Interstellar travel may be possible even without spaceships

(ORDO NEWS) — In about 5 billion years, the Sun will leave the main sequence and become a red giant. It will expand into a flaming, evil ball, engulfing and destroying Mercury, Venus, Earth, and possibly Mars.

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

Could they have survived by migrating to another star system without the use of spaceships?

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

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

It still takes us five years to get an orbiter to Jupiter at our technological level. There is a lot of talk about generational spaceships that people could live on for generations on their way to a distant habitable planet.

These ships do not need to reach speeds close to the speed of light; instead, generations of humans will live and die on a journey to another star that will take hundreds or thousands of years. It’s interesting to think about, but so far it’s pure fantasy.

Is there another way we or other civilizations could escape our doomed homes?

The author of a new research article in the International Journal of Astrobiology reports that extraterrestrial civilizations may not need spaceships to avoid existential threats and travel to another star system.

Instead, they could use free-floating planets, also known as outcasts. planets. Article “ET Migration and Interstellar Colonization: Implications for SETI and SETA”. Author Irina Romanovskaya. Romanovskaya is a professor of physics and astronomy at Houston Community College.

“I hypothesize that extraterrestrial civilizations could use free-floating planets as interstellar transport to reach, explore, and colonize planetary systems,” Romanovskaya writes. And when it comes to finding other civilizations, those efforts can leave behind technosignatures and artifacts.

“I propose possible technosignatures and artifacts that could be created by extraterrestrial civilizations using free-floating planets for interstellar migration and interstellar colonization, as well as strategies to search for their technosignatures and artifacts,” she said.

It is possible that rogue planets either in the Milky Way or in some other hundreds of billions of galaxies carry their lives with them in subsurface oceans warmed by radiogenic decay.

Then if they meet a star and become gravitationally bound, that life has effectively used the rogue planet to move, hopefully, to a more hospitable place. So why can’t civilization repeat this?

We think of free-floating planets as dark, cold, and inhospitable. And they exist, unless they have warm underground oceans. But they also have some advantages.

“Free-floating planets can provide constant surface gravity, large amounts of space and resources,” writes Romanovskaya. “Free-floating planets with surface and subterranean oceans could provide water as a consumable resource and for protection from cosmic radiation.”

An advanced civilization could also design the planet for even greater advantage by controlling and developing it. energy sources. Romanovskaya suggests that if we are on the cusp of using controlled fusion, then perhaps advanced civilizations are already using it, which can turn a cold rogue planet into something that can support life.

The author describes four scenarios. where extraterrestrial civilizations can take advantage of rogue planets.

The first scenario assumes that a rogue planet passes by the homeworld of extraterrestrial civilizations. How often this can happen depends on the number of rogue planets in general.

We don’t know how many there are yet, but they definitely are. In 2021, a team of researchers announced the discovery of 70 to 170 rogue planets, each the size of Jupiter, in a single region of the Milky Way. And in 2020, one study suggested that there could be up to 50 billion of them in our galaxy.

Where did they all come from? Most of them are probably ejected from their solar systems due to gravitational phenomena, but some of them may be formed by accretion, just like stars.

Another source of rogue planets is the Oort Cloud in our solar system. If other systems also have a cloud of objects like this, they could be a bountiful source of rogue planets thrown out by stellar activity.

Romanovskaya writes: “The evolution of the sequence, as well as a supernova from a progenitor 7–20 times larger than the Sun, can eject Oort cloud objects from their systems, so that such objects become unrelated to their parent stars.”

But how often can extraterrestrial civilizations or our civilization expect a rogue planet to get close enough to hitchhike to it? A 2015 study showed that the binary star W0720 (Scholz’s star) passed through the Oort Cloud in our solar system about 70,000 years ago.

Although it was a star and not a planet, this shows that the objects pass relatively close. If the studies that predict billions of free-floating planets are correct, then some of them likely passed near or right through the Oort Cloud long before we had the means to detect them.

The Oort Cloud is far away, but a sufficiently advanced civilization could see the approaching rogue planet and come out to meet it.

The second scenario involves the use of technology to guide a rogue planet closer to civilization’s planet. house. Given enough technology, they could pick an object from their own Oort Cloud – provided they have one – and use a propulsion system to steer it into a safe orbit near their planet.

Given enough lead time, they could adapt the facility to suit their needs, for example by building underground shelters and other infrastructure. Perhaps, given the right technology, they could change or create the atmosphere.

The third scenario is similar to the second. It is also associated with an object from an outer solar system civilization. As an example, Romanovskaya uses the dwarf planet Sedna in our solar system.

