A massive asteroid the size of a stadium is hurtling toward Earth. The impact could obliterate an area of 4,000 km². What should humanity do to avert this disaster?
 |
Simulation image of a spacecraft applying gravitational force on an asteroid to pull it into a different orbit (Image: Nasa) |
The traditional answer often involves using nuclear rockets or other techniques to bombard the dangerous asteroid. However, these methods may not be sufficient. Even if the asteroid were to explode, large fragments of it could still plummet to Earth.
Astronauts Edward Lu and Stanley Love from NASA proposed a much gentler solution. They believe that it is possible to deflect a hazardous asteroid by applying gravitational force.
Their plan is to use an unmanned spacecraft called a “gravity tractor.” The spacecraft would hover near the asteroid for several months or even years. The small gravitational force applied by the spacecraft, perhaps only equivalent to 0.2 kg, would be enough to nudge the celestial body into a slightly different orbit. This way, a collision between it and Earth could be prevented.
For instance, to deflect an asteroid that is 210 meters long, the two astronauts suggest using a 20-ton spacecraft, shaped like a pendulum. The heaviest part of the spacecraft would be positioned closest to the asteroid. The spacecraft would operate on nuclear energy. This method would generate the greatest gravitational force while also helping to keep the spacecraft stable as it maneuvers near the asteroid.
However, the first real-world test could be conducted on asteroid 99942 Apophis, weighing about 50 million tons and measuring 300-400 meters in length. The likelihood of this asteroid colliding with Earth in 2036 is extremely low.
Love and Lu believe that if a spacecraft is launched toward it before 2029, when the asteroid passes Earth at a close distance, the task would be relatively easy. A spacecraft weighing just 1 ton could adjust the trajectory of Apophis.
Minh Sơn
