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: http://davidleesummers.com/solar_sea.html.

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: https://greole.com/blog/2020/06/review-the-solar-sea-by-david-lee-summers-davidleesummers-sciencefiction/.

LightSail 2 – One Year After Launch

This past Thursday marked the one-year anniversary of LightSail 2’s launch into orbit. LightSail 2 is a crowdfunded solar sail project managed by the Planetary Society and it’s the first craft propelled entirely by sunlight. The Planetary Society hosted a webinar to celebrate the event. Planetary Society CEO Bill Nye, Chief Operating Officer Jennifer Vaughn, Program Manager Dave Spencer, and Project Manager Bruce Betts all spoke. The presentation was moderated by Planetary Radio host Mat Kaplan. I am pleased to have been one of the mission funders and I was delighted to have had an opportunity to attend the webinar live. I gather the presentation will be viewable soon at https://www.planetary.org/multimedia/planetary-tv/. I found the presentation fascinating and I took three pages of notes. I’ll touch on a few highlights below and in Tuesday’s blog post, but if you’re interested in this project, be sure to check out the full video at the link above. You can learn more about the Planetary Society by visiting http://www.planetary.org.

Screen shot of the live webinar featuring Bill Nye, Dave Spencer, Mat Kaplan, Jennifer Vaughn, and Bruce Betts

The most exciting news from the webinar is that LightSail 2 is still flying one year after launch. It was placed into an orbit about 720 kilometers above the Earth’s surface, which is still low enough to have a very small amount of atmospheric drag. Despite that, the spacecraft has only lost about 10 km of altitude over the course of a year. It’s not certain how long it will be before it de-orbits, but current estimates say LightSail 2 could continue its mission for another year.

Bill Nye opened the presentation by noting it was 17th century astronomer Johannes Kepler who first speculated on the possibility of solar sails after observing the comet that would ultimately be known as Comet Halley. He reasoned that whatever force from the sun could produce the comet’s tail could propel a sailing vessel to other planets. The specific particle that can be used to propel a solar sail is the humble photon. Light has momentum and that momentum can be transferred to the sail for motion.

LightSail 2 has been able to perform so well because it can be turned like a sailboat’s sail. In this case, the craft is turned by momentum wheels aboard the ship. Momentum wheels are just gyroscopes, but tradition suggests that the word “gyroscope” is used principally when applied to navigation. When LightSail 2 is in a position to get a boost from sunlight, it turns so the sail catches all the light. When the light pressure would work against the sail, the craft turns 90 degrees so it presents the sun with the least amount of surface to push against.

Many great photos were shared during the webinar. My favorite was this one showing LightSail 2 over the Nile and the Red Sea. As you’ll notice, there’s a thin blue line at the Earth’s left edge. That’s our atmosphere, which looks very thin and fragile. I also imagine measuring the spectrum of that thin film on a planet in some distant stellar system from a telescope in our solar system. It’s a real technical challenge, but it looks like we may be getting close to a point where we could do that. This is something we’ll need to do in order to determine whether or not an exoplanet is potentially habitable.

LightSail 2 over the Nile and Red Sea. Image from The Planetary Society.
The Solar Sea

One of the things that makes all of this personally exciting is that I first joined the Planetary Society when I was in high school as a result of a letter sent to Star Trek fan clubs by Gene Roddenberry. I first learned of the Society’s interest to make solar sails a reality in the society’s newsletter, The Planetary Report. The idea caught my imagination and in high school, I started to write a novel called The Solar Sea. I didn’t complete it then, but the idea stayed with me and I made several attempts until I wrote a version that pleased me. That version was published in 2008 and you can learn more about it at: http://davidleesummers.com/solar_sea.html

Revisiting Das Boot

I grew up knowing I had ancestors who came from Germany. What’s more, my uncle married a German woman. I wanted to be a scientist and I knew about a number of German scientists such as Kepler, Einstein, and Heisenberg just to name a few. So when it came to pick a language from my limited high school offerings, I chose German. My high school only offered two years of the language, so when I exhausted those, I was encouraged to take classes at Cal State San Bernardino. During this time, one of the most famous German films was released: Das Boot. The professor of my college German class offered us extra credit if we went to see the movie in German. Several of us went as a group. As with many at the time, I found the movie amazing, stunning, and sad at the end.

