The International Space Station photographed Hurricane Harvey bearing down on the Texas coast. (NASA)

After a weekend of bruising winds and relentless rain, Houston’s rising floodwaters reached the gates of the Johnson Space Center on Sunday.

The NASA facility typically bustles with some 10,000 scientists, engineers, other staff and contractors, including flight controllers for the International Space Station. But it is now closed to all but mission-essential personnel. The Twitter account for the center’s emergency management office reported that water in the neighborhood was knee-deep in some streets and inundating many sidewalks. Security officers had to be evacuated from the campus gates.

“Call if you need access,” one tweet read. “Highly recommend not traveling.”

The Spaceflight Meteorology Group based at JSC reported Sunday that the center had received more than 20 inches of rain.

Only a skeleton “ride-out” crew remains as staffing. Flight Director Royce Renfrew arrived Sunday to relieve one of his colleagues at Mission Control Center, where flight controllers are supporting the six astronauts on board the ISS. The scene was “kind of surreal,” he tweeted.

As of Monday, mission control “remains operational and fully capable of supporting the International Space Station station,” according to a statement on NASA’s website.

JSC also houses the huge thermal vacuum chamber where the James Webb Space Telescope is undergoing tests. The nearly $9 billion successor to the Hubble Space Telescope is to be launched in October 2018 — years behind schedule. The telescope is safe at the moment, as are the personnel who have stayed to protect it, a spokeswoman said.

The space center covers 1,700 acres southeast of Houston, almost within sight of flood-prone Clear Lake and about 30 miles from Galveston Bay. It is on low ground — just 13 feet above sea level at its lowest point, 22 feet at its highest. And it’s only getting more vulnerable as a result of climate change.

A 2012 NASA report identified storm surge and sea level rise as major threats to JSC: “The area has always been subject to hurricanes, and the associated high winds, storm surge and flooding. Rising sea level will increase the risk of catastrophic storm surge impacts on JSC and the surrounding high profile infrastructure assets, human capital and natural resources.”

Even under the most conservative climate change scenarios, another study found, coastal flooding events that happened once every 10 years near the facility are expected to occur 50 percent more often by 2050.

During Hurricane Ike, which struck this same part of the Gulf Coast in 2008, three-quarters of the buildings on JSC’s campus sustained some sort of roof damage — including mission control. Flight control for the International Space Station was temporarily moved to backup facilities in Austin and Huntsville, Ala. Power failures and piles of debris kept the center shut down for a week after the hurricane passed.

Crew on board the space station were briefed about the hurricane Friday, according to JSC news chief Kelly Humphries. From 250 miles above Earth, the six astronauts watched the corner of Texas where mission control sits become engulfed by a white whirlpool of cloud.

“Oh boy — looks like a ton of rain is about to unload,” astronaut Jack Fischer tweeted Friday.

Later, the main ISS account shared photos Fischer had taken through the space station’s six-sided observation dome. Harvey’s fearsome white mass filled the panoramic view — a monstrosity of wind and rain.

JSC Director Ellen Ochoa, a former astronaut, retweeted the images, adding: “Wish I was up there and not down here.”