Enlarge image
"Dart" mission: collision with asteroids next October
Photo: Johns Hopkins Applied Physics Lab / NASA
In view of the problems of our time, the scenario of an asteroid impact on Earth does not seem so urgent to the global community. But just a look at the scarred surface of our planet is evidence of violent collisions with cosmic chunks in the past - the best example is the Chicxulub crater on the Mexican peninsula of Yucatán. 66 million years ago a huge asteroid with a diameter of probably 14 kilometers struck there. The consequences of the explosion probably also contributed to a violent mass extinction, the most prominent victims of which were the dinosaurs.
It is true that our planet has now become quieter than it was at the beginning of its development. But it is clear that the consequences of an asteroid impact would be even more devastating today. That is why astronomers observe the movements of asteroids very closely and try to predict impacts.
The US space agency Nasa is now looking at how to throw such an asteroid out of orbit. For the "Dart" mission, for the first time, a probe is to be deliberately steered into an asteroid in order to change its trajectory. According to Clayton Kachele, nothing less than the future security of the earth is at stake. The NASA manager is one of the people responsible for "Dart" (Double Asteroid Redirection Test). If everything goes as planned, the probe will take off from the US state of California on Wednesday and crash into the asteroid Dimorphos next October.
The mission is reminiscent of Hollywood films such as "Armageddon - The Last Judgment", in which stars like Bruce Willis and Ben Affleck in a very short time with a complicated and dangerous maneuver destroyed an asteroid that was hurtling straight to earth. "Dart" is probably not worth an asteroid movie, says Kachele. The mission, which costs around 330 million dollars (around 290 million euros), is unmanned and Dimorphos is not racing towards Earth, but rather a first cautious attempt to see whether it might be possible to change the trajectory of an asteroid in this way. "But it's great to be able to help protect our planet and future generations."
For many years, NASA has been considering, also in cooperation with the European Space Agency Esa, how the earth could be protected from approaching asteroids.
At the moment, scientists are not aware of any asteroid that could speed directly towards Earth in the foreseeable future - but researchers have identified around 27,000 asteroids near our planet, around 10,000 of which are more than 140 meters in diameter.
"Asteroids are complicated," said mission astronomer Nancy Chabot.
"They look different, they have big stones, they have rocky spots, they have smooth spots, they have strange shapes." You need the mission to do a real test on a real asteroid.
According to Kachele, the probe, which is supposed to be launched by Elon Musk from the Vandenberg Air Force Base in California with the help of a "Falcon 9" rocket from the private space company SpaceX, is comparatively simple. She only has one camera on board. The probe will travel to Dimorphos for around a year, a kind of moon of the asteroid Didymos, with a diameter of around 160 meters. After the impact, the approximately twelve-hour orbit of Dimorphos is said to be at least 73 seconds and possibly up to ten minutes shorter.
Didymos is close enough to earth to observe and measure all of this with scientific instruments from our planet and from space. According to the calculations of the NASA researchers, the asteroid does not present a threat to Earth at the moment. And the mission is designed in such a way that it will remain so even after the impact of the asteroid. The Esa »Hera« mission is scheduled to start in 2024 to investigate the effects of the impact more closely.
All of this is a first attempt, says astronomer Chabot - because defending the earth in this way, which may one day really be necessary, will take a lot of time and advance notice. “If an asteroid threatened Earth, you would want to use this technique many years in advance, decades in advance. You'd give that asteroid a little nudge that would make a big change in its future position, and then the asteroid and Earth would no longer be on a collision course. "
The emerging space nation China has also asked itself questions about defending against asteroids on a collision course. One possibility would be to tackle the problem with concentrated rocket power. To do this, China could send almost two dozen of the country's largest missiles. At the National Space Science Center, headquartered in Beijing, researchers have shown in simulations that the impact of 23 rockets of the "Long March 5" type on an asteroid that is about 1.4 times the Earth's radius and is of a certain size, might be enough to distract it from its original path. Researchers also repeatedly carry out simulation games for such scenarios. Most recently, a simulation had shown that a strike with nuclear explosive devices could actually protect our planet from an asteroid impact.
joe / dpa