My aunt was excited that I had gone to watch a feature-length German film. She contacted one of her relatives in Germany and had them buy a hardcover copy of the original novel and send it to the US. She gave it to me as a Christmas present. It’s still one of my treasured possessions. I’m sorry to say I have not taken the time to wade through and read the whole thing, but I was delighted when I recently picked it up and discovered my German is still good enough to follow the gist of the story.

Writers are often told to “write what you know.” This can be tricky for science fiction writers. That said, we should pull from our experience to make what we imagine as believable as possible. One of the reasons Das Boot was fascinating to me was how real it made serving in a cramped, enclosed ship. Much as I loved the Star Trek-like future of grand, beautiful starships, I couldn’t help but think the reality of military space ships would look more like the U-96 in Das Boot than Captain Picard’s spacious Enterprise. When I started writing the stories that would become the foundation of my Space Pirates’ Legacy series, I made space vessels cramped and claustrophobic with crews who got on each others’ nerves.

Back in the days when I first saw the movie Das Boot, I’d heard rumors of a longer version than the one we saw in the United States. It turns out this was a 5-hour cut broadcast over five nights on British television in 1984. This cut (more or less) was eventually released in the United States as “The Original Uncut Version” shown above. I bought it a few years ago, then promptly moved to a new house where it disappeared under a stack of other videos. I finally found it again and watched the five-hour cut.

I have to say, I was impressed. The longer cut didn’t drag at all. What it gave us were more character moments. The 1980s American theatrical release focused on the captain, the chief engineer, and the war correspondent. The longer release gives us a chance to know the first officer, the third officer, the navigator and the radio operator much better. The crew began to feel even more like a family, albeit a dysfunctional one at times.

I’ve come to realize that space travel would be unsustainable if spaceships were as small and crowded as a World War II-era U-boat, but still, thinking about how they ate, the jobs they were assigned to, the “human” touches that made the sub a little more livable than sterile are all things that help me think about how to design space vessels in my writing. If you want to see how I’ve brought that into play, a good place to start is book one of my Space Pirates’ Legacy series, Firebrandt’s Legacy. You can learn more at: http://www.davidleesummers.com/Firebrandts-Legacy.html

Radio Interviews

One of the difficult things about the current COVID-19 crisis has been the cancellation or postponing of events all around the country. Last weekend, I had been scheduled to attend El Paso Comic Con. Hopefully, circumstances will allow me to make the rescheduled event in October. These events are vitally important to independent authors and publishers. They’re my opportunity to meet you face to face and talk to you about the books I’ve written and those written by others that I’ve felt passionate enough about to publish.

A little over a week ago, I made a pleasant discovery. Here at the web journal, I’ve promoted interviews I’ve done on Lynn Moorer’s show, “All About Books” at Las Cruces Community Radio Station KTAL-LP 101.5 FM. Thanks to the internet, you didn’t have to be in Las Cruces to hear these shows, you could stream them as they aired. Unfortunately, you did have to listen to them at the time they aired. I have now discovered that Radio Que Tal has archived many of its shows and you can now listen to two of my interviews at your leisure. Lynn asks me about the books and has me give a couple of readings. It may not be quite as good as meeting me face to face at a convention, but it will give you a taste and best of all, you can listen on your schedule!

