NanoSail-D has always held a special place in my affections, probably because the solar sail effort has, until recently, been stalled. The IKAROS sail brought us into the sail age with gusto, but the sail team at NASA's Marshall Space Flight Center has persisted through budget uncertainties and public indifference in finding a way to create a space-going sail seemingly out of thin air. No, it wouldn't be the large, free-ranging sail we might have expected a few years back that could have so easily grown out of MSFC's work, but it could be launched on the cheap. It could make it into space, and once there its short mission could break the trail for future sail efforts. Remember that NASA developed two different 20 X 20-meter solar sails between 2001 and 2005, one fabricated by ATK Space Systems, the other by L'Garde Inc. Both these sails were tested in ground vacuum conditions, and MSFC's Les Johnson pointed out in 2008 that they were solid designs, "... robust enough for deployment...

NanoSail-D is now in space, following a successful launch on the 19th that involved eight satellites for university research programs and the US government. The sail experiment was carried aboard FASTSAT (the Fast Affordable Science and Technology Satellite) and is scheduled for release seven days after launch, with sail deployment three days later. We'll soon know how well the deployment of the sail -- a five second process -- proceeds, but how energizing to have another sail experiment in motion as we continue to shake out this technology. The NanoSail Twitter feed (@NanoSailD) is active and bears an uncanny resemblance to the amiable, chatty and often obscure IKAROS tweets from that mission's launch. Colorful Imagery from WISE Meanwhile, other missions continue to pop up with intriguing results, including WISE (Wide-field Infrared Survey Explorer), which has been surveying the sky at infrared wavelengths since January and is now on its NEOWISE mission, the extended sequence of...

I notice that the Planetary Society is doing some fundraising for its LightSail program, in this case looking for money to help build a spare for the LightSail craft. Lou Friedman puts it this way in a recent mailing: "We need to build a spare to insure our plans. It's the prudent move; much cheaper than purchasing insurance and building an entire new back-up craft, as long as we do it now, while the first spacecraft is being built." The cost of a back-up craft during this window is roughly $200,000. Some basics about LightSail-1: Its mylar sails are 4.5 microns thick, the thinnest ever made for spaceflight. When they deploy, they'll extend to cover 32 square meters, and the four sails should throw quite a reflection, acting like mirrors that would be visible from Earth and may appear brighter than any visible star or planet. The vehicle is to be formed from three CubeSat spacecraft, forming a 'bus' about the size of a shoebox that weighs about 4.5 kilograms. We've covered the...

When engineer Carl Wiley brought solar sails to a wide audience in 1951, he envisioned a particular kind of sail. Wiley, who wrote under the byline Russell Saunders, published "Clipper Ships of Space" in the May issue of Astounding Science Fiction that year, seven years before the first technical paper on sails, Richard Garwin's "Solar Sailing: A Practical Method of Propulsion within the Solar System," appeared in the journal Jet Propulsion. As you can see in the illustration, which ran with the original essay in Astounding, Wiley envisioned the sail as taking a parachute shape, with the payload attached to the sail circumference. Varieties of Sail Design But there are many ways of doing sails. Square or rectangular sail designs (think of those images of IKAROS shot by its detached cameras) have been the focus of recent work, with the result that many alternatives have not reached the same level of technological readiness. But along with parachute sails, spinning disk sails,...

Japan's IKAROS sail has thus far conducted a triumphant mission, demonstrating the principles of sail deployment, solar photon propulsion and attitude control in a functioning space sail. While the solar sail community has never received the press attention I believe this innovative propulsion technology deserves, it's heartening to realize that a long and sustained effort, even one operating under the radar, so to speak, can produce such striking results. The 2nd International Symposium on Solar Sailing (ISSS 2010) has just wrapped up in Brooklyn, but if you go back to the first of these conferences, conducted in June of 2007 in Ammersee, Germany, you'll find that the program was laced with representatives of ESA, NASA and JAXA (presentations from that meeting are available online), attacking the issue of getting a solar sail operational from every angle even as the budgets of the representative agencies were being cut back. The needed theoretical work proceeds absent the necessary...

