(65803) Didim

(65803) Didim ( Greek Δ δυμος ) is a small rapidly rotating near-Earth asteroid from the Apollon group, which is characterized by an elongated orbit, because of which, in the process of its movement around the Sun, it intersects not only the Earth orbit, but also Mars . The asteroid was discovered on April 11, 1996 as part of the Spacewatch asteroid search project at Kitt Peak Observatory and is named after the ancient Greek music theorist Didim Muzykant .

• The orbit of the asteroid Didim and its position in the solar system
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The main feature of this asteroid is the presence of a small satellite, which received the provisional designation S / 2003 (65803) 1 and the unofficial name “Didymoon” ^[1] . The satellite has a diameter of only 150 meters and rotates around the main asteroid in an orbit with a radius of 1.1 km with a period of only 11.9 hours. Based on the period of rotation and size of the asteroid, it was possible to establish the mass and density of this body.

Owing to its orbit, this asteroid is the most readily accessible object for spacecraft starting from Earth, because the minimum change in speed required to transfer from near-Earth orbit to the approach path with this asteroid is only 5.1 km / s ^[2] , while even to reach the moon, a speed of 6.0 km / s is required. This is partly why this satellite of the asteroid in the future may become the target for two probes of the European Space Agency ’s research mission, during which the AIM probe (Asteroid Impact Monitor) will observe how the probe impacts into Didim’s satellite at a speed of about 6.5 km / s. It was assumed that the apparatus of the Aida mission will meet with an asteroid in 2022 ^[3] . Later, the plans of NASA and ESA changed, so that the European Hera device will go to Didim a few years after DART. The launch of the DART Falcon 9 launch vehicle from the US Air Force Base Vandenberg in California is scheduled for June 2021. Hera’s European probe is planned to be launched by the Arian-6 launch vehicle from the Kuru Cosmodrome in French Guiana, along with two small kubsats - Asteroid Prospection Explorer (“APEX”), developed by the Swedish-Finnish-Czech-German consortium and Juventas ^[4] .

For the Earth (65803) Didim is not dangerous. This asteroid approached the minimum distance with our planet in November 2003 and flew at a distance of more than 7.18 million km. Closer rapprochement with the Earth will take place only in 2123 and will amount to 5.9 million km. Also in 2144, the asteroid will come close to Mars to a distance of 4.63 million km.