Solar Sails

Solar Sail Space Crafts

 

Space craft propelled directly by the power of sunlight (solar cells are indirect power).

Two projects are set for launch this year:-

•   IKAROS – launched by Japanese Space Agency JAXA
•   SOLARSAIL-1 by US based Planetary Society

(These are demonstrations to show that it can work, but they are very tiny!)

Solar Sail Craft Basics

Constructed from Gossamer – thin reflective sails capture photons

•   Photons are packets of energy that make up sunlight

The sails gain momentum from the photons as they are reflected from their surface. Energy gained pushed the craft forwards gently. The force of sunlight is very little but this is fine as their CO2 acts against it in the vacuum of space.

Future sails could be made of nanotube mesh – 30 times lighter, and could increase acceleration dramatically.

Travel and Speeds

With the Sun set to shine for a good billion years or so yet, it can be considered an endless fuel supply therefore a Solar Sail Craft could in theory, reach speeds of hundreds of kilometres per hour making travel to Pluto a mere three years and to the outer limits of the Solar System years rather than decades. NASA’s Voyager craft took thirty years to reach these limits. A Solar Sail Craft launched today would pass it in ten years.

                                              

Other Solar Sails

They would need sails 100m across and a boost from a large and unrealistically expansive laser system as the Sun’s energy decreases with distance. However laser-boosted systems could see a Solar Sail Craft travelling at speeds of up to 20% speed of light (60,000km/hr or 45,000mph) every second. This would make visiting neighbouring stars in our lifetime our best possibility.

Brief History

1. Concept first proposed by German astronomer Johannes Kelper in seventeenth century
2. 1862 Scottish physicist James Clark Maxwell discovers that light exerts a pressure on a surface.
3. 1867 Jules Vernes suggests light pressure could provide a mechanical means of propulsion.

4. 1924 Russian scientist Fridrickh Arturovich Tsander wrote “For flight in Interplanetary Space I am working on the idea of flying using tremendous mirrors of very thin sheets capable of achieving favourable results.“

5. 1971 When NASA’s probe Mariner ran low on steering thrusters fuel en route to Venus engineers angled its solar panels into the Sun and used solar radiation pressure to steer it back on course.

6. 2005 Cosmos-1 a Solar Sail designed by US Planetary Society failed its test, due to rocket failure on launch vehicle, resulting in it being unable to reach its intended orbit.

                                                                        

7. 2008 NASA’s Nanosail-D mission, to test the Solar Sail’s deployment techniques. Lost during launch failure.