Based on the NSF-funded design study of the High Elevation Antarctic Terahertz (HEAT) telescope and successful deployment of its prototype at Dome A, this proposal seeks funding to build a fully automated, 0.6-meter THz astronomical observatory for remote operation at the highest location on the Antarctic Plateau (Ridge A, ~200 km south of the Chinese summer station Kunlun). The HEAT telescope will cover the 158 to 372 microns band observing the brightest spectral lines from the Milky Way Galaxy in which the most crucial astrophysical spectral diagnostics of the formation of galaxies, stars, planets, and life are found. The telescope will be mounted on top of the Australian University of New South Wales' PLATeau Observatory (PLATO) module that provide housing for the instrument's electronics and diesel engines used to generate electrical power during winter observations. The PLATO and telescope will operate autonomously for over a year at a time, with commands and data being received and transmitted from/to the home institutions via Iridium satellites daily. It is expected that HEAT will see good atmospheric transmission above the 200-microns band during much of the winter, and usable transmission in the pivotal 160 microns window will be seen for more than 10% of the wintertime. The Ridge A site is undeveloped but may actually be the driest, calmest, and clearest point on the Dome A summit. Thus, the proposed telescope will test this site while obtaining important astronomical spectral data and forging entirely new capabilities for ground-based infrared and submillimeter astronomy that otherwise would be unachievable except via expensive airborne or space-based platforms. This pioneering mission will pave the way for future astronomical investigations from the Antarctic Plateau and other potential high-altitude sites around the World. The proposed project contributes to the education of a graduate student, thus helping to grow a generation of young researchers in the field of astronomy.
This NSF-funded program has developed the first robotic, automated, astronomical observatory with cryogenic detectors at "Ridge A", the summit of the Antarctic ice sheet, a site that provides as close to space-like conditions as can be reliably produced on the ground. The exceptional conditions that we have measured at Ridge A are the product of the extreme cold, high, dry, clear, and calm nature at the isolated top of the Antarctic plateau. The High Elevation Antarctic Terahertz (HEAT) telescope deployed to Ridge A in January 2012 takes full advantage of these extraordinary conditions to perform astronomical observations that are otherwise unachievable except on very expensive space-based platforms. Technologically, HEAT represents the very first facility of its kind. It is a pathfinding facility that represents a new generation of Polar instrumentation. As a robotic, automated facility, it operates for a year at a time without direct human contact. As such, it bears more resemblance to a space satellite than most ground-based telescopes, both in design and in operation. Our successful realization of this concept permits the excellent conditions of remote sites to be harnessed without the costs and hazards of manned operations, and is the result of an international collaboration between this NSF-funded effort at the University of Arizona and our colleagues at the University of New South Wales in Sydney, Australia. The HEAT telescope observes at terahertz (THz) frequencies, about 1000 times higher frequency than those used by mobile phones and 1000 times lower frequency, or redder, than one can see with one's eyes. In this frequency range, the most crucial spectral diagnostics of the formation of galaxies, stars, planets, and life are found. HEAT has successfully operated for 2 years during this effort and has delivered the largest terahertz-frequency spectroscopic survey of the Milky Way in the light of atomic carbon at 810 GHz, or 0.81 THz. It has also observed high-mass star formation at frequencies as high as 1.5 THz and it has determined that such observations, nearly impossible to perform anywhere else, can be done reliably 80-90 days per year. This site may also be the only place on Earth where the 1.9 THz spectral signature of ionized carbon, the brightest feature in our Milky Way Galaxy, can be observed with regularity and the program continues towards this goal. The data that HEAT delivers are freely provided to everyone, without a proprietary period, on the web at soral.as.arizona.edu/heat/ HEAT has already allowed the isolation and determination of hundreds of molecular clouds in the Galaxy in the light of carbon monoxide (CO) and atomic carbon (C), two of the three main reservoirs of carbon in the Galaxy. It has discovered that weak, diffuse atomic carbon emission permeates the Galaxy, and that up to 40% of the molecular gas in the Galaxy has been missed by only looking at the millimeter-wave transitions of CO, as has been done up to this point. In some regions of the Galaxy, this missing "dark gas" even dominates that previously measured in the light of CO. HEAT is identifying regions in the Galaxy where clouds may be forming, a process never before witnessed. This is a crucial step to the formation of stars, planets, and life. HEAT’s new spectroscopic survey is timely; it provides the ideal counterpart to recent imaging surveys performed at infrared wavelengths by space missions such as Spitzer, Hubble, and Herschel. Its wide field of view and deep sensitivity represents an ideal "finder scope" to new exciting facilities like the ALMA interferometer in Chile, which can follow up the regions that HEAT is discovering in greater detail. Finally, the development of a fully-featured, portable, robotic telescope facility represents an outstanding educational and outreach tool. For example, one undergraduate student has developed a low-cost infrared sky brightness monitor which was deployed to the Ridge A site last season and has delivered insightful atmospheric data. Experiencing such unique engineering projects from concept to development to deployment is an extraordinary opportunity (and achievement) for students, and the space-like conditions in Antarctica galvanize the imagination. This program has provided undergraduate and graduate students with hands-on technical training and teamwork experience, both essential for their development to benefit both science and society.
