While the climate of Antarctica is extremely harsh and difficult to work in, it is an ideal place to conduct astronomy. The fact that the continent is cold, dry and far from any major sources of pollution make for clear atmospheric conditions. And due to its months-long polar days and nights, one can observe the long-term variation in the Sun during the austral summer and in the stars during the austral winter without the interruption of day changing to night and back again.
Astronomical observations have been going on in Antarctica since Martin A. Pomerantz Observatory at the American Amundsen-Scott Base at the South Pole was constructed in the late 1970s. However there are even more appropriate places in Antarctica to make astronomical observations, especially on the Antarctic Plateau, where low wind speeds make for smooth airflow near the ground, reducing the turbulent layer of the atmosphere, making for clearer observations than at other places on the planet, including at the South Pole.
Due to its high altitude (between 3 and 4 km above sea level), the Antarctic Plateau has one of the harshest climates on Earth. With average temperatures not rising above -20°C in the summer and often dropping below -80°C in the winter, this part of Antarctica is one of the most challenging environments to travel and work in on the continent, if not the planet. Yet the benefits of doing astronomical observations there are well worth the trouble. The special atmospheric conditions make it a more ideal place for astronomical observations, particularly in the thermal infrared, sub-millimetre (terahertz), and millimetre-wave regions of the electromagnetic spectrum. Moreover, the clarity of observations that can be made at certain places on the Antarctic Plateau can even approach the same quality of images taken from space with instruments like the Hubble Space Telescope, making it possible to have images of excellent quality at a much lower cost.
Along with the Chinese at Dome A and the Japanese at Dome F, the French and Italians have been investigating astronomical observation projects at Concordia Station at Dome C on the Antarctic Plateau in an EC-funded action called ARENA (Antarctic Research, a European Network for Astrophysics). The project is a consortium of 22 European and Australian partners including polar institutes, research laboratories and industrial companies.
Funded by the European Commission under the Sixth Framework Programme (FP6), ARENA was funded for a period of four years between 2006 and 2009. During this time the programme had two primary missions:
ARENA released its conclusions and recommendations in December 2009.
In addition to the unique benefits that being located in Antarctica offers, Dome C is a very ideal place to make observations since the atmosphere has a very low turbulent ground layer (TGL). Having telescopes that can reach above the TGL means having access to great conditions for making observations and obtaining higher resolution images.
The turbulent layer at Dome C is only 20-30 metres; at other observatories on the planet, the turbulent layer can be a few hundred metres high. This means it’s only necessary to construct telescopes tens of metres high at Dome C to rise above the turbulent layer and make clear observations or even use simple Adaptive Optics techniques (a technology used to improve the performance of optical systems by reducing the effects of rapidly changing optical distortion) to alleviate the effect of the atmospheric turbulence.
Sky background emission, which is a major drawback in the thermal infrared part of the spectrum, is also much lower than at other observatories in the mid-latitudes and the tropics.
Under ARENA, six working groups were set up, each working in different domains. The working groups were:
While the assessment phase is essentially over and continuous monitoring is needed, getting down to making some serious observations will be the next step forward. Many of the projects proposed are currently only at the proposal stage (constructing a kilometric interferometer at Dome C, for example, is a long way from being realized at the moment) although a few observations have already begun.
Dr. Epchtein from the Hippolyte Fizeau Laboratory of the CNRS at the University of Nice talks about current and planned observations in an interview conducted with Sciencepoles.