Image source: NASA On September 26, a vending-sized spacecraft will hit an "innocent" asteroid Dimorphos with a diameter of 160 meters at a speed of 6 kilometers per second.

Image source: NASA

htmlOn September 26, a vending-sized spacecraft will hit a 160-meter-diameter asteroid Dimorphos at a speed of 6 kilometers per second. This upcoming "violent" operation is the first field test of a planetary defense mission in human history, namely the NASA (NASA) dual asteroid redirection test (DART). The

DART mission team recently observed the dual asteroid system Didymos for the first time, and the target asteroid Dimorphos is one of the small satellites . NASA hopes the collision pushes Dimorphos into orbit closer to Didymos, reducing its nearly 12-hour runtime by a few minutes. In the future, similar impacts could cause threatening asteroids to turn. But new simulations and laboratory experiments show that the success of the mission depends on whether these asteroids are a solid rock or a loose pile of gravel.

answer will be revealed from the craters and ejections produced by the impact, which may determine the difficulty of impacting the asteroid. Compared to the larger planets that previously triggered mass extinction events, double asteroids are thousands of times more likely to hit Earth, and their ability to destroy a country makes these smaller bodies a top priority in planetary defense efforts. But for ground telescopes, they are nothing more than a small spot of light that is difficult to detect, let alone study.

When one celestial body blocks another, their light will dim. By monitoring tiny fluctuations in light from Dimorphos and Didymos, NASA scientists can learn about information such as its rotational speed. This will allow scientists to design an autonomous navigation system, , to guide the "dart" to approach "prey" with the help of a new solar ion thruster.

But no one can tell what will happen next. "Suppose it is a solid rock, we have a solid spacecraft that is essentially playing a big billiard game in space... basically it can be solved as a simple physical equation." Cristina Thomas, a planetary scientist at Northern Arizona University , said that when the target is composed of thousands of rocks, it is much harder to predict the consequences of hitting it than predicting a solid boulder. If DART hits a fragile gravel pile target, the crater will form within a few hours, a process that could take months or even years to model.

Recently, DART deployed a bread machine-sized cube satellite that will use two optical cameras to record the collision process and its results. Meanwhile, James Webb and the Hubble Space Telescope and 4 ground observatory will take turns to monitor. If Dimorphos was a fragile pile of gravel, the telescope should be able to capture images of it within hours of impact, Thomas said.

When an asteroid is really threatening the earth, the solution is to impact the asteroid body with enough force to make it turn, but at the same time it cannot be too fierce, causing it to launch small rock fragments to the earth. The DART mission will provide scientists with more data to improve their planetary defense plans.

Source: China Science Daily Guangzhou Daily·New Flower City Editor: Zhang Ying