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courtesy:
uanews.org
World's Largest Telescope Mirror Moves to the LBT
Lori Stiles
Monday, 03 November 2003
The world’s most powerful optical telescope, which
will allow astronomers to see planets around nearby stars in our galaxy,
took a giant step closer to completion late last week when the first of
its huge 27-foot diameter mirrors inched up a tortuous mountain road to
its new home at Arizona’s Mount Graham International Observatory.
The 18-ton borosilicate "honeycomb" mirror was escorted up the mountain by
a team of scientists, engineers, police, and heavy-haul specialists to the
Large Binocular Telescope (LBT) facility. The mirror and its all-steel
transport box, which together weighed 55 tons, were transported over 122
miles of Interstate and state highway, then up the narrow hairpin turns of
the 29-mile Swift Trail to the Mount Graham International Observatory (MGIO)
high above Safford, Ariz.
The
transport negotiated countless twists and turns to the 10,480-foot
summit (Photo: Lori Stiles) |
The journey to 10,480-foot-high Emerald Peak was a
two-stage, multi-day affair that required five months of intense planning
and preparation. This included a full-scale trial run with a dummy mirror
in September.
"Everyone is aware that there’s real glass in there this time," said J.T.
Williams as the huge, yellow 48-wheeled transport rig rolled off pavement
and onto the gravel road leading to the observatory. Williams, telescope
assembly supervisor, walked every inch of the mountain road to inspect the
surface and measure the turns during the transport operation.
Precision road grading by MGIO and Arizona Department of Transportation
crews smoothed the worst of the washboard stretches of gravel, and haulers
soon discovered that the near-vertical mirror load traveled best with a
slight increase in speed over the washboard sections.
The mirror’s journey to Mount Graham began on Thursday, Oct. 23, when the
Mirror Lab team and workers from Precision Heavy Haul, Inc. (PHH) loaded
the mirror transport box and its precious cargo at UA’s Mirror Lab, which
is located in the campus football stadium. The mirror-carrying convoy
pulled out of the lab hours before dawn on Friday, accompanied by a
25-vehicle police escort that was organized by Mike Thomas of the UA
Police Department. The police car-and-motorcycle escort formed a rolling
blockade as the mirror rolled down I-10 and State Highway 191. They
provided both traffic and mirror safety as the convoy averaged 45 mph to
the MGIO base camp at the base of the Pinaleno Mountains.
Last Monday, Oct. 27, the team at base camp transferred the mirror to
PHH’s Goldhofer trailer for the three-day, 29-mile journey to the
telescope’s home on Emerald Peak. This 8,000-foot climb was made at about
one mile per hour.
Paved
switchbacks on Swift Trail was a challenging stretch of the journey.
(Photo: Lori Stiles) |
The Goldhofer trailer rests on six sets of eight
wheels. Each wheel set has an independent hydraulic system that allowed
the trailer to be accurately leveled, keeping the mirror upright as it
negotiated the road’s banked turns.
"This is probably the most challenging job we’ve done," said PHH President
Mike Poppe, who expertly drove the Goldhofer to the telescope. PHH Vice
President Jim Mussmann rode on the Goldhofer and monitored hydraulics,
constantly adjusting the trailer to maintain the mirror's center of
gravity.
PHH, which is based in Phoenix, hauled the mirror cell (the structure that
holds the mirror and its support system) to the LBT a week earlier and
transported many other telescope parts to Mount Graham in 2002.
"Arizona was very fortunate to partner with Precision Heavy Haul, a group
that wanted to work with the university as a team of one," said LBT
Associate Director Jim Slagle. "The alliance of Arizona scientists and
engineers working alongside Precision Heavy Haul on the proper way to
bring these pieces up the mountain turned out to be a successful
operation."
Precision
Heavy Haul transported the giant mirror box 29 miles up to the LBT
site (Photo: Lori Stiles) |
Although the mirror was transported to the mountain
last week, its journey began back in 1997 when it was spun cast in the
Mirror’s Lab’s giant rotating furnace. The Mirror Lab team has been
developing new mirror technologies for the past two decades under the
direction of UA Regents’ Professor J. Roger Angel.
