2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
It is possible to search for extraterrestrial civilizations not only by radio signals, but also by space debris surrounding their planets, according to an article accepted for publication in the Astrophysical Journal. Spanish astronomer Hector Socas-Navarro (Hector Socas-Navarro) believes that satellites and stations should leave a characteristic imprint on the light curve of the star during the passage through the disk of the star, and it is possible to see it even with modern instruments.
The SETI projects for the search for extraterrestrial life are based on the assumption that a technologically advanced civilization, one way or another, will eventually have to come to the creation of radio communication systems, including artificial satellites. From this it follows that it is also likely to be engaged in space exploration - the construction of spaceships and manned stations. At the same time, over time, a sufficiently large number of devices, including those that have failed (space debris), can accumulate in orbit, and they will become noticeable even for modern telescopes studying other stars in search of exoplanets.
The devices surrounding the hypothetically inhabited planet (working and non-working), the author of the new work, Hector Sokas-Navarro, called Clark's belt. The scientist conducted several simulations in which he figured out what mark the Clarke belt would leave on the mother star's light curve during transit. In his work, Sokas-Navarro considered several planets, including Earth, Proxima b and TRAPPIST-1 d, e, f, g. The total mass of all artificial objects in orbit around celestial bodies varied from 1012 to 1014 kilograms; on average, each device or its fragment had a radius of about one meter and a mass of 100 kilograms.
The researchers concluded that the Clarke Belt (given its sufficient density) would be best seen in a system of a red dwarf and a planet in close orbit. According to simulations, a 10-meter telescope operating in the infrared range (for example, one of the instruments at the Mauna Kea Observatory in Hawaii) will be able to register artificial objects around Proxima b. In addition, such a telescope will be able to see the Clark belt around most of the TRAPPIST-1 planets - TRAPPIST-1d, -e and -f. With a planet similar to Earth, the situation is somewhat more complicated: alas, if it revolves around a sun-like star, modern instruments will not be able to see traces of extraterrestrial civilization around it - given the current pace of technology development, telescopes will be able to detect Clark's belt in orbit of another planet similar to Earth, not earlier than 200 years later.
The main difficulty that can arise when searching for space debris around planets is the similarity of its "fingerprints" on the light curve with signs of the existence of rings. On the other hand, Sokas-Navarro believes that follow-up observations will allow astronomers to distinguish one from the other. In addition, much will depend on the type of the planet itself (for example, it is a gas giant or an Earth-like body) and the results of subsequent searches for exoons and rings outside the solar system.
Despite the potential benefits for contact with extraterrestrial civilizations, space debris poses a great threat to future manned missions. According to the estimates of the European Space Agency, today there are 750 thousand debris in low-earth orbit, the size of which exceeds a centimeter. Some companies are trying to solve this problem by developing devices for cleaning near-earth space. For example, a Singapore-based startup Astroscale in 2016 created a prototype of a space velcro.