# PLATO - Dome A robotic observatory

# Plato

Dome A Robotic Observatory
Mission
Time

## Dome A, Antarctica

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, experiences 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 ran continuously for 204 days in 2008. It was serviced by the Chinese 2008-2009 Dome A expedition, allowing it to run throughout 2009. The Chinese 2010 expedition was greated by a warm operating PLATO when they arrived in late December 2009. PLATO was again serviced, and continues to run, uninterrupted since January 2009, until August 2012. Iridium satellite communication is used for monitoring and control, with the majority of the data to be returned by the traverse at the end of each year. Refer to the side menu on the left for detailed information regarding the instruments on PLATO.

Webcam image from the instrument module looking towards the CSTAR telescopes

## The PLATO 2008-2009 servicing mission

The PLATO observatory is designed for yearly servicing. This includes replacing the diesel engines and refilling the fuel and oil tanks.

After our first year of operation, we performed a number of upgrades to the engine module. There were also several new scientific instruments to install and commission.

Xuefei Gong, the astronomer on the PRIC 2008-2009 Dome A expedition, visited the University of New South Wales for a number of months in 2008 to help prepare the servicing mission. The other Dome A expeditioners were tasked with building a summer station at Dome A that will be upgraded to a full-year manned research station in the future.

On November 7 2008, the PRIC expedition left Fremantle for Zhongshan station on the Xue Long, a Chinese research ice breaker. The Chinese expedition reached Dome A in early January 2009 via overland traverse. Once at Dome A, Xuefei and other heroic volunteers from his team began work on making PLATO fully operational again before leaving Dome A on the 3rd of February 2009.

The PRIC expedition was extremely successful, finishing the summer station and completely servicing PLATO.

Xuefei Gong standing in front of the newly serviced engine module (Jan 2009)

### 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 fuel. 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 hourly:

PLATO power supply currents (time in UTC). Visit the status page for further information regarding the performance of PLATO and its instruments.

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 32MB 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 an 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 with each having 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.

The Nigel instrument is both a site-testing and scientific instrument designed to measure the optical sky brightness and the aurora contributions of the Dome A sky.

Gattini is an astronomical camera designed to accurately measure the sky brightness in a range of different wavelengths and cloud cover. These parameters are essential to predict 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

| California Institute of Technology, USA
| Harvard-Smithsonian Center for Astrophysics, USA
| Nanjing Institute of Astronomical Optics and Technology, China
| National Astronomical Observatories of China
| National Astronomical Observatory of Japan
| Polar Research Institute of China
| Purple Mountain Observatory, China
| Texas A & M, USA
| Tianjin Normal University, China
| University of Arizona, USA
| University of Auckland, NZ
| University of California at Berkeley, USA
| University of Chicago, USA
| University of Exeter, UK
| University of New South Wales, Australia

## Funding agencies in alphabetical order

| Chinese Academy of Sciences
| European Commission
| National Natural Science Foundation of China
| National Science Foundation, USA
| United States Antarctic Program