Tuesday, September 4, 2001

Stairway to the Stars

(Syndicated article for the Metro newspaper group).


Some of the telescopes at Mauna Kea's peak.

Interest in building an astronomical center on Hawaii caught on in the 1950’s, but the location of choice was Maui’s Haleakala, which had one thing the Big Island’s Mauna Kea did not have -- a road to the top. A solar observatory was built, but it soon became clear that Haleakala was not ideal, as clouds reached its summit, and its crater sometimes filled with fog that spilled over. Surrounded by fog, the scientists looked outward, and across the Pacific waters saw Mauna Kea rising tall above the clouds.

It took a lot more than clear air and a tall mountain to make a home for telescopes however, all of which is detailed in Barry Parker’s 1994 book Stairway to the Stars. Building on the mighty White Mountain took money and politics, as well as daring individuals willing to take risks. And in the case of Mauna Kea, tragedy also played a role, as the nearby city of Hilo was almost totally destroyed by a huge tidal wave on May 22, 1960.

With its capital city’s downtown in ruins, the mayor of Hilo began to look for new ways to generate income and jobs. Astronomy was one solution, and the governor of Hawaii was soon convinced to fund the building of a road up to Mauna Kea’s summit. (This decision would later translate into hundreds of new jobs and $80 million annually to Hawaii’s economy.)

The first big telescope to open on Observatory Hill was the 2.23-meter (88-inch) telescope built by the University of Hawaii, which opened in 1970, but wasn’t fully operational until 1976. In 1979, a 3.6 meter Canada-France-Hawaii telescope went into operation, followed by several more - including both infrared and radio telescopes.


The Keck Twins at Mauna Kea.  Photo: Hans Sandberg.

But the project that put Mauna Kea on the world map was the Keck observatory. This revolutionary giant telescope had a “honeycomb” mirror with a diameter of 10 meters (33 feet). Such a large disk would have been almost impossible to build and operate using the technology of the time: a single mirror. Keck designer Jerry Nelson instead opted for 36 smaller mirrors, which would all work together as one. To do this, it was necessary to develop a highly innovative system that could change the shape of every single mirror segment continuously, and then align them with extreme precision. This technology is called active optics (adjusting the shape of the mirrors.) By combining active optics with another new technology: adaptive optics (where computers calculate disturbances in the Earth’s atmosphere and “correct” them by continuously adjusting the telescope’s mirrors and lenses,) Keck began a new era for astronomers everywhere.

Behind the $76 million Keck project was the University of California and Caltech (California Institute of Technology,) and the Keck Foundation. Later on, the fund paid for a second Keck-telescope -- which today sits next to the first. The idea is to get them to function as a single telescope, thereby doubling the power. This technique -- which is common in radio astronomy -- is called interferometer. Since it is however much, much harder to perfectly match up optical images than it is radio signals, this goal has yet to be completed.

One problem that the new telescopes did not solve was the shortage of telescope time. Two-thirds of the observation requests made by astronomers were routinely turned down, which is why some of the world’s leading associations for astronomy proposed building two new large telescopes – one in the northern hemisphere and one in the south. The National Science Foundation (NSF), which funds most of the industry’s basic research in the US, financed half of the $176 million needed to build twin telescopes in Hawaii and Chile. Six other countries also funded the Gemini plan: Argentina, Australia, Brazil, Canada, Chile, and the UK.

Like Keck, Gemini broke new ground in many ways. They decided to use a single piece of glass, but a much thinner disk than those of previous generations. The 8.1 meter mirror is flexible, and is coated with a super-reflective silver solution, instead of aluminum. “Our thin mirror, which is basically a twenty-ton contact lens, no longer relies only on glass and steel to keep it aligned. Behind it, there are 120 computers, which constantly monitor the shape of the mirror, and adjust it as it moves across the sky,” says Matt Mountain, director of the Gemini Observatory on Mauna Kea. The result is a telescope that in some respects can match both the Hubble Space Telescope, and the Keck twins – a “fly-by-wire airplane” as Mountain calls it.

When completed in late 2001, Chile’s Gemini South will work with Hawaii’s Gemini North to give researchers a chance to study the entire hemisphere from remote locations - via super fast computer networks. “For example, the Magellan Cloud, our nearest galaxy, is not visible from the north. The center of that galaxy is very low down in north, and we have to look at a lot of atmosphere to see it, while in the south it goes straight overhead,” says Mountain. So theoretically, a team of observers -- one sitting in Brazil, one in Washington, and one in Hawaii -- can collaborate over a network using both telescopes. “It will be a long night if we get the right overlap, because you can get one twelve hour night, and then another seven hour (night) for certain parts of the sky,” he adds.

Gemini is designed to look far into the universe, and is especially good at capturing infrared light. Though infrared heat radiation is invisible to the human eye, it is tremendously important for modern astronomy. Infrared telescopes for example, can see right through the vast, dark clouds that obscure our view, and allow astronomers see the universe at its very early beginnings. “You can see into the heart of stellar nurseries, and can catch information about planets and planetary disks that you couldn’t catch (before.) You can also see into the heart of our own galaxy - to the galactic center where there is probably a black hole hidden,” says Mountain.

As telescopes get bigger and optics more precise, demands on the rest of the system increase as well. The machinery that moves the telescope and the dome, must do so without causing any vibrations. In an almost surreal act, Gemini’s 673-metric ton shiny silver dome rotates almost without a sound. Vertical “doors” open to expose the sky, while the rest of the dome splits horizontally in half and rises up in order to circulate the air. Another impressive sight is the cable room below the telescope, which holds its “spinal cord” in the form of hundreds of wires nested into dozens of thick bundles.

For an astronomer, it is essential to have good resolution as you focus on smaller and smaller objects. To give an idea of how sensitive the Gemini telescope is, Gemini’s Peter Michaud explains that it would be like seeing a pair of headlights on a car driving on the Golden Gate Bridge in San Francisco from the top of Mauna Kea 2,000 miles away. “That is assuming however, that the Earth had no atmosphere, and was completely flat,” adds Michaud.

As for the future, Matt Mountain foresees a new generation of 30 to 100-meter telescopes, one of which is actually slated to be built on Mauna Kea. This enormous telescope will however, be Mauna Kea’s last, he adds.

Hans Sandberg

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