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Caltech Submillimeter Observatory being decommissioned


California Institute of Technology Submillimeter Telescope. Hawaii 24/7 File Photo

California Institute of Technology Submillimeter Telescope. Hawaii 24/7 File Photo

(PASADENA, CALIFORNIA, DECEMBER 4, 2017) – Caltech is proceeding to decommission the Caltech Submillimeter Observatory (CSO) on Hawaii Island’s Maunakea. CSO began operations in 1987 and ceased scientific observations in September 2015.

The next steps are an environmental assessment (EA) and a conservation district use application (CDUA). A “public scoping period,” open until January 15, 2018, is the first opportunity the community will have to comment on removal and site restoration. There will be additional opportunities, including formal comment periods, once the drafts of the EA and CDUA are released.

The Office of Maunakea Management (OMKM), which is part of the University of Hawaii at Hilo, will coordinate procedures for this process. The CSO is the first telescope to be removed from the mountain under the Decommissioning Plan for Maunakea Observatories, a sub-plan of the Maunakea Comprehensive Management Plan, which aims to protect the cultural, natural, and scientific resources of the area.

As part of the EA, Caltech is preparing plans that include scenarios for observatory deconstruction, removal, and site restoration, all in accordance with its sublease with the University of Hawaii and the Decommissioning Plan.

Community input and analyses of the cultural, environmental, and financial benefits and impacts of the various scenarios will help determine the appropriate level of removal and site restoration, and future use of the site. Final plans require approval by Caltech, the Maunakea Management Board, the University of Hawaii, and the state Department of Land and Natural Resources (DLNR).

When the EA process is completed, a CDUA will be filed with DLNR. The state Board of Land and Natural Resources will decide whether to issue a conservation district use permit (CDUP). According to the Decommissioning Plan, once the CSO is removed and the site is restored, the site will not be used for future observatory development.

“We are grateful for the use of Maunakea for nearly three decades for astronomical research,” says Sunil Golwala, director of the CSO and a professor of physics at Caltech. “We are undertaking the decommissioning process respectfully and look forward to working with OMKM, University of Hawaii at Hilo, and the community.”

Caltech selected the team of M3 Engineering, Ho’okuleana LLC, and Hastings & Pleadwell: A Communication Company to handle project planning, permit applications, communication, and community outreach related to the CSO decommissioning.

More information is available at The community is encouraged to submit comments to Peter Young of Ho’okuleana LLC ( by January 15, 2018.

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