Interstellar visitors have arrived.
Two years ago, an Hawaii Automated Telescope discovered "Oumaamawa, the first known object in interstellar space to be observed passing through our solar system. Then, in August, an amateur astronomer in the Crimea found a second interstellar visitor, 2I / Borisov, suggesting that such sites regularly come our way.
Scientists are now eagerly developing plans to investigate these envoys from afar and learn their secrets.
"Imagine something that has traveled hundreds of thousands or even millions of years out of space, now reaching us," says Andreas Hein, an aerospace engineer at the Interstellar Research Initiative in Charfield, England. "What will it tell us about its origin? What is the composition of the planets orbiting this alien sun? Life spreads between the stars?
For the time being, responses have been slowly piling up from observatories on Earth and in orbit around Earth, including an intriguing new image of Borisov made by the Hubble Telescope. But in 2028, a European spacecraft called the Comet Interceptor may be on its way to a brief encounter with another, as yet undiscovered, interstellar object.
Hein and his colleagues are considering an even larger project. They have made plans for Project Lyra, a space probe that can travel fast enough to overtake 'Oumuamua or Borisov (or other interstellar object) as it accelerates its path from the solar system, reaching or mid-2040. .
For Heine, the launch of Project Lyra would be similar to the construction of humanity's first star ship – and make it cheap. "We won't be able to reach another star system for at least the next few decades, but to be able to study a large chunk of material from another star is a bit like flying to another star," he says. "This is a literal version of 'If you can't go to the mountain, let the mountain come to you.'"
Star Trek Visitors
The mysteries surrounding Oomuamua uh moo-uh) further intensified the desire to approaching one of these interstellar visitors.
Researchers suggested that the majority of interstellar objects would be comets, but "Oumuamua certainly did not look like one. It was strangely elongated, like a half-mile-long cigar spinning. It also showed no comet-like tail and accelerated slightly as it moved away from the sun. These oddities prompted the Harvard astronomer Avi Loeb to float the contradictory notion that "Oumaamua cannot be a comet at all, but an alien spacecraft.
By contrast, Borisov looks very much like a comet in our own solar system. "It seems to be of a completely different nature from Oumuamua," says Loeb. "But when you walk down the street and notice a strange person, the fact that you later meet a lot of normal people does not take away the strangeness of that first unusual person."
Alas, the Space Agency's comet interceptor will be unable to reach either one of these sites. In fact, it is not designed to search after an interstellar object at all. The original plan was that after its launch in 2028, a 1-ton spacecraft would orbit around the sun, waiting for the comet to arrive from the outskirts of our own solar system. Then she will ignite her engines, making an appointment and having smaller probes that could come within a few hundred miles of her target.