Robert Forward's Indistinguishable from Magic is a genial and absorbing read, a collection of essays and fiction illustrating some of the scientist's most memorable ideas. And while gigantic lightsails driven by laser beam to other stars always come to mind when Forward's name is mentioned, it's fascinating to page through his thoughts on antimatter, black holes and time machines. Long a Forward admirer, I was pleased to see that another of the concepts discussed in this book recently made an appearance at this month's solar sail conference in Brooklyn. 'Statites' are a Forward construct, a word he coined to describe a spacecraft that uses a solar sail to hover over a region rather than orbiting the Earth. Let Forward describe what he calls a 'technique for hanging things in the sky': ...I have the patent on it -- U.S. Patent 5,183,225 "Statite: Spacecraft That Utilizes Light Pressure and Method of Use"... The unique concept described in the patent is to attach a television broadcast...

With more attention now being focused on possible missions to an asteroid, we should keep in mind that DLR, the German Aerospace Center, has been looking into an asteroid mission via solar sail for some time now. One 2006 paper from DLR's Institute of Space Simulation pondered a 70-meter sail for use in a projected mission to the Near-Earth Object 1996FG3 within ten years of launch. It's an interesting notion, one that would involve the sail hovering over the NEA hemisphere opposite to the Sun, deploying a lander and return capsule. DLR has been into serious sail studies for some time now, as the photo below attests. It's a 1999 shot of the ground deployment of a square solar sail 20 meters to the side. As you can see, this is a square sail made up of four triangular sail segments, an exercise that could readily lead to a sail deployment in space if the European Space Agency opts for funding such a mission. Just what ESA has in mind for such technology was the subject of a...

The final day of the Second International Symposium on Solar Sailing (ISSS 2010) kicks off this morning with Roman Kezerashvili (City University of New York) discussing solar sail missions as a way of testing fundamental physics. Last year in Aosta I listened with fascination as Kezerashvili discussed close solar passes ('Sundiver' missions) that could approach as close as 0.05 to 0.1 AU to the Sun, depending on the development of materials technology. The remarkable feature of his talk, though, was the consideration of General Relativity's effects in such close proximity to the Sun, which could create huge navigation issues. The 'Sundiver' as an Exercise in Physics Fail to account precisely for spacetime curvature and frame dragging in this environment and such a mission could find itself with a million-kilometer deflection enroute to its target. Even more exotically, time slows in close proximity to the Sun due to relativistic effects, so that the observer on Earth measures about...

Solar Sails in Brooklyn I should probably clean out my office, and would, if I could find the time, but things keep happening in the deep space community and I keep writing about them. I had the program for ISSS 2010 (the Second International Symposium on Solar Sailing) right beside me when I started to write yesterday's entry, and by the time I got to the part on the conference, the program had disappeared into the wilderness of printouts, notebooks and letters. Thus I missed the fact that Colin McInnes would be in attendance at the sessions, a major addition to the already stellar lineup. McInnes could be said to have written 'the' book on solar sailing, a densely packed tome that lays out the principles and speculates on future missions. Meanwhile, it's heartening to see how international the solar sail effort has been from the outset, even if all the space agencies have continued to wrestle with their own funding demons. Much good work has gone on at Germany's DLR, for example,...

The solar sail news continues to be positive, a welcome relief after so many years of delay and frustration. Now that we finally have an operational sail in space, it's worth noting how the Japanese IKAROS sail differs from earlier sail concepts. For IKAROS is designed to use two kinds of power. The first comes from the momentum applied to the sail by photons from the Sun. The second (and this is just one of the areas where the Japan Aerospace Exploration Agency went in a new direction) is produced by the thin film solar cells built into the membrane of the 20-meter (diagonal) sail. Remember that we've been getting helpful imagery from two cameras that separated from the spacecraft and looked back on its operations. The image shown later in this post was taken by the DCAM2 camera, a cylindrical device about six centimeters in diameter and height that was detached from the spacecraft by a spring, as was DCAM1. JAXA is continuing to measure the power generating capabilities of the...

