Why NASA is betting on a 36-pixel camera

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NASA’s James Webb Space Telescope is making strides in astronomy with its 122-megapixel primarily infrared photos taken 1.5 million kilometers away from Earth. Impressive stuff. The space agency’s newest sky-peeper takes a different approach, however, performing groundbreaking space science with 36 pixels. That’s not a typo—36 pixels, not 36 megapixels.

The X-ray Imaging and Spectroscopy Mission (XRISM), pronounced “crism,” is a collaboration between NASA and the Japan Aerospace Exploration Agency (JAXA). The mission’s satellite launched into orbit last September and has been scouring the cosmos for answers to some of science’s most complex questions ever since. The mission’s imaging instrument, Resolve, has a 36-pixel image sensor.

It’s been a hot minute since we could count the individual pixels on an imaging chip, but here we are… The array measures 0.2 inches (5 millimeters) on a side. The device produces a spectrum of X-ray sources between 400 and 12,000 electron volts — up to 5,000 times the energy of visible light — with unprecedented detail. **Image Credit**s: NASA/XRISM/Caroline Kilbourne

“Resolve is more than a camera. Its detector takes the temperature of each X-ray that strikes it,” said Brian Williams, NASA’s XRISM project scientist at Goddard, in a press statement. “We call Resolve a microcalorimeter spectrometer because each of its 36 pixels is measuring tiny amounts of heat delivered by each incoming X-ray, allowing us to see the chemical fingerprints of elements making up the sources in unprecedented detail.”

Equipped with an extraordinary array of pixels, the Resolve instrument can detect “soft” X-rays, which possess an energy approximately 5,000 times greater than visible light wavelengths. Its primary focus is exploring the hottest cosmic regions, the largest structures, and the most massive celestial objects, such as supermassive black holes. Despite its limited pixel count, each pixel in Resolve is remarkable, capable of generating a rich spectrum of visual data encompassing an energy range from 400 to 12,000 electron volts.

The agency says the instrument can perceive the motions of elements within a target, essentially offering a three-dimensional perspective. Gas moving toward us emits slightly higher energies than usual, while gas moving away emits slightly lower energies. This capability opens up new avenues for scientific exploration. For instance, it enables scientists to understand the flow of hot gas in galaxy clusters and to meticulously track the movement of various elements in the remnants of supernova explosions.