The first ever interstellar asteroid discovered by astronomers in October can be chased by a swarm of hundreds of small probes with solar sails, which will be accelerated by powerful lasers on Earth, according to a group of scientists participating in the Lyra project. The research preprint is published on the arXiv.org portal.
Interstellar asteroid 1I / 'Oumuamua was discovered on October 18, 2017 using the Pan-STARRS telescopes in Hawaii. Initially, it was considered an interstellar comet, which received the designation C / 2017 U1 (PANSTARRS), but further observations with the VLT telescope at the European Southern Observatory showed that the object has no signs of coma and, rather, is an asteroid. After that, the "comet" index "C" in the name was changed to asteroid "A", and then the object was given the official name Oumuamua ('Oumuamua), which translated from Hawaiian can mean "scout" or "envoy from afar." Analysis of the data showed that the asteroid has a speed of about 26 kilometers per second relative to the Sun, arrived at us from a point close to the solar apex, in the constellation Lyra, moves along an open hyperbolic trajectory and will soon leave the solar system. Other observations showed that the asteroid can be elongated and about 230 meters long, its density can be six times that of water, and the surface has a reddish tint, which may indicate the presence of tholins.
The occurrence of extrasolar asteroids in our planetary system is very rare (one object per year according to astronomers 'estimates), and the probability of their successful detection is very low, so the 1I /' Oumuamua study, especially at close range, is a unique chance to learn more about the composition of interstellar matter. However, this task is very difficult, in particular due to the high speed of the asteroid, which is greater than the speed of any research spacecraft launched into space at the current time. The development of any project of an apparatus that will be able to catch up with an asteroid can give a powerful impetus to the development of space technologies.
The authors of the work from the British organization "Initiative for Interstellar Studies" and the company "Asteroid Initiatives" consider the period from 2023 to 2027 to be the most realistic date for the launch of the apparatus into space, in this case the value of the required excess hyperbolic velocity (the speed that the body has when moving in infinity) is from 33 to 76 kilometers per second, and the flight duration will be from 5 to 30 years. Launch from the Earth can be carried out using the developed rocket systems SLS (Space Launch System) or BFR (Big Falcon Rocket), in order to gain the required speed and correct the trajectory, the device will have to perform Obert's maneuvers near the Sun and Jupiter. It is assumed that the probe can have several additional accelerating solid-fuel stages, RTGs and will be equipped with multilayer thermal insulation. Calculations showthat in the case of a successful launch of the apparatus in 2025, its encounter with an asteroid could take place in 2039 or 2051, at a distance of 85 or 155 astronomical units from Earth.
Relationship between launch date and mission duration. The color code indicates the distance from Earth to the point at which the spacecraft will meet the asteroid. Andreas M. Hein et al./arXiv:1711.03155
However, the most promising project, the research team considers a "swarm" of hundreds of small probes (ChipSats) equipped with a solar sail. With a mass of less than one kilogram, the probes would be accelerated using a laser beam with a power of tens of megawatts. In this case, the launch could be carried out four years after the start of work and reach the asteroid in about ten years. At the same time, it is possible to solve the problem of navigation, searching for an asteroid and calculating the exact place of meeting with it, since a huge array of probes can cover a large area. Other options are magnetic or electric sails or the acceleration of probes in Jupiter's magnetosphere due to the Lorentz force. There is another idea - not to try to catch up with 1I / 'Oumuamua, but to create an apparatus capable of reaching a similar fast-flying object,and wait for the next interstellar "guest" to greatly reduce flight time, mission complexity and cost.
Various options for the calculated trajectories for the spacecraft leading to an encounter with the asteroid: a) launch of the spacecraft in 2017, reaching the target in 2037, b) launching the spacecraft in 2017, achieving the goal in 2018, c) launching the spacecraft in 2025, reaching the goal in 2055. Andreas M. Hein et al./arXiv:1711.03155
Alexander Voytyuk
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