The Starshot mission is tasked with reaching Alpha Centauri, the closest star system to Earth at 4.37 light years from the Sun. With current technology it would take 73,000 years to travel there, assuming travel at the speed of the Voyager (NASA). This project wants to use very small nano-probes attached to lightsails, which would be pushed by a beam of light from Earth. They propose that this way it would take just 20 years to reach Alpha Centauri. It would allow images of Proxima B, an Earth-like exoplanet orbiting Proxima Centauri, to be sent back to Earth and an analysis of the magnetic fields there. This approach could be more successful than an ordinary spacecraft, because the fuel would not run out. It would rely on a constant beam of photons instead of hydrazine, and the low weight of the sail would allow it to build momentum. A proof of concept LightSail 2 already flew in 2019, and it was a success.
One of the challenges to the project is developing a protective coating for the gram-scale Starchip. There would be numerous collisions with dust and particles in the interstellar medium, which would have a big impact on the probe due to its small size. They are considering using beryllium copper as a possible material, however there is still not a lot of research in this area. Another problem is cooling the light emitting device on Earth. The scale of the laser needed would be 100GW for the Alpha Centauri mission. Current lasers are 50% efficient, thus a lot of power would transform into thermal energy, which would need to be dissipated. They propose to use a conventional cooling system, however that would be tricky with the small optical instruments in the mirror. There is a whole list of problems here, which shows how many things still need to be addressed.
The team states that a seemingly impossible moonshot was already achieved, so they can overcome the technical challenges of this project. I think that the earliest this can happen is within 50 years, so just within our lifetimes. Nanotechnology is making tremendous leaps recently and the initiative has incredible financial support from Zuckerberg and Milner. The team is working on a 3 decade plan, however I think it will be pushed a bit longer than that. They expect to spend the first decade on the proof of concept, the second on constructing a prototype and the third on actually building the craft. I think that they should also account for about 10-20 years of additional research in lasers and nanotechnology before a prototype can be constructed.
If the project is successful, it could significantly advance nanotechnology and laser research. Developing a gram-scale device that contains a small camera, battery, processors and a transmitting device could be very important for medical applications in the future. Direct drug delivery that targets only specific cells, like cancer cells, would save many lives. Let’s hope that the Breakthrough Starshot goes well. Perhaps we might see its launch in our lifetimes, which would be breathtaking to witness.
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Stirone, S. (2019, July 23). LightSail 2 Unfurls, next step toward space travel by solar sail. The New York Times. https://www.nytimes.com/2019/07/23/science/lightsail-solar-sail.html#:~:text=LightSail%202%20Unfurls%2C%20Next%20Step%20Toward%20Space%20Travel%20by%20Solar%20Sail,-The%20Planetary%20Society&text=For%20centuries%2C%20it%20was%20only,laws%20of%20the%20planets’%20orbits.
Wall, M. (2019, May 29). Breakthrough needed? Starshot interstellar-flight project faces challenges. Space. https://www.space.com/interstellar-flight-breakthrough-starshot-challenges.html.