What are solar sails?
Solar sails are large, reflective sails that are attached to spacecraft and are alternatives to fuel in space travel. They are a fairly new technology and are being looked at to revolutionize space travel. One of the most popular kinds of solar sails is a photon sail, which uses the light’s pressure from solar radiation to be pushed forward. To do this, the sail reflects photons, so the photons, despite being small, push the sail forward because space is frictionless.
They are advantageous to more standard methods for many reasons, including that they rely on external sources. This both reduces space debris and makes spacecraft weigh less. With less weight from things like fuel, solar sails could make shipping cargo across space much easier. Not only is it easier, but it is faster too. Since they are continuously accelerating, they can reach fast speeds and make space exploration more efficient.
Exploring Space: Near and Far
Another benefit is that solar sails are able to face solar storms since their acceleration balances them out. This ability paired with their speed makes solar sails perfect for trips to Mercury and Venus. With current technology, it can take years to start orbiting Mercury or Venus.
As of right now, there are several missions planned that use solar sails to reach the inner parts of our solar system. For example, there is one mission planned to find mineral resources on Mercury and understand how the planet has evolved. Since solar sails also last a long time, unlike fuel, this mission could last over ten years. With ten years of data, researchers could get valuable information about the changes currently underway on Mercury.
For this specific spacecraft, a 5000 m^2 solar sail will be deployed. Technically, the mission only needed a 2500 m^2 sail, but with a larger sail it only takes 7 years to reach Mercury and it does not have to do planetary flybys to make it. An even larger sail of 10,000 m^2 would let the spacecraft reach Mercury in under four years, which just goes to show how impactful this technology will be in the future once it is more developed.
There are very clear benefits to using a solar sail, but it also makes the mission more complicated. If the solar sail simply does not deploy, the whole mission fails. This happened recently with NEA Scout. Also, researchers had to face the challenge of what to do when the sun is eclipsed. The solution for the trip to Mercury that they came up with was to create a backup battery for this situation. Another solution they had to come up with was rotating sails, which will solve the problem of the spacecraft rolling without being controlled by thrusters.
Solar sails are not just useful for trips inside our solar system though. They are also being looked to for our exploration of deep space. Their speeds give scientists hope for getting to closer to Alpha Centauri, the star closest to us that is not our sun. For some perspective, NASA’s Voyager 1 was launched in 1977 and has gone over 15 billion miles into space, however that is not even 1% of the way to Alpha Centauri. Theoretically, solar sails could reduce this travel time by thousands of years.
Recent Engineering Developments
Brown University has been working with TU Delft to make interstellar travel possible using solar sails. The researchers at these institutions have made a prototype that is about 2.4 inches across and 200 nanometers thick. This is thinner than a human hair! On the surface of the sail, there are billions of holes at the nanoscale that will make it lighter and increase reflectivity, meaning that it will have more acceleration. Not only is this prototype scalable, but it is also cost-effective.
The holes in the material are being optimized by artificial intelligence which is figuring out the best placement and shape of the holes to decrease weight and increase reflectivity. This idea could help reach the goals of the Starshot Breakthrough Initiative which was created by people including Stephen Hawking. Its goal is to use lasers on the ground to power lightsails that carry spacecraft the size of microchips. These lasers could be better at powering the solar sails than the sun itself.
Conclusion
Despite having design challenges to overcome, the advantages of solar sails are unmatched. They could both allow us to learn more about our solar system and explore deep space. Several missions are set to launch over the next few years, and this is only the beginning of solar sail use. Someday, they could be used not only as propulsion but also on satellites to speed up the end of a mission. They are also pushing limits on engineering overall by forcing creative solutions and advancements in nanoscale engineering. With solar sails, the future is looking bright and with any luck, they will push astronomical research forward for centuries to come.
References
Brown University. (2025, March 31). Breakthrough Lightsail: Ultra-Thin, AI-Optimized, and Ready to Race to Alpha Centauri. SciTechDaily. Retrieved September 9, 2025, from https://scitechdaily.com/breakthrough-lightsail-ultra-thin-ai-optimized-and-ready-to-race-to-alpha-centauri/
Dickinson, D. (2025, April 4). A mission that could reach Mercury on solar sails alone. Phys.org. Retrieved September 9, 2025, from https://phys.org/news/2025-04-mission-mercury-solar.html
Mirecki, A. (2022, January 13). Solar sails, a revolutionary innovation for space exploration – SOLAR MEMS Technologies. Solar MEMS. Retrieved September 9, 2025, from https://solar-mems.com/blog-news/solar-sails-a-revolutionary-innovation-for-space-exploration/
Parman, S., Fischer, E., Mustard, J., Pieters, C., Kremer, C., Bender, H., Green, R., Bramble, M., Johnson, L., Thomas, H., Baysinger, M., Puno, A., Ernst, C., Greenhagen, B., Donaldson Hanna, K., Capizzo, P., Diedrich, B., Fabisinski, L., Garcia, J., … University of Central Florida. (n.d.). Concept study of solar sail orbital mission to Mercury: Mercury Scout. Retrieved September 9, 2025, from https://www.hou.usra.edu/meetings/lpsc2025/pdf/2370.pdf
