Dome A
Dome A (click to enlarge)
Over a decade of site testing in Antarctica has shown that both South Pole and Dome C are exceptional sites for astronomy, with certain atmospheric conditions greatly superior to those at existing mid-latitude sites. The highest point on the Antarctic plateau, Dome A, is expected to experience even colder atmospheric temperatures, lower wind speeds, and a turbulent boundary layer that is confined even closer to the ground.
As part of the PANDA and Astropoles programs of the International Polar Year (IPY), an agreement was signed between the the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), the Polar Research Institute of China (PRIC), and the University of New South Wales (UNSW) to develop and deploy an autonomous observatory called PLATO to Dome A. The PANDA traverse successfully delivered PLATO to Dome A in January 2008. A large international team has contributed to PLATO and its instruments, with Iridium satellite communication being provided by the U.S. Antarctic Program (USAP).
Dome A (Xu Zhou and Zhenxi Zhu: 27 Jan 2008)
The PLATO observatory
PLATO, the PLATeau Observatory, is a self-contained automated platform for conducting year-round, experiments completely robotically from the Antarctic plateau.
PLATO shut down on 8 August after 204 days of continuous operation. It is currently hibernating, and is expected to return on-line when the sun rises sufficiently to thaw the batteries. This should occur in the first week of September. Iridium satellite communications are used for monitoring and control, with the majority of the data to be returned by the next traverse in January 2009. Refer to the sidebar for detailed information regarding the instruments on PLATO.
Mid-winter webcam image from the instrument module looking towards
the CSTAR telescopes illuminated by moonlight
Power systems and control
PLATO consists of two modules built into 10-foot shipping containers. The Engine Module contains six Hatz 1B30 diesel engines and 4000 litres of Jet-A1. The Instrument Module is 45m away and contains the computer systems, battery bank, power supplies, and some of the science instruments. Solar panels and some of the other instruments are external to both modules. The modules are extremely well thermally insulated.
PLATO - roll mouse over image to identify objects (Zhenxi Zhu: 27 Jan 2008)
The two modules are linked by a 120VDC cable distributing approximately 1kW of electrical power. A CAN (Controller Area Network) bus is used to control both modules. Two banks of ultracapacitors are used to start the engines. Solar panels provide an additional kW of electricity during the summer time.
PLATO has four independent sources of power:
- Solar array 1 consisting of three solar panels
- Solar array 2 consisting of three solar panels
- Engine bank 1 consisting of three engines
- Engine bank 2 consisting of three engines
Only one engine is used at a time except for testing purposes. The following power generation plot is updated daily:
PLATO power sources: (time 0 = Fri Aug 8 21:00:00 2008 UTC)
The PLATO computer system is based on two redundant PC/104 systems, each with an Iridium satellite modem for remote control and capable of sending up to 20MB of science data back per day. The computers boot from USB flash disks tested for low temperature and high altitude performance. A readonly filesystem is used for the Debian GNU/Linux operating system to maximise reliability.
Instruments
PLATO is a truly international collaboration, with instruments contributed from Australia, China, New Zealand, the United Kingdom, and the United States of America.
CSTAR is an array of four 14.5 centimetre telescopes that each has a different filter in the optical band. CSTAR will take advantage of the months of continuous darkness to search for time varying events such as the transit of planets, supernovae, and will accurately measure the sky background brightness.
The preHEAT telescope is mapping the Milky Way in the sub-millimeter band to confirm the atmospheric transmission in this region. Atmospheric modelling indicates that Dome A is probably the only place on Earth that can routinely observe at the terahertz frequencies crucial to the understanding of the interstellar medium, and in particular the life cycle of stars.
The height of the turbulent boundary layer between the ground and smooth air is of great interest to optical astronomers. The Earth's atmosphere makes the stars (and all other objects) twinkle in a similar way that a pebble seen through a rippling stream appears distorted. If the boundary layer is very low, as it is predicted to be at Dome A, it becomes feasible to build telescopes on small towers, greatly simplifying or even eliminating the adaptive optics needed to remove the effects of a turbulent atmosphere. SNODAR is an acoustic radar that probes the atmospheric turbulence, mapping the height of the boundary layer and other atmospheric structure. A second boundary layer experiment, DASLE, is an array of sonic anemometers placed along a fifteen meter tower. These measure the wind velocity and direction with very high accuracy.
Gattini is a pair of astronomical cameras designed to accurately measure the sky brightness and cloud cover. These two parameters are essential in predicting the uninterrupted length of time a large telescope can observe for, and how deep into space it can see.
Visit the science page for information on the science that PLATO is performing.
Participating institutions in alphabetical order
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California Institute of Technology, USA |
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Nanjing Institute of Astronomical Optics and Technology, China |
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National Astronomical Observatories of China |
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Polar Research Institute of China |
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Purple Mountain Observatory, China |
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Texas A & M, USA |
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Tianjin Normal University, China |
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University of Arizona, USA |
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University of Auckland, NZ |
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University of California at Berkeley, USA |
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University of Chicago, USA |
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University of Exeter, UK |
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University of New South Wales, Australia |
Funding agencies in alphabetical order
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Chinese Academy of Sciences |
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European Commission |
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National Natural Science Foundation of China |
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National Science Foundation, USA |
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United States Antarctic Program |