Sedna has a very eccentric orbit that goes from 76 AU from the Sun to 937 AU for about 11,000 years. With enough technology and time to prepare, a facility like Sedna could be turned into a rescue ship.

The author notes that “Civilizations capable of this will be advanced civilizations whose planetary systems have already been explored from a distance. at least 60 a.u. from their host stars.”

There are many potential problems. Moving a dwarf planet from the far reaches of the solar system to the inner solar system could disrupt the orbits of other planets, leading to all sorts of dangers.

But the dangers are mitigated if the civilization around the post-main-sequence star has already migrated outward with the change in the habitable zone. Romanovskaya discusses the required energy and timing in more detail in her article.

The fourth scenario also includes objects such as Sedna. As a star leaves the main sequence and expands, there is a critical distance at which objects will be ejected from the system rather than remain gravitationally bound to the dying star.

If extraterrestrial civilizations could determine exactly when these objects will be ejected as rogue planets, they could prepare it in advance and take it out of the dying solar system. This can be extremely dangerous, as periods of severe loss of mass from a star pose a huge danger.

In all of these scenarios, the rogue planet or other body is not the permanent home; it’s a lifeboat.

“For all of the above scenarios, free-floating planets cannot serve as a permanent means of escape from existential threats,” the author explains. “Due to the reduction in heat production in their interiors, such planets eventually cease to support oceans of liquid water (if such oceans exist).”

Free floating planets are also isolated and have fewer resources than planets in the solar system. For example, there are no asteroids to mine and no free solar power. There are no seasons, no day and night. There are no plants, no animals, not even bacteria. They are simply a means to an end.

“So instead of making free-floating planets their permanent home, extraterrestrial civilizations will use free-floating planets as interstellar transport to reach and colonize other planetary systems. ”, writes Romanovskaya.

In her article, Professor Romanovskaya reflects on what this might lead to. She imagines 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, a parent civilization can create a unique and autonomous child … civilizations inhabiting different planets, moons or regions of space.

“The space hitchhiker civilization will act as a ‘parent civilization’, spreading the seeds of ‘daughter civilizations’ as their colonies into planetary systems,” she writes. “This applies to both biological and post-biological species.”

Humanity is only in the early stages of protecting itself from catastrophic asteroid impacts, and we can’t handle our problems yet. planetary climate with any degree of stability. So the idea of ​​using rogue planets to keep humanity alive seems pretty far-fetched. But Romanovskaya’s research is not about us, but about the discovery of other civilizations.

All this activity could create technosignatures and artifacts indicating the presence of ETC. The research article describes what they might be and how we can detect them. Rogue planets used as lifeboats can create technosignatures such as electromagnetic radiation or other phenomena.

Extraterrestrial civilizations can use solar sails to control the rogue planet, or use them on a spacecraft launched from the rogue planet once they reach their destination. . In any case, solar sails produce a technosignatures: cyclotron radiation.

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

Infrared could be another technosignatures emitted by extraterrestrial civilizations as waste heat on a rogue planet. An excessive amount of infrared radiation or unnatural changes in the amount of infrared radiation can be detected as a technosignatures.

Infrared radiation can be emitted unevenly across the planet’s surface, indicating an underlying technique or technology. An unusual combination of different wavelengths of electromagnetic energy can also be a technosignatures.

The atmosphere itself, if it exists, may also contain technosignatures. Depending on what has been observed, it may contain evidence of terraforming.

At the moment, astronomers do not know how many rogue planets exist and whether they are concentrated in certain regions of the galaxy. We are on the starting line when it comes to figuring these things out. But soon we may have a better idea.

The Vera Rubin observatory should see the first light by 2023. This powerful observatory will capture the entire available sky every few nights and do so in great detail. . It houses the largest digital camera ever made: a 3.2 gigabyte CCD.

Vera Rubin will be especially good at detecting transients, i.e. anything that changes position or brightness in a couple of days. It will have a good chance of detecting any intruders, such as rogue planets, that may approach our solar system.

There is a strong possibility that some of these rogue planets will exhibit unusual outbursts or mysterious phenomena. Scientists will probably puzzle over them, as over ‘Oumuamua.

Perhaps another civilization, more advanced than ours, is already facing an existential threat from its dying star. Maybe they made a Herculean effort to take over a rogue planet and design it to suit their needs.

Maybe they had already boarded her and sent her to a distant, stable, long-lived yellow star from a rocky planet in their habitable zone. Maybe they are wondering if there is life at their destination and how they might be met after a long journey.

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