WHAT HAS CARA DISCOVERED SO FAR FROM THE SOUTH POLE?
11/22/94 J. S. Sweitzer
The Center for Astrophysical Research in Antarctica (CARA) operates
three different fundamental experiments from the South Pole. All are for
determining how objects like stars and galaxies began forming in the universe.
A fourth line of investigation is working to understand how good the South
Pole is as an astronomical site. This research requires observing at several
different wavelengths of light from the near infrared to waves a few millimeters
long. Several specially designed telescopes have been created to observe
cosmic objects and structure at these wavelengths. CARA is only a few
years old, so up until now most of the efforts of its scientists and engineers
have gone into establishing the buildings and telescopes necessary to
make the observations. Nevertheless, a few of the experiments are now
beginning to provide an answers to questions about the early universe
and about the quality of the air above the Pole.
The Cosmic Background Radiation Anisotropy Experiment (COBRA) seeks
to measure small changes in the radiation from the big bang. This radiation
began its journey when the universe was as hot as the surface of our Sun
and a thousand times smaller than it is now. COBRA scientists have twice
detected slight irregularities in this light of the big bang. These irregularities
are about one degree in scale and extremely subtle (34 million times dimmer
than the cosmic background radiation itself). Although these first results
have been confirmed, they are still limited, because they only map a few
positions on the sky. In the coming years, the COBRA team will create
a 100 square degree map of the early universe with a resolution scale
of one degree. This is very important, because the largest structures
(clusters of galaxies) that we know of in the universe arose from irregularities
of just this scale.
The South Pole Infrared Explorer (SPIREX) has just finished its first
winter season at the Pole. Its first objective is to measure how much
infrared light is emitted by the sky. The results of the current experiments
have not been totally analyzed, but the first look at the data indicates
that indeed the sky over the Pole emits very little infrared light --
many times less than the sky over the observatory on Mauna Kea in Hawaii.
This is good because it means that the site is the best know on the Earth.
SPIREX investigators got and extra bonus this past season. During the
time of the collision of comet Shoemaker/Levy with Jupiter in July, the
SPIREX telescope observed ten of the impacts*. No other telescope on Earth
could perform such a feat. This is because during July, Jupiter was above
the horizon continuously at the South Pole and never set.
ATP is the acronym given by CARA to the Advanced Telescopes Project.
Its primary goal is to evaluate the South Pole and other Antarctic locations
for how steady the air is (seeing) and for sky transparency. The only
results that have been published are for the transparency and steadiness
of the air due to water vapor. The ATP researchers have shown that the
polar air is extremely dry and stays so for very long periods of time.
This is especially important for astronomers working in the sub millimeter
region of the spectrum.
AST/RO is the fourth project that CARA operates. AST/RO scientists have
constructed and tested their sub millimeter telescope in Boston. At the
end of this year the AST/RO telescope will be shipped to the South Pole.
Some time around Christmas it will be installed atop its specially designed
laboratory building at the South Pole. In the first part of 1995 it will
begin mapping clouds where stars are forming in our galaxy.
* A great poster showing all these collisions can be obtained from Yerkes
Observatory. Write J. Bausch (firstname.lastname@example.org)
for information on how to order it. The file "spposter" describes the