Many of us dream of traveling across the stars, but it is a far-off goal for the human race. However, technology is being investigated to send probes that could cross interstellar distances in tens rather than thousands of years, and a new study suggests that it could be interesting to have living passengers on those special crafts.
And they are special. These spacecraft are expected to weigh at most 1 gram (0.04 ounces) and will be accelerated by powerful lasers to a fifth of a speed of light. They are not designed with occupants in mind. But they would reach Proxima Centauri, the closest star to the Sun, in less than a quarter of a century.
While human occupants couldn’t travel on such a wafer-thin craft, there are other living organisms that could. And sending them might actually be of great scientific interest. They could be used to study the effects of fast interstellar travel on lifeforms.
As reported in the journal Acta Astronautica, potential missions would require organisms that are radiation tolerant and can enter stasis. Two of such animals are tardigrades and C. elegans, a type of worm often used in scientific research. Both candidates have already experienced space, in experiments on and outside the International Space Station.
"We can ask how well they remember trained behavior when they're flying away from their earthly origin at near the speed of light, and examine their metabolism, physiology, neurological function, reproduction and aging," co-author Professor Joel Rothman, from UC Santa Barbara, said in a statement. "Most experiments that can be conducted on these animals in a lab can be performed onboard the StarChips as they whiz through the cosmos." The effects of such long journeys on animal biology could be extrapolated to potential effects on humans.
"We could start thinking about the design of interstellar transporters, whatever they may be, in a way that could ameliorate the issues that are detected in these diminutive animals," Rothman said.
The paper also poses some ethical questions. First, it discusses the risk of sending Earthly-life to another star system in case it might contaminate it. Planetary protection is something being taken very seriously and given the size of the craft and plan, there’s no such risk. Even if it were to encounter a planet, it would burn up before reaching the ground.
The other is even more philosophical. Should Earthly life be sent purposely into the cosmos to spread to other worlds? This concept, known as Directed Panspermia, has been discussed as a way to explain the origin of life as the consequence of a civilization planting “seeds” across the galaxy.
"Some people have mused and published on ideas such as 'is the universe a lab experiment from some advanced civilization,'" co-author and UC Santa Barbara professor Philip Lubin said. "So people are certainly willing to think about advanced civilizations. Questions are good but answers are better. Right now we simply ponder these questions without the answers yet."
The answers are not pressing yet but they might be worth starting to think about now, rather than after we have the technology to send life across the stars.