Trillions of tiny, self-replicating satellites could unlock interstellar travel

Inspiration for space exploration can come from all angles. One of the most inspiring, or terrifying, sources of inspiration for some in space exploration came from computer scientist John von Neumann, who presented a framework for self-replicating machines in a series of lectures he gave in 1948. Since then, scientists and engineers have discussed the advantages and dangers of such a system.

However, while technology has indeed come a long way since the 1940s, it seems that we are still a long way from having a fully functional von Neumann machine. That is unless you major in biology. Even simple biological systems can perform amazing feats of chemical synthesis. And there are few people in the world today who know that better than George Church. The Harvard geneticist has been at the forefront of a revolution in the biological sciences for the past 30 years. Now, he posted a new job on Astrobiology thinking about how biology could help create a pico-scale system that could potentially explore other star systems at almost no cost.

“Pico scale” in this context means weighing on the order of one picogram. Given that the smallest operational satellite ever built so far weighed just 33 grams, scaling it to 10-12 times that size might sound ambitious. But that’s exactly what biological systems could do.

A typical bacterium weighs about one picogram. And with advanced enough genetic modification, bacteria can do anything from process toxic waste to emit light. As such, Dr. Chert believes they could be an excellent tool for interstellar exploration.

UT video on the difficulties of going interstellar.

The basis for this argument is based on a combination of cost and statistics. Cost is the simple explanation of how much money is required to get hardware into orbit. Researchers could launch trillions of pico-sized satellites for the same cost as launching a one-gram satellite into orbit. On the surface, it seems like a pretty good value proposition.

Statistics dictate the uncertainty that comes with sending a probe to another star system. Since humanity has never done this before, it’s hard to know what chance anyone might have of surviving. But it is clear that, at relativistic velocities that would allow a probe to reach a star in a reasonable amount of time, a collision with literally anything would mean the end of the mission, likely resulting in an explosion the size of several nuclear bombs.

With trillions of smaller probes, there is a much higher chance that at least some will get through and reach the destination star system. Even those traveling at relativistic speeds wouldn’t have too much of an impact on anything they come into contact with, so they wouldn’t necessarily obliterate all of their companions at once.

So there are obviously some advantages to a pico-gram-sized probe, but what happens when the probe reaches the star system? It wouldn’t be particularly interesting to just push a bacterium into Alpha Centauri, just to do nothing but speed through that star system upon arrival.

Von Neumann machines have the potential to revolutionize space travel – as Isaac Arthur discusses. Credit – Isaac Arthur YouTube Channel

Church suggests that a single bacterium (or von Neumann probe) could, in theory, create a communication device that we could detect from Earth. To do this, it could use the presence of either bioluminescence or reflection.

Bioluminescence, or light emitted by biological organisms, would theoretically be detectable on the surface or atmosphere of exoplanets. The probe itself could be programmed to reproduce and fluoresce brightly enough for us to detect. It could also, in theory, send back some kind of information as part of that signal, such as by changing the frequency of the pulses or the wavelength of the light, if it had been properly trained in advance.

Alternatively, another biological phenomenon could provide the basis for communication using light. Reflection, and more interestingly, modifiable reflection, could again serve as the basis for a communication protocol. Many biological materials have very high reflection rates and some can be modified based on the living creature controlling them. By reflecting a laser aimed at the planet it inhabits, a von Neumann probe could potentially send coded messages back to Earth by changing the wavelength of that reflected signal.

Although experiments on these kinds of potential outcomes push the boundaries of what is known in biology, as Dr. Chert himself willingly admits, as he says repeatedly in the paper, much further work on this topic would constitute an “interesting laboratory challenge ». This may be an understatement, but it helps remind those interested that inspiration and possible solutions could come from unexpected places.

This article was originally published on Universe today by ANDY THOMASWICK. Read the original article here.

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