Japan's Solar Sail Photographed in Orbit

[n2doc]

Analysis by Irene Klotz
Thu Jun 17, 2010 12:49 AM ET


If seeing is believing, this picture comes as sweet relief to a satellite operations team in Japan that has been overseeing the flight of an experimental solar sailing spacecraft. The Japanese Aerospace Exploration Agency, known as JAXA, captured the image after the IKAROS spacecraft deployed a small camera last week. The picture was released on JAXA's website Thursday.

IKAROS -- an acronym for Interplanetary Kite-craft Accelerated by Radiation Of the Sun -- was launched May 21 to test how a very thin, very large membrane can be used much like a sail on ship. Rather than wind, the craft relies on the slight but ever-present force of photons from the sun.

The idea for solar sailing dates back more than 100 years ago and there have been several attempts to test the technology in space. IKAROS, with its 20-meter diagonal sail, is the most ambitious mission to date.

IKAROS also draws electricity from thin film solar cells embedded into the sail, power that can be used to operate an ion propulsion engine for added acceleration. JAXA plans to test the sail over the next five months, as the spacecraft heads to Venus. Of particular interest is whether the satellite's spin can keep the 0.0075 mm-thick sail flat and fully extended.

http://news.discovery.com/space/japans-solar-sail-photographed-in-orbit.html

[On the Road]

1. Been Hearing About This Concept for Years

Good that the Japanese finally took the plunge and are using it to go to Venus. I assume it's just going to orbit and take photos.

It looks oddly primitive, though -- almost like an early 60s-era design.

[Fumesucker]

2. Since 1951 in fact..

http://www.planetary.org/programs/projects/innovative_technologies/solar_sailing/science_fiction.html

Then in May 1951 the leading SF magazine of its time, Astounding Science Fiction, published a detailed account of how solar sails could be assembled in orbit and used for space travel. The account was a nonfiction article, "Clipper Ships of Space," by an engineer named Carl Wiley. Given that he published his article in a science fiction magazine, and wrote it under a pseudonym (Russell Saunders), Wiley himself apparently feared that respectable scientific circles were not yet ready for the solar sailing concept. It took another seven years for a paper on solar sails (by Richard Garwin) to appear in a professional journal, Jet Propulsion. Meanwhile, however, several influential science fiction writers had absorbed Wiley's Astounding article into their creative preconscious. In the early 1960s, they began to produce.

The April 1960 issue of Galaxy Magazine included a novelet titled "The Lady Who Sailed The Soul," by Cordwainer Smith. The story began with the legendary romance of two sailors of space, Helen America and Mr. Grey-no-more. Thousands of years in the future, everyone knows the legends, but they have forgotten the details. "Out of it all, two things stood forth - their love and the image of the great sails, tissue-metal wings with which the bodies of people finally fluttered out among the stars." The story then describes, according to the omniscient narrator, the reality behind the legend: how Helen and the veteran space sailor Mr. Grey-no-more fall in love, become separated by many light-years of space, and are reunited only after Helen endures the dangers and rigors of a forty-year space voyage as the first female sailship pilot.

[Canuckistanian]

3. They're sailing it to Venus?

Wouldn't that be going "against the wind" that they're trying to use for propulsion?

[Posteritatis]

4. Solar sails can tack into the wind in a similar way to nautical sails

If you angle them one way, the craft gains velocity and goes to a "higher" orbit as a result; the other way, it slows down and falls further towards the sun.

[Ready4Change]

5. Orbital Mechanics.

Our instinctual thoughts about how to go from place to place in space don't work well. I've played a couple of orbital spaceflight simulators, and it gets REALLY frustrating.

That basic idea is that you don't fly the spaceship. Instead you use thrust to change the shape of your orbit, at the precise times you WANT to change the shape. To make the orbit bigger (say, to go out to Jupiter) you increase your orbital velocity. That, in effect, flings you outward a ways. Or if you want to go inward you use thrust to slow down your orbital speed, and that makes your orbit shrink, taking you in towards Venus or Mercury.

A solar sail, by tilting 'forward' or 'backward', can increase or decrease it's orbital velocity, and thus, increase or decrease the size of it's orbit. And the sun always shines in space, so it can 'run it's engines' 24/7. It could be might darn cool.

[Canuckistanian]

6. Oh yeah, that's right

Space travel in the Solar system is really just using orbits to get around. I guess that's why you always hear about "windows of opportunity" for launch times.