What is Solar sail: Definition and 26 Discussions

Solar sails (also called light sails or photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The first spacecraft to make use of the technology was IKAROS, launched in 2010.
A useful analogy to solar sailing may be a sailing boat; the light exerting a force on the mirrors is akin to a sail being blown by the wind. High-energy laser beams could be used as an alternative light source to exert much greater force than would be possible using sunlight, a concept known as beam sailing. Solar sail craft offer the possibility of low-cost operations combined with long operating lifetimes. Since they have few moving parts and use no propellant, they can potentially be used numerous times for delivery of payloads.
Solar sails use a phenomenon that has a proven, measured effect on astrodynamics. Solar pressure affects all spacecraft, whether in interplanetary space or in orbit around a planet or small body. A typical spacecraft going to Mars, for example, will be displaced thousands of kilometers by solar pressure, so the effects must be accounted for in trajectory planning, which has been done since the time of the earliest interplanetary spacecraft of the 1960s. Solar pressure also affects the orientation of a spacecraft, a factor that must be included in spacecraft design.The total force exerted on an 800 by 800 metre solar sail, for example, is about 5 newtons (1.1 lbf) at Earth's distance from the Sun, making it a low-thrust propulsion system, similar to spacecraft propelled by electric engines, but as it uses no propellant, that force is exerted almost constantly and the collective effect over time is great enough to be considered a potential manner of propelling spacecraft.

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  1. D

    B Could solar sails be used as turbines for power generation?

    It seems as though two advantages to using a solar sail turbine system instead of solar panels would be (1) the sails may not degrade as quickly as the solar panels, and (2) a sail turbine system may be lighter than a solar panel (and therefore less expensive to launch into orbit). The drawback...
  2. V

    A Calculation of the "lightness number" for solar sails

    Hello, In the wikipedia article about solar sails the lightness number is mentioned and the calculation is the characteristic acceleration ac divided by the Sun´s local gravity (distance: 1AU): λ = ac / 5.93 why do they use 5,93 m/s^2 for the sun´s gravity and not 274 m/s^2?
  3. N

    On board a laser powered solar sail

    Can an on board laser be used to propel a solar sail spacecraft if the laser is pointed at the sails ? Would Newtons third law affect the laser and maybe prevent the ship from moving ? Thank you for answering my very ignorant questions. NineNinjas911
  4. MARX

    Kleppner-Mechanics Solar sail 2

    Homework Statement 4.18 With reference to Example 4.21, consider the design of a solar sail intended to reach escape velocity from the Earth 2gRe = 11.2 km/s using only the pressure due to sunlight. The sail is made of a Kapton⃝R film 0.0025 cm thick with a density 1.4 g/cm3. Take the solar...
  5. wolram

    B Can a solar sail be accelerated 20% speed of light

    This seems over optimistic to me but is 20% the speed of light feasible? https://www.sciencedaily.com/releases/2017/02/170201162456.htm
  6. Stefen

    B Da Vinci's flying machine meets solar sail?

    so the question has been previously answered as to what would happen if a fan was in the vacuum of space. but the responses I seen all ask what the fan would push on or up against. what if the fan where to push against light? solar sails are able to have a force push against them in space?
  7. G

    Solar Sail/ Mirror Redshift & Blueshift

    Hi all, I was hoping you could help me out with this one. Im trying to calculate the redshift or blueshift of a photon that strikes a mirror and reflects. I know E=pc, and that 2p is the momentum transfer. I also know that kinetic energy is 2p/M (of the mirror). However, this says that...
  8. cyberdiver

    Equilibrium distance for solar sail

    This is not actually a homework assignment, but something I decided to try in my own time. I wanted to find the radius from a star at which a solar sail would be held at equilibrium (radiation pressure = gravity), given mass per unit area and stellar luminosity at a reference radius. So I...
  9. Monsterboy

    Future possibilities of Planetary society's solar sail idea.

    I don't know how long this solar sail idea has been here , the Planetary society's second solar sail failed to achieve its objective right ? I am interested in the applications of this technique. 1) Is it possible to use them to deflect large asteroids and comets away from the Earth ? 2) Is...
  10. GiantSheeps

    Can We Combine Solar Sails and Ion Thrusters for Faster Space Travel?

    I've heard a lot of people talk about solar sails versus things like Ion thrusters, and it seems that both have their advantages and disadvantages. So I was wondering whether or not it's possible to use both on a single spacecraft ? That way you could get the speed of an ion thruster along with...
  11. M

    Solar Sail Physics - Do they work on a large scale?

