Huygens probe

The IRIS spectra of Titan s atmosphere returned from Voyager I show extensive organic composition across the entire disc of Titan (Figure 10.7) and only promises (or threatens) more organic complexity when the measurements from the gas chromatography/mass spectrometry instruments on the Huygens probe are returned. 

It is clear that a complex hydrocarbon polymer chemistry must exist in the atmosphere of Titan involving polyyne species, polynitrile species and mixtures of the two, and additional routes to polyaromatic hydrocarbon formation. This presents a significant problem for the gas chromatography/mass spectrometry instruments on the Huygens probe. There should be hydrocarbon fragments, producing perhaps... 

Finally, and tantalizingly for this book and astrochemistry, there is Titan. The Cassini-Huygens mission is now in orbit in the Saturnian system as the book is published. The Huygens probe has already made the descent to the surface of Titan and the data have been transmitted back successfully. Scientists, astronomers, astrochemists and astribiologists are trying to understand it. I have taken a brief look at Titan as a case study to apply all that has been learnt and to review the possibilities for astrochemistry in what is surely to be a very exciting revelation of the structure and chemistry of Titan. 

The Cassim-Huygens spacecraft consists of two parts. Cassini is the orbiter, designed to attain orbit around Saturn, while Huygens is a space probe, designed to be released into the atmosphere of the planet s moon, Titan. NASA was responsible for the design and construction of the Cassini orbiter, while ESA was responsible for the Huygens probe. 

On its way to Saturn, Cassini-Huygens passed by the asteroid Masursky (on January 23, 2000) and Jupiter (December 30, 2000). In early June it passed near one of Saturn s outermost moons, Phoebe, and there took photographs and collected data that promise to reveal important new details about that moon s origin. The spacecraft arrived in the Saturnian atmosphere exactly on schedule, on June 30, and sent back some of the most astonishing astronomical photographs of any solar system object ever collected. The Huygens probe... 

Mission to Saturn Cassini and the Huygens Probe. New York Praxis... 

In early 2005, the European Space Agency s Huygens Probe landed on Saturn s largest moon Titan. Soon after the 319-kg probe impacted the surface at a speed of 5 m s, a sudden increase in methane gas concentration was detected. The methane is believed to have been produced by the conversion of liquid methane in the soil to vapor as a result of heating from the impact. Determine the maximum amount of liquid methane that could have been evaporated in this process. State any assumptions that you make. 

Titan is both like and unlike Earth. The most striking likenesses can be seen in pictures taken by the Huygens probe in 2005. Huygens was launched as part of the Cassini mission to explore Saturn. Actually, it was more dropped than launched. As it fell through Titan s atmosphere, the clouds parted and it sent back the first pictures of the moon s surface. An online video titled Huygens Titan Descent Movie shows what Huygens saw. 

Sarani, S., 2005. Cassini attitude control configuration for Huygens probe release. In AIAA-2005-6390, Guidance, Navigation, and Control Conference, San Francisco, CA, August 15-18. 

ROBERT SAMUELSON was a research scientist at the Goddard Space Flight Center for 39 years and is presently a research associate with the Astronomy Department at the University of Maryland. His specialities include radiative transfer in scattering atmospheres and the interpretation of radiometric and spectroscopic data from ground-based and space-borne infrared instruments. He is a co-investigator for the Cassini Orbiter infrared spectrometer and the Huygens Probe aerosol collec-tor/pyrolizer experiment. 

A review about the results from the Huygens probe was given by Lebreton et al., 2009 [197]. 

Radar-bright channels are interpreted as riverbeds, where debris, likely shaped and transported by fiuvial activity, have been deposited. Similar debris were observed in the landing site of the Huygens probe. The size of the icy peebles is larger than the radar wavelength (2.18 cm) (Cassini Radar Team, 2010 [333]). 

Lebreton, J.-P, Coustenis, A., Lunine, J., Raulin, F, Owen, T, Strobel, D. Results from the Huygens probe on Titan. Astron. Astrophys. Rev. 17, 149-179 (2009)... 

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