The sounds of Titan (Forwarded)

ESA News
http://www.esa.int

21 October 2004

The sounds of Titan

The sound of alien thunder, the patter of methane rain and the crunch (or
splash) of a landing, all might be heard as Huygens descends to the surface of
Titan on 14 January 2005.

What's more, they will be recorded by a microphone on the probe and relayed back
so that everyone on Earth can hear the sounds of Titan. Although the Russians
took a microphone to Venus in the 1970s, few scientific results came out of that
endeavour. A similar microphone for Mars was destroyed when NASA's Mars Polar
Lander crashed a few years ago.

The new microphone is part of the Huygens Atmospheric Structure Instrument
(HASI), one of six multi-functional experiments carried on the Huygens probe. It
is designed to help track down lightning by listening for the clap of thunder
usually associated with such an event.

Although there is only a small chance that the spacecraft will pass near a
thunderstorm, it is an extremely important investigation to carry out. It may
help us to understand if thunderstorms are an important energy source for
organic chemistry on Titan.

This may hold clues about how life began on Earth. Titan's atmosphere is laced
with chemicals and many scientists think these are the same as those that formed
the building blocks of life on Earth, 4000 million years ago. But how did they
join together on Earth to ultimately become DNA?

One possibility is that sudden discharges of energy, as occur in lightning,
could have forced the simple chemicals together, making more complicated ones.
So Huygens will listen for thunder and 'sniff' for chemicals that might have
been produced in lightning strikes.

In fact, a second microphone experiment can also be found on Huygens. It is part
of the Surface Science Package (SSP) and contributes to an experiment to measure
the speed of sound in Titan's atmosphere.

These results present an exciting possibility because if the HASI microphone
does hear thunder, electrodes on the same instrument will register the
lightning's electrical discharge and scientists will be able to calculate how
close Huygens passed to the storm.

If Huygens actually passes through a storm, the microphone will detect the
splash of the rain onto the spacecraft casing. Unlike on Earth, this rain will
not be water but probably liquid methane.

Marcello Fulchignoni, of the Universitè Denis Diderot, Paris, is the principal
investigator of HASI. He says, "Combined with the camera images, temperature and
pressure profiles, and altitude data, the 'soundtrack' will provide a
fascinating look at the details of the mission's descent. We will be working
hard to bring the voice of Huygens to the public as soon as we can after the
descent."

More about ...

* Exploring Saturn and Titan
http://www.esa.int/SPECIALS/Cassini-Huygens/index.html
* More on Cassini-Huygens spacecraft
http://sci.esa.int/science-e/www/obj...objectid=35026
* More on Huygens instruments
http://sci.esa.int/science-e/www/obj...objectid=31193
&fbodylongid=1604

In depth

* Status reports
http://sci.esa.int/science-e/www/obj...objectid=31521
&farchive_objecttypeid=30 &farchive_objectid=30930
* How to drop in on Titan
http://www.esa.int/SPECIALS/Cassini-...NPYO4HD_0.html

Related articles

* Surviving extreme conditions in space
http://www.esa.int/esaSC/SEMPT2V4QWD_extreme_0.html
* Discoverer of Titan: Christiaan Huygens
http://www.esa.int/esaSC/SEMJRT57ESD_people_0.html
* Astrology to astronomy: Jean-Dominique Cassini
http://www.esa.int/esaSC/SEMJ2T57ESD_people_0.html

Related links

* NASA's Cassini-Huygens site
http://saturn.jpl.nasa.gov
* Italian Space Agency (ASI)
http://www.asi.it

IMAGE CAPTIONS:

[Image 1:
http://www.esa.int/export/SPECIALS/C...30A90E_1.html]
Huygens probe descending through Titan's atmosphere

[Image 2:
http://www.esa.int/export/SPECIALS/C...html#subhead2]
On 6 June 2003, scientists gathered at the Italian Space Agency's Trapani
balloon-launch facility in Sicily. To launch the 500-kilogram gondola carrying
the mock-up Huygens space probe, they used a helium balloon that fully inflated
to a diameter of 100 metres at its maximum altitude. When the balloon reached a
height of 33 kilometres, a release mechanism opened and dropped the probe.

Credits: ESA

[Image 3:
http://www.esa.int/export/SPECIALS/C...html#subhead3]
Huygens probe descending through Titan's atmosphere