Sunday, August 15, 2010

New space telescope is preparing to replace Hubble

full scale model of the James Webb Space Telescope (JWST) >

James Webb Space Telescope (JWST or Webb) is a planned infrared space observatory and is the scientific successor to the Hubble Space Telescope. The JWST or Webb Telescope's main scientific goal is to observe the most distant objects in the universe beyond the reach of either ground based instruments or the Hubble. 

Achievements of Hubble

Hubble Space Telescope (HST)
Since it’s launch in 1990, the Hubble Space Telescope (HST) is our eyes in outer space and it’s ability to take an extremely sharp images with no background light helped NASA to discover and study many crucial phenomenons such as black holes (super massive stars collapsing in themselves due to a huge gravity force) , supernovas (the death explosions of massive stars), nebulaes (gas clouds forced outwards by a dying star), proplyds (protoplanetary disks - flattened disks of gas and dust, the likely birthplaces of new planetary systems), distant planets size of Jupiter, and many others.. Hubble also helped astronomers to calculate how old is our universe (roughly 13.75 billion years).
You can check the list of top 10 Hubble discoveries here

So what is the next step in astronomy? 

The Webb’s primary scientific mission has 4 main components: to search for light from the first stars and galaxies which formed in the Universe after the Big Bang, to study the formation and evolution of galaxies, to understand the formation of stars and planetary systems and to study planetary systems and the origins of life. No doubt that the improved abilities of this new generation space telescope will spot distant planets which have a size of the Earth, and it also should lead astronomers deeper into the secrets of the dark matter and the dark energy.
This crucial scientific goals has united the United States space agency (NASA), the European Space Agency (ESA), the Canadian Space Agency (CSA) and contributions from additional fifteen nations to work together on Webb project. Current plans call for the telescope to be launched on an Ariane 5 rocket in June 2014 on a five-year mission.

Webb’s technological advantages over Hubble

Because it takes the time for light to travel, the further away an object is, the further back in time we are looking.

As shown in this illustration, Hubble (HST) can see the equivalent of young galaxies and Webb (JWST) will be able to see young stars and “baby galaxies”. The Big Bang caused the universe (and galaxies in it) to expand, so most galaxies are moving away from each other. The most distant (and thus youngest) galaxies are moving away so quickly that the light they emit gets shifted towards the red and infrared of spectrum. This can be compared to listening to a train whistle shifting from higher to lower frequency as it passes by. This phenomenon is main reason for creating the Webb as a primary infrared space observatory, with wavelength coverage from 0.6 to 28 micrometers (from 6.0x10ˉ⁷m to 2.8x10ˉ⁵m). This is the basic advantage over Hubble, which is mostly oriented to visible and UV light – it’s coverage is from 0.8 to 2.5 micrometers (more micrometers means lower frequency = deeper infrared coverage).
wavelenght of rays

Webb's telescope mirror
The Webb’s key element is it’s eye - the characteristic mirror made of 18 hexagonal segments with three different prescriptions. This mirror is made of segments so that it can fit up to rocket and unfold in outer space after launch. Diameter of this mirror is 6.6m and collecting area is 25m², which is 6.25 times more then Hubble’s 4m² mirror (2.4m diameter). This enlargement became possible thanks to light and strong mirror material – beryllium, which securely keeps it’s shape at cryogenic temperatures (-220 degrees C, as planed for this opservatory). Beryllium is also a good conductor of electricity and heat, and is not magnetic. That’s why it is often used to build parts for supersonic (faster-than-the-speed-of-sound) airplanes and the Space Shuttles.

Webb’s mirror also have longer focal length (131.4m compared to Hubble’s 57.6m) which allows larger magnification of distant objects.


Other new technologies and light materials made possible for Webb to be much lighter then Hubble (6,200kg compared to 11,110kg) beside larger dimensions and improved abilities. More detailed informations about Webb can be viewed on these links:

Webb FAQ     Webb technology     Webb telescope site      Webb wikipedia

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