When ʻOumuamua visited our solar system last year, the world’s collective interest (and imagination) was firing on all cylinders. Despite astronomers’ insistence that asteroids from other star systems likely zip through the solar system all the time (and the reason why we spotted this one is because our survey telescopes are getting better), there was that nagging sci-fi possibility that ʻOumuamua wasn’t a natural event; perhaps it was an interstellar spaceship piloted by (or at least once piloted by) some kind of extraterrestrial — “Rendezvous With Rama“-esque — intelligence. Alas, any evidence for this possibility has not been forthcoming despite the multifaceted observation campaigns that followed the interstellar vagabond’s dazzling discovery.
Still, I ponder that interstellar visitor. It’s not that I think it’s piloted by aliens, though that would be awesome, I’m more interested in the possibilities such objects could provide humanity in the future. But let’s put ʻOumuamua to one side for now and discuss a pretty nifty project that’s currently in the works and how I think it could make use of asteroids from other stars.
Asteroid Starships Ahoy!
As recently announced by the European Space Agency, researchers at Delft University of Technology, Netherlands, are designing a starship. But this isn’t your run-of-the-mill solar sail or “warpship.” The TU Delft Starship Team, or DSTART, aims to bring together many science disciplines to begin the ground-work for constructing an interstellar vehicle hollowed out of an asteroid.
Obviously, this is a long-term goal; humanity is currently having a hard enough time becoming a multiplanetary species, let alone a multistellar species. But from projects like these, new technologies may be developed to solve big problems and those technologies may have novel applications for society today. Central to ESA’s role in the project is an exciting regenerative life-support technology that is inspired by nature, a technology that could reap huge benefits not only for our future hypothetical interstellar space fliers.
Called the MELiSSA (Micro-Ecological Life Support System Alternative) program, scientists are developing a system that mimics aquatic ecosystems on Earth. A MELiSSA pilot plant in Barcelona is capable of keeping rat “crews” alive for months at a time inside an airtight habitat. Inside the habitat is a multi-compartment loop with a “bioreactor” at its core, which consists of algae that produces oxygen (useful for keeping the rats breathing) while scrubbing the air of carbon dioxide (which the rats exhale). The bioreactor was recently tested aboard the International Space Station, demonstrating that the system could be applied to a microgravity environment.
Disclaimer: Space Is Really Big
Assuming that humanity isn’t going to discover faster-than-light (FTL) travel any time soon, we’re pretty much stuck with very pedestrian sub-light-speed travel times to the nearest stars. Even if we assume some sensible iterative developments in propulsion technologies, the most optimistic projections in travel time to the stars is many decades to several centuries. While this is a drag for our biological selves, other research groups have shown that robotic (un-crewed) missions could be done now — after all, Voyager 1 is currently chalking up some mileage in interstellar space and that spacecraft was launched in the 1970’s! But here’s the kicker: Voyager 1 is slow (even if it’s the fastest and only interstellar vehicle humanity has built to date). If Voyager 1 was aimed at our closest star Proxima Centauri (which it’s not), it would take tens of thousands of years to get there.
But say if we could send a faster probe into interstellar space? Projects like Icarus Interstellar and Breakthrough Starshot are approaching this challenge with different solutions, using technology we have today (or technologies that will likely be available pretty soon) to get that travel time down to less than one hundred years.
One… hundred… years.
Sending robots to other stars is hard and it would take generations of scientists to see an interstellar mission through from launch to arrival — which is an interesting situation to ponder. But add human travelers to the mix? The problems just multiplied.
The idea of “worldships” (or generation ships) have been around for many years; basically vast self-sustaining spaceships that allow their passengers to live out their lives and pass on their knowledge (and mission) to the next generation. These ships would have to be massive and contain everything that each generation needs. It’s hard to comprehend what that starship would look like, though DSTART’s concept of hollowing out an asteroid to convert it into an interstellar vehicle doesn’t sound so outlandish. To hollow out an asteroid and bootstrap a self-sustaining society inside, however, is a headache. Granted, DSTART isn’t saying that they are actually going to build this thing (their project website even states: “DSTART is not developing hardware, nor is it building an actual spacecraft”), but they do assume some magic is going to have to happen before it’s even a remote possibility — such as transformative developments in nanotechnology, for example. The life-support system, however, would need to be inspired by nature, so ESA and DSTART scientists are going to continue to help develop this technology for self-sustaining, long-duration missions, though not necessarily for a massive interstellar spaceship.
Hyperbolic Space Rocks, Batman!
Though interesting, my reservation about the whole thing is simple: even if we did build an asteroid spaceship, how the heck would we accelerate the thing? This asteroid would have to be big and probably picked out of the asteroid belt. The energy required to move it would be extreme; to propel it clear of the sun’s gravity (potentially via a series of gravitational assists of other planets) could rip it apart.
So, back to ʻOumuamua.
The reason why astronomers knew ʻOumuamua wasn’t from ’round these parts was that it was moving really, really fast and on a hyperbolic trajectory. It basically barreled into our inner star system, swung off our sun’s gravitational field and slingshotted itself back toward the interstellar abyss. So, could these interstellar asteroids, which astronomers estimate are not uncommon occurrences, be used in the future as vehicles to escape our sun’s gravitational domain?
Assuming a little more science fiction magic, we could have extremely advanced survey telescopes tasked with finding and characterizing hyperbolic asteroids that could spot them coming with years of notice. Then, we could send our wannabe interstellar explorers via rendezvous spacecraft capable of accelerating to great speeds to these asteroids with all the technology they’d need to land on and convert the asteroid into an interstellar spaceship. The momentum that these asteroids would have, because they’re not gravitationally bound to the sun, could be used as the oomph to achieve escape velocity and, once setting up home on the rock, propulsion equipment would be constructed to further accelerate and, perhaps, steer it to a distant target.
If anything, it’s a fun idea for a sci-fi story.
I get really excited about projects like DSTART; they push the limits of human ingenuity and force us to find answers to seemingly insurmountable challenges. Inevitably, these answers can fuel new ideas and inspire younger generations to be bolder and braver. And when these projects start partnering with space agencies to develop existing tech, who knows where they will lead.