The older interview featured on line is for my steampunk novel Owl Riders. This novel is the fourth in my Clockwork Legion steampunk series, but it’s set about a decade after the other books in the series, so it stands very much alone. Taking place in 1885 with protagonists Fatemeh and Ramon Morales settled in New Orleans, Ramon, now a U. S. Assistant Attorney, is called upon to settle a dispute between the Chiracahua Apache and the U. S. Army over a sliver of land in southern Arizona.  Healer and pharmacist Fatemeh is kidnapped by Hamid Farzan, a Persian merchant to whom she was originally betrothed.  Fatemeh’s and Ramon’s daughter Alethea uses her intelligence and resourcefulness to help rescue her mother. You can listen to the interview at: http://www.lccommunityradio.org/archives/all-about-books-david-lee-summers

In October, Lynn spoke with me about my science fiction adventure, The Solar Sea, the first in a series, about a solar sail ship, the Aristarchus, which travels to Mars, Jupiter, and Saturn, battling hazards in space amidst conflict among crew members.  As the fascinating story develops, readers learn how whales and their songs fit into the universe and into the hierarchy of beings. You can listen to this interview at: http://www.lccommunityradio.org/archives/all-about-books-david-lee-summers-author-of-the-solar-sea

I’ll be visiting with Lynn next month to talk about the next book in this universe, Firebrandt’s Legacy. That interview is scheduled for May 22 at 12:30pm Mountain Daylight Time. Hopefully I’ll be able to share an archive link soon after the interview airs, but you can mark your calendars and listen live at: http://www.lccommunityradio.org/listen.html

Another thing I’m pleased to announce is that my website http://www.davidleesummers.com now lives on a devoted web server. Until about a week ago, I relied on web forwarding from the name registrar to point to my site at the internet service provider. Unfortunately, the forwarding wasn’t very reliable and there were times it just didn’t work, making it look like my website was down. Links to my site throughout the web journal should work much better now.

Upstart Mystique

Today I’m excited to announce the release of the latest novel I’ve had the pleasure to edit, Upstart Mystique by Don Braden.

The novel opens with the space vessel Marco P on its way to a distant colony world. It loses all power and an unknown force convinces the navigator that a distant, dead world is the vessel’s true destination. Commander Malcolm Carpenter orders the crew to abandon ship to protect them and to learn how to defeat whatever force has intercepted his ship. The crew discovers a small group of inhabitants, the only people on the planet who were not uploaded into a vast computer network—a computer network captivated by upstart humans and their imaginations. To free his crew and his navigator from the planetary network’s grip, Commander Carpenter must face a moral dilemma. Can he save his crew without condemning a planet’s inhabitants and their digital ancestors to death?

The idea that humans may reach a point where they can upload their consciousness into a computer is a familiar science fiction trope and one I’ve even explored a few times in my Clockwork Legion novels. In his novel, Don questions whether or not this is something that’s possible and what it would mean for all of a person’s memory and personality to be uploaded into a machine. He wraps these questions up in an action oriented novel full of great characters I enjoyed spending time with.

As it turns out, I’ve known Don Braden longer than any author I’ve worked with. He was my brother’s high school English teacher when my family lived in Barstow, California and by our best recollection, I would have been two years old when I first met Don. We reconnected a few years ago through my brother and have maintained a friendship since. At the very least, we’ve seen each other at least once a year since Don started attending the TusCon Science Fiction Convention in Tucson, Arizona.

Don has often used science fiction as a teaching tool in the classroom, and I’ve long been impressed with his knowledge of the genre and the themes it explores. We share a number of favorite authors and shows. In particular, we’re both fans of Star Trek: The Next Generation. It’s a real pleasure and privilege to be able to publish Don’s debut novel. I hope you will take a look. I know you will be caught up in the world of Upstart Mystique.

