The US space agency boasts that it will literally "look back in time to see the very first galaxies that formed in the early Universe". As if those claims were not bold enough, scientists have now surmised that the eventual successor to the world famous and beloved Hubble Space Telescope may - thanks to its 6.5m golden mirror and exquisitely sensitive cameras - have a another extraordinary talent. The JWST, as it is called, may be able to look for signs of alien life - detecting whether atmospheres of planets orbiting nearby stars are being modified by that life.
Webb contains novel technologies that have never previously been flown in space
Despite this, the project to build it narrowly survived cancellation by the US Government in 2011. That was in no small part down to its (perhaps appropriately) astronomical cost - an estimated $10bn rather than its originally planned $1bn. Back on Earth, however, astronomers - including the University of Washington team who proposed "life-detection" observations using the telescope - are unerringly thrilled at the prospect of its launch.
How do you detect life on distant planets?
University of Washington astronomer Joshua Krissansen-Totton and his team have looked into whether the telescope could detect signs of what they call "biosignatures" in the atmospheres of planets that are orbiting a nearby star. "We could do these life-detection observations in the next few years," says Mr Krissansen-Totton. The basis for this search may lie in JWST being so sensitive to light that it could pick up so-called "atmospheric chemical disequilibrium". It may not be a catchy term, but it is an idea with a long heritage, promoted by celebrated scientists James Lovelock and Carl Sagan. The reasoning is that if all life on Earth disappeared tomorrow, the many gases which make up our atmosphere would undergo natural chemical reactions, and the atmosphere would slowly revert to a different chemical mixture. It is continually held away from this state by organisms on our planet expelling waste gases as they live.
Because of this, searching for signs of oxygen (or its chemical cousin ozone) has long been thought to be a good way of finding life. But this does rest on the assumption that extraterrestrial life runs by the same biological rules as our own. It might not. Therefore, assessing atmospheric chemical disequilibrium - looking for other gases and figuring out how far out of kilter from "normal' a planet's atmosphere sits - could be key to finding alien life of any kind. The chemical make-up of the atmosphere of a planet orbitin g another star can be measured in light by carefully measuring the minuscule dip in starlight as the planet passes between us and the star during the planet's orbit. The gases in the planet's atmosphere cause the light reduction to vary with the wavelength - or colour - of light, revealing information about how much of each chemical is present.
Where is the best place to look?