This is what a solar sail looks like in space. The images below were taken by a camera flown aboard the IKAROS mission and then separated from it using a spring, according to the Japan Aerospace Exploration Agency (JAXA). These pictures (and you can find several more here) take me back to my first reading of Cordwainer Smith's 'The Lady Who Sailed the Soul,' in which a far future sail mission involving a sail tens of thousands of kilometers across plays against the tangled relationship of two lives (full text here). IKAROS may be far smaller, but if seeing a deployed sail in space doesn't fire the imagination, what will? A brief snippet from the story: The first sailors had gone out almost a hundred years before. They had started with small sails not over two thousand miles square. Gradually the size of the sails increased. The technique of adiabatic packing and the carrying of passengers in individual pods reduced the damage done to the human cargo. It was great news when a sailor...

For those of you interested in the key IKAROS post describing the final deployment of the sail, Lionel Ward has been so kind as to translate it in context. I'm leaving out the actual photographs, which you can see via the links posted in my previous IKAROS coverage -- and also here in context -- but here is the text from JAXA: ------- 2010?6?11?[??]? A world first! Solar Powered Electrical Sail deployment and power generation is successful! ????????????????&????? On June 8th the finalization of the primary deployment was executed, and on June 9th the secondary deployment was executed. 6?8?????????????????6?9?????????????? IKAROS’ state at the end of the primary is detailed over on the Ikaros blog. ???????????????????????????? Upon sending the command to initiate secondary deployment, a state of nervousness persisted in the command center during the 46 second propagation delay (the separation from earth is 7.4 million km!) until the initial data could be seen. That deployment had...

IKAROS now appears to be fully deployed and generating power from its photovoltaic cells. The IKAROS blog even has a photo of the cake with which the sail team celebrated the success, but you'll also want to go to this IKAROS page for a look at further imagery, one of which is the photo shown below. The page has four similar photographs from different cameras aboard the spacecraft, and if I'm reading this right, more photos will be posted here as they become available. JAXA has also made available this news release about the deployment. Lionel Ward, our Japanese translator extraordinaire, will be sending translations of the IKAROS blog postings and recent tweets from JAXA later today, and I'll post these as a way of archiving the information here. This afternoon (1800 or so UTC) I'll have today's regular Centauri Dreams post up, but I wanted to share this image and give you the pointer for more as soon as possible. What an achievement this mission has turned out to be even this early...

Update: The IKAROS blog reports "The operation ended today as planned." That must count as good news for the sail, now 7,480,787 kilometers from Earth, but we still need confirmation that the sail's 'secondary' deployment is now complete. Maybe this is it: Japanese space journalist Mitsunari Kita, who is attending a press conference re the Hayabusa mission, has sent out a tweet (@kitamitsunari) congratulating the IKAROS team on full deployment of the sail (1805 UTC). What extraordinary times these are for the Japan Aerospace Exploration Agency (JAXA). We are in the midst of an interplanetary solar sail mission even as the Hayabusa asteroid explorer prepares for re-entry over Australia, an event that should occur around 1400 UTC on June 13. The Hayabusa craft will release its 16-inch-wide entry capsule some three hours before landing. We've concentrated on IKAROS in these pages, but what a story Hayabusa has been, launched in 2003 to explore the asteroid Itokawa, which it did, but not...

Update: The IKAROS team has not confirmed full deployment of the sail, but does indicate we'll have an update tomorrow. The IKAROS solar sail is partially deployed but the complete deployment was delayed while the mission's engineers tried to figure out why the spacecraft's spin rate has been increasing. JAXA's updates are in Japanese, but the Planetary Society's Emily Lakdawalla seems to be more skilled at untangling Google Translate than I am and has also used a translation from a user on the excellent unmannedspaceflight.com site to come up with IKAROS details. Thus we learn that the sail is currently deployed about five meters. A new update just in from JAXA points to an attempt at full sail deployment just a few hours from now. This video shows the process at work. [youtube 7Mb47w0vB04 500 375] From what JAXA says, there is no danger to the spacecraft from the increased spin rate, but the pause in deployment arose simply because the team wanted to pin down an explanation for the...

