Interstellar travel

Interstellar travel without a spaceship is possible – Here’s how:

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Interstellar travel without a spaceship is possible – Here’s how:

Research published in the International Journal of Astrobiology proposes a fascinating theory where advanced extraterrestrial civilizations can travel among the stars without the need for an interstellar spaceship. 

In her paper, physics and astronomy professor Irina K. Romanovskaya postulates the possibility of using rogue planets (or free-floating planets, as she calls them) for interstellar transport. 

Image Credit: Dotted Yeti via Shutterstock / HDR tune by Universal-Sci

SEARCH FOR EXTRATERRESTRIAL LIFE

Romanovskaya also proposes potential ‘technosignatures‘ (measurable characteristics or effects that offer scientific evidence of past or present technology) that may be produced by extraterrestrial civilizations employing rogue planets for interstellar migration. Additionally, she stipulates approaches on how to potentially search for these technosignatures to enhance our search for extraterrestrial life.

One can imagine several reasons for extraterrestrial civilizations to leave their home planetary systems: Out of curiosity, aiming for exploration, or out of necessity because of the existence of an existential threat such as climate change that got out of hand, war, or a dying home star. 

BENEFITS OF EMPLOYING A ROGUE PLANET FOR INTERSTELLAR TRAVEL

In the latter scenario, civilizations are likely to run into problems fairly quickly as they attempt to migrate away from their home system. Romanovskaya explains that they would probably face severe or insurmountable problems if they were to use spacecraft to migrate substantial populations over interstellar distances. (See the problem with ‘world ships’)

These issues got Romanovskaya thinking. Is there another method for advanced extraterrestrial civilizations to migrate to another planetary system? She concluded that rogue planets could be a viable solution if utilized cleverly.

The benefit of using rogue planets for interstellar migration is that they provide travelers with a lot of space and resources in addition to protection from radiation and consistent gravity. Think of liquid water just below the surface sustained by radiogenic and primordial heat of the planet, which can be used for consumption or to build underwater habitats that shelter inhabitants from the high radiation levels encountered in interstellar space. 

HOW USE A ROGUE PLANET FOR INTERSTELLAR MIGRATION?

But how would we be able to catch a lift on a rogue planet? This can be achieved in several ways, according to Romanovskaya. 

One possibility is just to wait for one to pass through their home planetary system. Research has shown that there may be more rogue planets than stars in the Milky Way. This means that from time to time, rogue planets may pass through the outer regions of planetary systems. If the outer regions are colonized, it is relatively manageable to cover the distance to such a passing rogue planet. 

Romanovskaya describes a situation in our own solar system where, for example, propulsion systems could be attached to a trans-Neptunian object. Clever use of gravity assists events involving other Oort cloud objects, could change the object’s trajectory, and bring it close to a rogue planet passing through the Oort cloud. When the object nears its periastron, a migrating civilization could use conventional spacecraft to ‘hop on,’ so to say. 

The distance from the Oort cloud to the interior of the Solar System, and two of the nearest stars – (Image Credit: NASA / JPL-Caltech)

Of course, this approach has a significant downside as one has to wait for such a planet to pass by. This is certainly not ideal in case of an existential threat. 

Another option for an advanced extraterrestrial civilization would be to release an existing dwarf planet from its gravitational bounds to their home planetary system and its parent star, effectively converting it into a rogue planet. 

Dwarf planets akin to Sedna in our own solar system are ideal for this type of scenario due to their highly eccentric orbit. Energy requirements for changing the speed of larger planets located at a distance of 40 astronomical units or less are significantly higher compared to the amount of energy needed to change the speed of a dwarf planet like Sedna at a distance of 500 astronomical units or more. 

The amount of energy needed to move a dwarf planet at highly eccentric would still be huge. However, Romanovskaya puts this in perspective by identifying that only a few hundred years ago, our primary method of transportation over land was by horse, while currently, we are capable of outputting millions of times that power with modern rocket engines.

Romanovskaya: “A civilization, which is several hundred years or millennia ahead of humankind in its technological development, may use advanced propulsion technologies and gravity-assist events to convert Oort-cloud objects to free-floating planets.”

It is also possible for a dwarf planet to be flung out of its planetary system by the parent star. This can happen when the star transforms into a supernova or red giant. (In such a case, there is reason enough for an advanced civilization to leave the planetary system, to begin with). 

In theory, the advanced extraterrestrial civilization could relocate to a dwarf planet in the outer reaches of the planetary system to be flung out of the system by the parent star as it expands from a main sequence star to a red giant, as there is a critical distance from which objects are pushed out of the planetary system instead of remaining bound to the dying star.

The life of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant star on the right .

WHY NOT PERMANENTLY SETTLE ON A ROGUE PLANET

In all the scenarios mentioned above, the civilization ends up on a planet wandering through the galaxy. So why not stay there instead of going to the trouble of moving again? 

