Scaling traditional optical telescopes is very difficult and costly, because making giant mirrors is an extremely laborious undertaking. Whether it is a radio telescope, which is, in fact, an antenna field. Facilities such as the VLA in New Mexico or the ALMA in Atacama are composed of dozens of relatively small antennas controlled as a single complex. Now scientists want to build GRAND, a giant array of transceivers for detecting neutrinos.
Neutrino is an elusive particle, it is extremely difficult to detect it due to the fact that it has no charge, is subject only to weak and gravitational influences and therefore passes through the detectors without activating them. However, high-energy neutrinos can be detected indirectly when they collide with other particles and generate many secondary particles. Here they can be detected by a radio telescope, but there is one catch - where exactly to catch the particles?
The theoretical basis is allowed to calculate the behavior of a neutrino, its flight trajectory and other parameters, by analyzing secondary particles. A comparison with the flight of a projectile and the dispersal of fragments from it is appropriate here. However, in order to reduce the error, you need to catch as many particles as possible at a time, which is why GRAND was conceived. It will include 200, 000 separate huge antennas, which together will occupy 207, 000 square meters. km of the area. For comparison, this is more than the size of Nebraska, and it is far from the smallest in the United States.
The GRAND will be built in parts, 10, 000 antennas each; a mountain site in China has been chosen to accommodate the first segment. Here, the most likely to catch secondary particles immediately after the collision of neutrinos with air or rocks. It is believed that the first neutrinos will be detected by 2025, although construction will last until 2030. In fact, the project has no exact boundaries, and if scientists see success, they will complete the required number of antennas, in theory, occupying at least all the important mountain ranges of the world.