Upstart Mystique is available at the following online retailers:

Explore New Worlds from Home

In my last post, I mentioned how fortunate I am to have a fairly secure income during this difficult time of the COVID-19 pandemic. Many people are finding themselves unemployed or under employed. Fortunate as I am, it’s likely our family will also be affected by current events. I’m waiting to hear whether events I attend to promote my writing will be going forward. If not, this could result in a loss of sales for my books. What’s more, my wife performs bookkeeping duties for many small service-industry businesses. So far, these businesses have continued to operate, but some have had to limit their operations and depending on how long we’re asked to practice social distancing, may have to shut down for a time.

This crisis also comes at a time when my youngest daughter is preparing to graduate from high school and go to university. She’s been busy working on assignments at home, but we have had to defer a visit to her future school because of current events.

So far, my writing and editing work is keeping me busy, but I know this enforced period of isolation is hard on many people. That’s one of the reasons I’m participating in the “Authors Give Back” event at Smashwords. On Saturday, I shared two books I’m giving away for free. Because I do have family responsibilities, I can’t afford to give away all of my books, but I can offer deep discounts on two additional titles and give you a chance to explore the solar system and the galaxy in the process.

The first book I’m offering at 60% off the cover price is my novel The Solar Sea. In the novel, whales around the world changed their songs the day scientists announced the discovery of powerful new particles around Saturn’s largest moon which could solve Earth’s energy needs. The Quinn Corporation rushes to build a solar sail space craft to unlock the secrets of these strange new particles. They gather the best and brightest to pilot the ship: Jonathan Jefferson, an aging astronaut known as the last man on Mars; Natalie Freeman, a distinguished Navy captain; Myra Lee, a biologist who believes the whales are communicating with Saturn; and John O’Connell, the technician who first discovered the particles. Charting the course is the mysterious Pilot who seems determined to keep secrets from the rest of the crew. Together they make a grand tour of the solar system and discover not only wonders but dangers beyond their imagination.

In the novel, I use my experience as a professional astronomer to bring the solar system to life for the readers. You can get The Solar Sea for 60% off the cover price at: https://www.smashwords.com/books/view/805692

The second book I’m offering at a discount is Firebrandt’s Legacy. In this book, Ellison Firebrandt fights the good fight for Earth. Under a letter of marque, he raids the ships of Earth’s opponents, slowing down their progress and ability to compete with the home system. On the planet Epsilon Indi 2, he rescues a woman named Suki Mori from a drug lord, only to find she isn’t so happy about living a pirate’s life. However, when the captain finds a new engine that will make him the most successful pirate of all, Suki is the only one who can make it work. Now Firebrandt must find a way to keep his crew fed and his ship supplied while relying on a woman who barely trusts him and while every government in the galaxy hunts him to get the engine back!

This book sets the stage for The Pirates of Sufiro, which I’m working on right now, along with the rest of the Space Pirates’ Legacy series. In the opening chapter, Captain Firebrandt attacks a ship and discovers a whole cargo hold of … toilet paper. It’s just a small moment, but who knew that would be a thing? You can get Firebrandt’s Legacy for 60% off the cover price at: https://www.smashwords.com/books/view/916916

Voyage of the Space Beagle

These are the voyages of the Space Beagle. It’s mission: explore new worlds, seek out new life … and kill it!

Wait, what?

Let me step back a moment. When I married my wife, a friend quipped that I was marrying her for her collection of science fiction novels. One of those novels was A.E. van Vogt’s classic science fiction tale, Voyage of the Space Beagle. It’s one of those novels I’ve long meant to read and I came across it the other day on the bookshelf and decided to give it a go.

The novel is a fix-up of four novellas written between 1939 and 1943 that describe a large space ship full of scientists sent out to the galaxy to learn everything they can. The primary point of view character is Elliott Grosvenor, an early practitioner of a science called nexialism which endeavors to take the results of all the sciences and come up with comprehensive results that specialists in those fields can’t achieve alone. This is probably a good thing, since the Space Beagle’s all-male crew consists of a bunch of scientists from different specialties, most of whom don’t seem to work and play well with others. Even Grosvenor felt like something of a know-it-all jerk at times.

