To the naked eye, the stars are diamond flecks scattered across the inner surface of a celestial sphere. Telescopes have brought depth to our vision, mapping the true distances to cosmic objects. But the universe they reveal appears utterly beyond the human scale of space and time. Even the closest stars seem infinitely remote, and reaching them a thing of science fiction, save for a few dead and dying probes drifting outward for eternity.
Now, though, a cadre of researchers are working to make interstellar travel a reality, at least to our nearest neighbors. They are coalescing around an approach that could lead to closeup images of a star and an exoplanet just 25 years after mission launch.
Most of each 4-meter probe will be a disc of aerographene or similar material, just a few micrometers in thickness, with optical sensors and transmitters on one side and a reflective surface on the other that the launch laser will aim at. The rim of the probe will be a 2-centimeter-thick band. The trailing edge will have apertures for interprobe laser communications. Power and processing electronics will form a ring inside the rim. The swarm’s optical transmitters will pulse in unison to send data to Earth at a rate of around 1 kilobit per second.Chris Philpot
The first generation of theoretical starship designs had featured massive vehicles propelled by fission or fusion drives. Top speed was estimated at about 10 percent of the speed of light, or 0.1c. This meant that a flyby mission to the closest star system, Proxima Centauri, would take over 42 years to reach its target.
In contrast, the new generation of starship designs are tiny, and they have no drives at all. The spacecraft have a mass of a few grams each. They’ll be accelerated out of our solar system by ground- or space-based lasers, traveling at an estimated 0.2c.
A 100-gigawatt laser beam made by combining many smaller lasers will propel hundreds to thousands of tiny probes. Pushing against interstellar magnetic fields, the probes will turn edge on to minimize radiation and impact damage. By adjusting the launch laser to accelerate later probes to higher speeds than earlier ones, the string of probes will coalesce into a swarm by the time of arrival.Chris Philpot
One version of this small-and-fast approach calls for sending a swarm of these puny flyers to the Proxima Centauri b exoplanet. Data would be returned by having the swarm emit light pulses in synchrony, detectable by telescopes on Earth. Put forward by a team led by Thomas Marshall Eubanks at Space Initiatives, this mission was selected for a 2024 phase one study by NASA’s Innovative Advanced Concepts program. It didn’t make the list for a phase two study this year, but Eubanks plans to retry in 2026.
With a swarm, “we could do gigapixel imaging of the planet,” says Eubanks. “That’s at a level where if it was a planet like Earth, we’d be able to see things like coral reefs and airports.”
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