Archive for April 2010

Solar Sails   14 comments

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.

                                               voyager_1 voyager_2

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.

solarsail4. 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.“

Mariner Probe

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.

Where Life Begins –Earth and Beyond   10 comments


Hydrothermal Origins of Life Theory


hydrothermal_ventUntil 1977 scientists believed that all forms of life ultimately depended on the Sun for energy. With the 1977 discovery of the first hydrothermal vent, (Geysers that billow out from the sea floor.) and the teeming, diverse arrays of life surrounding its base Astrobiologists are now believe that life on Earth might have originated in the sulphurous base of hydrothermal vents.

Vent ecosystems are the only system on Earth that we know of where life can thrive in the complete absence of sunlight offering an alternative way for life to meet its fundamental need for energy. They depend on microbes that tap into the geyser water’s chemical energy – energy originating from within the Earth itself.

hydrothermal vent Amino acids, the building blocks of life from which many of the primitive molecules required to jump-start life form from, could have occurred within these hydrothermal vents. Vent environments minimize oxygen and radiation, which can damage primitive molecules. Along with geothermally-heated mineral-rich water these molecules could have been thrown up into cooler waters where life may have originated

Astrobiologists have struggled for years to define the range of conditions in which “life as we know it” could exist. The discovery of hydrothermal vent ecosystems expanded that range. They were the first discovery of life as we don’t know it and suggest this is a realistic and possible scenario.

The ability of life to tap such geothermal energy raises interesting possibilities for other worlds like Jupiter’s moon Europa, and ancient Red planet Mars.

                                                 Europa (Thera and Thrace Macula (2dark features)   Mars

BlackSmokerGeysereuropa Europa is squeezed and stretched by gravitational forces from Jupiter and neighbouring Galilean satellites. Its icy surface has, gradually, broken up and reformed into icebergs, but the core is considered molten. Tidal friction heats Europa’s interior possibly enough to maintain beneath the icy surface, the solar system’s biggest ocean where active hydrothermal vents are believed to exist. Astrobiologists theorize that much like the hydrothermal vents at the bottom of Earth’s oceans the ones in Europa’s dark seas be similar enough to provide all of the ingredients needed to support life.


NASANASA is planning to send a probe to Europa within the next 20 years, which will penetrate the ice  layer in search of water and vent debris. Work carried out on Earth suggests that if basic ingredients for the origins of life are there, there is a chance of discovering vent-based life forms,