After it was cast, the mirror was polished using the lab’s innovative
stressed-lap technique. The face of the deeply parabolic mirror (f/1.14)
mirror is precise within a millionth of an inch over its entire surface.
The Mirror Lab is about to begin polishing the LBT’s second 8.4-meter
primary mirror.
Work on the LBT began with construction of the telescope building in 1996
and is scheduled to be completed in 2005 when both mirrors are installed
at the $100 million facility. The two mirrors together are valued at $22
million. The telescope building is a 16-story structure, the top ten
floors of which rotate.
The LBT will have twin 8.4-meter mirrors on a single telescope mount,
giving it the light-collecting area of an 11.8-meter (39-foot-diameter)
telescope. But what really excites astronomers is that the LBT will make
images of even faint objects as sharp as a 22.8-meter (75-foot) telescope
would. This is nearly ten times sharper than the images from the Hubble
Space Telescope. When the LBT is fully operational, it will be the world’s
most powerful optical telescope, capable of imaging planets beyond our
solar system. It will allow astronomers to peer deeper into the universe
than ever before.
Astronomers won’t have to wait to 2005, however, to begin using the
telescope. It will see first light with its first mirror next summer.
The telescope is a compact, stiff and innovative design produced by UA
engineer Warren Davison in collaboration with Roger Angel and engineers in
Italy. The major mechanical parts for the LBT were fabricated,
pre-assembled and tested at the Ansaldo-Camozzi steel works in Milan, one
of Italy’s oldest steel manufacturers. Then the telescope was disassembled
and shipped by freighter to Houston, Texas, and overland to Safford, Ariz.
The Italian-made mirror cell continued to the Mirror Lab, where
Integration Team Leader Steve Warner and his team integrated the mirror
support system into the cell for final optical tests before PHH hauled the
mirror cell to the mountain two weeks ago.
Huge
C-rings that support the LBT's two mirror cells give the telescope
exceptional stiffness (Photo: Lori Stiles) |
Astronomers were delighted when the mirror reached its
home last week.
"I’m both excited and exhausted simultaneously," said LBT Project Director
John M. Hill, who couldn’t be pried away from the mirror after it arrived
at the 10,000-foot-high telescope enclosure on Thursday, Oct. 30. "We’ve
been working on this mirror for a long time, and it’s great to see it
ready to install in the telescope."
LBT Associate Director Jim Slagle echoed Hill’s enthusiasm. "I’m
terrifically excited," he said. "Today we’re going to have an observatory.
For the first time, we have a mirror. We have a mirror cell. And we’re
going to have a telescope."
Steward’s Associate Director Buddy Powell added, "This is a significant
milestone in the process to make available the most powerful optical
telescope in the world. It would not have been possible without the
support of people in Graham County (Arizona), the State of Arizona, Ohio,
Italy, and Germany. It is a perfect example of what people from wide and
diverse backgrounds can accomplish by working together. We are very proud
of their accomplishment."
Steward Observatory Director Peter Strittmatter said, "Getting the first
LBT 8.4-meter mirror to the observatory on Mount Graham is a major
accomplishment, and a huge relief. The LBT team and those involved in the
transportation are to be congratulated on their achievement. Arizonan’s
can take enormous pride in this project."
The University of Arizona, which also represents Arizona State University
and Northern Arizona University on the project, holds a quarter
partnership in the LBT. The Instituto Nazionale di Astrofisica,
representing observatories in Florence, Bologna, Rome, Padua, Milan and
elsewhere in Italy, is also quarter partner in the project. The Ohio State
University and the Research Corp. each holds a one-eighth share, with
Research Corp. providing participation for the University of Notre Dame,
the University of Minnesota, and the University of Virginia. Germany is
the fourth quarter partner in LBT, with contributing science institutions
in Heidelberg, Potsdam, Munich, and Bonn. |
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