The world is now facing many earth crises, so it is easy to forget that huge space rocks may one day threaten the survival of the entire civilization. Yes, the threat of an asteroid impact is a distant threat, but despite this, mankind will have to face it one day, and soon there will be.
NASA takes this issue seriously and has staffed its Planetary Defense Coordination Office since 2016. For these efforts, it also developed a task to study how dangerous robots might be deflected. The double asteroid redirection test, or DART, It is planned to be launched within next year.
DART is designed to change the path of an asteroid through a dynamic impact, or in layman’s terms, to hit an asteroid. The spacecraft will target Didymos, a dual asteroid system consisting of Didymos itself and the smaller asteroid Dimorphos orbiting it. This asteroid will pass by 11 million kilometers from the Earth without a collision orbit, which makes it a good candidate for mankind’s first attempt at asteroid deflection.
The larger asteroid Didymos in the pair is 780 meters in diameter, while Dimorphos is much smaller, only 160 meters in diameter. The goal of the DART spacecraft is to hit Dimorphos head-on and reduce its orbital period around Didymos in the process. The observatory on Earth will measure this change in orbit to gauge the success of the mission.
The main size of the DART spacecraft is only 1.2 x 1.3 x 1.3 meters, and the entire spacecraft weighs about 500 kilograms. DART is designed to hit Dimorphos at a speed of 6.6 km/s. In doing so, it will change the orbital period from 11.9 hours to 11.8 hours and 4.2 minutes. The change in orbital period is expected to be about 10 minutes. This may not sound like a big change, but hopefully within millions of kilometers, this will make a major change in the original trajectory of the asteroid system.
DART tasks will also be used for trials Multiple innovative technologies. The new member of the project is Roll Out Solar Arrays or ROSA. These flexible solar panels can be rolled up and launched, and deployed after the spacecraft enters space. They are also lighter and more compact than traditional arrays, and at the same time more robust. When fully unfolded, each double-rolled display panel has a span of 8.5 meters. A similar technology was recently deployed to the International Space Station, which laid roll-out panels on the original rigid solar panels to increase the power budget of the aging space station. A small portion of the ROSA array will also be used to test conversion solar array technology, which uses reflective concentrators combined with high-efficiency solar cells, which may provide three times the available power of a typical solar array.
Propulsion is through NASA’s NEXT-C xenon fuel Grid ion thruster. This uses an electric field to accelerate the ions to a huge speed of 40 km/s in order to generate thrust for the spacecraft. Although the thrust generated is very small, only a few hundred millinewtons, the ion thruster is very fuel-efficient. Therefore, it can run for a long time to slowly accelerate the aircraft to extremely fast speeds. We have introduced this technology before, and it is expected to play a role in various long-range space missions.
In order to target and accurately hit the asteroid, the DART mission requires a first-class navigation system. Therefore, the vehicle is equipped with Didymos reconnaissance and asteroid cameras for optics, or DRACO. This device is used for terminal navigation to ensure that DART has a good solid collision with asteroids.High resolution camera input SmartNAV autonomous navigation system This will control the spacecraft to fly to the asteroid in the last four hours. It is important to have a spacecraft guide itself, because of the distance involved, the round-trip delay for commands from Earth will be 1.5 minutes. Therefore, the aircraft must fly to the target by itself.
The DART mission will also carry LICIACube, a small cube built by Agenia Spaziale Italiana (ASI). Five days before impact, LICIACube will be deployed to image the effects of DART into Dimorphos. The purpose is to capture a lens of the impact site itself, as well as the material cloud ejected immediately after the impact. This should provide a lot of material for analyzing the effectiveness of the DART mission in asteroid redirection.
This is an interesting way to solve the problem of asteroid deflection. As DART will prove, using relatively small spacecraft to hit asteroids well in the early stages of their approach is something that should be easy to achieve with current technology. Compared with other ideas involving the last use of nuclear weapons to reject or destroy an incoming object, it is also less desperate and less intense.
Currently, no major asteroids are expected to hit the Earth in the near future. However, this is not to say that there are not many asteroids floating there.The Planetary Defense Coordination Office found 19,000 near-Earth asteroids By the beginning of 2019, an average of 30 new objects were detected every week. These detection and tracking tasks are the key to planetary defense. The sooner we know that an object is facing the earth, the more time we have to plan a task to deal with it, and the more choices we have on the table. To get an asteroid too close, the energy required to deflect it away from the Earth will become greater and the task will become more difficult.
Although the impact of DART is small, this is only the first time humans have tried to redirect asteroids. The brave people on earth will be able to rest more easily because they know that great thoughts are solving the problem of how to protect us from the big rocks from above.