소행성 지구충돌 막는 방법 ‘태양광 암석에 반사’가 최고


지구와 소행성의 충돌로부터 인류를 구해줄 가장 좋은 방법은 무엇일까. 영국의 한 연구진에 따르면, 정답은 ‘거울’이다.

영국 BBC방송은 5일 글래스고대 연구진이 지구로 돌진하는 소행성이나 혜성의 궤도를 변경시키는 가장 좋은 방법으로 태양광을 거울에 반사시켜 암석에 쏘는 방법을 꼽았다고 보도했다.

연구진에 따르면 궤도를 따라 도는 거울에 태양광을 반사시켜 소행성 표면에 일정 기간 집중적으로 빛을 쏘면 소행성 온도가 최대 2100도까지 상승한다. 이어 암석이 녹으면서 소행성의 진로를 바꾸는 추진력이 형성된다. 연구진은 거울 100개를 사용하면 며칠 안에 지름 150m인 소행성의 궤도를 바꿀 수 있다고 말했다. 또 직경 약 10㎞ 크기의 소행성은 거울 5000개로 3~4년간 태양광을 쏘이면 진로가 바뀐다고 연구진은 주장했다.

연구를 이끈 마시밀리아노 바실(Vasile) 박사는 “소행성 충돌은 실질적인 위협”이라며 “이 기술은 공상과학이 아니다. 파편이 발생하는 위험도 없고 실제로 가능하다”고 말했다.


이석호 기자 yoytu@chosun.com
입력 : 2007.10.09 00:20



Mirror satellites 'could divert asteroid'
By Nic Fleming, Science Correspondent
Last Updated: 4:01pm BST 04/10/2007

사진#02

The best way to divert an asteroid from a potentially catastrophic collision course with Earth is to deploy a "swarm" of mirror-bearing satellites to focus a beam of sunlight onto its surface, scientists say.

Artist's impression of how the mirror-bearing satellites might work
Researchers compared a series of methods for deflecting asteroids such as ramming them, targeting them with nuclear weapons and pulling them off course using the gravity of a nearby spacecraft.

They concluded the easiest and safest approach was "solar sublimation" – concentrating sunlight so that rock on the surface material turns to gas, creating a rocket-like thrust capable of nudging the asteroid onto a new orbit.

The 500ft-wide Apophis asteroid will pass within 22,400 miles of Earth in 2029 – closer than the satellites used in our communication systems.

It will then pass through a region known as the "gravitational keyhole", in which the Earth's gravity could divert it onto an orbit that would lead to it colliding with our planet - with a force 100,000 times that of the Hiroshima nuclear bomb – on April 13, 2036.

Dr Massimiliano Vasile, from the University of Glasgow, unveiled the results of his study at the Jodrell Bank Observatory near Manchester as part of today's celebrations to mark the 50th anniversary of human space flight.

Dr Vasile said: "Asteroid impacts are a real threat. The Tunguska explosion in 1908 devastated an area bigger than Greater London.

advertisement"As with other deviation techniques, the solar concentrator works best when the deviating action is applied well in advance before the impact.

"Our studies show this technology is genuinely feasible and, unlike methods where an explosion or impactor is used to divert the asteroid, there is no further risk from fragments."

In the 1998 film Armageddon, which starred Bruce Willis, Ben Affleck and Liv Tyler, a group of deep-core drillers were sent by Nasa to drop a nuclear device deep into the centre of an asteroid to prevent it colliding with Earth.

Dr Vasile and colleagues assessed deflection methods according to the amount of force they could generate, how much warning would be required and the complexity of the required technology.

They concluded using a nuclear weapon or another form of missile might be the most effective method for a small asteroid measuring up to around 300ft in diameter, but that with larger objects there was a risk of their splitting into unpredictable and dangerous fragments.

Methods involving landing on the asteroid and creating a thrust using fuel or through digging out and ejecting material were rejected as too complex.

The "gravity tug" method of pulling an asteroid off course using the gravity of a nearby spacecraft was deemed impractical, as was using a giant single solar concentrator mirror.

The team calculated 10 satellites bearing reflective metal surfaces of a diameter of 60ft orbiting an asteroid the size of Apophis in formation and focusing the Sun's energy onto its surface for 200 days would push it off course.

Alternatively 1,000 satellites carrying mirrors 6ft wide could accomplish the task in 90 days.

Today was the 50th anniversary of the launch of Sputnik I, the first manmade object to orbit Earth.

http://www.telegraph.co.uk/earth/main.jhtml?view=DETAILS&grid=&xml=/earth/2007/10/04/sciaster104.xml

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