Earlier this year, NASA selected a rather interesting proposal for Phase I development as part of its NASA Innovative Advanced Concepts (NIAC) program. It is called Swarming Proxima Centauri and is a joint project between Space Initiatives Inc. and the Initiative for Interstellar Studies (i4is) led by Marshall Eubanks, the Space Initiative's chief scientist. The concept was recently selected for Phase I development as part of this year's NASA Innovative Advanced Concepts (NIAC) program.
Similar to other proposals that use gram-scale spacecraft and lightsails, the “swarm” concept involves using a laser array to accelerate tiny spacecraft to as much as 20% of the speed of light. Last week, on the final day of the 2024 NASA Innovative Advanced Concepts (NIAC) Symposium, Eubanks and his colleagues presented an animation illustrating what that mission will look like. The video and their presentation provide tantalizing hints of what scientists expect to find in our closest star system, including Proxima b, the rocky planet orbiting within the circumsolar habitable zone (CHZ) of its parent star.
As we've touched on in previous articles, the concept of swarming Proxima Centauri has evolved significantly in recent years. The concept originated in 2017 as a proposal from i4is called “Project Lyra,” whose goal was to send tiny spacecraft to catch up with the interstellar object (ISO) 'Oumuamua. But it has since evolved into a collaboration between i4is and Space Initiatives Inc., a Florida-based aerospace component manufacturer dedicated to developing gram-based “femtospacecraft” – even smaller than nanospacecraft!
More recently, Eubanks and his colleagues have authored research papers addressing some of the big questions in interstellar exploration, including communications and what we might learn from a flyby of Proxima b. During the 2024 NIAC Symposium, held September 10-12 in Pasadena, California, Eubanks and his colleagues had the opportunity to present their latest findings. As the video shows, the swarm they envision will consist of a thousand “picocraft” (between nano and femto), which they have dubbed “coracles” (a small, rounded, lightweight boat).
The probes are solid, armored on one side and covered with optical rings (reflective material) on the other. They are about two centimeters thick (0.8 inches) and four meters (about 13 feet) in diameter, and weigh no more than a few grams each. According to their NIAC proposal, they will be accelerated by a laser array with a power of about 100 gigawatts (GW) that will be available by mid-century. The probes are also equipped with side-mounted lasers to facilitate communication between them and mission controllers on Earth.
As Eubanks noted during the presentation, the animation actually features a thousand probes and an artistically accurate depiction of the Proxima Centauri system. The red dwarf is clearly visible as the probes approach Proxima b, while Alpha Centauri AB is visible in the background. Once the probes pass the planet, we also get an accurate depiction of many of the things scientists expect to find:
“This is in real time. This is more or less what you would expect at a redshift, a blueshift and then a redshift. And we had the artists draw the planet as an 'eye planet,' where there is a central warm spot surrounded by a cold zone, because we think this planet is probably rotationally locked.”
Team member Robert Kennedy III poses in front of an 88% scale model of the coracle sail. Image credit: 2024 NIAC/i4is/Interstellar Initiatives Inc.
As Eubanks further explained, their collaboration has already produced prototypes of their Coracle spacecraft. One was recently unveiled at the World Science Fiction Convention in Glasgow, while another is currently in Pasadena. While giving an overview of the design of each spacecraft, Eubanks emphasized the importance of coherence and how the swarm's configuration will facilitate communication and cohesion:
“Operational coherence is essential to the success of this mission. By operational coherence we mean that all the probes act as one. I notice that this does not mean photonic phase coherence – we will not be able to achieve that. But if we have good enough clocks and can measure distance with lasers, we can determine our location to within a few centimeters. We can determine the relative clocks more or less at the same level. And [they] can then function as one thing.
“And the key thing is that we can do that with lots of things, like images of the planet and so on. But the key thing is what we call the wall of light. The wall of light is created when all the probes send a coherent set of photons back to Earth so they can be received together. We think we can get a data rate of one kilobit per second back and therefore send about four gigabytes back to Earth per year. And that's enough to get good data and really understand the system.”
Although the Swarming Proxima Centauri concept did not receive Phase II or Phase III funding from NIAC this year, it is still a project worthy of study and further development. Like Breakthrough Starshot and other lightsail proposals, it shows what interstellar missions will look like in the coming decades. In that respect, ideas like this also show that we have reached a point in our history where exploring the nearest star systems is no longer considered a far-off idea that requires serious technological innovation.
Further reading: NIAC Symposium 2024
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