By Thomas Guengerich
SOCORRO, N.M., July 31, 2008 – New Mexico Tech has awarded a $3.3 million contract option to Advanced Mechanical and Optical Systems, or AMOS, of Liège, Belgium, to build the first telescope for the Magdalena Ridge Observatory Interferometer (MROI) telescope.
Right: from left are Carlo Flebus, Pierre Gloesener, Colby Jurgenson, Michelle Creech-Eakman and Jean-Pierre Chisogne. MRO Interferometer Project Scientist Michelle Creech-Eakman led the New Mexico Tech contingent at the SPIE conference in Marseille. In photo, she and Tech instrument specialist Colby Jurgenson visit with three representatives of AMOS, the Belgian firm that is building the telescope mounts.
“This is a major event. I’m very excited,” said interferometer project manager Eric Bakker. “This will drive our entire schedule. The first telescope will arrive in less than two years and will provide us with the tools to look at starlight for the first time.”
New Mexico Tech and the University of Cambridge are the two main collaborators in the design and construction of the interferometer. Already, Tech has received more than $52 million for the observatory, which also includes a 2.4-meter optical telescope.
Tech and Cambridge scientists will periodically visit the AMOS facility in Belgium and company representatives will periodically visit Socorro over the next 18 months.
The interferometer will use a three-mirror telescope that will boost the efficiency of the telescopes and reduce the amount of light loss.
“Most telescopes have five to nine mirrors,” Bakker said. “With each reflection you lose light to scatter or absorption. The fewer mirrors you have, the higher the throughput and the more photons enter the vacuum pipes.”
“We made an important decision in May 2007 to use telescopes that only need three reflections to get light into the vacuum pipes,” program director Cormier said. “We could have bought more telescopes with the money, but they would have had more reflections.”
Dr. David Westpfahl is the chief scientist for both telescopes and chairman of the Department of Physics. He said with each reflection, a telescope loses 2 to 4 percent of the light. The MRO interferometer telescope will have a total of three reflections on the telescope and two more sending the light into the vacuum system, which will result in light loss of about 10.5 percent. The system architects maintain a detailed “throughput budget” that accounts for every reflection loss and optical wavefront aberration in the interferometer, Creech-Eakman, interferometer project scientist said.
In contrast, a telescope with 10 mirrors before the vacuum pipes – which is an average number – loses about 34 percent of its light, Westpfahl said.
After entering the vacuum pipes, the light reflects off another 14 optics before completing the beam-combining process and producing an image.
Phase A for the facility calls for six 1.4-meter telescopes and infrared observing capabilities. Phase B includes another four telescopes and the addition of optical capabilities.
Stellar interferometry combines light from multiple telescopes to form “interference fringes.” A complex optical system with multiple light reflections from the light-collecting surfaces to the detectors measures these fringes.
At full capacity, beams from the 10 telescopes will be combined in a 190-meter long facility that includes more than 2 kilometers of aluminum pipe. The facility will mimic the resolving capabilities of a telescope that is up to 340 meters in diameter.
The interferometer is expected to see first light in early 2010. Project leaders hope that they will have “first fringes” – which requires two telescopes – in late 2010.
“Ultimately, the Magdalena Ridge Observatory Interferometer has one main goal – producing very-high-resolution images of faint astronomical targets,” Creech-Eakman said. “The facility will be capable of producing images with resolution 100 times greater than the Hubble Space Telescope.”
Magdalena Ridge Observatory facility will employ a variety of new technologies that are revolutionizing interferometry. Tech and Cambridge scientists unveiled several of their breakthroughs in late June at an optics conference in Marseille, France.
Westpfahl was the initial champion of bringing an interferometer to New Mexico Tech.
“It’s been a long haul,” Westpfahl said. “We consider our start date October 5, 1995. It’s been 13 years to get here.”
The project has overcome several challenges, including the dissolution of the initial consortium of university partners. One technical challenge was devising an appropriate bid package. In 2005, the Tech team requested proposals to construct the entire telescope assemblage – telescopes, mirrors and protective domes. That attempt yielded no acceptable bids.
On a second attempt, Tech solicited three separate bids for the mounts, mirrors and protective domes. That move led to the working relationship with AMOS. An Albuquerque company, Optical Surface Technologies, is building the mirrors. The bid for the protective domes has not yet been awarded.
– NMT –