In the fruitful chronicle of space exploration, September 26, 2022 deserves a special mention. And for a simple reason: the mission that reached its climax that day, DART, was not looking to reach some unexplored planet, get samples, or launch new probes or a billion-dollar telescope into orbit. Its objective was quite another: to crash into Dimorphos, the satellite of the Didymos binary system, and thus prepare ourselves for any possible future threat in the form of an asteroid. As NASA was in charge of emphasizing then, pulling space epic, it was a true “planetary defense” mission.
That mission had NASA behind it. Now China wants to star in another similar one. And he already has his sights set on an ideal asteroid: 219 VL5.
What does China want? Something similar to the approach of DART. Although with some relevant differences. China’s objective is to impact a ship against an asteroid to alter its course. After the crash, a second spacecraft will be in charge of documenting the results and evaluating its changes, a follow-up task that will also be carried out with the support of terrestrial telescopes and the Xuntian space observer, which -according to the forecasts that the authorities of the Asian giant handled in summer – will start its operations in 2024 and will orbit near Tiangong.
What’s new? We’ve known about China’s plans for a year or so, even before DART collided with Dimorphos. What then transpired was that the CNSA was working on its own “planetary defense” plan and that its goal was to “contribute to the protection of the Earth and human security”, a rhetoric very similar to that deployed by NASA with DART. Now, however, we are dealing with new details, which include, for example, the when and how of the Chinese operation, as well as what its specific objective is.
During a conference in Austria, Chen Qi of China’s Deep Space Exploration Laboratory provided some fresh insights into the Chinese mission. Its ‘target’ will be 2019 VL5, an Aten-class asteroid with an orbit that brings it close to Earth. According to its file in Space Reference, it is a small object, with a diameter of between 53 and 12 meters, similar to a school bus. As for the schedule, China plans to launch its planetary defense mission as early as 2025.
What will the mission be like? It will use a Chinese Long March 3B rocket with two ships: one designed to hit the asteroid and another that will be in charge of gathering information. The news about the operation has been advanced by Space News with the information shelled by Chen Qi himself in Austria.
The mission roadmap foresees that at some point, after launch, both spacecraft will separate. The first to reach VL5 2019 will be the observation station, which will be dedicated to documenting the asteroid and evaluating its topography. The culminating moment will come when —some time later, once the reconnaissance stage has been completed— the second spacecraft deliberately collides with the asteroid at a relative speed of 6.4 kilometers per second.
And then? The observation ship is in charge of evaluating the result of the impact. To ensure that the experts can collect all the necessary information, the mission includes optical, radar and laser sensors, a device to analyze particles and a high-resolution camera that will be in charge of observing the impact and the subsequent ejection. In addition to the spacecraft or future help from Xuntian, scientists will take advantage of the observation windows in the coming months —October and November— to study the asteroid with ground-based telescopes.
What outcome does China expect? At the end of last year, Wu Weiren, from China’s lunar exploration program, left some interesting thoughts during an interview with CCTV plus: “The impactor will follow our order to collide with the asteroid and, hopefully, deflect it 3 or 5o centimeters from its course. Such a deviation would change the trajectory by more than 1,000 kilometers after about three months,” says the expert: “The longer the time, the greater the change in trajectory. This is a very important mission.”
Does it look like the DART mission? Yes and no. From the outset there is a substantial difference between Dimorphos, which had a diameter of 160 meters, and 2019 VL5, much smaller. It is not the only point in which both missions differ. As Space News points out, China somehow combines elements of DART and the Hera operation, of the European Space Agency (ESA) and that it plans to observe Didymos and Dimorphos at the end of this decade to assess the effects of the September 2022 collision His goal: “A detailed follow-up”
NASA has already advanced in any case that DART has had very appreciable effects. Not long after the impact, in October, the agency detailed that it had altered the orbit of Dimorphos: if before the mission it took almost 12 hours to orbit Didymos, after the crash that cycle was shortened by around 32 minutes. The collision also displaced more than a million kilos of rock from the asteroid into space, enough debris to fill six train carriages.
Imagen: NASA/Johns Hopkins APL/Steve Gribben
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