Hubble Hubble

The revived Hubble telescope still orbits the Earth, well into its outer atmosphere, and after 20 years still sends us sharp pictures of its observations.

Astronomer Michael Shull, professor of astrophysical and planetary sciences at the University of Colorado, told the Boulder Rotary Club recently that the telescope’s last retrofit, completed by astronauts in 2009, gave the now 20-year-old container, about the size of a school bus, at least a 10-year continuation of its useful life.

The telescope, named after Edwin Hubble, whose astronomical work included observational verification of the expanding universe, is in a 97-minute orbit around the Earth. With its final retrofit, all of the instrumentation on Hubble has a “made in Boulder” label from Ball Aerospace. New instruments added in 2009 were a wide field camera and a cosmic origins spectrograph designed at CU-Boulder.

“Telescopes have two purposes,” Shull said. “One is to provide magnification and so make distant objects seem closer. The other is to increase the amount of light that forms the observed image by focusing all the light that comes through a large aperture onto a small region that is observed."

As used by Shull, “light” means more generally electromagnetic radiation. Hubble's instruments make use of both ultraviolet and infrared regions of the electromagnetic spectrum that fall outside the region of visible light.

About 100 billion stars make up the Milky Way, our home galaxy, Shull said, “and that is a small galaxy.”

Considering all the millions of galaxies, that multiplies out to a whole lot of stars.

“For a long time there has been speculation that around at least one of those stars there would be a planet like earth,” he said. “Photos from Hubble have identified some 500 planets at about the right distance from their respective stars to be earth-type planets, but we don't have the ability yet to observe conditions on these planets and see whether other important characteristics are present.”

Hubble’s orbit is not completely outside the Earth's atmosphere, and the small friction it experiences causes the telescope to gradually lose energy and spiral downward toward Earth. The 2009 fix boosted Hubble to its original orbit, and it should remain close enough to that orbit to be useful for another 10 years.

By then, the larger James Webb telescope, scheduled for launch in five years, should be in position, continuing Hubble's pioneering observations of the universe with the added power of nine times the light-collecting ability.

“With Hubble we have enough light-gathering power to see light from stars that left those stars ten to fifteen billion years ago,” said Shull. “Because light travels at a finite speed, we can’t know what’s happened to those stars while the light was traveling to us.

“But because of the long time of travel, that light was emitted when our universe was ten to fifteen billion years younger, and so Hubble is showing us what things were like in a much younger universe.”

With the Webb telescope we will be able to look even further back in time, he said. No one knows what we will be able to see.

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