 |
Solar-Photon Hoop Sails For Extrasolar Travel
The solar-photon hoop sail idea was once again advanced by CUNY physicist Gregory Matloff at the Second Solar Sail Symposium held last month in New York City.
The idea for hoop-shaped solar sails was first placed before a larger audience (and specifically the sf community) in a 1951 paper Clipper Ships of Space, published in Astounding Science Fiction by engineer Carl Wiley. The idea of a starlight sail or light sail was later picked up by sf writer Cordwainer Smith in his 1960 story The Lady Who Sailed The Soul. which explicitly details the use of solar sails in extrasolar travel. Matloff provides an analysis of this possibility in his paper.
Just two years later, in 1962, Jack Vance published Sail 25, an excellent short story that provides a fairly meticulous description of a hoop sail:
In the story, Vance ups the ante for a group of space cadets under the tutelage of grizzled spaceman Henry Belt, making it clear that poor solar sailing could result in visiting the outer planets or even leaving the solar system entirely.
Matloff concludes:
Take a look at Matloff's paper The Hoop Solar-Photon Sail and Extrasolar Travel (PDF) via Centauri Dreams via Atomic Rockets.
A solar-photon hoop sail consists of a thin reflective membrane within a supporting, possibly inflatable hoop. Hoop sails may be an alternative to parachute and hollow-body sails for extra-solar application. In all likelihood, payload would be suspended from the rim... Hoop sails appear to have competitive performance to parachute and hollow-body sails. They are easier to deploy than parachute sails, and are less susceptible to micrometeoroid damage than hollow-body sails. Scaling hoop sails from small test items to very large radii seems possible.
(From The Hoop Solar-Photon Sail and Extrasolar Travel [PDF})
Massaging the numbers for a hoop sail to deep space, Matloff comes up with a ‘sundiver’ trajectory that allows a hoop sail spacecraft to exit the Solar System at about 635 kilometers per second (130 AU per year). This is sufficient to reach the inner fringe of the Oort Cloud in several decades, while a crossing to the Centauri system would involve 2,000 years. That’s about twice the time for an optimized mission with a space-manufactured sail.
(From Hoop Sails: An Interstellar Possibility? [Centauri Dreams])
The pressure of radiation, of course, is extremely light - on the order of an ounce per acre at this distance from the sun. Necessarily, the sail must be extremely large and extremely light. We use a fluro-siliconic film a tenth of a mil in gauge, fogged with lithium to the state of opacity. Such a foil weighs about four tons to the square mile. It is fitted to a hoop of thin-walled tubing, from which mono-crystalline iron cords lead to the hull.
(Read more about Vance's hoop light sail)
The performance of a hoop sail will be competitive with other solar-photon-sail interstellar configurations. The payload fraction is lower than that of certain other configurations, which may not be a disadvantage since sail mass can be used as cosmic-ray shielding during the interstellar cruise.
Advantages of the hoop sail over the parachute sail include scalability and ease of deployment. The hoop sail is less susceptible to micrometeoroid-caused deflation than the hollow-body sail.
A ripstop array is almost certainly necessary to prevent sail ripping due to micrometeoroid impacts. Such an array will increase total mass spacecraft mass and degrade performance by only a few percent.
The work presented here should be viewed as a very preliminary analysis. Much additional research is required before interstellar hoop sails can be declared feasible.
(From The Hoop Solar-Photon Sail and Extrasolar Travel [PDF})
Scroll down for more stories in the same category. (Story submitted 8/13/2010)
Follow this kind of news @Technovelgy.| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
Would
you like to contribute a story tip?
It's easy:
Get the URL of the story, and the related sf author, and add
it here.
Comment/Join discussion ( 0 )
Related News Stories - (" Space Tech ")
How Do You Put An Asteroid Into Earth Orbit? Carefully!
'...she would have to be coaxed by another series of pats into a circular orbit.' - Robert Heinlein, 1939.
PD Aerospace Space Plane By 2023
'The sleek, tapered space shuttle lay immobile upon the private landing field...' - Frederic Arnold Kummer, Jr., 1940.
International Space Station Leak Plugged - With Finger
'These tag-alongs search out stray leaks' - Robert Heinlein, 1948.
Space Drones - UK's Effective Space To Launch Rocket Tugs
'Twenty rocket tugs towed it from its Earth hangar out into space.' - Nat Schachner, 1937.
Technovelgy (that's tech-novel-gee!) is devoted to the creative science inventions and ideas of sf authors. Look for the Invention Category that interests you, the Glossary, the Invention Timeline, or see what's New.
Current News
Sleeep PRO Earplug For Maximum Rest
'Merton... placed the electrodes of the sleep-inducer on his forehead.'
Inspired By Japan, Nap Pods For Hajj
It's always a good time for a nap.
Amphibio 3D Printed Gill Shirt
'... we can descend and live down there at one of those year-round aquatic resorts.'
How Do You Put An Asteroid Into Earth Orbit? Carefully!
'...she would have to be coaxed by another series of pats into a circular orbit.'
PD Aerospace Space Plane By 2023
'The sleek, tapered space shuttle lay immobile upon the private landing field...'
Foldimate Folds Your Clothes Perfectly
Look ma, my room is clean! I can hear you now.
Robots Help People Get Dressed, As Predicted In 1931
Yes, people of the future, robots will dress you.
International Space Station Leak Plugged - With Finger
'These tag-alongs search out stray leaks.'
Robot Snake Flies, Fights Fires
Just a prototype, but still amazing.
IPAL Chinese Robot Babysitter
'But Nanny is different...'
ZKZM-500 LASER Assault Rifle
'The Iranian reached back into the locker and got a pair of laserifles.'
LA Subway Scanner, As Seen In 'Total Recall'
'I'm afraid to tell you this Mr. Quaid, but you have suffered a schizoed embolism...'
Sion Electric Car Covered With Solar Panels
'It drew its power from six square yards of sunpower screens on its low curved roof.'
PAL-V Liberty Flying Helicopter Car
'...lifted themselves to skimming flight upon whirling helicopters."
Space Drones - UK's Effective Space To Launch Rocket Tugs
'Twenty rocket tugs towed it from its Earth hangar out into space.'
DIY Autonomous Robot Detects Trash
'The search-bug detached itself and rolled forward.'
