The James Webb Space Telescope (JWST)

About JWSTThe James Webb Space Telescope (JWST) is a large, infrared-optimized

space telescope, scheduled for launch in 2013. JWST will find the first galaxies that formed in the early Universe, connecting the Big Bang to

our own Milky Way Galaxy. It will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. It's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability

in the visible range.

It will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Both the mirror and sunshade

won't fit onto the rocket fully open, so both will fold up and open only once JWST is in outer space. JWST will reside in an orbit about 1.5

million km (1 million miles) from the Earth.

The James Webb Space Telescope was named after a former NASA Administrator.

Four Themes

Planetary Systems and the Origins of Life

The Birth of Stars and Protoplanetary Systems

Assembly of Galaxies

First Light and Reionization

Planets & Origins of Life

The first planet outside our solar system was discovered in 1995.

Since then, we have discovered a multitude of planets around other

stars. We have come to the realization that planets may in fact

be quite common. Most of the planets discovered so far are large

gas giants like Jupiter, although modern detection techniques are

now helping scientists detect smaller planets. The ultimate

objective of the search is to find another Earth and perhaps even

signs of life elsewhere in the Universe.

The Birth of Stars and Protoplanetary Systems

Stars, like our Sun, can be thought of as “basic particles” of the Universe, just as atoms are “basic particles” of matter. Groups of stars make up galaxies, while planets and ultimately life arise around stars. Although stars have been the main topic of astronomy for thousands of years,

we have begun to understand them in detail only in recent times through the advent of powerful telescopes and computers.

A hundred years ago, scientists did not know that stars are powered by nuclear fusion, and 50 years ago they did not know that stars are

continually forming in the Universe. Researchers still do not know the details of how clouds of gas and dust collapse to form stars, or why most stars form in groups, or exactly how planetary systems form. Young stars within a star-forming region interact with each other in

complex ways. The details of how they evolve and release the heavy elements they produce back into space for recycling into new

generations of stars and planets remains to be determined through a combination of observation and theory.

The Assembly of Galaxies

How did the very first galaxies form? How did we end up with the large variety of galaxies we see today? We now know that extremely large black holes live at the centers of most galaxies – what

is the nature of the relationship between the black holes and the galaxy that hosts them?

These are some of the fundamental questions about galaxies that the JWST will tackle.

First Light and Reionization

Until around 400 million years after the Big Bang, the Universe was a very dark place. There were no stars, and there were no galaxies. Scientists would like to unravel the story of exactly what

happened after the Big Bang. The James Webb Space Telescope will pierce this veil of mystery and reveal the story of the formation of the first

stars and galaxies in the Universe.

James Webb Space Telescope vs. Hubble Space Telescope

Size

HST is 13.2 meters (43.5 ft.) long and its maximum diameter is 4.2 meters (14 ft.) It is about the size of a large tractor-trailer truck. By contrast, JWST's sunshield is about 22 meters by 12 meters (72 ft x 39 ft). A Boeing 737-200 is 100 feet long! HST is 13.2 meters (43.5 ft.) long and its maximum diameter is 4.2 meters (14 ft.) It is about the size of a large tractor-trailer truck. By contrast, JWST's sunshield is about 22 meters by 12 meters (72 ft x 39 ft). A Boeing 737-200 is 100 feet long!

JWST will have a 6.5 meter diameter primary mirror, which would give it a significant larger collecting area than the mirrors available on the current generation of space telescopes. HST's mirror is a much smaller 2.4 meters in diameter and its corresponding collecting area is 4.5 m2, giving JWST around 7 times more collecting area! JWST will have significantly larger field of view than the NICMOS camera on HST (covering more than ~15 times the area) and significantly better spatial resolution than is available with the infrared Spitzer Space Telescope.

Orbit

The Hubble Space Telescope orbits around the Earth at an altitude of ~570 km above it.

JWST will not actually orbit the Earth - instead it will sit at the L2 Lagrange point, 1.5 million km away! Because HST is in earth orbit, it was able to be launched into space by the space shuttle. JWST will be launched on an Ariane 5 rocket and because it won't be in earth orbit, it is not designed to be serviced by the space shuttle.

A Lagrange point is one of the five positions in interplanetary space where a small object (like a satellite) can be relatively stationary with respect to two larger objects (like the Earth and the Sun). It is analogous to an earth satellite in a geosynchronous orbit that allows it satellite to stay stationary over one spot on the Earth. At a Lagrange point, a satellite can stay "fixed" in space, rather than orbiting the Earth.

JWST is an international collaboration among NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). Over 1000 people in more than 17 countries are developing the

James Webb Space Telescope.