- Solar Cruiser is a NASA mission launching in 2025 to test a large solar sail at an artificial orbit between the Earth and Sun.
- Solar sails use the gentle push of sunlight for propulsion, giving them unlimited fuel to reach unique orbits and perhaps one day visit other stars.
- Solar Cruiser’s sail will be the largest ever tested in space, covering an area of more than six tennis courts.
What are solar sails?
Solar sails are spacecraft that use large, thin sails to reflect sunlight, giving them a gentle push and unlimited fuel. They can reach unique destinations that are difficult or impossible to access with traditional rockets, and may be our best option for visiting other star systems.
Solar sails are particularly well-suited to small, low-cost spacecraft limited by a lack of propulsion options. Thanks to advances in technology miniaturization these spacecraft have grown in capabilities, just as solar sails have advanced over the years. Japan’s IKAROS successfully changed its orbit around the Sun in 2010, and The Planetary Society’s LightSail 2 demonstrated flight by light in Earth orbit in 2019. NASA’s NEA Scout launches to lunar orbit in 2021, where it will use a solar sail to fly onward to a near-Earth asteroid.
What will Solar Cruiser do?
Solar Cruiser will build on that legacy in 2025 by deploying a sail with an area of 1,650 square meters (17,800 square feet), big enough to cover more than six tennis courts. It will orbit an artificial spot between the Earth and the Sun that can be used for solar science or to provide advance warning of solar storms that damage satellites and disrupt power grids on Earth.
By demonstrating the feasibility of large solar sails, Solar Cruiser paves the way for even more ambitious missions. The spacecraft will also change the angle of its orbit, showing how a similar mission could hover high above the Sun’s poles, continuously monitoring them in a way that could revolutionize solar physics.
How Solar Cruiser works
Solar Cruiser will hitch a ride to space in 2025 with NASA’s Interstellar Mapping and Acceleration Probe, IMAP. IMAP will study how the constant flow of charged particles coming from our Sun known as the solar wind interacts with cosmic radiation coming from the rest of the universe. This interaction creates a bubble that surrounds and protects our solar system.
Solar Cruiser will coast with IMAP and another small satellite towards Lagrange point 1, or L1, a location where Earth and the Sun’s gravity balance to create a place for spacecraft to orbit. L1 lies along the Earth-Sun line about 1.5 million kilometers (0.9 million miles) from Earth. Solar Cruiser will fly beyond L1 and use a solar sail to make its own artificial orbit closer to the Sun, but still on a straight line between the Sun and Earth as Earth revolves around the Sun. Only a solar sail can provide the forces necessary to maintain such an otherwise unstable orbit, since doing so requires constant fuel.
Solar Cruiser will then use its sail to slowly change the angle of its orbit. The spacecraft will also test out a number of supplemental solar sailing technologies, including lightweight solar panels built into the sail structure. The sail will also use LCD panels that can be turned on and off to change the direction of thrust gained from solar sailing.