In the first part, the Space Beagle lands and takes the cat-like creature from the cover aboard as a specimen. This coeurl turns out to be a lot smarter than anyone anticipated and it goes on a killing rampage through the crew until they figure out how to dispatch it. In the second part, hypnotic suggestions begin flooding the ship and causing the crew to turn against each other. Grosvenor figures out that they’re receiving communications from an alien race. In the third part, they encounter a living creature out in space called an Ixtl and decide to bring it aboard as a specimen. It promptly begins going around the ship and inserting its eggs into the intestinal tracts of the crew. Finally, the Space Beagle leaves the galaxy and encounters a galaxy-spanning entity at M33. It transforms planets into jungle planets with lots of life that it can feed on.

I found it difficult to sympathize with a lot of the characters in this novel. While it was interesting that they had egos and that led to conflict, I just wanted them to get over themselves and work together once in a while as something nasty attacked the ship. What’s more, for a thin novel, it was rather plodding and methodical in its pacing. Despite that, the real importance of this novel is in its influence. The first thing I noticed was the cat-like creature on the cover. He reminded me of one I’d seen on another recent novel.

It turns out that Haruka Takachiho, the author of the Dirty Pair light novels was a fan of A.E. van Vogt and Mughi, the third lovely angel, shown on the cover, is supposed to be a coeurl. There are obvious parallels in this novel with movie and TV space opera that followed, such as Forbidden Planet and Star Trek. When van Vogt mentioned his all-male crew, I immediately thought of the problems the crew of the C-57D had when it’s all-male crew encountered a woman on Altair IV. Although I poke fun at the Star Trek connection in the opening of this blog, it does resemble Star Trek in that the Space Beagle ostensibly is an exploratory ship that finds itself in the position of defending Earth against creatures that would do Earth harm. For that matter, the coeurl feeds on the potassium in human bodies, not unlike the creature that kills people for salt in an early episode of Star Trek.

One thing that’s quite striking in this novel is its resemblance to the plot of 1979’s movie, Alien. Most people point to the obvious parallels of the egg-implanting Ixtl, but the coeurl story also resembled Alien quite a bit. I was especially struck at the end of that story when the biologist, Kent, suggests that a crew should return to the coeurl’s planet and exterminate the species before they become more of a problem, the setup for this universe’s version of Aliens. Apparently van Vogt did sue the producers of Alien and was awarded a settlement.

Although it feels dated, and I’ve read novels from the period that I enjoyed more, I was glad to discover this influential science fiction novel and travel with the crew of the Space Beagle for a little while, and survive the experience.

Weighing Planets

At this month’s meeting of the American Astronomical Society, the team developing the NEID spectrograph at Kitt Peak National Observatory announced the instrument’s first light and released a great, processed image of the first spectrum that illustrates much of what I’ve talked about when giving behind-scenes-glimpses of the work. This is a spectrum of 51 Pegasi, which happens to have been the first star discovered to have an exoplanet back in 1995.

Credit: Guðmundur Kári Stefánsson/Princeton University/Penn State/NSF’s National Optical-Infrared Astronomy Research Laboratory/KPNO/AURA

The rainbow in the image above shows light from the star 51 Pegasi spread out by the spectrograph. To the left, you see the spectrum magnified so you can see more details. In particular, you see dark lines bisecting the rainbow in different places. These lines are caused when elements in the star’s atmosphere absorbs a little bit of the light. The dots above the lines come from a “calibration” image. They serve as a road map to tell you where you are in the spectrum. When a planet pulls the star toward us, those dark lines move a little bit toward the blue end of the spectrum (to the left in the image above). When the planet goes behind the star, those lines move a little toward the red end of the spectrum (to the right, in the image above).