According to Romanovskaya, a rogue planet should only be considered as a means of transportation between stars and not a new home. Rogue planets do not remain very hospitable over a long stretch of time. 

Eventually, the heat produced in the interior of a rogue planet will start to diminish, which means that it won’t be able to sustain liquid water indefinitely. In addition, rogue planets have a limited supply of resources and energy compared to a planetary system with a star at its center. 

THE PROBLEM WITH ‘WORLD SHIPS’ 

So how likely is it that there are actually inhabited rogue planets moving through our galaxy? As it stands, the answer to this question remains a mystery. Nonetheless, the scenario is not an unthinkable one if you ask Romanovskaya. 

Research tells us that building an interstellar spaceship capable of moving entire civilizations (sometimes referred to as ‘world ships’) is extremely difficult. Ezoic

If such an interstellar world ship treks at less than one percent of the speed of light, it would take hundreds of years to reach its destination in another planetary system. 

Romanovskaya: ”Passengers’ health and their ability to transfer knowledge and skills to next generations on the ship would require a very large number of passengers.” 

In fact, a 2014 study published in Acta Stronautica indicates that approximately 44 thousand travelers would be required to survive a 150-year interstellar trip in good health. (This estimation is at the lower end, other studies put this number closer to a quarter of a million) 

However it may be, the larger the number of passengers, the more enormous their world ship would need to be and the more difficult it would be to construct it and send it to other planetary systems. At a certain point, it becomes more viable to employ a rogue planet for this task benefiting from plentiful space, the protection from radiation, the enduring gravity, and the availability of liquid water. 

After more than 60 years of searching for intelligent extraterrestrial life, we have yet to find anything. Traditionally scientists look for life within the habitable zone of planetary systems. If it’s up to Romanovskaya, we should expand our search to incorporate the outer regions of planetary systems and rogue planets as well. 

If you are interested in reading more about the subject, be sure to explore the paper published in the International Journal of Astrobiology listed below.EzoicEzoic

FUTURE’S 10 MIND-BLOWING SCENARIOS FOR INTERSTELLAR TRAVEL

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watch the video.URL: https://www.youtube.com/watch?v=zaJC8XFywBc

Meet the NASA scientist devising a starship warp drive.

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To pave the way for rapid interstellar travel, NASA propulsion researcherHarold “Sonny” White plans to manipulate space-time in the lab

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The idea that nothing can exceed the speed of light limits our interstellar ambitions. How do we get round this?
Within general relativity, there are two loopholes that allow you to go somewhere very quickly, overcoming the restriction of the speed of light. One is a wormhole and the other is a space warp.

What is a space warp and how can it help?
A space warp works on the principle that you can expand and contract space at any speed. Take a terrestrial analogy. In airports we have moving walkways that help you cover distance quicker than you would otherwise. You are walking along at 3 miles an hour, and then you step onto the walkway. You are still walking at 3 miles an hour, but you are covering the distance much more quickly relative to somebody who isn’t on the belt.

What would a starship with warp drive be like?
Imagine an American football, for simplicity, that has a toroidal ring around it attached with pylons. The football is where the crew and robotic systems would be, while the ring would contain exotic matter called negative vacuum energy, a consequence of quantum mechanics. The presence of this toroidal ring of negative vacuum energy is what’s required from the math and physics to be able to use the warp trick.

What would it be like to travel at warp speed?
You would have an initial velocity as you set off, and then when you turn on the ring of negative vacuum energy it augments your velocity. Space would contract in front of the spacecraft and expand behind it, sending you sliding through warped space-time and covering the distance at a much quicker rate. It would be like watching a film in fast forward.

Even if travelling at warp speed is theoretically possible, don’t the huge energy requirements make it unlikely?
When the idea was first proposed mathematically in 1994 it required a vast amount of negative vacuum energy which made the idea seem impossible. I did some work in 2011 and 2012 as part of the 100 Year Starship symposium and discovered ways to reduce the energy requirements by many orders of magnitude, so for a 10-metre diameter spacecraft with a velocity of 10 times light speed, I can reduce the negative energy needed.

How close are you to making this a reality?
We are very much in the science rather than the technology phase. We have got some very specific and controlled steps to take to create a proof of concept, to show we have properly understood and applied the math and physics. To that end we will try to generate a microscopic instance of a warp bubble in the lab and measure it.

If successful is the next stop Alpha Centauri?
We don’t just go from the lab to an interstellar mission. There will be intermediate steps, other things we would do with this long before we get to some of the romantic pictures of a captain on the bridge telling the helmsman to engage warp drive.

 

Profile

Harold “Sonny” White is advanced propulsion theme lead at NASA’s Johnson Space Center in Houston, Texas. He is also a keynote speaker at this week’s Icarus Interstellar Starship Congress.

 

Source: newscientist.com