The crescent Earth is lovely in this ultraviolet photo taken by the Japanese Akatsuki probe, now enroute to Venus. The shot was made at a distance of about 250,000 kilometers and keeps me in mind of the IKAROS solar sail demonstrator, which was launched along with Akatsuki and several other payloads on May 20. It's been tricky keeping up with IKAROS (let's just say my Japanese is not up to speed, and neither is Google Translate), but a 'tweet' from JAXA yesterday said that four cameras aboard the spacecraft had captured images of deployed tip masses, a cause for applause in the IKAROS control room. Photos of that deployment (on May 28) are available on this JAXA site. The sail deployment procedure begins with release of the tip masses and proceeds through stages, as shown below. Image: Deployment procedure for IKAROS. We'll follow IKAROS with great interest as we move toward full sail deployment. Meanwhile, word from Louis Friedman at the Planetary Society is that LightSail-1 is...

Congratulations to JAXA, the Japan Aerospace Exploration Agency, for the successful launch of the IKAROS space sail, launched from the Tanegashima Space Center along with the Venus Climate Orbiter yesterday evening US time. The launch was a beautiful sight via JAXA's Internet feed and we now have the opportunity to shake down solar sail technologies in space, from deployment to navigation and maneuvering. The mission sequence ahead is shown in the diagram below, but as we wait for further news, a special nod of appreciation for IKAROS project leader Osamu Mori and the fine team that has made this solar sail a reality. Image: After separation from H-IIA, IKAROS will spin at up to 20 rpm, deploying the sail membrane and generating solar power by means of thin film solar cells (minimum success level) within several weeks. Acceleration and navigation using the solar sail will then be demonstrated (full success level) within half a year. Credit: JAXA. The AKATSUKI climate orbiter is a...

With its May 18 launch date fast approaching, Japan's IKAROS hybrid sail mission is at last getting a bit of press attention, long overdue in my opinion. The Daily Mail, at least, has just run a story on IKAROS, which will combine two mission concepts within a single spacecraft. Its solar sail works conventionally, using the momentum of photons from the Sun to accelerate the craft. But the JAXA designers have added thin film solar cells on the sail membrane. These produce the electricity that could be used in future (and larger) iterations to drive an ion engine. But IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun) is a demonstrator, not only taking the sail concept into space but pushing it into interplanetary regions. Launched in tandem with the Venus Climate Orbiter AKATSUKI, the spacecraft will deploy its sail a month after launch on the way to Venus, and having swung by the planet, will test out its propulsion and navigation systems. Kelvin Long, head of...

Not long ago we looked at IKAROS, an interesting solar sail concept out of JAXA, the Japanese space agency. Osamu Mori, project leader for the sail mission, offers up further background in an interview available at the JAXA site. IKAROS is notable because rather than relying solely on photons for propulsion, it would use solar cells covering part of the sail to generate electricity. In addition, the sail will operate with a unique attitude-control system. Here's what Osamu Mori says about the latter: The solar-powered attitude-control system uses a technology that controls the reflectivity of the sail. It works just like frosted glass: normally, the entire area of the sail will reflect sunlight, but by "frosting" part of the film, we can reduce the reflectivity of that area. When the reflectivity is reduced, that part of the sail generates less solar power. So by changing the reflectivity of the left and right sides of the sail, we can control its attitude. Interesting stuff, and it...

My interest in solar sail concepts goes back to the days of Cordwainer Smith's "The Lady Who Sailed the Soul," a science fiction tale (Galaxy, April 1960) whose evocative conjuring of a fantastic future has always stayed with me despite far more realistic sail concepts from the pen of Arthur C. Clarke and Poul Anderson, to name but a few. But magsails -- craft that operate by creating a magnetic field that can interact with the solar wind -- offer possibilities just as robust, provided we can tame the propulsive effects of that wind. And this may not be easy, given the changing speed and strength of this stream of charged particles outbound from the Sun. Moving in some cases faster than 400 kilometers per second, the solar wind seems to offer a clear path to the outer system, but we know all too little about it. That's why I always keep an eye on attempts to measure the solar wind, including the IBEX (Interstellar Boundary Explorer) mission that examines the interactions between the...