Telescope will take the twinkle
out of twinkling little stars
Controversy concerns project staffBy Rod Thompson
HILO -- When the stars twinkle, Gemini telescope's mirror will wrinkle.
Officials from seven nations will travel to the summit of Mauna Kea tomorrow to dedicate the new Gemini North telescope, which distorts a mirror to match and erase the twinkling of stars.
The result will be an instrument that sees light as well as the Hubble Space Telescope and will see infrared light even better, says Gemini director Matt Mountain.
Gemini North is one of two twin telescopes being built by a partnership of the United States, United Kingdom, Canada, Chile, Brazil, Australia and Argentina.
The other half of the $184 million project, the identical Gemini South, will be completed in 18 months in northern Chile.
Air makes stars twinkle.
Since the 1950s, scientists have dreamed of straightening out the twinkle to get unblurred light, said Gemini project scientist Fred Gillett.
Now technology has made the dream possible.
Similar to other Mauna Kea telescopes, Gemini has a main mirror 8.1 meters, or 26.5 feet, across.
Light from that is concentrated on a second mirror, then concentrated again on a third mirror 4 inches across and less than 1/8-inch thick.
Part of the light will be analyzed to see how it pulsates. Then "actuators" on the small mirror will make tiny bends in it to counteract the twinkling.
The Canada France Hawaii telescope on Mauna Kea has been using the system for three years and one of the Keck telescopes is just starting to apply it, Gillett said.
This "adaptive optics" improves images fivefold to tenfold, Gillett said.
The deliberate distortion of the small mirror is the reverse of another system first made known on the segmented 10-meter main mirror of the Keck I telescope.
There, as on the 8.3-meter mirror of Japan's Subaru telescope, actuators prevent distortion.
Gemini also uses computers to prevent distortion in its secondary mirror.
The machine is in constant adjustment while in use. "It's a living entity," Mountain said.
The secondary mirror has to be adjusted because it's shaken slightly when huge vents are opened on the sides of the telescope building. They allow winds up to 78 mph.
Astronomers want the wind to carry heat away from the telescope, which would interfere with infrared astronomy.
Although slight, that heat is enough to create "boiling air" inside the building without the wind, Mountain said.
Occasionally some dust will get on the mirror, Mountain said.
It will be cleaned once a week with carbon dioxide "snow," which carries dust away, he said.
Since astronomy began on Mauna Kea in the late 1960s, scientists have struggled to work at the 2.6-mile-high summit, where due to the altitude, there's 40 percent less oxygen.
"One of the most difficult things to do up there is to think critically," said Gemini operations manager Jim Kennedy.
Gemini solved the problem by removing the control room from the telescope, placing it at sea level in Hilo.
Eventually astronomers in Chile will control the telescope from South America, should the need arise, and astronomers in Hilo will do the same on the Chilean telescope. This is made possible by fiber-optic connections, funded like the adaptive optics by the National Science Foundation, which will increase the capacity for information transfer thirtyfold, Kennedy said.
Controversy over MaunaBy Rod Thompson
Kea telescope concerns
HILO -- People told Elizabeth Alvarez del Castillo she was lucky when they learned she would be organizing astronomy education among the Tohono O'odham Indians of southern Arizona this year. "They always approach everything from a very positive point of view," said Alvarez, whose duties include serving as a Gemini telescope press officer.
Forty years ago, astronomers approached the Tohono O'odham -- also known as the Papago -- to lease Kitt Peak on their reservation as an observatory site. "The initial reaction was kind of negative," said Gemini operations manager Jim Kennedy.
But astronomers and the tribe came to agreements that included hiring tribal members and prohibiting alcohol.
"They came to the conclusion that what we do is not at odds with the use of a sacred mountain," Kennedy said. The attitude continues today, Alvarez said.
The Tohono O'odham have a strong verbal tradition that includes stories about the stars, she said. They also are eager to learn about modern astronomy.
They view the two as different ways of looking at the same thing.
The Gemini staff is aware their telescope is opening amid controversy about a proposed University of Hawaii plan for the next 20 years on Mauna Kea. "Our observatory is very concerned about the fact that we live here on the Big Island in a community that's very divided on how the mountain is being used," Kennedy said. He hopes the UH plan will provide a means to find solutions.
Gemini director Matt Mountain says it is critical for astronomy to inspire learning in Hawaii.
"You're going to have to have the snowplow of knowledge going into the next century or you're going to get left behind," he said.
In Hilo, Gemini's outreach takes the form of bringing schoolchildren to the facility. Mountain, who is dyslexic and didn't learn to read until he was 11, keeps a letter from a dyslexic boy at St. Joseph School in Hilo who visited the observatory headquarters.
"Thank you for letting me come to your project," the boy wrote. "I'll try not to give up."
The headquarters building was designed with a large lobby from which the telescope control room is visible. School groups can easily see where astronomers work.
While some of the criticism of astronomers on Mauna Kea has come from native Hawaiians, another source has been the Sierra Club, which is concerned about the environment. Mountain said Gemini's parent organization, the Association of Universities for Research in Astronomy, found Chile lacked an environmental review agency when it proposed a telescope there.
The organization assisted the Chilean government in creating the equivalent of an Environmental Protection Agency, he said.