    Hello physicists! I'm hoping you can help me with a question I'm pondering for a book. At what acceleration could a 4 km^2 solar sail move a 1 metric megaton starship? Assume we're using the solar radiation from the Sol system as our force and that the solar sail in questions is as low mass...
  12. N

    Conservation of momentum and laser powered solar sail

    I was watching a show on the science channel called "Alien Encounters". Well in one of them they showed a ship that looked as if it was propelling itself by firing a laser at it's solar sail. Now I am pretty sure that from what I understand about physics, that would not be possible. Correct if...
  13. T

    Equations of Motion of a Solar Sail HELP

    Homework Statement I am reposting an edited version of this problem from a previous post of mine, due to it not being entirely relevant to that post, and also the question was asked after the thread had been replied to, so looks like an answered question. I also aim to give more detail here...
  14. U

    Can Laser-Pushed Solar Sails Achieve Near Light Speed by Circling Back?

    What if you had a laser solar sail and in front of the sail was a small thruster (either chemical or itself a laser)...thrusting constantly at a right angle to the forward direction of the craft so that the sail's trajectory would bring it back towards the first (main/stationary) laser that...
  15. Y

    Can Graphene Be Effectively Used in Solar Sails?

    I am wondering if the properties of graphene could have implications for solar sails. I don't know much about graphene but I do know that it is only an atom thick and very very strong and theoretically can be made of infinite size. Are there any problems that graphene would face in terms of...
  16. U

    Solar sail using radioactive decay

    Could you make a solar sail that derives it's energy from the decay of a radioactive element such as plutonium, uranium, or palonium? I understand that such elements radiate in all directions but if you had a 1 kg sphere of it attached to a boon which was attached to a reflective sail (e.g...
  17. J

    Radiation Pressure and Solar Sail

    Consider a spacecraft attached to a sheet of material, a "sail," that absorbs sunlight. Assume that the sail is positioned to face the Sun and that the combined mass of the spacecraft and the sail is m. How large does the area of the sail have to be to propel the spacecraft away from the...
  18. R

    Solar Sail Acceleration: A vs B - Which is Faster? Find Out Now!

    if you had two spacecraft which had a solar sail as its means of Propulsion A & B, and were both identical. Spaceship A has light from the sun to push it along its way. Spaceship B has only gamma rays to push it along.(both craft have the whole of their sail surface covered with their...
  19. S

    Does Photoelectric Conversion Affect Momentum Transfer in Solar Sails?

    Suppose you have a solar sail that was capable of perfect photoelectric conversion. So this means that photons from the Sun are striking your solar sail, and also being photoelectrically converted to electrical current. My question is - does the photoelectric conversion at all affect the...
  20. Y

    Using BEC to Propel a Solar Sail - What Do You Think?

    This is kind of a weird question, so I'll just throw it out there. So I was talking to my mate about BEC a couple of weeks ago and he proposed an interesting idea. I was telling him how BEC was used to slow down light to 38mph, what he suggested was using this concept to move a solar sail. So...
  21. J

    Solar Sail Questions: Analyzing & Approximating Motion

    I did a simulation of a solar sail in Java. It seems to be accurate; when you face the sail in one direction, it approaches the sun, in the other direction it goes outward, when it's parallel to the sun's rays it moves in an ellipse and when it's perpendicular, the ellipse is elongated. (This...
  22. J

    Why did I make this error?What is the error in my equation?

    The problem is that I'm doing what seems to be perfectly reasonable algebra but I'm getting a result that makes no sense. Let's say a photon travels from the left and hits a stationary solar sail which is perpendicular to the light. There is perfect reflection and a change in momenta for both...
  23. Gokul43201

    Cosmos-1: Solar Sail Spacecraft Launches Tuesday

    http://news.bbc.co.uk/2/hi/science/nature/4110912.stm http://msnbc.msn.com/id/8291710/ http://www.rferl.org/featuresarticle/2005/6/5B9C7AAC-6F11-424A-9CD3-2B12F1B9252D.html http://planetary.org/solarsail/prelaunch_report1_20050523.html
  24. P

    When will the Cosmos 1 solar sail spacecraft be launched?

  25. I

    Why doesn't the orbit increase in radius?

    The following site shows that when a sail is orientated so that it faces away from the sun, the net force is pushing outwards from the sun and is also opposing the orbit. http://solarsail.jpl.nasa.gov/introduction/how-sails-work.html It makes sense that the craft should slow down, but why...
  26. D

    Understanding Solar Sails: The Physics Behind the Poofing Effect

    Greetings ! Please read this short story about solar sails' physics: http://www.spacedaily.com/news/rocketscience-03zg.html Can the experts here provide their opinions, please ! I personally thought that was all simple and basic stuff long since solved by physics. I mean, a photon...