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Ikaros Spacecraft Successfully Propelled In Space

Posted by timothy on from the best-place-for-it-really dept.

An anonymous reader writes "Japan's IKAROS spacecraft has already successfully deployed the first solar sail in space, but today it made the only first that really matters: it successfully captured the sun's rays with its 3,000-square-foot sail and used the energy to speed its way through space. Each photon of light exerts 0.0002 pounds of pressure on the 3,000-square-foot sail, and the steady stream of solar exposure has succeeded in propelling the nearly 700-pound drone."

8 of 229 comments (clear)

  1. Sad writing (and summary) by waives · · Score: 5, Insightful

    stupid writers reported the total force on the sail (1.12mN) = 0.0002 lbf as the per-photon pressure.

  2. Top Speed ? by meerling · · Score: 5, Insightful

    Great, now they can see if it's acceleration is anywhere near what proponents and sci-fi writers have been saying for decades.
    Also, maneuverability, as I just don't see most of those sailing techniques working in a vacuum.
    Can't wait for final results :)

    1. Re:Top Speed ? by jpmorgan · · Score: 4, Insightful

      No, not really. Photons carry several orders of magnitude more momentum than solar wind. The only "practical" way to capture momentum from solar wind is with a magnetic sail, since the surface area required (hundreds of square km) would be unfeasible with any physical material.

  3. Re:I wouldn't call it IKAROS by Anonymous Coward · · Score: 3, Insightful

    Also, it's going the wrong direction.

  4. Use scientific units... by Anonymous Coward · · Score: 4, Insightful

    Use SI-units for crying out loud. This is a scientific context. Not a grocery list. Also so the rest of the 90% of the world population can understand it.

  5. Use scientific units... by Co0Ps · · Score: 5, Insightful

    Use SI-units for crying out loud. This is a scientific context. Not a grocery list. Also so the rest of the 90% of the world population can understand it..

  6. Epic unit fail by johndoe42 · · Score: 4, Insightful

    > Each photon of light exerts 0.0002 pounds of pressure on the 3,000-square-foot sail

    C'mon people, can't you even check if what you're saying makes the slightest sense before posting it? There are two impressive errors in that sentence. First, each photon [1] applies some impulse to the sail. Impulse is what you feel pushing you back when someone punches you. It's a one-time effect and is neither a force (impulse per unit time) nor a pressure. Second, a pound might be a unit of force or of mass, depending who you ask, what you're talking about, and how pedantic you are, but it is never a unit of pressure. (If it were, you might say that the Earth's atmosphere weights 14 pounds, a statement that makes no sense at all.)

    [1] For the physically inclined, there's a more subtle error, too. The impulse supplied by a photon is related to its momentum, which is a function of wavelength. So, unless something weird's happening in the sail, blue photons supply a larger impulse than red photons.

  7. Ok, we get it by FleaPlus · · Score: 4, Insightful

    Ok folks, we get it -- almost every single comment so far has been about the unit error in the article. You noticed how silly it is, and are therefore smart. Can we get past that now and talk about how ridiculously awesome it is that the first-ever solar sail has been successful, and is propelling through the inner solar system by riding photons from the Sun?