Successful Solar Sailing

The Planetary Society’s LightSail 2 spacecraft launched into orbit on June 25, 2019 and deployed its 32-square meter sails almost a month later on July 23. In the time since sail deployment, it raised its orbit some seven kilometers. Here we see a great shot of the LightSail 2 over Australia.

LightSail 2 image courtesy The Planetary Society

In 1619, astronomer Johannes Kepler noticed that comet tails always point away from the sun and realized that some solar force must produce that effect. Two centuries later, in 1862, James Clerk Maxwell suggested that light has momentum and it was finally demonstrated in 1900. The goal of the LightSail 2 mission was to show that momentum from light could propel a spacecraft. The process of solar sailing is not unlike sailing on the water, only in space, gravity acts like water currents while light acts like wind. As with a sail at sea, the sails must be turned in flight to take the best advantage of the “wind” while the ship moves on the “current.” LightSail 2 accomplishes this via internal reaction wheels. The gif below shows how the sail is turned to take the best advantage of sunlight and raise its orbit.

Josh Spradling / The Planetary Society

The following graph shows the elevation of LightSail2 over the course of the mission. The apogee is the highest point in orbit, the perigee is the lowest point. At LightSail2’s elevation, there are two forces working on the sail besides gravity. The first is light pressure from the sun. The other is atmospheric drag from the Earth. Even though LightSail 2 is in a relatively high orbit, it’s still in the most tenuous parts of the upper atmosphere. The upshot is that the apogee increases because of light pressure, but the perigee decreases because of atmospheric drag. That noted, LightSail 2 has accomplished the mission it set out to do, demonstrate that light can propel a spacecraft.

Image from the LightSail Mission Control Page supported by the Planetary Society

You can keep up to date with the LightSail mission and visit their mission control page by going to http://www.planetary.org/explore/projects/lightsail-solar-sailing/#the-lightsail-2-mission.

It’s worth noting this is a technology in its infancy. That said, with the lessons learned from this mission, there’s promise that solar sails could be used for small unmanned probes in the not-too-distant future, or perhaps they could be used to deflect dangerous asteroids, especially if caught early enough that they only need a small nudge.

In the long run, with much more development and technical innovation, I would like to think solar sails could be used to propel humans across the solar system as I imagine in my novel The Solar Sea. In a little under a week, on Friday October 11, Lynn Moorer will interview me about the novel on her radio show from 12:30-1:00 pm mountain daylight time. If you’re in Las Cruces, you can tune in to 101.5 FM on your radio dial. If you aren’t in Las Cruces, or just don’t listen to shows on the radio, you can stream the show at  https://www.lccommunityradio.org/stream.html. It looks like KTAL Community Radio is building up their archive of past shows, so I’m hoping I can share these interviews with you soon. If you want to read the book before the interview, you can find all the places it’s available by visiting http://www.davidleesummers.com/solar_sea.html.

Holiday Owls

Since today is Christmas Eve, I thought it would be fitting to share a short excerpt from my novel Owl Dance. In this scene, Ramon and Fatemeh find themselves on the run with little money in San Francisco. It’s a simple moment that gets to the heart of the season. Keep reading after the segment to learn about a special event later this week.


Ramon returned to the room he shared with Fatemeh late on Christmas Eve. Fatemeh noticed he wore a new pair of glasses. Like his old pair, they were round and gave his face an owlish appearance. He held his hands behind his back. Fatemeh stood and wrapped her arms around Ramon, but was surprised when he didn’t return the embrace. “What’s the matter?”

“Nothing.” Ramon’s voice held a sly edge.

“It looks like you were successful in finding new glasses.”

 Ramon smiled.“Yes, these are even better than the old ones.” He shrugged. “The optometrist thinks my eyes have been getting a little worse.”

“That’s too bad.” Fatemeh returned to her chair.

“However, I did have enough money left over to get you something.” He brought his arms out from behind his back. In his hand was a narrow box, about eight inches long. “Merry Christmas!” Just then he pulled the box back. “Do Bahá’ís celebrate Christmas?”

“Not normally,”said Fatemeh, “but as I’ve said, we respect the teachings of Jesus. I’m happy to celebrate his birth with you, Ramon.” She held out her hand and Ramon handed her the box. She opened it and saw a necklace. Adorning it was a hand-carved wooden bead in the shape of an owl.

“I bought the necklace. I carved the owl myself, though.”

“It’s very sweet.” Fatemeh smiled and put the necklace on. She stood and kissed Ramon, but held his hands as they parted. “How is our money doing?”

“I think I can find a job, but it’s not going to pay much,” admitted Ramon. “We could stay here about six more days and I could keep looking, or we could move on.”

