Search

 

PressCNRS international magazine

Table of contents

Antarctica An Ideal Observation Outpost

Though the sun only shines half the year, Antarctica turns out to be the best location for scientists–cosmologists, geophysicists, space mission coordinators or even psychologists–to pursue research in their field. Though conditions are inhospitable, the continent is itself an ideal observatory for a host of scientific disciplines.

 

silhouettes

© G. Polenta/CNRS Photothèque/APC

Researchers working on installing the Brain experiment, dedicated to the detection of cosmic background radiation.


 

CLEAR SKIES

For astronomers, there is no doubt that it is a short step from the poles to the stars. And nowhere is this more evident than at Concordia, the French-Italian station built on the site of Dome C, 1100 kilometers inland from the coast of Antarctica. At 3200 meters, its altitude is already an advantage when it comes to observing the sky, but it presents a number of other qualities that have got astronomers quite excited. As Éric Fossat from LUAN1 explains, “we are still determining whether or not Dome C fully qualifies for astronomy research, but what we do know is that as far as visibility goes, this is the best Earth-based observatory... nearly as good as a space telescope.”

With temperatures sometimes dropping below -80°C in winter and almost no precipitation, Dome C is one of the driest places on Earth, making it an ideal location for observing the sky at infrared wavelengths. Indeed, in most terrestrial environments, infrared radiation is absorbed by water vapor in the atmosphere, and thus can only be observed from space. As for cloud cover, conditions are astoundingly favorable. “During the last overwintering2 we reckoned that stars were hidden by cloud cover only 6 to 10 percent of the time. That doesn't happen anywhere else on Earth,” Fossat enthuses. Furthermore, there is very little atmospheric turbulence at the site during daytime, which bodes well for solar astronomy. The only downside is that a layer of slightly turbulent air comes with night, soaring to an altitude of 30 meters. But this should not be a problem for the giant telescope3 planned by the ESO4 which could be operational in just 10 years if the Dome C site is selected for its construction. It will be so large that its mirror will be more than thirty meters above ground.

For now, a number of projects adapted to Concordia's logistics are under study or in progress. And as of next year, two Italian instruments, the International Robotic Antarctic Infrared Telescope (IRAIT) and the extremely powerful Antarctic Multiband Infrared Camera (AMICA), will be operational at Dome C. Likewise, by 2009, CNRS should have installed its automatic telescope for detecting extrasolar planets.

Another area of research that could benefit from the remarkable atmospheric conditions at Dome C is cosmic background radiation. This refers to radiation emitted approximately 300,000 years after the Big Bang, at the moment when the temperature became low enough for electrons to permanently bind to protons. This fossil radiation, which still fills the whole Universe, contains valuable information not just about the evolution of the structure of the Universe, but also about its history during its first moments of existence. But detecting these radiations from Earth proves to be difficult, since the atmospheric water vapor absorbs microwave radiation. The only really effective solution is to use cosmology-dedicated satellites like COBE, WMAP, or the forthcoming Planck, scheduled for launch next year. However, to detect the polarization of the cosmic background information–a parameter that should give astrophysicists information about “inflation,” a very early phase of rapid expansion of the Universe–we will have to wait for a new generation of satellites, scheduled to be operational by 2020. To try to gain time, a French-Italian-UK team, as part of the BRAIN project, began the installation in 2004 of a number of bolometers all around Concordia, where we can find the best atmospheric conditions for microwave radiation detection on earth. These detectors, placed inside a cryostat–a device that cools them down to a temperature of just a few hundred millikelvins5–are made up of a crystal whose temperature varies according to the energy of the particles that strike it. “We hope that this experiment will start giving results by 2009,” enthuses Yannick Giraud-Héraud, from the APC Laboratory.6

 

VISITORS FROM SPACE

Meanwhile, Jean Duprat from the CSNSM7 has already shown that Dome C was a wonderful location for collecting micrometeorites. Although approximately 5-6000 micrometeorites fall to Earth every year, finding one in the average shovelful of dirt is like looking for a needle in a haystack. Not long ago, scientists concluded that the best place to look for them was in the extremely clean snow found at the poles. All they had to do was melt the snow and filter the water. This type of research was first conducted in Greenland, then in the 1980s at Cape Prud'homme in Antarctica, and since 2000 at Concordia. “The summer 2006 campaign was a tremendous success. Approximately 1500 grains between 20 and 500 micrometers in diameter were collected,” explains Duprat. “The central regions of Antarctica harbor entire collections of micrometeorites. We hope to find cometary micrometeorites–originating in the outer solar system–in these samples. That would be a world premiere.This means that scientists would have at their disposal, right here on Earth, objects thought to be the oldest in the solar system and whose composition would shed light on the formation of the planets, some 4.5 billion years ago.

Since Antarctica seems to be the final destination for most extraterrestrial phenomena, it's no surprise that cosmic ray research is also quite active on the continent. These very high-energy particles–such as protons and heavy nuclei–are accelerated to high speeds by exploding stars in our galaxy or, in the case of less energetic particles, by the Sun. But as Ludwig Klein from the Observatoire de Paris in Meudon points out, “the less energetic particles only reach the Earth's surface at high latitudes, due to the fact that cosmic rays are deflected by the Earth's magnetic field.” This is why it is necessary to look for them in such inhospitable regions. Not only for the sake of astrophysical research, but also to monitor the radiation doses received by civil aircraft crews. Something that French astrophysicists have been doing since the 1960s, using detectors set up in the Kerguelen islands and in Terre Adélie.

 

glacier b

© Duprat, Engrand/CNRS Photothèque

The researchers at Dome C are extracting micrometeorites from the snow.


