Cassini orbiter. The ground-based telescopes will eavesdrop on this transmission.

"The signal will be extremely weak - about as weak as a signal from a mobile
phone on Venus would be," says CSIRO's Dr Chris Phillips, who is coordinating
the Australian observations.

The Parkes telescope will be particularly important in the network because of
its large size, which makes it ideal for collecting weak signals.

Parkes will also be used for a separate, extra experiment, to determine the
position of the probe by measuring the Doppler shift of its signal.

Information on the probe's position from these experiments will be combined
with data from the Cassini orbiter and used to calculate the speed of the winds
in Titan's atmosphere.

Titan is the second-largest moon in our Solar System, with a diameter about
one-and-a-half times that of our Moon. It has a thick atmosphere, and is thought
to harbour organic compounds that might be important in the formation of life.

Seventeen countries are contributing to the Cassini-Huygens mission. The Huygens
probe is supplied by the European Space Agency (ESA) and the Cassini orbiter
by NASA. Huygens operations will be controlled by ESA from its operations centre
in Darmstadt, Germany. NASA is providing the mission operations and telecommunications
through its Deep Space Network of antennas, which includes the Canberra Deep
Space Communications Complex at Tidbinbilla.

The US-based telescopes taking part in the experiment belong to the Very Long
Baseline Array (VLBA) operated by the National Radio Astronomy Observatory (NRAO).
NRAO is a facility of the National Science Foundation, operated under cooperative
agreement by Associated Universities, Inc.



Dr Chris Phillips, Bolton Fellow, CSIRO Australia Telescope National Facility

Office: 02-9372-4608

Mobile: 0439-487-601

Dr John Reynolds, Officer-in-Charge, CSIRO Parkes Observatory

Office: 02-6861-1733

Mobile: 0413-026-998

Professor John Dickey, University of Tasmania

Office: 03-6226-2447

Dr Leonid Gurvits, Project Manager, Huygens VLBI tracking experiment

Joint Institute for VLBI in Europe, Dwingeloo, The Netherlands

Office: +31 (0)521 596514

Dr Rosemary Mardling, Centre for Stellar and Planetary Astrophysics, Monash

(Dr Mardling's interest in Titan is related to how the Solar System was formed,
and in particular whether or not Titan is a captured satellite of Saturn.)

Office 03 9905-4506

Mobile 0409 808 218


ESA’s Cassini-Huygens website

NASA’s Cassini-Huygens website

TV broadcast

ESA-TV will broadcast Huygen's descent into Titan live on 14/15 January.

Details of the broadcast will be posted at in early