填空题

How long does his tour generally last.()

【参考答案】

A few weeks
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70()。

A. One such place is Dome C (located in the Australian sector, at roughly 73 degrees South latitude), where French and Italian scientists are now setting up a permanent base, called Concordia Station.
B. The logistical difficulties and great expense prompt one to ask. Why maintain a permanent science base at the South Pole at all One answer is that certain kinds of research can be done in no other spot. In particular, the South Pole is said to offer an ideal setting for astronomers, because the air is exceptionally cold, thin and dry, making this locale the next best place for sitting a telescope.
C. European and Australian astronomers are indeed quite interested in the opportunities that Dome C affords. Still, U.S. participation will probably not amount to much, because, as Bally notes, "the U.S. has put all its eggs in the South Pole." This strategy is hard to defend on the basis of doing the best astronomy, the discipline most often cited in official statements about the scientific importance of Amundsen-Scott Station.
D. The submillimeter to millimeter-scale observations are, however, critical to the study of the cosmic microwave background radiation, and they are useful, too, for examining molecular clouds in stellar nurseries.
E. Also, the air at the South Pole is, in fact, not so perfect for astronomy, because it is colder at the surface than a few hundred meters above. John Bally, an astronomer now at the University of Colorado, Boulder, who was responsible for site testing at the South Pole, points out that this temperature inversion combined with the stiff winds there give rise to a turbulent layer of air that blurs optical and infrared images. Bally also notes that there is a perpetual ice fog at the South Pole in winter and that the base is situated on the auroral circle, the locus where charged particles in the upper atmosphere light up the sky most intensely: "You would not go about picking astronomical sites the way this was done."
F. Built in the 1970s to replace an even older South Pole base (which is now buried under nine meters of snow), the Amundsen-Scott Station consists of a large geodesic dome and several smaller outbuildings. The dome is half-buried in drifts and suffers from an unstable foundation that threatens its integrity. Many other parts of the infrastructure—from fuel distribution to waste disposal—are also in dire need of refurbishment.