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Asteroid Hunting

March 07, 2003

A lot of attention has been paid in recent years to the asteroid threat issue. The International Asteroid Patrol has been set up to monitor the flight of potentially dangerous celestial rocks in visual diapason. However, the accuracy of optical methods for determining the trajectory leaves much to be desired. That accounts for inaccuracy of numerous forecasts predicting the date when the space "killer" is to collide with the Earth.
      
The scientists of the Radio-Astronomical Institute (National Academy of Sciences of Ukraine) have suggested that RT-70 radio-telescope (located in the town of Yevpatoria) should be used to determine and refine the coordinates of selected asteroids. The radio-telescope is equipped with a special guidance system which permits to point the telescope at any spot in the sky. The specificity of RT-70 is its ability to perform two functions: to send radio signals into space and to receive them. There are only two of such universal telescopes in the world.
      
The Kharkov radio-astronomers have carried out the first radio-location session. The RT-70 telescope antenna radiated radio-frequency pulses in the direction of 1998 WT 24 asteroid, and the echo pulse was synchronously received by Russian and foreign radio-astronomers at several antennas simultaneously. Application of the radio-interferometry method, i.e. coordinated effort of several radio-telescopes located at a distance from each other, allowed to determine the celestial body coordinates at that point with the highest possible precision, and, consequently, to calculate its trajectory. A successful experiment of this type, which took place for the first time in the world, proved that the radio-location method could discover an asteroid, calculate peculiarities of its orbit and surface when it was at a large distance from the Earth.
      
This method is also applicable for discovering the space garbage. Thirty years of cosmonautics have contaminated the near-earth space with a lot of fragments of worn out space vehicles. Of course, as time passes, part of the debris falls down to the Earth and gets burnt in its atmosphere, but the remainder (dozens of thousands of fragments varying in dimensions) stay firmly in the geostationary orbits and can threaten spaceships. To efficiently track the movement of these fragments around the Earth and to avoid the collision when planning new launches and landings, a special catalogues were made and are continuously filled up with new and more precise data.
      
The study primarily involves optical devices and laser location. Experiments with RT-70 have proved that radio-location is able to help in compiling such catalogues. The Kharkov specialists sent signals from RT-70 radio-telescope in the direction of one of the fragments in the geostationary orbit, the signal reflection being steadily accepted by the English, French, Italian, Poles, etc., i.e. all the countries that have appropriate equipment. This allowed to determine the fragments dimensions, speed of rotation, orbit and other parameters necessary for the catalogue.
      
The research also involved the specialists from the Astro-Cosmic Center (Physical Institute of Academy of Sciences), Institute of Radio Electronics (Russian Academy of Sciences) and Institute of Applied Astronomy (Russian Academy of Sciences).

Informnauka (Informscience) Agency