The Planetary Society, a citizen-led non-profit that focuses on space exploration, announced Monday that it has received the official designation for its next solar sail mission—LightSail 2—and is moving towards the final stages of testing.
A solar sail is like the sail of a ship—but instead of harnessing the power of wind to propel itself across the sea, it harnesses photons from the sun in order to move in space. This technology could eventually be used in lieu of rockets in future spacecraft.
Solar sails can also be used to be an early warning system for solar storms or clean up old satellites in Earth’s already crowded orbit, former Science Guy and current CEO of Planetary Society Bill Nye told Motherboard.
“Our mission at the Planetary Society is to advance space science and exploration. That’s what we do. That’s the elevator speech,” Nye said. “Empower the world’s citizens to advance space science and exploration to know the cosmos and our place within it.”
The Society has raised over $1.2 million on Kickstarter for the project.
The mission, expected to deploy in fall 2016, will be the second time the society has sent a solar sail in orbit. The first time was in May of 2015, when the society deployed a 32-square-meter mylar sail.
The first LightSail awaits further testing during a full run through of its flight plan ahead of the launch in 2015. Photo: The Planetary Society
LightSail 2 will head to space on the SpaceX Falcon heavy rocket. It will be packed inside Prox-1, a 30-by-30-by-60-centimeter microsatellite built by students at Georgia Tech. Once in orbit, the solar sail will deploy from Prox-1; later, Prox-1 will autonomously relocate the sail and inspect it. The test will measure how well the teams can maintain specific distances between spacecraft in orbit and attempt orbital maneuvers using solar pressure, effectively sailing in low earth orbit.
“In the Navy and at sea you call it station keeping, to keep the ships in the same orientation and spacing relative to one another,” Nye said. “If you’re setting a table, maintaining relative position between knives and forks is relatively straightforward. In space, this is not so easy.”
We spoke with Nye to learn about the mission.
MOTHERBOARD: Why the solar sail?
Bill Nye: The solar sail is this romantic thing that goes back years. I took one class from Carl Sagan, in the spring of 1977. And he had been talking about solar sailing all that year. Forty years later, we’re going to fly one.
What’s your role in the project?
I run the whole thing! It’s all about me; I’m the key. No, No…
I just was around while these skilled engineers figured out these problems out. What I did as CEO, was get the program under control. It had gotten a little out of hand. Contractors were doing things not especially well supervised, and we had gone over budget, which is the curse of space flight.
"As long as the solar sail is deployed, it can orbit at a slower speed."
We came up with a new scheme for raising the missing money which was the Kickstarter. People were really engaged and excited about it. The other decision was a question whether to wait for a better altitude, on a better rocket. Whether to skip that last launch. Somebody has to make that decision, and it was I.
These decisions go back to the legacy or ancient times of the Planetary Society. There was a question about whether to keep messing around and try to resolve these couple of software issues, or deploy the sail and take a picture and we’ll sort that other stuff later. Even though it might not remain in orbit long enough to sort the software problems out, I decided somebody’s gotta do it, let's deploy the sail and take pictures. I think it was a right thing to do. The guys and gals had worked hard to resolve the software problems on the ground and, I thought, they had.
LightSail fully deployed during the May 2015 test flight. Photo: The Planetary Society
The whole thing was the picture. So, the Planetary Society was started by Carl Sagan and Lou Friedman. [Friedman] wrote a book about solar sailing in the 1980s. The third founder of the Planetary Society was Bruce Murray. Bruce Murray went on to be the head of the Jet Propulsion Laboratory during the Voyager and Viking missions. These were heydays at JPL. These were huge, successful missions.
He is generally credited with being in meetings during the Mariner missions. Which was the Ranger spacecraft repurposed to go Venus and Mars. He insisted these spacecraft have cameras. And people at that time, scientists and engineers, thought that cameras were just for the public. “They’re a publicity stunt, taking pictures from space.” And Bruce Murray, by all accounts, was like: “no dude, there’s scientific information in pictures.”
