Following its March 11 launch, SPHEREx completed a six-week phase of checkouts and calibrations. On May 1, it began operations aimed at capturing high-resolution data on hundreds of millions of galaxies. The two-year mission will help scientists answer fundamental questions about the origins of the universe and the building blocks of life.

"Thanks to the hard work of teams across NASA, industry, and academia that built this mission, SPHEREx is operating just as we'd expected and will produce maps of the full sky unlike any we've had before," said Shawn Domagal-Goldman, acting director of NASA's Astrophysics Division. "Together with NASA's other missions, SPHEREx will play a key role in answering the big questions about the universe we tackle at NASA every day."

Operating in Earth orbit, SPHEREx circles the planet roughly 14.5 times per day on a north-south path, completing more than 11,000 orbits over 25 months. Each day, it scans one circular band of sky, and after six months, it will have observed the entire celestial sphere. The spacecraft does not use thrusters for maneuvering but relies on reaction wheels to shift its orientation between exposures.

SPHEREx captures light using six detectors that split the incoming light into different infrared wavelengths. Each exposure includes six images, and the observatory collects about 600 exposures daily. These will be digitally stitched into four full-sky maps by mission end. Scientists expect this massive dataset to reveal how matter was distributed in the early universe, influenced by a brief yet intense expansion phase known as cosmic inflation.

"We're going to study what happened on the smallest size scales in the universe's earliest moments by looking at the modern universe on the largest scales," said Jim Fanson, SPHEREx project manager at NASA's Jet Propulsion Laboratory. "I think there's a poetic arc to that."

Cosmic inflation theories predict that the massive energy required left subtle fingerprints in the large-scale structure of the universe. By mapping the 3D positions of galaxies, SPHEREx offers scientists a powerful tool to explore these signatures.

"Some of us have been working toward this goal for 12 years," said Jamie Bock, principal investigator at Caltech and JPL. "The performance of the instrument is as good as we hoped. That means we're going to be able to do all the amazing science we planned on and perhaps even get some unexpected discoveries."

Unlike earlier missions, SPHEREx maps the entire sky across 102 wavelengths of infrared light, far beyond the visible spectrum. Using spectroscopy, the mission will help determine distances to distant galaxies, allowing researchers to construct three-dimensional cosmic maps. It will also quantify the total infrared glow from all galaxies and track its evolution over time.

Spectroscopy further enables the identification of chemical compositions. SPHEREx will scan over 9 million interstellar clouds in the Milky Way, hunting for water and other life-supporting molecules. These studies could shed light on how Earth-like materials formed in the galaxy.

Related Links
SPHEREx
Understanding Time and Space