Happy 25th Birthday, Hubble
A quarter century ago, the Space Shuttle Discovery launched with the Hubble Space Telescope aboard. Originally slated as a 400 million dollar project, its combination of contractor problems, schedule slippage, the loss of the Space Shuttle Challenger, and the cost overruns that resulted from all of that inflated the price tag to 2.5 billion dollars. Many breathed a sigh of relief at that shuttle launch.
After that it was found that the contractor that built the 2.4 meter mirror had misshaped it, but did so so precisely that corrective optics were able to reverse the problem, first for the entire telescope and then later for each instrument. Hubble was planned from the start to be repaired in orbit, but that means that it flies in low orbit where the Space Shuttle could reach it. Then the Shuttle had to boost the orbit because Hubble flies low enough that the upper atmosphere puts drag on it. The amount of that drag has so many built-in variables that some types of long-term observations have had to be watched carefully to make sure that Hubble keeps its aim true. Low orbit also means that the Earth, Moon, and Sun often swing around into the viewer, requiring operators to interrupt a study and point away to protect delicate instruments from the glare.
In spite of it all, Hubble has been called the most successful scientific instrument of all time.
Most folks who visit http://hubblesite.com go there to see the many pretty pictures, but those are just the icing on the cake. Like all of NASA’s and ESA’s other robotic spacecraft, most of what Hubble does involves science that most of us do not understand. Hubble has performed an unprecedented series of break-through science that only a general purpose orbiting telescope of its size can achieve. Also, five repair and upgrade missions have swapped in more advanced instruments and other tech to help today’s Hubble achieve astonishing images and science that the older technology of the corrected Hubble version 1 had not never been equipped to do.
In celebration of the 25th anniversary of Hubble, they’ve offered up a host of cool stuff for us to savor. It’s a mixed bag of goodies that would take me too long to go through and tell you about, so I’ll just pass on the links…
You might also be interested in ESAs production called HubbleCast…
They expect Hubble to last another six years or more, to give the James Webb Space Telescope time to fly and work in tandem with it. The JWST is an infrared telescope that can acheive science that Hubble can’t do, because Hubble’s instruments are too warm to do infra-red observations very well. The JWST will not fly in low Earth orbit, but will orbit a gravitational pocket called a Lagrange Point on the far side of Earth from the Sun. There, it will be able to keep its sun-shield pointed at the Sun, and the Earth and Moon will not shadow it, so as to maintain JWST’s instruments at a constant, very low temperature. It will also be able to observe targets for much longer periods and view them in far greater resolution with its 6.5 meter wide system of mirrors.
The Space Shuttle that made Hubble possible has retired, but the telescope lives on and continues to teach us new things about our area of space, as well as distant times and galaxies. May we all remember the little telescope that could and the science that it provides. However, the Shuttle is not going back up to upgrade and boost the telescope again, it is on its final journey. The most recent upgrade included a package of equipment to safely de-orbit it. What will replace Hubble if the JWST dies of budget cuts before Arian can launch it?