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The largest camera on earth for astronomy built by SLAC is seen in a lab in Menlo Park, Calif.

The largest camera on earth for astronomy built by SLAC is seen in a lab in Menlo Park, Calif.

In a sterile room within an unmarked warehouse hidden in the hills west of Stanford University, engineers in white bodysuits have built the largest digital camera on earth.

Called the Legacy Survey of Space and Time Camera, it is the size of a minivan, weighs 3 tons and takes two people to lift off the lens cap, which is 5 feet in diameter.

When it leaves the campus of SLAC National Accelerator Laboratory where it was designed constructed, it will be flown on a chartered 747 plane with a team of 10 to assemble it on the other end.

A camera of this size has limited practicality, but the LSST Camera, as it is branded, serves just one purpose: to capture the night sky with a mirror that is 25 feet across and a focal plane that is 3.2 billion pixels.

The largest camera on earth for astronomy built by SLAC is seen in a lab in Menlo Park, Calif.

“That’s billion, with a ‘B,’’’ said LSST Camera program manager Aaron Roodman, a professor of particle physics and astrophysics at Stanford. “The idea was to build a camera capable of taking a picture of the entire night sky.”

Funded by the U.S. Department of Energy, the camera cost $168 million, and though Stanford may have been the right place to build it, Palo Alto does not have the right sky for using it. The place to use a camera like this is at the Rubin Observatory in the high desert of Cerro Pachon, Chile.

“It has the conditions that we want, with the air smooth at 20,000 feet,’’ said Roodman, who will soon be commuting to the Southern Hemisphere.

The LSST camera will be mounted on a giant swivel, which can be rotated like a gun turret, and at night images will be recorded every 15 seconds. From there, images that translate to 3,200 megabytes each will be transmitted by a designated fiber -optic line connecting Chile to Menlo Park.

A tour group visits the largest camera on earth for astronomy built by SLAC is seen in a lab in Menlo Park, Calif.

SLAC has a 10-year contract to run the Rubin Observatory in partnership with the National Optical-Infrared Astronomy Research Laboratory.

“LSST is making a 10-year movie of things that move in the sky,” said Risa Wechsler, a physics professor and the director of the Kavli Institute for Particle Astrophysics and Cosmology at SLAC/Stanford.

“I’m just in awe seeing it for the first time,” she said Wednesday.

SLAC has a long history of doing things big, going back to 1962 when it started construction on a two-mile atom-splitting laser beam that commonly known as “the world’s longest flashlight.” The linear accelerator is used to study the small picture — particles of energy that make up the universe. The LSST Camera is built for the big picture.

“We expect to see six billion solar system objects, most of these asteroids’’ predicted Roodman, “which is 50 times what has been observed already.”

Unlike many inventions and technical innovations that have come out of through Stanford, the LSST Camera team is not motivated by the potential for profit.

A detail of the sensor on the largest camera on earth for astronomy built by SLAC in Menlo Park, Calif.

“This is pure science,” said Roodman, who estimates that there will be 10,000 scientific users for the data. Plus there are the non-scientific uses.

Wechsler gives a free monthly public lecture on campus and in a few years she will start showing snippets from the 10-year movie at these lectures.

But first the crew must finish the LSST, get it on the charter jet to Chile and get it reassembled. Like all cameras, it is a hassle to maintain. That is why they put on white suits with hoods up and cover their shoes with plastic booties before entering the clean room and put on gloves to touch the camera.

“We don’t want any dust on anything,” Roodman said. “You get dust on the image sensor and you can’t get it off.”

Sam Whiting is a San Francisco Chronicle staff writer. Email: swhiting@sfchronicle.com Twitter: @SamWhitingSF

Sam Whiting has been a staff writer at The San Francisco Chronicle since 1988. He started as a feature writer in the People section, which was anchored by Herb Caen's column, and has written about people ever since. He is a general assignment reporter with a focus on writing feature-length obituaries. He lives in San Francisco and walks three miles a day on the steep city streets.