Cosmos 1 Solar Sail

The Planetary Society’s LightSail 2 spacecraft has been demonstrating the viability of solar sailing for a little over two years now and the society recently debuted a retrospective video called Sailing the Light. Given these events, I thought it would be interesting to look back at the Planetary Society’s first attempt at launching a solar sail, the ill-fated Cosmos 1. The design ideas implemented in Cosmos 1 were ones I used when creating the Aristarchus for my novel, The Solar Sea.

Cosmos 1 Model Built by David Lee Summers

Cosmos 1 was primarily developed in Russia with oversight from The Planetary Society in the United States. The Planetary Society also provided system design expertise along with subsystem development, such as designing the onboard radio system. The craft’s design involved eight triangular sails deployed on inflatable booms. Motors at the ends of the booms allowed the sails to turn in pairs. This allowed them to optimize the amount of sunlight collected. Solar sails are propelled by the momentum from sunlight, so a solar sail in orbit wants to catch as much sunlight as possible when moving away from the sun. When moving toward the sun, the blades turn sideways, so the solar sail doesn’t slow down. I incorporated the turning boom design into my fictional solar sail. By the way, if you would like to build a Cosmos 1 model, I discovered that the instructions are still online. The pattern and instructions are free at:

The Russians finished building Cosmos 1 in 2005. They planned to send it into space with a Volna Rocket launched from a nuclear submarine. The expectation was that the rocket could carry Cosmos 1 to an orbital distance of 820 kilometers above the Earth’s surface. Just as a comparison, LightSail 2 orbits at about 710 kilometers above the Earth’s surface. Unfortunately the June 21, 2005 launch of Cosmos 1 failed and the rocket crashed into the sea. As I mentioned, The Planetary Society debuted a video about the current LightSail 2 mission called Sailing the Light. I watched the YouTube premier as it happened. You can see it here.

In the video, they talk about upcoming NASA solar sail missions Solar Cruiser and NEA Scout. Solar Cruiser is a significantly larger solar sail than Lightsail 2. Solar Cruiser would be 1650 square meters compared to LightSail 2’s 32 square meters. NEA Scout will be 86 square meters and will have the mission of looking for potentially harmful asteroids.

The Solar Sea

LightSail 2 accomplishes the turning maneuvers I mentioned above, not by turning its sails, but by using momentum wheels inside the space craft. It takes a couple of minutes to turn the craft ninety degrees. With new NASA solar sails in the works, I wondered if anyone was considering a return to the Cosmos 1 design anytime in the near future. I was able to pose that question to LightSail 2’s project scientist Dr. Bruce Betts at the end of the video. In effect, he says that in the near term, most projects are now developing square sails with reaction wheels to turn the craft.

You can read about my fictional solar sail in my novel The Solar Sea. It imagines an entrepreneur building a manned solar sail spaceship and taking it to Titan to search for mysterious particles that appear to travel through time. Along the way, the crew visits Mars and Jupiter and they find clues that we may not be alone in the universe after all. Learn more about the book and watch the book trailer at:

Upcoming Solar Sail Missions

Last week, the Planetary Society’s LightSail 2 mission celebrated the one-year anniversary of its launch date. The project has made great strides in demonstrating that solar sails are a practical method of propulsion. LightSail 2 was able to raise its orbit using sunlight as the only source of propulsion. The craft can be steered using momentum wheels so it can maximize the light received when moving away from the sun and minimize the light received when going toward the sun. It also set the record for the highest acceleration achieved by a solar sail to date.

LightSail 2 Over Australia. Image by The Planetary Society

As it turns out, the LightSail 2 mission hasn’t been completely trouble free. Two of the solar panels it uses to energize its momentum wheels and power systems like the onboard camera did not deploy correctly and are in a tipped position, so they don’t receive sunlight equally. This is seen in the shadow on the sail in the above image. Also, one of the sail booms appears to be bent. You can see what appears to be a gap in the left hand part of the sail and a structure visible through the gap. My takeaway is that despite these issues, LightSail 2 has done remarkably well.

I was pleased to learn that NASA has an upcoming solar sail mission and it’s investigating another one. The upcoming mission is the Near-Earth Asteroid Scout Mission or NEA Scout. Like LightSail 2, it will be a small solar sail deploying from a CubeSat. It’s currently scheduled for 2021 and the plan is for the craft to visit the asteroid 1991 VG. The larger goal of the mission is to better understand the larger Near Earth Asteroids that might be a threat to life on Earth. Another goal of this mission is to show that solar sails can be used to send scientific payloads to objects at low cost compared to craft that burn conventional fuel. This would be a somewhat larger solar sail than LightSail 2’s 32 square meter area. NEA Scout would deploy a 68 square meter solar sail. In the image below, we see the NEA Scout sail deployed in the lab along with some of the people working on it, to give an idea of the scale.

NEA Scout sail deployed. Image by NASA.

Another mission being considered is NASA’s Solar Cruiser. This would be a 1200 square meter solar sail used to provide views of the sun not easily available with current technology. It would measure the Sun’s magnetic field structure and the velocity of coronal mass ejections which at times can interfere with utility grids on Earth. This craft could be very useful as an advance warning system for at-risk infrastructure on Earth.

The Solar Sea

It’s exciting to see solar sails being scaled up into new projects. There have even been discussions of using solar sails for interstellar missions. A rocket can never go faster than its exhaust velocity. However, a solar sail can continue to accelerate as long as it gets light on its sails. It’s not yet practical to build a solar sail to propel a payload big enough to carry humans, but I suspect if the technology keeps being developed, it will get there one day. This dream is what I captured in my novel The Solar Sea. If you would care to join me on an imaginary voyage through the solar system using one of these sails pushed by light, visit:

Greg Long in Australia recently posted a review of the novel, so I’m especially pleased to have shared the photo of LightSail 2 above. You can read Greg’s review at: