A blue-tinged image of a fully unfurled solar sail. (NASA/MSFC/D. Higginbotham)
Artist's rendering of a four-quadrant solar sail propulsion system, with payload. NASA is designing and developing such concepts, a sub-scale model of which may be tested on a future NMP mission. (NASA)

More Information
› NASA Link: Nanosail-D
› Gallery: Nanosail-D
› Image: Solar Sail Concept
› Wikipedia: Solar Sail NASA is now one step closer to sailing among the stars! In a historic milestone on Jan. 21, 2011, NASA engineers confirmed that the NanoSail-D nanosatellite deployed its 100-square-foot polymer sail in low-Earth orbit and is operating as planned. The deployment was confirmed with beacon packets data received from NanoSail-D and additional ground-based satellite tracking assets.

NASA hopes to one day use thin membranes to de-orbit satellites and space debris. While NanoSail-D's relatively low altitude means drag from Earth's atmosphere may dominate any propulsion from the sun, the nanosatellite remains a small first step towards eventually deploying solar sails at higher altitudes.

On Thursday, Jan. 27, Dean Alhorn, the principal investigator for NanoSail-D at NASA's Marshall Space Flight Center in Huntsville, Ala., answered your questions about the NanoSail-D mission and solar sails.

More About Chat Expert Dean Alhorn

Alhorn, a NASA Marshall employee since 1991, is an expert in electro-mechanical systems and the principle investigator for NanoSail-D. Alhorn has prior flight systems experience with the Chandra X-ray Observatory telescope; the Fast, Affordable, Science and Technology Satellite; and the Suppression of Transient Accelerations by Levitation Experiment. Alhorn continues to perform research in the area of solar sail propulsion technology.

He is a native of Albuquerque, N.M., and holds a Bachelor of Science degree in Mechanical Engineering from the University of New Mexico, and a Master of Science degree from the Massachusetts Institute of Technology.

Chat Transcript

Dean: Hi everyone, and welcome to the chat! We're getting everything finalized and will get the chat underway at the top of the hour. Thanks for being here.

hello43: hi remeber there was same topic earlier this year...how different is this topic...?

Dean: Hi! We have a deployed system now! Now you can ask questions about the operations...plus we have the image competition in place that we didn't have before.

(Moderator Jason): Welcome to today's chat. We've already got some questions in the queue and we're working on getting you answers right now. To ask you own question, please type it in the box at the bottom of the window and click 'Ask' on the right.

Sabine: Hello Dean. Do you plan to involve ham radio operators in future missions and projects, too? Thanks for answering. Sabine

Dean: Hi Sabine. It was a pleasure working with the HAM radio community. It all depends on the mission requirements - for small cubesats, it's economical to use HAM frequencies if we can get the authorization.

spacegirl: Does the solar sail use radiation pressure or solar winds to power it?

Dean: Radiation pressure - solar winds are high-energy particles.

spacegirl: Why did you use polymer not aluminum or carbon fiber?

Dean: CP1 is our sail material - it's a polymer that resists space degradation. It has aluminum coating on the inside. It was a leftover from a previous sail design mission and therefore free to us!

spacegirl: What's your favorite part of your job?

Dean: Innovating and design!

(Moderator Jason): To learn about the NanoSail-D Amateur Astronomy Image Contest, please visit http://go.nasa.gov/Nanosail-DContest.

JohnWilliams: Hello Dean. With such a milestone acheived so close to the end of the shuttle era, do you expect this advancement to have an effect on the next generation of practical human space travel. If not, what technology do you think will replace the shuttle? Thanks for answering, John.

Dean: No, we're many years away from using this for manned spaceflight. Many more tests and many more missions before manned utilization.

astroguyz: Am curious; is orbit of NanoSailD specifically devised to take advantage of its use as a solar sail, and how much maneverability does it have?

Dean: Unfortunately, we're too low in attitude to be a solar sail, we don't have onboard attitude control, only four months to design, manufacture, and build. (Also, thank you so much for all the tweets!)

Sabine: Are you a ham radio operator yourself? I hold Amateur Extra Class license. And it was a pleasure to contribute to the NanoSail-D2 mission.

Dean: No, unfortunately I'm not - but appreciate your contribution! Keep looking up and maybe you can win a prize for a photo!

spacegirl: What other research projects have you worked on throughout your career at NASA?

Dean: Microgravity isolation (STABLE, g-LIMIT), Chandra, SMART, and various other innovative designs. I have about 11-12 co-patents.

Sabine: I also would like to pose a question on nomenclature. Sometimes the satellite is called NanoSail-D and sometimes NanoSail-D2. Why?

Dean: The project is just NanoSail-D. NanoSail-D2 is the serial #2 version.

spacegirl: How long will it be until you use the solar sail for unmaned missions?

Dean: I'm actively designing the next generation based upon my knowledge learned from this mission and from studying other sail missions, such as Ikaros, Cosmos-1, LightSail, etc.

aggelos: What materials has been used to make the sail?

Dean: We used CP1, a space-age polymer with aluminum coating.

astroguyz: No problem...noticed NanoSailD spends a large part of its orbit in sunlight and thought that might be by design...but not great for observers!

Dean: In general, solar sails would spend a lot of time in light. Over the U.S. we're in sunlight and not near the terminator so it's hard to see.

(Moderator Jason): Got a question you've been waiting to ask? Go for it! Ask it by typing the question in the bottom of the chat window and then clicking the 'Ask' button on the right.

aggelos: Hello Dean. What's the maximum acceleration of a satelite acquired using a solar sail? What's the ratio between acceleration and the area of the sail?

Dean: Unfortunately, I don't have your answer. The best way to answer your question is to state that we could reach the outer limits of the solar system - where Voyager is - in about 10 years, whereas it took Voyager 30 years to get there.

aggelos: What's actually CP1?

Dean: It's like plastic food wrap made for the space environment.

spacegirl: What other technology has used CP1 material?

Dean: The sunshield for the James Webb Space Telescope.

chetman1020: Can sails be used to propel spacecraft out into space, or will they strictly be used for de-orbiting satellites?

Dean: Both!

Sabine: Do you already know why the P-POD did not launch the satellite properly?

Dean: We haven't had enough time to analyze this properly - it's possible we may never know why aand only have hypotheses. Sorry I can't be more definite!

chetman1020: So sails can provide protection (James Webb telescope) and propulsion (Nanosail)?

Dean: James Webb has a sunshield to protect and to ensure that the optics stay really cold. It's deployed as a shield in this case - it's about the size of a tennis court.

spacegirl: What's your favorite part of working at NASA?

Dean: Innovation and design.

spacegirl: How expensive has the solar sail research and constructon been compared to other space propulsion research?

Dean: NanoSail-D has been relatively low cost. It's very hard to test sails on the ground and almost requires on-orbit validation because of their light weight.

chetman1020: Have there been any other sails in space?

Dean: Yes, Ikaros deployed last year on the way to Venus.

CraigNASA: What are you hoping to find with this sattelite?

Dean: Hoping to demonstrate deploying sails from a very compact structure, and deorbit capability - plus the ability to eject a nanosatellite from a microsatellite.

aggelos: Can sails be used to get rid of already excisting space debris?

Dean: Great question! There is a perception that sails can be used like a pool skimmer to remove debris from orbit. This is not the case. Sails may be used on future satellites to prevent them from winding up as "space junk."

chetman1020: Why did you choose Mechanical Engineering instead of Aerospace Engineering?

Dean: I like to make things move and operate, then I went in to controls, that led me to electrical engineering - so I'm more an electro-mechanical engineer.

wobblyearth: Can sails be also used as sun shield similar to James Webb ?

Dean: Yes, they can. It's not so much the sail, but the sail material - James Webb will not sail like a solar sail.

Sabine: What kind of battery did you use ? It is cold out there what accelerates self-drain.

Dean: Lithium ion battery - off-the-shelf. There are eight of them.

spacegirl: What was the budjet of the Nanosail?

Dean: The cost was estimated at $250K.

(Moderator Jason): We're working on getting you answers to your questions. Go ahead and ask them by typing it out in the box on the bottom of the chat room and then submit it by clicking 'Ask' on the right.

aggelos: When will Ikaros will reach Venus?

Dean: Not known - please consult JAXA. Sorry!

astroguyz: Has anyone yet seen NanoSailD flare worldwide "Iridium-style?"

Dean: There have been flares that people have seen, but we haven't yet confirmed them. Other experts believe that these are NanoSail-D.

aggelos: Aren't sails very fragile to space debris? Is there a way to prevent any damage?

Dean: Sails don't remove space debris that's existing. The goal is to prevent future satellites from ending up as space junk.

spacegirl: Has the nanosail deorbited anything yet or is that in the plans for this nanosail?

Dean: This is a first step for this technology.

George: Why isn't TLE Data (AKA Keps) released from Space Track for this or any other satellites that were on this launch ?

Dean: Our TLEs are on our dashboard, per our agreement. I'm not in control of that process - sorry. We're working to get you a link...

CraigNASA: What is a nano satelilte?

Dean: A nanosatellite is a satellite from 1-10 kgs in mass.

(Moderator Jason): To learn more about the Japanese Space Agency (JAXA)'s IKAROS project, see http://www.jaxa.jp/projects/sat/ikaros/index_e.html.

CraigNASA: What is the purpouse of this sattelite?

Dean: Demonstrate compact deployment of solar sails, deorbit satellite, and eject nanosatellites from microsatellites.

JohnWilliams722: What is average degree and field of study for those working at NASA for space and air based projects? Is it usually an engineering degree or a science degree?

Dean: It's both - depends upon your focus.

Dean: This is that URL for the dashboard: http://nanosaild.engr.scu.edu/dashboard.htm

CraigNASA: Why is NASA going to stop sending Space Shuttles? How will people get to the ISS? Are they stoping it because of the economy? Is NASA shutting down?

Dean: Sorry, this is a little off-topic. But thanks for the question. :)

aggelos: Is it possible to maneuver NanoSail-D from the Earth?

Dean: No, we only had four months and couldn't incorporate any attitude control (ACS).

chetman1020: Are any future missions considering to use sails?

Dean: Yes, I'm actively conceiving and designing a next-generation sail called FeatherSail-2.

George: Where can I get current Keps to be able to Track Nanosail?

Dean: See the dashboard link: http://nanosaild.engr.scu.edu/dashboard.htm

chetman1020: Why do current sails have a rectangular shape?

Dean: That's just the way it was designed - some of that is about packing efficiency.

astroguyz: Any tips for us citizen backyard satellite imagers/spotters?

Dean: Yes - try http://www.nanosail.org for tips.

mesh: How heavy are the satellites that the nanosails are supposed to be able to push out of orbit? Could it knock the hubble space telescope out of orbit?

Dean: Mass of the satellite drives the size of the sail. If it was big enough, it could knock Hubble from orbit, but not likely.

spacegirl: What's the most important subject to study in school to work in your field?

Dean: Mechanisms, controls, and electronics.

George: Thank you for the link to Dashboard...

Dean: You're welcome :)

quod_erat: What exactly is the "wind" for a solar sail? And how is it utilized?

Dean: The "wind" is the stream of photons, as opposed to the high-energy particles.

JohnWilliams722: With this new solar sail technology and stopping of the shuttle program, it seems as if NASA has shifted its focused towards unmanned space missions. Is this NASA's plan or do they plan to integrate this and other technologies into manned missions?

Dean: I really don't know. I'm focused on designing the next generation of solar sails.

Sabine1: Did you use a PIC or ATMEL or other kind of processor to start the countdown and launch the deployment?

Dean: That is internal to the Ames Research Center in California. Their Genesat bus used some type of microcontroller - not sure which they used.

Sabine1: My connection was lost, so Sabine1=Sabine.

Dean: Welcome back, Sabine.

spacegirl: Did you do any programs at NASA before becoming a full time employee?

Dean: No, I was hired straight out of graduate school at MIT.

astroguyz: Any plans in the works for a more ambitious version of NanoSailD to fly in the future?

Dean: Actively designing FeatherSail-2 - roughly the size of half a football field when deployed.

spacegirl: Were you interested in this field when you were younger?

Dean: I LOVED to tear things apart to see how they worked. Unfortunately, I couldn't always put them back together...so yes, in some ways, I simply love to explore how things work.

(Moderator Jason): Got a question to ask? Go for it! Type it out at the bottom of the chat room and then submit it by clicking the 'Ask' button on the right.

Hyper: Thanks for holding this chat with us. I read up what was asked from the beginning, really nice to get this kind of info.

Dean: You're welcome - thank you for being so thorough. Any questions that you have?

spacegirl: What one peice of advice would you give students entering highschool?

Dean: Study hard! And don't be afraid to challenge yourself.

quod_erat: How does NanoSail-d differ from The Planetary Socieity's LightSail-1?

Dean: LightSail-1 looks very similar and functions very similar to NanoSail-D - circa 2008 design - with enhancements that we didn't have time to incorporate. LightSail-1 is still in design development.

spacegirl: Do you think it is better to take AP classes or post secondary?

Dean: I would suggest that you would take the AP course, then repeat it so you have a mastery of the information and can focus in on your desired field of interest quicker.

Hyper: Would you be up to sail in the space with your own sails ? :)

Dean: No - they'd have to be too big for my mass. :)

abku95: How is the energy transferred and where is it transfered to?

Dean: The photons reflect off the sail and provide small momentum change to the sail.

deepspace: Is there any specific program college students are supposed to take inorder to work with NASA?

Dean: No - NASA utilizes the expertise from all fields of study.

chetman1020: Where was Nanosail launched from?

Dean: Kodiak, Alaska aboard FASTSAT.

spacegirl: Why was there such a rush to launch the nanosail?

Dean: Opportunity knocks - strike while the iron is hot!

spacegirl: Have you ever worked with interns?

Dean: Yes, they helped design NanoSail and have provided help with FeatherSail. I'll probably have two this summer and one in the fall.

CraigNASA: I am going to middle school next year. Are there any programs in the summer for that grade level?

Dean: Not at NASA, but I know of a middle-schooler who designed and built his own cubesat - you could do that, too!

aggelos: Can a physicist work for NASA?

Dean: Yes, they can. Gravity Probe B is a good example.

Hyper: Will we see ''hybrids'' spaceships using both sails and propulsors in the future, much like in the idea of boats using both sails and engines ?

Dean: That's the most likely scenario, but the technology is in its infancy, so it will be many years.

Sabine1: What was the transmission power of the packet radio beacon in Watt?

Dean: Very low - not sure, about half a watt or less.

quod_erat: Does NASA work together with The Planetary Society on solar sail development?

Dean: Not at the moment.

CraigNASA: How long have NASA been working on this?

Dean: Solar sails - since early 70's with Lou Friedman who went on to the Planetary Society. In 2006 or so, NASA had a new millineum program, and NanoSail-D was a result.

Hyper: What's the surface:mass ratio for spacesails ? I mean, the surface it requires for, let's say, 1kg.

Dean: If you want to go very fast, the solar sail should be roughly 10 grams per square meter.

spacegirl: Would nanosails be reasonable for human spaceflight or would they be too slow?

Dean: Too slow right now.

CraigNASA: Do you work in any other feilds in NASA?

Dean: Electronics development - I've worked in microgravity isolation research. Whatever they ask me to do, I do. :)

chetman1020: Which would be the fastest: a sail, an ion engine, a nuclear engine, or a conventional fuel engine?

Dean: Depends on how much fuel you have! And how much mass you want to propel.

Hyper: Are there openings in the chemistry field of study in Nasa ? Is there a chance of a Canadian being ''chosen'' ?

Dean: We'll get you a URL on that. But yes, we have chemistry at NASA - how about looking into CSA?

CraigNASA: Can you give us a link to see news on the sattelite?

Dean: Follow us on Twitter (@nanosaild) and our home page: http://www.nasa.gov/mission_pages/smallsats/nanosaild.html

CraigNASA: Where do you see Solar Sails in 2050?

Dean: At the outer reaches of the solar system, circling the sun and orbiting the Earth.

aggelos: Is there an intership for undergraduate students at NASA?

Dean: Yes, this is the URL: http://intern.nasa.gov/

astroguyz: Any proposals for active sail projects, using laser technology?

Dean: Not that I know of...

quod_erat: What material are the sails made out of. Was graphene considered as an option?

Dean: CP1 - graphene wasn't considered an option.

aggelos: Is NASA cooperating with any other space program like JAXA or ESA?

Dean: Not actively right now, that I know of.

chetman1020: Would solar sails be able to pull a boat in water here on Earth?

Dean: No - you'd have to have a solar sailor instead of a nautical sailor! :)

Hype: I have to go. Keep up your good work, and thanks again for holding this chat with us. And remember, in the past, they probably never thought sails would bring boats to other continents. I do think that in the ''not-so-far'' future, we will see sail-propelled space engines. Have a good day !

Dean: Thank you! Great to have you here.

chetman1020: Haha

Dean: :)

CraigNASA: What is the speed of a nano sattelite at this time?

Dean: If orbiting the Earth, it's going about 18,000 mph.

aggelos: What's the maximum acceleration of a satelite acquired using a solar sail? What's the ratio between acceleration and the area of the sail? Could you give any formulae?

Dean: It depends on the areal density, or mass per area of sail. The lower the value, the faster you will go.

Zethian: As a response to aggelos: i know that they are cooperating with ESA with the James Webb telescope, using ESA's rocket to launch it.

Dean: That's true - I just don't know of any active solar sail cooperation.

spacegirl: Thanks. I really enjoyed this chat. I love learning about all these different topics. :-)

Dean: You're welcome!

chetman1020: How long can sails last in space?

Dean: We don't have enough history of this material in space to know how long they'll last. Only tests have been done on Earth in simulated conditions - but we hope they'll last a long time!

astroguyz: I'm out... great chat. We'll be watching for those late February passes of NanoSailD over the US South East!

Dean: Me, too! Please send pix to http://www.nanosail.org.

SoCal_watcher: With all the space debri isn't it a high risk experiment in LEO?

Dean: No because we're large enough that we'll be coming down quickly.

aggelos: Thanks.

Dean: Have a good day, aggelos.

Dean: Thanks to all of you for the great questions. Keep checking http://www.nasa.gov/mission_pages/smallsats/nanosaild.html for the latest status of NanoSail-D and don't forget about the amateur astronomer image competition: http://www.nanosail.org and http://www.nasa.gov/home/hqnews/2011/jan/HQ_11-027_NanoSail.html. Also follow us on Twitter: http://twitter.com/nanosaild (@nanosaild).

quod_erat: This may seem like a silly question, but is the nanosail project in some way generating revenue? Or is the venture non-profit and of a purely exploratory nature?

Dean: Non-profit in nature, and research into deployable systems.

chetman1020: Can the sails be recycled after use?

Dean: No, they'll burn up on re-entry.

CraigNASA: I wish this chat would neaver end!!! :-)

Dean: I'm having fun, too!

SoCal_watcher: Thanks for the chat!

Dean: My pleasure! Thanks for your questions.

Sabine1: Dear Dean, dear Jason. I have to leave now. Thank you soooooo much for chatting with us. That is a great thing. Ya´ll have a nice day, good luck and every success for your future projects. Best wishes, Sabine (KF5DVW) and Hans-Juergen (DF2RH).

Dean: Jason, a message from Sabine! She thanks you.

Dean: Thanks for being here, everyone! Appreciate the questions and your support of the NanoSail-D project. Keep looking up!

(Moderator Jason): Thanks Dean for taking time out of your day to sit down and answer everyone's questions today. We'll have a transcript posted here in the next few days. Thanks for coming and asking great questions!

Sabine1: But first of all, I thank you Dean :-)

Dean: And I thank you. :)