NASA's Jet Propulsion Laboratory seems to be in the clear from the threat of a nearby wildfire, but the historic observatory atop Mt. Wilson is potentially facing a closer call.
The so-called Station fire is burning in the Angeles National Forest near homes on the north side of La Ca?ada Flintridge, according to news reports. The fire came within one quarter to one eighth of a mile of JPL on Saturday, but has since retreated.
Despite the lessened threat to JPL, the facility remained closed on Monday "except for mission-critical personnel," according to an update on the JPL website. The closure was made because of concerns about air quality.
Concerns over the fire have shifted to nearby Mount Wilson, where many of the L.A. Basin's cell phone and broadcast towers, as well as the historic Mount Wilson Observatory, are located. The observatory was found in 1904 by George Ellery Hale, who used the observatory to prove that sunspots are regions of reduced temperature on the sun's surface.
On Monday morning, firefighters who were working to stop the spread of the fire were instructed to withdraw from the mountainside, and Mount Wilson employees who had been making helicopter trips to the observatory also left, according to updates on the observatory's website.
Firefighters had cleared brush from the mountain and laid down Phos-Check fire retardant by airplane near the broadcast towers.
The station fire doubled in size overnight and now covers about 85,000 acres, according to L.A. Times reports. While the observatory appeared doomed last night, the Times reported, brush-clearing efforts and fire-retardant drops seemed to have helped.
Ryan Anderson, a graduate student at Cornell who is also a Pancam Payload Downlink Lead for the Mars rovers, Spirit and Opportunity, said via Twitter that rover operations have been suspended for the day.
"The team working on extracting Spirit from Troy is not at JPL today since a one-day delay in those operations will not impact the rover," said NASA spokeswoman Veronica McGregor.
JPL has also been impacted by the fire through employees who have had to evacuate their homes.
Astronomer Mike Brown of Caltech snapped a picture of the fire's smoke plume on Friday, from the 9th floor of the Caltech library, looking northeast towards downtown Pasadena and JPL. The picture was taken when the fire was still about 2 miles away from JPL. Air quality has improved over the day today, McGregor told SPACE.com, and JPL will decide later whether to keep the facility closed tomorrow.
"We?re monitoring the fire and the air quality and will announce later today whether JPL will reopen to all personnel tomorrow morning," McGregor said.