The first test subject for the world’s largest space camera? Broccoli!

The camera that will snap 3,200-megapixel panoramas of the southern night sky is nearly finished.

• The world’s largest astronomical camera is on its way to Chile’s Vera C. Rubin Observatory.
• The camera captures images with billions of pixels.
• It has the ability to record objects 100 million times fainter than the human eye.

This camera captures massive digital images. To display just one of them at full size, 378 4K ultra-high-definition screens would be required. So, what type of photoshoot might one do with such a beast? Of course, there’s a head of broccoli.

The world’s largest digital camera for astronomy shoots images with a resolution of 3,200 megapixels. It’ll capture panoramic pictures of the night sky in unparalleled detail for the Legacy Survey of Space and Time (LSST) database at Chile’s Vera C. Rubin Observatory, which sits atop Cerro Pachón at 8,700 feet above sea level. The SLAC National Accelerator Laboratory of the Department of Energy is currently completing its construction. In January 2020, the camera’s focal plane was tested using an extraordinarily detailed broccoli picture.

Regardless of everyday produce, project manager Vincent Riot says, “This is a major milestone for us.” The Rubin Observatory’s powerful and sensitive eye will create the images for the LSST’s focal plane.”

The focal plane’s technology is quite advanced, and its assembly is downright terrifying.

Charge-coupled devices, or CCDs, are the sensors that capture 16-megapixel images in high-end digital cameras. (CMOS sensors are used instead in our phones and tablets.) There are 189 CCD sensors in the LSST camera. The sensors are divided into 21 squares, each with nine CCDs – each square is referred to as a “science raft.” The 20-pound, 2-foot-tall rafts are arranged in a grid inside the camera. All of this comes out to 3.2 billion pixels, each of which is about a tenth of the width of a human hair at 10 microns.

As you can think, putting together such complex hardware is not easy. The rafts must be placed in the grid with such precision that they are separated by only five human hairs. If they come into contact, they will crack, resulting in a loss of $3 million per raft. Before starting the six-month assembly process, the SLAC team practiced the assembly procedure for a year.

The camera will be well worthy of time and work.

The flatness of its massive focal plane — nearly 2 feet wide compared to 1.4 inches in a consumer camera — will allow it to capture photos of the skies covering 40 moons. When zoomed in, the team claims the image it generates will be as clear as seeing a golf ball from 15 miles away. The camera will also be extremely sensitive to dim objects, allowing it to capture images of objects that are more than 100 million times dimmer than what our eyes can see – equivalent to seeing a candle from 1,000 miles away. “These standards are really astounding,” says project scientist Steven Ritz.

The focal plane was then placed within a custom-built cryostat for cooling — the needed operating temperature is -150 degrees Fahrenheit.

Broccoli has a lot of small details on its surface, therefore it’s a good candidate for evaluating the focal plane. The scientists constructed a pinhole device that projected the broccoli’s picture onto the focus plane because the camera housing wasn’t finished yet.

Aaron Roodman, who is in charge of creating and testing the LSST focal plane, adds, “Taking these photographs is a big accomplishment.” We really pushed the limits of what’s feasible with the tight constraints to take advantage of every square millimeter of the focal plane and maximize the science we can perform with it.”

The SLAC team’s next task is to integrate the cryostat/focal plane structure, as well as the camera’s lens assembly, which is similarly impressive – it’s the world’s largest optical lens. Ball Aerospace and Arizona Optical Systems created the three-lens array, which was driven 17 hours from Boulder, Colorado to SLAC’s Menlo Park, New Jersey location (slowly).

JoAnne Hewett, SLAC’s chief research officer, says, “Nearing completion of the camera is tremendously exciting.” “And we’re happy to have played such a significant role in the construction of this important component of Rubin Observatory.” The goal of the LSST camera is to capture one complete, extraordinarily detailed panoramic photograph of the Southern sky every day for the next ten years. “It’s a watershed moment,” Hewett continues, “bringing us closer to answering fundamental questions about the cosmos in ways we haven’t been able to before.”