SRON Netherlands Institute for Space Research

Our mission is to bring about breakthroughs in international space research

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SRON Netherlands Institute for Space Research

SRON Netherlands Institute for Space Research

SRON Netherlands Institute for Space Research

Our mission is to bring about breakthroughs in international space research

SEE MORE

SRON Netherlands Institute for Space Research

BOTH SRON BUILDINGS, IN GRONINGEN AND UTRECHT, ARE CLOSED UNTIL FURTHER NOTICE

LATEST NEWS

Since 2012, an enormous cloud is floating high above the South Pole of Titan, a large moon of Saturn. Astronomers have now discovered that this cloud consists of extremely toxic hydrogen cyanide ice. The ice has probably formed after a rapid cooling of the atmosphere. The results have this week been published in Nature.

Titan ice cloud.jpg
On this Cassini image the Titan ice cloud is clearly visible above the South pole (NASA/JPL-Caltech/Space Science Institute).
Titan is the second largest moon of the solar system and the only one with a thick atmosphere. A year on Titan lasts 29 times as long as on Earth and since 2009 Titan's southern hemisphere is heading towards winter. Since 2012, a mysterious cloud was visible above Titan's South Pole in image from the Cassini satellite, which is currently orbiting Saturn and regularly passes Titan at a close distance. Remco de Kok (Leiden University, SRON Netherlands Institute for Space Research), who led the research team: "The appearance of this cloud was a great mystery and no one knew what this cloud was made out of. To determine the composition of this cloud we studied infrared spectra taken by Cassini. In these spectra we found, to our great surprise, at very specific wavelengths the unique fingerprint of hydrogen cyanide ice."

In Titan's atmosphere many chemical reactions take place under the influence of sunlight, which convert the present nitrogen and methane gas into other gases, of which the very toxic hydrogen cyanide (or prussic acid) "The fact that this cloud is composed of hydrogen cyanide is completely unexpected," co-author Nick Teanby (University of Bristol) says. "Hydrogen cyanide only starts to form clouds at extremely low temperatures. At the great altitudes where the cloud is visible (roughly 300 km) we had measured relatively high temperatures only a few months before. The atmosphere there must have cooled about 50 degrees, to a temperature of -150 C, in a very short time."

Rapid cooling

Titancloud_esa.jpg
On this image of Titan red is wavelength in which the surface can be seen. Blue is the wavelength of the HCN feature; green is a wavelength that probes haze in the middle atmosphere (ESA/Remco de Kok)
"This rapid cooling is probably caused by a high concentration of gases, such as HCN and C2H2," says Remco de Kok. These gases emit a lot of heat in the form of infrared radiation, while the south pole receives only little heat from the Sun during the polar winter. Till the end of the Cassini mission in 2017 there will be new measurements that can measure the temperature and gas concentrations at the place where we see the cloud. These will confirm or reject this hypothesis. "It is not clear whether the cloud will remain visible in the coming years. We already see the cloud changing. This will be an interesting time to see what will happen."

Publication
The paper HCN ice in Titan's high-altitude southern polar cloud has this week been published in Nature. The authors are Remco de Kok (Leiden University, SRON Netherlands Institute for Space Research), Nick Teanby (University of Bristol), Luca Maltagliati and Sandrine Vinatier (both University Paris-Diderot), Patrick G. J. Irwin (University of Oxford).

Remco de Kok likes to thank the PEPSci program of the Netherlands Organisation for Scientific Research (NWO). Nick Teanby and Patrick Irwin thank the UK Science and Technology Facilities Council. Luca Maltagliati thanks the Agence Nationale de la Recherche (ANR Project"APOSTIC" no11BS56002, 968 France).

RESEARCH

SRON has four programme lines, Astrophysics, ExoplanetsEarth, and Technology, with science groups attached, and two expertise groups, Instrument science and Engineering.

ASTROPHYSICS

The Astrophysics programme at SRON is dedicated to unraveling the history of the universe, from the first stars and black holes to large-scale structure.

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EXOPLANETS

The Exoplanets programme is dedicated to atmospheres of planets beyond our solar system and is an in-between of SRON's Astrophysics and Earth programmes.

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EARTH

The Earth programme is aimed at the climate and air quality of planet Earth, with focus on the global carbon cycle and aerosols.

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ENGINEERING

The Engineering group covers SRON's skills and know-how with regard to product assurance, quality assurance, configuration control, design engineering – electronic & mechanical – and parts procurement. It is an expertise group that provides resources for all SRON instrument projects.

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INSTRUMENT SCIENCE

The Instrument science group covers SRON's skills and know-how with regard to instrument physics, system engineering (up to full-instrument level) and project management. It is an expertise group that provides resources for all SRON instrument projects.

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TECHNOLOGY

The Technology programme is SRON's backbone for the development of enabling technology.

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SRON’s mission is to bring about breakthroughs in international space research 

Therefore the institute develops pioneering technology and advanced space instruments, and uses them to pursue fundamental astrophysical research, Earth science and exoplanetary research. As national expertise institute SRON gives counsel to the Dutch government and coordinates - from a science standpoint - national contributions to international space missions. SRON stimulates the implementation of space science in our society.



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