Headline Dec 14, 2014/

''' O* ALIEN LIFE ''' : 

'' WE COME IN PEACE !?'' : !WOW!

TWINKLE, twinkle, little star,

How I wonder  what you are?

Up above,....the sky so high-

Like a diamond..... in the sky

MOST ASTRONOMICAL telescopes employ reflection to focus starlight. A concave mirror creates an image from this light using a design pioneered in the 17th century, by Sir Isaac Newton.

Those telescopes that do not employ reflection use refraction. They have a system of lenses, an idea first used to look at the  stars by Galileo.

But there is a third way to focus light. A century and a half after Newton, and more than two after Galileo, a Frenchman called Augustin-Jean-Fresnel worked out that you can do it using diffraction.

A set of concentric rings, alternately transparent and opaque, will scatter and spread light waves in a manner that causes them to reinforce each other some distance away, and thus form an image.

The rings are known as a zone plate. And Fresnel's countryman, Laurent Koechlin, of the  Midi-Pyrenees observatory, thinks zone plates are the way to find out if there is life on other planets.

Seeing oxygen in another planet's atmosphere would be a giveaway of biological activity because the gas is so reactive that it needs to be continuously renewed.

That would almost certainly mean something akin to photosynthesis was going on, for no known non-biological process can produce oxygen from common materials in sufficient quantity.

Looking at such an atmosphere, though, is tricky. Stars are so much brighter than the planets which orbit them that their light overwhelms the small amount reflected from a planet surface.

And this is where Fresnel comes in.

Fresnel telescopes have not been developed in the past because the image formed by one that was large enough to rival a useful-sized reflecting telescope would be several kilometres from the zone plate.

But Dr Koechlin does not worry about that, because his Fresnel telescope will be in space. Free of the confounding effects of the Earth's own atmosphere, it will be able to isolate images of alien planets-

Make spectra of the light from their sir, and examine those spectra for the characteristic dark lines that are caused by part of the light being absorbed by particular gases.........oxygen among them.

Space telescopes are nothing new, of course, and several more in the works.

But existing plans to photograph extrasolar planets in this way involve orbiting arrays of reflecting telescopes all pointing in exactly the same direction.

An array is needed because a single mirror big enough to do the job of separating star from the planet would be too large to launch.

The problem is the word  ''exactly'' .

It means just that. The formation would have to fly ''with a precision of a few billionth of a metre.''

The Honour and Serving of the operational research continues. Thank you for reading and maybe, learning. And see Ya on the next post in the future.

With respectful dedication to Almighty  God, -the creator of heavens and all things, great and small:

The earth year comes to an end, and we the World Students Society Computers- Internet- Wireless,   seek your blessings to go forward with honour, dignity, and hard work, in the highest traditions of serving your creations.

'''Grant us the courage, and the will, to build a world based on human endeavour and sharing. Please!'''

Ameen!

''' Spiritual Tectonics '''

'''Good Night and God Bless

SAM Daily Times - the Voice of the Voiceless