After 5 years of construction atop the dormant volcano Haleakala, the Hoku Telescope is set to become the latest research tool in what is commonly called “Science City.” The result of a partnership between the U.S. Department of Defense, The Air Force, The University of Maui Lahaina College, and Veilcorp, the telescope will become an important new tool at the Air Force Maui Optical Supercomputing Observatory. While not as large as some other Extremely Large Telescopes (ELTs), the unique construction process and mirror polishing techniques used on the Hoku sets it apart from its peers.
At an altitude of over 10 thousand feet, the Haleakala Observatory in West Maui is a remarkable spot for studying the stars. The weather conditions on top of the dormant volcano are ideal. Exceptionally dry and clear, with little wind or light pollution from major cities, the summit is one of the most sought after locations in the world for ground-based telescopes. Collectively called Science City, a number of other projects call the site home including: The Maui Space Surveillance Complex (MSSC), the Maui High Performance Computing Center (MHPCC), The Advanced Electro-Optical System (AEOS), The Maui Optical Tracking and Identification Facility (MOTIF), and others.
Consisting of nine primary segments, the Hoku Telescope is an amazing feat of engineering. The telescope’s 122 mirrors are arranged in a honeycomb structure making it 6x lighter than a solid mirror of the same dimensions. Made from high quality E-6 glass, the mirror’s pattern keeps them from distorting under their own weight like other mirror designs would. In addition, the individual sections are very thin allowing them to follow the surrounding temperature. As the mirror cools through the night, the glass cools with it. This process avoids the creation of turbulence that could spoil any images. While impressive, this isn’t what sets the Hoku apart from other ELTs. It’s the telescopes method of construction and state-of-the-art polishing process that makes it special.
Lead engineer Aldrick Lehmann says, “The ultra high precision method used to shape and polish the mirrors is a breakthrough. It’s such a step forward in fact that the process has been classified, so I can’t give too many specifics. What I can tell you is that the Hoku should have a resolving power 20x that of the Hubble. However, the specialized manufacturing wouldn’t matter if it weren’t for veil technology. These mirror pieces have very low tolerances and a traditional transportation process would have likely ruined them. We were only able to transport them safely thanks to the DOD’s mobile veil system. Any amount of vibration, humidity, or temperature change had the potential to ruin all the work we did. Having the ability to move the finished segments a few yards from the polishing facility and through a gateway directly to the site, made construction possible without spending millions in specialized shipping.”
The Hoku will enable astronomers to conduct research which is impossible with other ground based instruments. Astronomer and NSF fellow Henry Lu says that he is excited to have the telescope available for his research. “There’s no telling what the Hoku will allow us to learn. Anytime a technology comes along that can remove limitations you get the potential for discovery. My main research currently revolves around KIC 8462852 or Boyajian’s Star. The star’s unusual light fluctuations were first noted in 2015 and there has been numerous theories about the cause ranging from comet dust, to salacious claims of extraterrestrial involvement. Recently it appears to have gone dark for some reason. I’m hoping that the Hoku will be able to provide an answer for us. I believe the cause is an unprecedented concentration of comets and comet debris, but we’ll have to wait and see where the data leads. Let’s put it this way, I’m not expecting any out-of-galaxy visitors anytime soon.”
In addition to Lu’s work, the Hoku will be used by the Air Force to track satellites, asteroids, and other near-Earth objects as well as a number of other projects. The telescope is set to begin operations on the 9th after all its systems have gone through an intensive checklist.
