Rescuing Hubble

The Hubble Space Telescope has enabled scientists to make incredible discoveries since it was placed in orbit in 1990. The Hubble Deep Field is a point in the sky where 3,000 galaxies were found, some 10 billion years old. The Hubble Deep Field gives astronomers clues to how galaxies form.

The telescope also has provided information that has led scientists to estimate the age of the cosmos at 12 to 14 billion years. Another finding based on data only available through the telescope is that the expansion of the universe began speeding up only relatively recently -- 5 billion years ago. Scientists are trying to figure out why that happened.

In 1994 Hubble scientists obtained spectroscopic evidence of the existence of supermassive black holes. These black holes are millions or billions of times more massive than our sun. In 1997 scientists discovered that any large galaxy often is home to a supermassive black hole.

The telescope also showed the existence dust disks around young stars, support for the theory that the stuff of making planets and planetary systems is available elsewhere in the universe.

Until last week the discoveries from Hubble were in danger of coming to an end because its batteries were running down and its gyroscopes needed to be replaced. After the space shuttle Columbia tragedy in 2003, NASA determined that a flight to repair Hubble was too risky. But now the space agency has reversed itself.

A crew of seven astronauts will fly to the Hubble in 2008 to make repairs that will keep the telescope operating until at least 2013. The shuttle's payload will include two new instruments, the Wide Field Camera 3 and the Cosmic Origins Spectrograph. The WFC3 is 15 to 20 times better at searching for distant galaxies than Hubble's current setup. The COS will replace the Hubble's current spectrograph, which hasn't worked since 2004. The instrument will enable astronomers to study how stars develop.

All this comes at a cost -- $900 million -- and some danger to the astronauts. But three safe shuttle flights since Columbia and a corps of astronauts eager to fly the 380 miles up to the Hubble orbit convinced NASA administrator Michael Griffin to authorize the project.

More is to come. In 2013 NASA is scheduled to launch the James Webb Space Telescope. That telescope is expected to be able to provide information about the birth of the universe and the Milky Way from an orbit 1 million miles above the Earth.