UH 2.2-meter Telescope Recovers from Lightning Strike

UH 2.2-meter telescope. Photo by Karen Teramura.

On June 5, lightning struck the weather station attached to the University of Hawai‘i 2.2-meter telescope and severely damaged both. It took a team of electronic and software engineers and technicians, led by astronomer and Telescope Director Colin Aspin, until August 18 to replace or repair all the damaged subsystems to make the telescope fully operational again.

The engineering team of Bob Calder, Luke McKay, Hubert Yamada, Mike Yabe, and Scott Caceres faced numerous challenges in repairing the 41-year-old telescope. One was a personnel problem: The new senior telescope engineer, Bob Calder, was not supposed to transfer to his new position until June 16, and a state law prohibited UH from rehiring his predecessor as a consultant until July 1, six months after his retirement.

Initially, the team hoped that getting the telescope working again would be fairly straightforward and happen quickly. But as they checked each of the telescope’s subsystems, they found that many of them had been damaged. Several electronic systems were so old that they had to be reverse engineered. By August 8, they had the telescope working well enough that some observations could resume with the dome being rotated manually. Getting it to rotate automatically required the replacement—twice—of the motion controller card. The telescope was finally in full working order on August 16, and plans are afoot to improve the reliability of its components and increase observing efficiency.

The weather station, which tells the telescope operator if weather conditions are favorable enough to open the dome, is still inoperable. Information from other telescopes is being used for that purpose. According to Aspin, the weather station will be replaced with more modern equipment that is electrically isolated from the telescope to prevent a future lightning strike.

When completed in 1970, the UH 2.2-meter telescope was the largest telescope on Mauna Kea, the eighth largest optical telescope in the world, and one of the first professional telescopes controlled by a computer, something that is now considered routine. It was built by UH with money from NASA, which wanted it to support its solar system missions. NASA accepted a proposal from astronomy-novice UH over ones from Harvard and the University of Arizona, which both had well-established astronomy programs that they wanted to enhance with a telescope on Mauna Kea. Because of the success of the 2.2-meter telescope, which demonstrated the unparalleled observing conditions on Mauna Kea, this Hawaiian summit soon became the most-sought after telescope site in the world.

The 2.2-meter telescope has been used to make several important discoveries, and it is still used for important research. Its most significant detection occurred in 1992, when then-IfA astronomer David Jewitt and Jane Luu (UC Berkeley) found the first object, other than Pluto, in the region of the solar system beyond the orbit of Neptune. This discovery confirmed the existence of the Kuiper Belt and eventually led to Pluto being downgraded from planet to Kuiper Belt object and dwarf planet. In recent years, the telescope has been used to track the near-Earth asteroid Apophis, determine the mass of the dwarf planet Haumea, measure the precise size of exoplanet WASP-10b, study merging galaxies, and make observations for many other projects.

The UH 2.2-meter telescope has also provided the very first opportunity to test new generations of optical and infrared sensors for astronomical observations. Notable are a 4-megapixel sensor, the precursor of 15 to be flown on NASA’s James Webb Space Telescope, and a 16-megapixel sensor now being developed with National Science Foundation support for the coming generation of 30-meter-class telescopes, such as the Thirty Meter Telescope (TMT) proposed for Mauna Kea.

While IfA astronomers have access to all the larger telescopes on Mauna Kea, the 2.2-meter telescope is the only operational telescope on Mauna Kea that is totally controlled by UH. It is still an extremely valuable tool for both research and training graduate students.