The Hubble Space Telescope is ailing — its main camera stopped working a few weeks ago, and several of its stabilizing gyroscopes have failed. One more space shuttle servicing mission is scheduled for September 2008. The HST has not only been a marvelous scientific tool, it may well be the best public relations tool astronomy has ever had. In addition, it has added deeper meaning to what David wrote 3000 years ago in Psalm 19:
The heavens declare the glory of God,
and the sky above proclaims his handiwork.
Day to day pours out speech,
and night to night reveals knowledge.
There is no speech, nor are there words,
whose voice is not heard.
Their voice goes out through all the earth,
and their words to the end of the world. (ESV)
The next generation space telescope is the James Webb Space Telescope. Its main mirror will have six times the reflecting surface area of the Hubble’s mirror, but the overall satellite will be smaller than the Hubble. It is presently in the planning and design phase, and is scheduled to be launched in 2013.
The design of the telescope is a radical departure from that of the Hubble. It’s primary mirror is made out of a number of smaller hexagonal mirrors which will act together as if they were one mirror (this has become common for large telescopes on earth). It will operate at a cold 50 K (-220°C or -370°F), so the mirror and instruments will need to be shielded from the heat of the sun and earth by a large screen, which will unfold once the telescope is in orbit.
The orbit of the JWST will also be quite a bit different. While the HST orbits at about 600 km above the earth, the JWST will be in an orbit around the sun at a point 1.5 million kilometers above the earth, at the point designated “L2” on the diagram below. This is a mathematical point known as a Lagrangian point, where the gravitational attraction of the earth and sun work together to keep an object stationary with respect to earth.
Wikipedia article — JWST
Wikipedia article — Lagrangian points
Grace and Peace