Monday, February 2, 2009

Xinhua: East Asia VLBI moves ahead

According to a Xinhua report, picked up by sources throughout East Asia reports, progress has been made in the six years "astronomers in East Asia" have been experimenting and building the world's largest VLBI radio telescope array, "to see deep into the galaxy and its black holes" and more accurately determine the orbits of lunar probes such as China's Chang'e-1.

Called the East Asia Very Long Baseline Interferometry consortium, the virtual appature will consist of "19 radio telescopes" in China, Japan and South Korea, "that have a virtual will cover an area with a diameter of 6,000 kilometers," from Hokkaido to western China's Kunming and Urumqi.

The VLBI technology is widely used in radio astronomy. It combines observations simultaneously made by several telescopes to expand the diameter and increase magnification.

Icons of the future, the worlds radio telescopes, tuned to their optimum resonances by literally moving to harmonic distances by means of railways, have been piercing the optically opaque atmosphere from Earth since Karl Jansky's experiments of the 1930s.

Today, deep within a fog of spurious radiations, MIT and the Naval Research Laboratory, along with NASA are designing an array to focus on the Universe's Dark Ages from hopefully "Radio Quiet" basaltic beds within the terraced walls of Mare Tsiolkovski on the Far Side of the Moon. While the lower gravity on the Moon will allow construction of steerable radio telescope dishes far larger than is possible on Earth, being situated just over the eastern limb, and not directly in the middle of the Far Side will make the Dark Ages Radio Telescope at Tsiolkovski able to be joined, for a period during each lunar orbit, with similar arrays on Earth and creating a simulated appature 400,000 kilometers wide, able to resolve several orders of magnitude deeper into the radio sky than can be presently imagined.

As traffic increases in lunar orbit, with Japan, China and India each presently probing the lunar surface from similar lunar orbits and the U.S. ready to join that fleet, the ability to track the speed and location, as well as downloading data, requires similar precision at a relatively great distance. To accomplish this, the United States led in creating the worldwide Deep Space Network to act as a simulated radio appature the size of the Earth's diameter, in tracking Apollo.

Since then, the Very Long Baseline Interferometry Network (VLBN) in New Mexico leads the way in the size of a single facility composed of multiple dished combined to act as a single ear, popularized in the motion pictured "2010" and "Contact." There are also the iconic telescopes throughout the Earth, such as the world's largest steerable dish at Greenbank in West Virginia and Jodrell Bank in the U.K., where confirmation first arrived of the launch of Sputnik in 1957.

In the caldera of Arecebo, Puerto Rico is the world largest Radio Telescope, steered by way of the positioning of its focal point. It was long suggested that the craters of the Moon's Far Side should one-day be home to a fixed dish, similar to Arecebo, but of spectacular dimensions. But, at a time when radio telescopes can be combined by computers synchonizing data while accounting for lightspeed and doppler effects, building a super-sized fixed telescope make little sense.

As German radio astronomers Enno Middelberg of Astronomisches Institut in Bochum and Uwe Bach of the Max Planck Institut in Bonn wrote in an introductory paper last June, "Very long baseline interferometry, or VLBI, is the observing technique yielding the highest-resolution images today. In the last decade, much progress has been made in all of these fields."

Shen Zhiqiang, secretary general of the East Asia VLBI consortium committee, said yesterday that the consortium had carried out experimental observations and frequent academic exchanges since the idea came into being in 2003.

One main task of the consortium is to improve the three-dimensional map of the Milky Way obtained by Japan's VERA (VLBI Exploration of Radio Astrometry).

Hideyuki Kobayashi, director of Japan's Mizusawa VERA Observatory, said the consortium would help astronomers obtain high quality data on galactic structures.

Full-scale observations are due to start in 2010 and will connect at least 12 Japanese and four Chinese stations, in addition to three South Korean ones under construction.

Shen said: "The actual number of telescopes included could change as the countries involved are building new ones ¨? like the 65-meter-diameter radio telescope being built in Shanghai."

"In addition," said Shen, who is also a researcher at the Shanghai Astronomical Observatory. "Chinese astronomers have made huge success in applying VLBI technology to determine the orbit of Chang'e-1, China's first lunar probe."

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