Dr. Michael Catelaz at work on the GAMMA II imaging machine, at the Pisgah Astronomical Research Institute (PARI) in North Carolina.

Dr. Michael Castelaz, the Science Director at the Pisgah Astronomical Research Institute, knows GAMMA II is a sleeping giant.  He just needs a little help waking up the beast.

GAMMA II and its sister, GAMMA I, are legendary imaging machines that were used to create the 19-million strong Guide Star Catalogue for the Hubble Space Telescope (HST).   Think of the Guide Star Catalogue as a souped-up GPS, enabling the Hubble to set its scope on stars thousands of miles away.

Four years ago, the Space Telescope Science Institute at Johns Hopkins University announced it was retiring the image-makers after nearly 20 years of service.

The news swept across the astronomy community and Castelaz and his colleagues at PARI jumped at the opportunity to bring the GAMMA machines to their Western North Carolina campus and reconfigure them for a new cataloging gig.

“It’s old, but it’s still state of the art.  It’s incredible what was done in terms of designing these instruments and getting them going,” Michael Castelaz.

But why bring this beast to PARI? PARI houses a collection of old photographic plates known as the Astronomical Photographic Data Archive, or APDA. Those analog plates contain invaluable data of the night sky, but are not easy to share and use. Catelaz and ADPA director Thurburn Barker believe the re-commissioned GAMMA II can help convert those plates– some of which date back to the 1890s – into new digital maps for future astronomers.  The maps will unlock data on thousands of unclassified stars known to exist in the APDA collection that can then be cataloged by their size, temperature and distance.

When PARI finally obtained the machines they were in pieces: three-tons of granite and lasers awaiting their next mission.  The sheer mass of the machines was intended to absorb vibrations from the floor as well the Earth.  In order to effectively serve the Hubble, GAMMA precisely mapped stars down to the exact micron.  That’s a thousandth of a millimeter to you and me. Castelaz and his cohort eventually reassembled GAMMA II and got all the electronics up and running.  However, do to the jerry-rigging and hand-written code used to reconfigure the original machine, they have not been able to recreate the imaging capacity … yet.

As soon as PARI can get GAMMA humming, the APDA collection will no longer be a black hole.  The meticulous work by generations of astronomers will be ushered into the 21^st century, bringing analog data back to the future.

The Hubble Space Telescope being serviced by Space Shuttle
Atlantis astronauts in May 2009. Credit: NASA

Galileo's telescope had a magnification of only about 27x, allowing him to see that Venus has phases like the Moon, Jupiter has four large moons of its own, Saturn does not appear as a simple disk but has unusual "projections" to either side, and the Milky Way contains far more stars than is apparent to the naked eye. And though these are features that can be seen through the least powerful home telescopes today, Galileo's observations changed the way we look at the universe.

Hubble has done the same thing, but on a modern scale of magnitude. Not a large telescope by the standards of ground-based behemoths like Keck in Hawaii (Hubble's primary mirror is 2.4 meters in diameter), Hubble's "edge" is it's location in space, orbiting the Earth over 300 miles high, outside of our atmosphere. Particularly in its earlier days before ground based telescopes were using adaptive optics techniques to compensate for atmospheric distortion, Hubble's vision on the universe was unparalleled in its clarity.

Here's is a recap of a few of the many big discoveries Hubble has made possible:

Dark Energy: By accurately measuring the distance and velocity of distant supernovae, over a large range of distances, Hubble has refined out knowledge of the rate of expansion of the universe–leading to the discovery that the expansion of the universe is actually accelerating, contrary to what was expected. Scientists suggest the existence of a mysterious "dark energy" throughout the universe that exerts an antigravitational repulsive pressure on the cosmos.

Age of the Universe: Since Edwin Hubble (for whom the Space Telescope was named) discovered that the universe is expanding, astronomers have been trying to determine how long ago the expansion began–how long ago the "starting gun" of the Big Bang was fired, and thus the beginning of the universe. Through precise observations with the Hubble, astronomers in recent years have been able to peg it between 12 and 14 billion years. (Most recently, observations made with the WMAP mission have honed that down to 13.7 billion years, give or take 0.13 billion.)

Supermassive Blackholes: Hubble found the clues that point to the existence of "supermassive" blackholes at the heart of maybe most–or every–galaxy. The Milky Way's own central blackhole has a mass equivalent to four million Suns.

Stellar Dust Disks: Before the first extrasolar planets were actually detected, Hubble observations revealed that flat disks of dust encircling young and developing star systems–aka "protoplanetary disks"–is commonplace. This has given us a glimpse at what our own solar system may have looked like before the planets formed.

It has been seven years since the last Hubble servicing mission, with another servicing scheduled a few years ago cancelled in the wake of the Columbia disaster. Several failing systems will be repaired or replaced this time, and other instruments are receiving upgrades that will make Hubble more powerful than ever in its declining years.

This mission to service the Hubble will be the last. Since NASA is retiring the Space Shuttle fleet after 2010, we will no longer have a space vehicle large enough to carry upgrade and replacement equipment to and from the Hubble. After that, the next new big space-based descendent of Galileo's spyglass will be the James Webb. Stay tuned…

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