What’s cool about this kind of measurement is that how far the planet moves those lines is directly related to how massive the planet is. If you measure the line movement precisely, you can measure how much the planet weighs. If you then use another telescope and take images of the star and watch for the planet to cross in front of the star, you can measure how much the planet makes the star’s light decrease. That tells you the diameter of the planet. With the diameter and the mass, you can calculate the density, which tells you whether you’re looking at a gas giant, a rocky world, a water world, or an ice giant world.

What’s more, I was on-hand when that first image was taken. We celebrated by pulling out a bottle of sparkling cider and toasting the instrument’s success. Afterwards, we got back to work characterizing and testing the instrument’s behavior. As you can tell from the image below, we have lots of people in the control room on these commissioning nights!

This past week has been especially fun as a science fiction writer and long time fan. We’ve been starting our nights by observing the star Tau Ceti, which appears in many science fiction novels, movies, and TV series. Among the notable novels where Tau Ceti appears are such classics as Isaac Asimov’s The Caves of Steel, Robert A. Heinlein’s Time for the Stars, and Samuel R. Delaney’s Empire Star. In Star Trek, Tau Ceti is known as the home of the doomed cargo ship, Kobayashi Maru. The system is the home of the planet Sea of the Morningstar in Bodacious Space Pirates, a wonderful anime series.

In fact, the star itself is very similar to the sun. It has a similar spectral type and a mass about 0.78 times the mass of the sun. It has four candidate planets in orbit and it’s a little less than 12 light years away, so it seems conceivable these are planet humans could eventually visit. I even gave it a cameo in the new, upcoming edition of my novel, The Pirates of Sufiro.

Christmas in Space

Last year was the 50th anniversary of the first celebration of Christmas in space. This happened during the Apollo 8 mission commanded by Frank Borman with James Lovell Jr. serving as command module pilot and William Anders serving as lunar module pilot. On Christmas Eve 1968, Apollo 8 entered orbit around the Moon. During the mission, they took the famous Earthrise photo, showing the Earth rising over the Lunar horizon. Ten hours later, they took turns during a transmission to Earth to read the opening verses of Genesis. Borman concluded the transmission by saying, “And from the crew of Apollo 8, we close with good night, good luck, a merry Christmas, and God bless all of you, all of you on the good Earth.” During a transmission four hours later, James Lovell reported, “Please be informed there IS a Santa Claus.”

Image credit: NASA

After he retired from NASA, Borman lived for a time to Las Cruces, New Mexico and was still living there when I moved to town in 1995.

In December 1993, Mission Specialist Jeffrey Hoffman celebrated Hanukkah on the Space Shuttle Discovery. He brought a dreidel and a travel menorah and spoke about Hanukkah during a live television broadcast. During the mission, the shuttle captured the Hubble Space Telescope, brought it into the shuttle bay and performed a full service of the instrument over the course of five space walks.

Although we have never achieved the science fictional promise of cities in space, we have achieved more regular habitation of space in the years since Apollo 8 through the International Space Station. Christmas is regularly celebrated there and its fun to see stockings hung on the station and astronauts with fuzzy, red hats. That said, Americans aren’t the only crew members. Russians who serve aboard the ISS often emphasize New Year celebrations over Christmas. When they do celebrate Christmas, many celebrate Orthodox Christmas in January.

When I wrote my novel The Solar Sea, it seemed only natural that people would make an effort to celebrate those holidays that were special to them. December arrives as the solar sail Aristarchus travels to Mars. The character Vanda Berko finds special meaning in the menorah’s light while traveling through the darkness of space. The ship’s cook brings a small tree aboard the ship and the crew decorate it and sing carols on Christmas morning.

James Lovell, the astronaut who declared “there IS a Santa Claus” on Apollo 8 would go on to become commander of the ill-fated Apollo 13. When the Aristarchus crew gets into trouble, they cheer themselves by remembering that dire as that early mission was, Lovell helped to bring the crew home safely.

You can learn more about The Solar Sea and found out how to get your own copy by visiting http://www.zianet.com/dsummers/solar_sea.html

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.