The interstellar visitors have arrived.

Two years ago, an automated telescope in Hawaii discovered Oumuamua, the first known object from interstellar space, flowing through our Solar system. Then in August, an Amateur astronomer in Crimea found a second interstellar visitor, 2I/Borisov, suggesting that such objects come to us on a regular basis.

Now scientists are eagerly developing plans to study these messengers from afar and learn their secrets.

Imagine something that has traveled for hundreds of thousands or even millions of years through space, now reaching us, says Andreas Hein, aerospace engineer at The initiative for interstellar research in Charfield, England. What will he tell us about his origins? What is the composition of the planets that orbit this alien sun? Does life spread between the stars?

The path of interstellar comet 21 / Borisov is now passing through our Solar system. NASA, ESA, J.Olmsted, F. Summers (STScI). / ESA / Hubble

Currently, answers are slowly trickling out of observatories on earth and in orbit around the Earth, including an intriguing new image of Borisov just taken by the Hubble telescope. Come 2028, however, a European spacecraft called the Comet Interceptor may be on its way to a brief encounter with another, as yet undetected interstellar object.

Hein and his colleagues have an even grander project in mind. They have developed plans for the Lira project, a space probe that can travel fast enough to overtake either Oumuamua or Borisov (or another interstellar object) as it speeds its way out of the Solar system, reaching either one by the mid-2040s.

For Hine, launching project Lear would be akin to building humanity’s first starship and doing it on the cheap. We won’t be able to reach another star system for the next few decades, at least, but being able to study a large chunk of material from another star is a bit like flying to another star, he says. This is the literal version, if you can’t go to the mountain, let the mountain come to you.

Inching to interstellar visitors

In contrast, Borisov seems to be very similar to comets in our solar system. It seems to have a completely different character than “Oumuamua,” Loeb says. But when you walk down the street and notice a strange person, the fact that you later encounter many normal people doesn’t take away the strangeness of that first unusual person.

Alas, the European space Agency’s comet interceptor will not be able to reach any of these objects. In fact, it was not designed to go after an interstellar object at all. The original plan was that after launch in 2028, the 1-ton spacecraft would Park in orbit around the Sun in anticipation of the arrival of a comet from the outskirts of our Solar system. It will then fire its engines, making a collision and deploying small probes that can come within a few hundred miles of its target.

Opening Omwamwi and Borisov has led to the fact that the team of interceptors Comet changed the plans. According to one estimate, there are about 100 interstellar objects in orbit around the Sun at any time, and there is a good chance that at least one of them will be within reach of the spacecraft.

If the interstellar object happens to be on the right trajectory at the right time, it would be too good an opportunity to give up, says mission co-leader Colin Snodgrass, an astronomer at the University of Edinburgh.

While Comet Interceptors flying past an interstellar visitor will be quick and brief, it could prove highly revealing. It would be interesting to see one up close, Snodgrass says. Either it will look like nothing we’ve ever seen before and require new theories, or it will look surprisingly familiar, implying that there are some universal similarities in planetary systems.

Hit the space accelerator

If you want to chase Oumuamua or Borisov to determine their true nature, you will need a spaceship with a much larger ball than a comet interceptor. Oumuamua is now more than 1 billion miles from Earth and accelerating away from us at nearly 18 miles per second. Borisov will make his closest approach to the Sun on December 7, and then he, too, will travel back to interstellar space at high speed.

Thats where Project Lyra comes in. The engineers at the nonprofit Initiative for Interstellar Studies came up with this concept based on their research into technologies for advanced space travel. The team concluded that the most promising way to reach an interstellar object is with a so-called Oberth maneuver, in which a spacecraft swoops to within 2 million miles of the sun and then fires its rockets full-blast to slingshot toward its target. Using a giant rocket like NASAs long-awaited Space Launch System, combined with solid-rocket boosters, Hein and his group calculate they could get a speed boost of about 12 miles per second, just enough to do the job.

With a 2033 launch, this scheme could deliver a small but capable probe weighing perhaps 100 pounds to Oumuamua by 2048. Slowing down at the other end would be another problem. Maybe we can use electric or magnetic sails, Hein suggests, referring to giant metal networks that would create resistance against the magnetic field and charged particles found in deep space.

A fleet of laser sails arriving at ‘ Oumuamua.Maciej Rebisz / Project Lira

The survival of the sun’s intense heat may be easier to solve the problem. The NASAs current Parker solar probe, which will repeatedly swing within 4 million miles of the Sun during the 2020s, is testing a carbon-composite heat shield that can effectively withstand temperatures of 2,500 degrees Fahrenheit.

Foreigners closer to home

But there’s another way to speed up a mission to an interstellar object: instead of going faster, aim closer. Loeb notes that not all incoming objects return to the stars. He calculates that some might get gravity-deflected Jupiters and absorbed into orbit around the sun. If so, a conventional spacecraft could reach them within a few years.

There are already a number of candidate facilities known, Loeb Said. In particular, he cites the example of 2015 B ‘ 509, a newly discovered asteroid that orbits near Jupiter but in the opposite direction of all planets is a likely sign of interstellar origin.

Loeb also suggests combing the moon’s surface for debris left behind by other interstellar objects that may have collapsed there over billions of years of lunar history. This is a timely proposal, as the NASAs Artemis program could send astronauts back to the moon as early as 2024.

The realization that so much interstellar material has passed through our solar system over the eons, with more coming all the time, provides another powerful motivation to study incoming objects up close. It’s possible that a small fraction of them carry evidence for life, Loeb says.

He’s not talking about abandoned alien spacecraft, but about possible extraterrestrial microorganisms or their remains, which in many ways would be just as shocking. Searching for such evidence would open up the possibility that alien life struck us from far between the stars and across the galaxy, Loeb says, and that humans could be descendants of extraterrestrial microbes that landed on Earth billions of years ago.

Its a Hollywood worthy twist: Looking far away for interstellar visitors, but it may turn out they’ve been here all along.

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