“I like the idea of moving on.” Fatemeh returned to her chair. “I really didn’t like the reception we had on our first day and it’s loud here, even late at night.” She looked out the window at a saloon across the street.

“Where would you like to go?”

She pulled out a map and set it on the small table between the room’s two chairs. “What do you know about Los Angeles?”

“It’s a small town. There’s some farms and some industrial work.” Ramon shrugged.

“What does Los Angeles mean?”

“It means ‘belonging to the angels,’ The name’s short for something like town of the queen of angels.”

“Sounds lovely. Can we leave tomorrow?”

Ramon laughed.“Tomorrow’s Christmas. I doubt the trains are even running. What about the next day?”

“That sounds perfect.” Fatemeh put her hand to the new necklace. “I’m afraid I didn’t get you a present. What else do people do on Christmas?”

“We sing songs.” Ramon sat in the empty chair next to Fatemeh.

“Teach me a Christmas song worthy of the angels, Ramon.”


I hope you enjoyed this little snippet of Owl Dance. On Friday this week, Lynn Moorer of KTAL Radio in Las Cruces will interview me about the fourth book of the series, Owl Riders. If you’re in Las Cruces, you can listen from 12:30-1:00pm mountain standard time by tuning in to 101.5 FM on your radio dial. If you aren’t in Las Cruces, or just don’t listen to shows on the radio, you can stream the show at  https://www.lccommunityradio.org/stream.html. I had a great time earlier this year when I spoke to Lynn about The Brazen Shark. Be sure to mark your calendars so you can catch the show live!

Gamera

I think it’s fair to say that I grew up watching a lot of media from Japan. A lot was anime such as Tetsujin 28, Mach Go, Go, Go, and Gatchaman, perhaps better known here in the United States as Gigantor, Speed Racer, and Battle of the Planets respectively. However, I can’t overlook the role of giant monsters, or kaiju. Godzilla is clearly the most famous, but when I was a kid, my hero was Gamera.

I was thrilled to find Blu-ray copies of Gamera’s first eight films a few weeks ago. I’ve slowly been working my way through them. I’ve run into some people who think Gamera is part of the menagerie who battled Godzilla during his ongoing reign as King of Monsters. In fact, Gamera was the property of an altogether different movie studio. Godzilla’s stories were filmed at Toho Studios. Gamera was competitor Daiei’s entry into the kaiju arena.

For those not familiar with Gamera, he’s a giant fire-breathing turtle with tusks awakened from arctic ice during a dogfight between US and Soviet forces. Although he goes on a rampage for energy in the first film, he seems to have a soft spot for humans, and children in particular. In later films of the series, he’s revealed to be something of a guardian for humanity, protecting them from other monsters. The first eight films take place during Japan’s Shōwa period—the reign of Emperor Hirohito.

To be perfectly honest, the first eight Gamera films are far from great cinema. There’s a good reason several of them were featured on Mystery Science Theater 3000. However, I’ve long had the sense that the people behind the film series knew their limitations and had fun with them. At one point Gamera defeats a shark monster called Zigra, then plays a couple of bars of his own theme song on its back. Afterwards, he does a little dance. Another great moment comes in Gamera Super Monster when Gamera is ordered to go on a rampage by aliens and knocks over a sandwich board advertising a Godzilla film. Scenes like these make me think the Shōwa Gamera films have more in common with the 1960’s televised Batman than with films like Manos: The Hands of Fate filmed just down the road in El Paso, Texas.

As it turns out, Gamera was reimagined for a trilogy of really good films in the 1990s. These Heisei-era Gamera films gave a solid backstory to the titular turtle. He still attempts to protect mankind as a whole, but he’s still a giant monster and is prone to mass destruction. Not everyone likes Gamera in these films. The Heisei-era Gamera films also presented some cool glimpses into life in many different parts of Japan. I highly recommend Gamera: Guardian of the Universe and its two sequels.

My love of these films is a small part of what makes me the writer I am today. As a kid, I was drawn to the action and good-natured humor of these films. If it weren’t for these films, I probably wouldn’t have sought out more serious Japanese films like those of Akira Kurosawa, which gave me a deeper appreciation of Japanese culture and storytelling. Writing what we know is, among other things, writing what interests us. So watching Gamera films as a kid, was a first step toward writing my novel The Brazen Shark about samurai resisting cultural change in an alternate, steampunk Japan.

If you’d like to learn more about The Brazen Shark and my inspirations for the novel, I’ll be interviewed on the radio this Friday, July 13 on KTAL Community Radio from 12:30 to 1:00pm Mountain Daylight Time. My friends in Las Cruces can listen on the radio on 101.5 FM. For my friends outside the area, you can listen at: https://www.lccommunityradio.org/stream.html