"It’s such a small community, the solar sailing people"
Bruce’s voice was in the back of my head. We gotta get a picture, you guys. I know we like messing with the software, and I know it’s fun, learning something on every orbit. It’s so much fun saying up to 2:38 in the morning trying to get the antenna to transmit to this one crazy place in Georgia, but we got to get a picture, and the guys and gals did. I’m very proud of them.
This thing is really a result of our legacy. It’s really a result of Carl, Bruce and Lou. We named our image library after him, the Bruce Murray Image library, because he was such an influence on planetary exploration. It wouldn’t happen without those guys. Lou is still alive, but Bruce and Carl are gone.
What have you learned during the development of LightSail?
What you learn about are the subtle and obnoxious problems. Getting the cameras to take pictures and send them down in an orderly fashion. It’s tricky when the electronics are so compact. And then the other thing, I won’t say it shocked anyone, but our eyebrows went up a bit. It doesn’t pull tight; it looks more like a sail on a tall ship.
It was expected when you stop and think about it. But when you look at the artist conceptions and the pictures on our bow ties and earrings. It’s just a little different shape. It’s a little more romantic. Billowing more.
The other thing is: there’s these subtle software problems. Having, apparently, to do with cosmic rays. It’s a real effect. It acts like 1 and 0s. It adds and cancels bits. Everybody knew this, but the effect was real. To shield this, traditionally used is a type of stainless steel that’s very malleable. It adds a lot of weight, and you can’t count on it. Instead, we made the software more robust. That’s what the engineers been working on.
What are some long-term missions envisioned for LightSail?
People talk about monitoring solar weather. The sun will have these coronal mass ejections where huge blasts of high energy particles shoot off the surface of the sun. It reminds me of hurricanes and tornados. The bubbling, boiling swirling roiling gasses which make up a star have discontinuities. Places where it burps if you will.
These events send enormous numbers of charged particles towards us. These particles can damage our satellites, our assets in space. This is a huge thing, everyone in the world really depends on space assets. For communication, for planning cell towers and weather forecasting. Somebody in the battle zone in Syria reporting on the latest air strikes; that’s all done with space assets.
What we would do is put a spacecraft about the same distance from the Sun as Venus. 0.7 astronomical units. This spacecraft would monitor the particles, when there’s a coronal mass ejection and send us a radio signal, which travels faster than the particles. So we can batten down or harden our satellites for a few hours, so they don’t get damaged by these charged particles.
Now when you’re in closer to the Sun, your orbit has to be faster or else you’ll fall in. Mercury goes around the sun much faster than Earth. But with the solar sail, you can hold that position, you could keep station in an inner orbit and stay in line with the Earth. It’s like a parachute. As long as the solar sail is deployed, it can orbit at a slower speed. This is written in Lou’s book in 1985, this old romantic, very cool application of the solar sail.
A version of LightSail’s CubeSat used in the launch of May 2015. Photo: The Planetary Society
Another example is NanoSail-D. These guys at Marshall Space Flight Center, built a solar sail, which they called NanoSail-D. NanoSail-D was this drag system, and what’s been proposed, people have talked about for decades.
You’re required to have your satellite deorbit in 25 years. That’s an international rule being informally embraced, and people are working on treaties to formalize it. Getting a spacecraft to come down when you want it takes either fuel or dumb luck. With a sail, you can create all this drag. For example, where the ISS is, there are still a few air molecules. So when you deploy a sail, the thing comes down a thousand times faster than otherwise. Satellite manufacturers could very reasonably meet the requirements by including a little drag sail.
Our mission at the Planetary Society is to advance space science and exploration. That’s what we do. That’s the elevator speech. Empower the world’s citizens to advance space science and exploration to know the cosmos and our place within it. That’s what LightSail did. It’s such a small community, the solar sailing people. So we’re excited, and we feel good about it. We’ve advanced space science and exploration.
There’s two questions we all want to answer. Where did we come from and are we alone in the universe and the cosmos? If you want to answer those questions, you have to explore space. LightSail is part of that. It’s an arrow in the quiver of humankind.
The interview has been edited for length and clarity.