 

DETECTING THE EARTH'S MOVEMENTS

With a surface network of seismometers as the only tool for probing the internal structure of the Earth, “seismologists can hardly do without the polar regions,” emphasizes Jean-Jacques Lévêque, from IPG in Strasbourg.8 A seismic observatory has indeed been in continuous operation at the Dumont d'Urville base for the last forty years or so. But a few intrepid French and Italian scientists are also hoping to have a seismic observatory up and running soon at Concordia Station. As Lévêque explains, “Dome C is a particularly interesting place to study the propagation of seismic waves in the Earth's core, which we know to be faster along the North-South axis than in the equatorial plane.” But before the new observatory can be operational on a continual basis, the seismologists will have to prepare both themselves and their equipment for extremely harsh working conditions.

Magnetic field specialists are in a similar situation. They already have an observatory at the Dumont d'Urville base, part of the worldwide network of magnetic observatories, but they're hoping to extend its coverage by setting up sensors at Dome C. “Although they are quite close to one another, the Dumont d'Urville and Concordia sites are very different with regard to the Earth's magnetic field,” explains Jean-Jacques Schott, also from IPG in Strasbourg. “Dumont d'Urville is located near the magnetic pole, where the magnetic field lines are vertical. Since the magnetic pole constantly moves, it is interesting to observe how it changes over time, particularly since we know that the Earth'magnetic field has reversed several times over the course of the planet's history. As for Dome C, it should help us to get a better understanding of the interaction of solar wind with the Earth's magnetic field.” However, all this is contingent on solving human and material failures that plagued the first two overwinterings at Concordia, problems obviously linked to doing research in very hostile environmental conditions.

 

NEXT STOP: SPACE

Interestingly, it is precisely the harshness of the conditions found at high latitudes that delights those scientists involved in preparing extraterrestrial experiments. Michel Menvielle from CETP9 is testing and carrying out research on a magnetometer designed to measure the Martian magnetic field. “With temperatures often as low as -60 to -80°C, we can test equipment intended for space exploration over long periods of time,” he explains.

Of course, this type of research also applies to human beings, who are put to the test when living in such harsh conditions. Stations like Concordia are invaluable observatories for psychologists who study humans' ability to adapt to extreme conditions. Since overwintering began at Dome C two years ago, Élisabeth Rosnet from the University of Reims, has gone to the site every year to debrief the people stationed there. “We analyze the effects of remoteness, of living in isolation and in confinement, the problems that are linked to cultural differences in small groups, etc.,” she explains. Answers to these questions will better prepare scientists for the next polar missions, but also for the long space missions of tomorrow, because as Rosnet puts it, “life at the poles offers the environment with the most resemblance to life in space.”

So whatever the discipline, it seems likely that scientists won't be leaving Antarctica any time soon. The scientific fertility of this frozen continent seems directly proportional to the harshness of its environment. And despite the freezing cold, the rapid deterioration of equipment, and the bitter isolation, the number of scientific projects in Antarctica increases with every year.

 

Mathieu Grousson

 

The French Polar Institute at the Helm

The French Paul-Émile Victor Polar Institute (Institut polaire français Paul-Émile Victor, IPEV), a public interest group set up in 1992, provides a legal framework as well as the human, logistical, technical, and financial means needed for the development of French research in the polar regions. It brings together nine partners: CNRS, the French Atomic Energy Agency (CEA), the Research Institute for Marine Resources (IFREMER), the National Center for Space Studies (CNES), the Ministry of Research and New Technologies, the Ministry of Foreign Affairs, the French Meteorological Office (Météo-France), the French Southern and Antarctic Territories, and French polar expeditions. The IPEV is responsible for the construction, administration, and maintenance of French bases in Antarctica (Dumont d'Urville and Concordia), in

Every year, the IPEV issues a call for scientific projects. After being reviewed for interest and feasibility by the institute's Scientific Council, close to sixty projects end up receiving funding and logistical support. Operational until 2014, the IPEV has a full-time dedicated staff of fifty, but recruits every year approximately 80 employees for overwintering missions, mostly civilian volunteers for technical assistance.

M.G.

 

Contact:

Alain Lesquer, Department of communication.

alesquer@ipev.fr

  

Notes :

1. Laboratoire universitaire d'astrophysique de Nice (CNRS/ Université de Nice joint lab).
2. Winter period during which an expedition is completely cut off from the rest of the world due to weather conditions.
3. The European Extremely Large Telescope.
4. European Southern Observatory.
5. 0 kelvin (K) = -273.16 degrees Celsius (°C).
6. Laboratoire Astroparticule et cosmologie (CNRS / Université Paris-VII / CEA / Observatoire de Paris joint lab).
7. Centre de spectrométrie nucléaire et de spectrométrie de masse (CNRS / Université Paris-XI joint lab).
8. Institut de physique du globe (CNRS / Université Strasbourg-I joint lab).
9. Centre d'étude des environnements terrestres et planétaires (CNRS / Université Paris-VI / Université Versailles St-Quentin joint lab).

Contacts :

> Éric Fossat
eric.fossat@unice.fr
> Yannick Giraud-Héraud
giraud-heraud@cdf.in2p3.fr
> Jean Duprat
duprat@csnsm.in2p3.fr
> Ludwig Klein
ludwig.klein@obspm.fr
> Jean-Jacques Lévêque
jeanjacques.leveque@eost.u-strasbg.fr
> Jean-Jacques Schott
jeanjacques.schott@eost.u-strasbg.fr
> Michel Menvielle
michel.menvielle@cetp.ipsl.fr
> Élisabeth Rosnet
elisabeth.rosnet@univ-reims.fr


Top

Back to homepageContactcredits