The fact that the attention of all mankind is now drawn to the fight against the threat posed by the coronavirus pandemic, other types of threats have not disappeared, although they have temporarily moved to the background. The very real threat of an asteroid hitting the Earth seems now to be something ephemeral, despite the fact that such a cataclysm can end all of humanity literally at one moment in time.
And leading space agencies such as the European Space Agency and the US agency NASA continue to work on plans to protect the Earth from the "asteroid threat."
launch a DART (Double Asteroid Redirection Test) mission. This mission is of a demonstration nature and its purpose is to study the possibility of providing a kinetic effect to deflect an asteroid from a trajectory dangerous for the Earth. The spacecraft of the DART mission will travel to a binary asteroid system called 65803 Didymos, which currently does not pose a threat to Earth.
The large asteroid Didymos A has a diameter of approximately 780 meters, while its smaller "satellite", Didymos B, is 160 meters in diameter. It is on the surface of a smaller asteroid that the DART spacecraft will be smashed, because its (asteroid) size and mass are closest to those of asteroids that pose a threat to humanity.
The DART spacecraft will have to travel a long way to reach the Didymos asteroids. After launching in July 2021, the device will travel 11 million kilometers and reach the rendezvous point with the asteroid in September 2022. And to overcome such a huge distance, the DART vehicle will help its main ion thruster NEXT-C (NASA Evolutionary Xenon Thruster - Commercial).
The NEXT-C is the most powerful ion thruster available today. Of course, its capabilities do not even come close to resembling the capabilities of rocket engines capable of overcoming Earth's gravity, but among ion engines it is the undisputed leader. NEXT-C is three times more powerful than the NSTAR ion thrusters used in NASA DAWN and Deep Space One spacecraft.
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The NEXT-C motor operates in a pulsed mode, one such pulse requires 6.9 kW of power, and in terms of resource, the motor can produce 236 million pulses. During the tests, the NEXT-C engine demonstrated the highest thrust impulse value, which was 17 mN * s. Ion engines also have an indicator of fuel efficiency, which is conventionally the time that the engine will run on a certain amount of fuel. For the NEXT-C engine, this time is 4190 seconds, while the NSTAR engine shows a reading of 3120 seconds.
When the spacecraft reaches the Didymos asteroids, it will not immediately "crash into a cake" on the surface of a small asteroid, but will first complete its research mission. To do this, he carries on board six mini-satellites LICIA (Light Italian CubeSat for Imaging of Asteroids) of the CubeSat standard, created by specialists from the Italian space agency. These satellites will make a preliminary survey of the asteroid's surface, record the moment the DART spacecraft hits the asteroid, record the collision site and debris flows from it, transmitting all data to Earth in an almost continuous mode.
The DART impact is expected to change the speed of Didymos B's orbital motion by about half a millimeter per second. Such a slight change in speed will be very strongly reflected in the period of its rotation around a large asteroid, which will be detected using ground-based telescopes. The impact will also leave a crater on the surface of the asteroid, about 20 meters wide.
After the destruction of the DART apparatus, the apparatus of the European Hera mission will go to the Didymos asteroids, which, according to plans, will be launched in 2024 and arrive at the asteroids in 2027. This device examines the place of impact and analyzes the consequences caused by it. In addition, Hera will carry a range of scientific instruments that will allow scientists to learn more about binary asteroid systems and the structure of individual asteroids.