Alamogordo NM
8-27-2026 4:34pm

Sunspot Demolition to Proceed

Sunspot Demolition to Proceed. Cutaway diagram of the Dunn Solar Telescope. (Thornton Tomasetti) - AlamogordoTownNews.org Dave Dooling Space & Science Correspondent

Sunspot N. M.- Demolition of Sunspot Solar Observatory, starting with the Dunn Solar Telescope, will proceed because of extensive mercury contamination, the National Science Foundation announced in a statement released mid-morning Thursday.

NSF and its contractor, Thornton Tomasetti, concluded that in addition to the Jan. 5 leak of 186 pounds of mercury, 57 years of tiny liquid and vapor leaks make it impossible to remediate and return the Dunn to safe operations.

“The DST’s metal structure has been exposed to elemental mercury for over 50 years,” Thornton Tomasetti wrote NSF in their official summary. “When mercury travels in a liquid or vapor form, it can be retained on or within steel surfaces, seams, roughness, corrosion products, connections, and inaccessible crevices. In addition, mercury can penetrate the steel, causing localized corrosion or embrittlement. The extent of any such conditions cannot be reliably determined from visual observation or air monitoring alone.”

About 18,000 pounds of mercury — in a small bearing at the bottom of the telescope and two larger ones at top — ensured smooth rotation of the 530,000-pound telescope as it followed the Sun. On Jan. 5, operators found mercury leaking onto the observing platform. Additional leaks, only now reported, were found and contained in April and July, and the actual source was not fully determined.

Thornton Tomasetti was initially awarded a $$320,679 contract to assess the Dunn. NSF expanded it to $670,679 to purchase cleanup equipment, and, on July 10, awarded an additional contract for $3.1 million for the cleanup itself. This was completed in early August.

But Thornton Tomasetti wrote that they “recovered approximately 2% less in total volume of mercury than anticipated … .” The difference may be hidden in inaccessible spaces, adhering to surfaces, amalgamated to metals, or other losses. Draining, cleaning, or even partial demolition cannot ensure complete removal.

“It is our opinion that complete remediation of the DST for mercury should be performed through controlled deconstruction and demolition of the telescope and surrounding concrete structure,” Thornton Tomasetti advised.

As a result, NSF plans “full remediation of the observatory footprint,” even though they have not been contaminated.

As part of this process, the U.S. Forest Service “will continue to explore potential future opportunities [and] plans to engage local partners and interested stakeholders to better understand community priorities and interests.

Cutaway diagram of the Dunn Solar Telescope. (Thornton Tomasetti)

This is a continuing story and Alamogordo Town News is requesting additional information. Report by David Dooling. The journalist served as education officer at Sunspot during 2002–12 and, yes, he actually rotated the Dunn several times when doing public tours. 

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