MOSCOW. (RIA Novosti commentator Tatiana Sinitsyna) – Astronomers are closely watching a 50-meter wide asteroid that could be on a collision course with Mars.
The asteroid, known simply as 2007 WD5, was discovered in the constellation Taurus on November 20, 19 days after passing near the Earth at an apparent magnitude of +20. That is about 400,000 times fainter than most people can see with the naked eye on a dark night.
Early observations of the asteroid caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 75 chance of colliding with Mars on January 30, 2008. Wikipedia estimated such chances as 1 in 25.
However, by January 9, additional observations allowed NASA’s Near Earth Object Program (NEOP) to narrow the field of uncertainty, resulting in only a 1-in-10,000 chance of impact.
Nevertheless, humankind is quite interested in the situation around Mars because manned missions will be launched to the Red Planet in the foreseeable future.
Alexander Bagrov, Doctor of Physics and Mathematics from the Astronomy Institute of the Russian Academy of Sciences, said future space missions must be planned carefully because the area of space between Earth and Mars has been swarming with meteors since times immemorial, and consequently astronauts bound for the Red Planet faced much greater chances of collision than in near-Earth space.
Bagrov said the discovery of 2007 WD5 was a mere coincidence because various agencies locate up to 300 asteroids every 24 hours and catalogue them in line with the Asteroid/Comet Emergency Prevention/Preparedness Program.
He said two months were not enough to accurately calculate the asteroid’s orbit, and that 2007 WD5 had to be watched for at least one circuit.
The orbital period of any celestial body depends on the distance it travels. For instance, it takes a near-Earth satellite 90 minutes to circle our planet. The Moon revolves around the Earth in 30 days.
But astronomers are still unable to accurately measure asteroid trajectories. Bagrov said measuring errors make it impossible to calculate the orbits of Earth-bound celestial bodies discovered 5-6 million km from our planet, whose gravitational pull changes their flight paths.
Scientists now want to calculate the angular and line speeds of asteroids by simultaneously watching them from two or three observatories. However, Mars does not offer any convenient observation points.
2007 WD5 is of similar size to the notorious Tunguska meteorite that exploded 5-10 kilometers (3-6 miles) above East Siberia on June 30, 1908, felling an estimated 80 million trees over 2,150 square kilometers (830 square miles) – an area larger than Moscow. Fortunately, no one was killed in the sparsely populated region.
Estimates of the energy of the blast range from 3-5 to 30 megatons of TNT. 10-15 megatons has been considered the most likely to be accurate – about 1,000 times more powerful than the bomb dropped on Hiroshima, Japan.
According to Bagrov, about 40,000 asteroids between 3 and 150 meters in diameter fly through near-Earth space each year.
The Tunguska meteorite did not slam into the Earth because it was deflected by the planet’s dense atmosphere. But if a similar body ploughs into Mars, it would gouge a crater, called an astrobleme. However, there would be no negative long-term effects because there is apparently no life on Mars.
Nonetheless, humankind should take the asteroid threat seriously because it still cannot cope with this problem. Most meteorites burn up in the Earth’s atmosphere; but some of them hit the ground and form impact craters, including the 130-kilometer Popigai crater in Siberia, formed by a large bolide impact about 35 million years ago.
There are also many impact craters on the Moon and the Red Planet. Bagrov said the Moon, which lacks an atmosphere, was hit by at least 19 meteorites in 2007.
Remote-sensing satellites located the largest impact crater on earth, 300 km across, in the Antarctic only last May.
Astroblemes are a major problem because they sometimes alter the earth’s terrain completely. A huge meteorite is thought to have formed the Gulf of Mexico over 60 million years ago.
The thin Martian atmosphere nonetheless destroys or deflects most asteroids and would cushion a possible impact.
The opinions expressed in this article are the author’s and do not necessarily represent those of RIA Novosti.