Scientists say interstellar travel could be possible even without spaceships

In about 5 billion years, the Sun will leave the main sequence and become a red giant. It will expand and transform into a malicious glowing ball, consuming and destroying Mercury, Venus, Earth and possibly Mars.

Can humanity survive the red giant phase of the sun? Extraterrestrial civilizations (ETCs) may already have faced this existential threat.

Could they have survived it by migrating to another star system without using spaceships?

Universe Today readers are well aware of the difficulties of interstellar travel. Our closest neighboring solar system is the Alpha Centauri system.

If humanity had to flee an existential threat in our solar system, and if we could locate a planetary home in Alpha Centauri, it would take us more than four years to get there – if we could travel at the speed of light!

It still takes five years to reach Jupiter in our technological stage. There is a lot of talk about generation ships, where humans can live for generations while on their way to a distant habitable planet.

These ships do not need to reach anywhere close to the speed of light; Instead, entire generations of humans will live and die on a journey to another star that will take hundreds or thousands of years. It’s fun to think about fiction but purely at this point.

Is there another way we, or other civilizations, can escape from our devastated homes?

Author of a new research article in International Journal of Astrobiology He says that ETCs may not need spaceships to escape existential threats and travel to another star system.

They can instead use free-floating planets, also known as rogue planets. The article is “Extraterrestrial Civilization Migration and Interstellar Colonization: Implications for SETI and SETA”. The author is Irina Romanovskaya. Romanovskaya is Professor of Physics and Astronomy at Houston Community College.

Romanovskaya wrote: “I suggest that extraterrestrial civilizations might use freely floating planets as interstellar transport to access, explore and colonize planetary systems.” And when it comes to researching other civilizations, these efforts can leave technical and artefacts imprints.

“I propose potential technical signatures and artifacts that extraterrestrial civilizations can produce using free-floating planets of interstellar migration and interstellar colonization, as well as strategies to search for their technological fingerprints and artifacts,” she said.

It’s possible that rogue planets, whether in the Milky Way or in some hundreds of billions of other galaxies, carry their own lives with them in subterranean oceans kept warm by radioactive decay.

Then if they meet a star and become bound by gravity, that life has effectively used a rogue planet to transport itself, hopefully, to a more suitable location. So why can’t civilization imitate that?

We think of free planets as dark, cold, and inhospitable. And they are unless they have warm subterranean oceans. But it also offers some advantages.

“Floating planets can provide constant surface gravity, large amounts of space and resources,” Romanovskaya wrote. “Freely floating planets with surface and subterranean oceans could provide water as a consumable resource and to protect against space radiation.”

An advanced civilization could also engineer the planet to achieve greater advantage by directing it and developing energy sources. Romanovskaya suggests that if we were about to use controlled fusion, perhaps even advanced civilizations might already be using it, which could turn a frozen rogue planet into something that could support life.

The author outlines four scenarios where ETCs could benefit from rogue planets.

The first scenario involves a rogue planet that happens to pass the original world of ETC. How often this happens is related to the number of rogue planets in general.

So far, we don’t know how many there are, but there are certainly some. In 2021, a team of researchers announced the discovery of between 70 and 170 rogue planets, each the size of Jupiter, in one region of the Milky Way. And in 2020, one study suggested that there could be as many as 50 billion of them in our galaxy.

Where do they all come from? Most of it is likely ejected from their solar systems by gravitational events, but some may be formed by accretion as stars do.

Another source of rogue planets is the Oort cloud in our solar system. If other systems also contain a cloud of things like this, they could be a bountiful source for rogue planets that have been kicked out by stellar activity.

Romanovskaya writes: “Stars with 1–7 solar masses undergoing post-main sequence evolution, as well as a supernova 7–20 times solar mass progenitors, can eject Oort cloud objects from their systems so that these objects become unbound from their host stars “.

But how often can the ETC, or our civilization, expect a rogue planet to get close enough to wander around? A 2015 study showed that the binary star W0720 (Scholes star) passed through the Oort cloud in our solar system about 70,000 years ago.

While this was a star and not a planet, it does show that things pass relatively close to it. If studies predicting billions of free-floating planets are correct, it is possible that some of them passed near or just through the Oort Cloud long before we had the means to detect them.

The Oort Cloud is still far away, but a sufficiently advanced civilization could have the ability to see an approaching rogue planet, eject, and meet it.

The second scenario involves using technology to steer a rogue planet closer to the home of civilization. With enough technology, they can choose an object from their Oort cloud – assuming they have one – and use the propulsion system to steer it toward a safe orbit near their planet.

With sufficient lead time, they can adapt the object to their needs, for example, by building underground shelters and other infrastructure. Perhaps, with the right technology, they can change or create an atmosphere.

