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Ikaros Spacecraft Successfully Propelled In Space
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."
A 3000 square foot sail is about 16 metres across. Imagine what you could do with a sail one kilometre across. To get to Titan: kill your orbit around the sun with your sail. Gravitational slingshot off the sun with a single burn, possibly combining the sail with a solar thermal rocket, then aero-brake in the atmosphere of Saturn, then repeat at Titan. How's that for a fast trip?
http://michaelsmith.id.au
> Based on total force of 1.12mN and assuming a static photon count, that looks like an acceleration of 4E-6 m/s^2, so each day it will pick up a velocity of about 0.3 m/s.
Yep. ( ((1.12 millinewton) / (700 pounds)) * (1 day) = 0.304767031 m / s )
Most people don't know what a N/m^2 is, sure, but a N/m^2 also has the name Pascal (Pa), which a lot of people do know. Even U.S. high schools are pushing students to use Pa for pressure units instead of atmospheres or Torr or the dreaded inches of Hg. In any case, grams times the standard "g" constant still isn't pressure, it's force, and gram is never an SI unit of pressure or force, nor is gram times g.
The best way to predict the future is to invent it.
This means they have a most precise frequency standard behind their doppler measurements.
Bruce Perens.