NEWS NATURE|Vol 451|14 February 2008

Chinese astronomers look to Antarctic

A Chinese expedition returned last week from Cold comfort: a 14-day crawl across the East Antarctic ice China has set sheet in cargo containers, pulled by tractors, up a remotely that doubled as living quarters. The trip, spon- operated sored by the Polar Research Institute of China, observatory on completes only the second traverse to Dome A Dome A, the — the highest point on the eastern ice cap and summit of East the place where China intends to start building Antarctica’s a research base next year. ice cap. The team also set up a suite of research instruments to study the atmosphere and sky above Dome A, most notably a remotely oper- ated observatory called PLATO, which will assess how good the skies are for astronomical ‘seeing’. PLATO includes four 14.5-centimetre telescopes, built in China, that will take advan- tage of more than three straight months of dark- ness during the Antarctic winter. “We think Dome A is the best site on Earth for astronomy,” Such conditions make Dome A attractive to says Xiangqun Cui of the Nanjing Institute of Chinese astronomers, who have begun work Astronomical Optics and Technology. on a suite of three 0.5-metre telescopes that The hope is that the desolate plateau, which they hope to deploy at the site in 2009. They sits 4,100 metres above sea level, will boast are also eyeing the location for a potential conditions unrivalled elsewhere on the planet US$40-million, 4-metre infrared and optical tele- Dome A — even at the French/Italian base at Antarctica’s South Pole scope. A proposal on that may be submitted this Dome C, 1,200 kilometres away, which set up summer to the Chinese Academy of Sciences. its own automated test observatory in 2003 and ANTARCTICA The true potential of Dome A may lie in has since ramped up to larger projects. Dome C observations outside optical wavelengths. The Proponents of Antarctic astronomy have McMurdo Station efficiency of infrared astronomy is particularly looked to Domes A and C as alternative sites sensitive to temperature, and winter nights that to the South Pole, above which 300 metres of drop as low as –90 °C will eliminate much of turbulent air cause observations of stars to the noise from the atmosphere and the tele- jitter and blur1. Dome C, by contrast, has only additional 100 metres is very important because scope itself, researchers say. 30 metres of turbulent air above it, and less it knocks out a huge chunk of the atmosphere,” The potentially unparalleled dryness of atmospheric interference than astronomical says Michael Ashley of the University of New the air may also allow astronomers to access observing sites in Hawaii and Chile2. South Wales in Sydney, which built PLATO. parts of the electromagnetic spectrum that are Although it lacks infrastructure, Dome A, Models suggest that Dome A may have a obscured by water vapour elsewhere, including which sits some 900 metres higher than Dome turbulent layer as thin as 5 metres, he says, and Dome C. “We’re hoping to observe at very high C, could be an even more promising site. “Each thus even better seeing. radio frequencies that you would only other- wise be able to do in a plane or in space,” says Craig Kulesa of the University of Arizona, who has an instrument on PLATO that will assess Stars on ice the transparency of the atmosphere. If condi- Most astronomical projects construction this Antarctic projects include: tions are as dry as expected, Kulesa hopes to in Antarctica are based at the summer; completion is set Italy’s Small IRAIT, a deploy a telescope to Dome A that will map South Pole. They include: for 2011. 25-centimetre prototype for the Milky Way in the far infrared, to learn more The US 10-metre South Pole At the McMurdo Station an 80-centimetre microwave about star formation. Telescope, which saw first in the Ross Sea, the United telescope, was installed But future projects will depend on PLATO, light in February 2007, scans States launches payloads last year to study objects which researchers hope will yield meaningful the sky in the millimetre and aboard scientific balloons such as brown dwarfs in the data before next year’s trip to refuel the station. sub-millimetre range, focusing reaching up to 42 kilometres. Milky Way. “We already know Dome A will be the best spot primarily on the cosmic This year’s missions include France’s ASTEP, a on Earth,” say Kulesa. “But the question is, how microwave background left US and Japanese instruments 40-centimetre telescope good is that?” ■ over from the Big Bang. examining cosmic rays and dedicated to photometry Rachel Courtland IceCube, the underground antimatter. and exoplanet searches, is US neutrino observatory, At the more recently scheduled to be mounted on reached its halfway point in established Dome C, Dome C in January 2009. R.C. 1. Travouillon, T. et al. Astron. Astrophys. 409, 1169–1173 (2003). 2. Lawrence, J. S. et al. Nature 431, 278–281 (2004).

752