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 Unraveling the nature of 'whistlers' from space in the lab
15.08.2018 | American Institute of Physics

nachricht Early opaque universe linked to galaxy scarcity
15.08.2018 | University of California - Riverside

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: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Unraveling the nature of 'whistlers' from space in the lab

15.08.2018 | Physics and Astronomy

Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide

15.08.2018 | Earth Sciences

Early opaque universe linked to galaxy scarcity

15.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>