The third scenario is similar to the second scenario. It also includes a body from the outer solar system of a civilization. Romanovskaya uses the dwarf planet Sedna in our solar system as an example.

Sedna has a very eccentric orbit that takes it from 76 AUs from the Sun to 937 AUs in about 11,000 years. With enough technology and enough lead time, a being like Sedna can be turned into an escape ship.

The author notes that “civilizations capable of doing this will be advanced civilizations that already have explored planetary systems at distances of at least 60 AU from their host stars.”

There are a lot of potential problems. Bringing a dwarf planet from great distances from the solar system into the inner solar system can disrupt the orbits of other planets, creating all kinds of dangers.

But the risks are mitigated if a civilization around a post-main sequence star has already migrated outward as the habitable zone changes. Romanovskaya discusses the required power and timing in more detail in her article.

The fourth scenario also includes things like Sedna. When a main-sequence star leaves and expands, there is a critical distance where things will be pushed out of order rather than remain gravitationally bound to the dying star.

If the ETC can accurately determine when these bodies will be ejected as rogue planets, they can prep them and eject them from the dying solar system. That could be extraordinarily risky, because periods of extreme mass loss from the star create an enormous danger.

In all of these scenarios, a rogue planet or any other body would not always be home; It’s a lifeboat.

“For all of the above scenarios, free planets may not function as a permanent means of escaping from existential threats,” the author explains. “Because of diminished heat production in their interiors, these planets ultimately fail to maintain oceans of liquid water (if such oceans exist).”

Free-floating planets are also isolated and have fewer resources than planets in the solar system. There are no asteroids to mine, for example, and no free solar energy. There are no seasons, no day and night. There are no plants, animals, or even bacteria. It is just a means to an end.

Romanovskaya wrote: “Instead of making free-floating planets their permanent homes, extraterrestrial civilizations will use free-floating planets as interstellar transport to reach and colonize other planetary systems.”

In her article, Professor Romanovskaya speculates where this could lead. She envisions a civilization doing this more than once, not to escape a dying star, but to spread throughout the galaxy and colonize it.

“In this way, patriarchal civilization may create unique and independent daughter civilizations that inhabit different planets, moons, or regions of space.

She wrote: “The civilization of the cosmic nomads will be a ‘patriarchal civilization’ that spreads the seeds of ‘daughter civilizations’ in the form of its colonies in planetary systems.” “This applies to both biological and post-biological species.”

Humanity is only in the early stages of protecting ourselves from the effects of catastrophic asteroids, and we cannot yet manage our planet’s climate with any degree of stability. So the thought of using rogue planets to keep humanity alive seems far fetched. But Romanovskaya’s research is not about us. It is about discovering other civilizations.

All this activity can create signatures of art and artefacts indicative of the presence of ETC. The research article explains what it could be and how we can detect it. Rogue planets used as lifeboats can create technical fingerprints such as electromagnetic emissions or other phenomena.

ETC can use solar sails to control a rogue planet or use it on a spacecraft launched from a rogue planet once it reaches its destination. Either way, the solar sails produce a technical signature: cyclotron radiation.

Maneuvering either a spacecraft or a rogue planet with solar sails would produce “… cyclotron radiation caused by the interaction of the interstellar medium with the magnetic sail”.

Infrared emissions could be another technical sign of waste heat being emitted by ETC on a rogue planet. Excessive amount of infrared radiation or abnormal changes in infrared amount can be detected as a technical signature.

Infrared radiation can be emitted unevenly across the surface of a planet, indicating underlying engineering or technology. An unusual combination of different wavelengths of electromagnetic energy can also be a technical signature.

The atmosphere itself, if present, can also carry technological fingerprints. Depending on what was observed, it could contain evidence of reclamation.

Currently, astronomers don’t know how many rogue planets there are or if they are concentrated in some regions of the galaxy. We’re at the starting line when it comes to figuring out these things. But soon, we may get a better idea.

The Vera Robin Observatory should see the first light by 2023. This powerful observatory will image the entire available sky every few nights, and will do so in fine detail. It houses the largest digital camera ever made: the 3.2GB CCD.

Vera Rubin will be especially good at detecting transients, i.e. anything that changes position or brightness within a couple of days. It would have a good chance of spotting any intruders like rogue planets that might approach our solar system.

There is a strong possibility that some of these rogue planets will exhibit unusual emissions or puzzling phenomena. Perhaps scholars are as baffled by them as they did with Oumuamua.

Perhaps another civilization more advanced than us has already faced an existential threat from its dying star. Perhaps they have made a supernatural effort to capture a rogue planet and engineer it to suit their needs.

Perhaps they had actually ascended to it and launched it toward a distant, stable and long-lived yellow star, which had rocky planets in its habitable zone. Perhaps they are wondering if there is life at their destination and how they can be greeted after their long journey.

This article was originally published by Universe Today. Read the original article.

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