Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How the world watched Huygens

28.07.2006
As Huygens parachuted to the surface of Titan in January 2005, a battery of telescopes around the world were watching or listening.

The results of those observations are now being collected together and published for the first time. The work gives valuable additional context within which to interpret the 'ground truth' returned by Huygens.

Hundreds of scientists, working at 25 radio and optical telescopes situated mainly around the Pacific, from where Titan would be visible at the time of Huygens descent, observed the moon before, during and after the Huygens descent. It was one of the largest ground-based observational campaigns ever to take place in support of a space mission.

The first observations began well over a year before Huygens entered the alien world's atmosphere, when scientists used the fact that Titan would pass directly in front of two distant stars. By watching the way the light faded from the stars, scientists analysed the density, wind and temperature of Titan’s atmosphere. It helped to build confidence by confirming that the atmosphere was similar to their expectations.

A year later, telescopes monitored Titan's atmosphere and its surface at infrared wavelengths for the days and weeks around the Huygens descent. Even now, those observations are of critical importance to the scientists as they continue to interpret the data returned by the probe. "We wanted to know whether the day of the descent was a special day or not on Titan, so that we can place the Huygens data in the correct context," says Olivier Witasse, a Huygens scientist at ESA's European Space Research and Technology Centre (ESTEC) in The Netherlands.

Radio telescopes were used to track Huygens. Both Single-Dish Doppler-tracking, and a Very Long Baseline Interferometry (VLBI) observation that included 17 telescopes, were planned. Doppler-tracking was expected to complement the radio experiment onboard Huygens that used the probe-orbiter link. The VLBI project was initiated about two years before the Huygens entry as a test experiment. No one could predict for certain that the Huygens signal would be detectable but, if it were detected, it would provide unique information.

"One goal of the VLBI observation was to reconstruct the probe's descent trajectory to an accuracy of ten kilometres. At Titan's distance of more than 1 billion kilometres, this is the equivalent of determining positions with an accuracy of just three metres on our own Moon. Another goal was to demonstrate this as a new technique for future missions," says Jean-Pierre Lebreton, Huygens Project Scientist.

The radio experiments worked beyond expectations and even proved to be a 'safety net' when the reception of Huygens' second communications channel failed during the descent. The data from several of Huygens’ six experiments was lost, including that required for the Huygens radio experiment to track the winds during the whole descent. The Doppler-tracking data from the Green Bank Telescope (West Virginia, America) and from Parkes (Australia) provided real-time information about the probe's drift in the winds. The processing of the VLBI data set is not yet completed but initial results look very promising.

The combined analysis of the Huygens data with that acquired by the Cassini orbiter in the past two years allowed scientists to reconstruct the movement of the probe precisely. They pinpointed its landing to 10.33 degrees south and 192.32 degrees west. The VLBI data set will provide an independent reconstruction of the trajectory. It should help to confirm and most likely refine the whole descent trajectory and the coordinates of the landing site.

Jean-Pierre Lebreton | alfa
Further information:
http://www.esa.int/SPECIALS/Cassini-Huygens/SEMJ83EQMPE_0.html

More articles from Physics and Astronomy:

nachricht NASA mission surfs through waves in space to understand space weather
25.07.2017 | NASA/Goddard Space Flight Center

nachricht A new level of magnetic saturation
25.07.2017 | Georg-August-Universität Göttingen

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>