NSF NCAR’s Mauna Loa Solar Observatory fully reopens after 2022 volcanic eruption
Rebuilt road will allow observers to support Artemis II mission
Apr 1, 2026 - by Laura Snider
The road to the Mauna Loa Solar Observatory was closed for more than three years, restricting access to the site.
The Mauna Loa Solar Observatory (MLSO) in Hawaii has reopened more than three years after lava flows blocked road access to the site. The observatory, operated by the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR), is resuming normal operations just in time to support NASA’s Artemis II mission to the moon by sending advance warnings should the observatory’s main coronagraph detect potentially dangerous space weather.
MLSO has been closed since Mauna Loa, the largest active volcano in the world, erupted in late November 2022. The observatory was established in 1965 on the flanks of the volcano, an ideal location to provide high-altitude, clear-sky observations of the Sun because the volcanic landscape reduces atmospheric contamination from dust and pollen.
While the observatory has not been able to operate normally since the 2022 eruption, it has been used in limited circumstances with alternate power sources, including solar panels and a generator. For example, staff were flown into the site via helicopter to observe the Sun’s corona during the total eclipse on April 8, 2024, using the MLSO coronagraphs. Such observations provided important benchmarks for other scientific measurements taken during the eclipse.
Now that the road is reopened, observers will return to staffing MLSO seven days a week during daylight hours. This includes monitoring for coronal mass ejections (CMEs), which are the root cause of radiation storms in space that can damage satellites and endanger astronauts. MLSO sends out alerts when a CME is detected that is likely to cause a radiation storm, and because of the observatory’s unique capabilities, these alerts are produced about one hour before similar space-based coronagraphs are able to detect the same hazard.
During the Artemis II mission — the first crewed lunar flyby mission in 50 years — MLSO will provide alerts to NASA’s Space Radiation Analysis Group should any hazardous CMEs occur. The launch window for the 10-day mission begins today.
