In late February, if all goes according to Lplan, NASA will introduce a new player to its growing fleet of space telescopes. SPHEREx, a compact, conical probe with an eggshell-white exterior, is set to launch on a mission that promises to revolutionize our understanding of the universe.
An illustration of the SPHEREx spacecraft with cosmic structures in the background. The craft's "cone" shape is halved so you can see the inside of it. (Image credit: NASA/JPL-Caltech)
SPHEREx—short for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer—is designed to scan the cosmos in both visible and infrared light. While the James Webb Space Telescope (JWST) has been groundbreaking in its ability to peer deep into the universe, SPHEREx will provide a different kind of insight—offering a panoramic view of the entire sky in unprecedented infrared detail.
A New Way to View the Cosmos
"Taking a snapshot with JWST is like taking a picture of a person," explained Shawn Domagal-Goldman, acting director of the Astrophysics Division at NASA Headquarters, during a January 31 briefing. "What SPHEREx and other survey missions can do is almost like going into panorama mode, when you want to catch a big group of people and the things standing behind or around them."
Rather than focusing on narrow, high-resolution views of deep-space objects like JWST, SPHEREx will systematically map the entire sky every six months, capturing 102 infrared color bands that will allow scientists to analyze cosmic structures like never before.
NASA's SPHEREx space observatory photographed at BAE Systems in Boulder, Colorado, in November 2024 after completing environmental testing. The spacecraft's three concentric cones help direct heat and light away from the telescope and other components, keeping them cool. (Image credit: BAE Systems)
Launch and Mission Logistics
SPHEREx is set to launch no earlier than February 27, 2025, aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California. However, it won’t be the only passenger on this mission. As part of NASA’s Launch Services Program, the telescope will share its ride with PUNCH (Polarimeter to Unify the Corona and Heliosphere), a constellation of four small satellites designed to study the Sun’s outer atmosphere.
"This is the third launch of this reusable booster, which was previously flown on the Transporter 12 mission on January 14," said Cesar Marin, a SPHEREx integration engineer at NASA's Kennedy Space Center. "The booster will be applying its phenomenal capacity of returning once again to land in zone four at Vandenberg Space Force Base about eight minutes after launch."
What Will SPHEREx Study?
Once in orbit, SPHEREx will begin a two-year mission (with the possibility of extension) dedicated to three key scientific objectives:
1. Mapping the Cosmic Infrared Background – By surveying the sky in near-infrared wavelengths, SPHEREx will help scientists study cosmic inflation, the theory that describes the universe's rapid expansion immediately after the Big Bang. “Literally a trillionth of a trillionth of a billionth of a second after the Big Bang, the observable universe went through a remarkable expansion,” said Jamie Bock, SPHEREx principal investigator at the California Institute of Technology. “We still don’t know what drove inflation or why it happened.”
2. Tracing the Evolution of Galaxies – By observing galaxies at different points in their histories, SPHEREx will provide crucial insights into how galaxies evolve over billions of years. It will also create three-dimensional maps of hundreds of millions of galaxies, helping astronomers better understand the large-scale structure of the cosmos.
3. Investigating the Origins of Life – SPHEREx will scan interstellar ice in regions between stars, identifying organic molecules that could have contributed to the formation of life. "Shout out to our team at OSIRIS-REx in the Planetary Division," Domagal-Goldman said, referencing NASA's asteroid-sampling mission. "They pick up that story and then tell how it traverses in our solar system to
planets like our home."
The electromagnetic spectrum with Hubble and the JWST’s ranges. credit: NASA, J. Olmsted (STScI)
The Technology Behind SPHEREx
SPHEREx is a lightweight and efficient observatory, weighing approximately 1,100 pounds—slightly less than a grand piano—and consuming just 270–300 watts of power, less than a standard refrigerator. "It produces more power than it needs using a thick solar array, very much like one you might have on the roof of your house," said Beth Fabinsky, deputy project manager for SPHEREx at NASA’s Jet Propulsion Laboratory.
One of the biggest engineering challenges of an infrared telescope is managing heat. Infrared instruments are highly sensitive to heat signatures, including those from their own equipment. “If they are too warm, they will be blinded by their own warm glow,” Fabinsky explained.
To maintain the necessary frigid temperatures for infrared observations, SPHEREx will operate in a dawn-dusk Sun-synchronous orbit, which minimizes exposure to sunlight. Additionally, the spacecraft is equipped with three concentric, cone-shaped photon shields, along with curved cooling plates called V-group radiators, which help radiate heat away from its sensors.
SPHEREx’s role as an all-sky infrared surveyor will complement the work of JWST, helping scientists identify regions of interest for Webb’s detailed observations. “No single instrument, no one instrument, no single mission can tell us the full story of the cosmos,” Domagal-Goldman said. “Those answers to the big questions come from the power of combined observations from combined observatories.”
In addition to JWST, the upcoming Vera C. Rubin Observatory, expected to see first light later this year, will map the sky in different wavelengths, providing yet another layer of data for astronomers to analyze.
Once SPHEREx reaches orbit and deploys successfully, scientists will begin the telescope’s first six-month sky survey. Data will be released within two months of observation, providing researchers with calibrated spectral images that could unlock new cosmic discoveries.
However, for the SPHEREx team, the real moment of truth will come when the telescope’s cover is removed, and it captures its first image. “That’ll tell us everything’s working as expected,” said Bock.
With a relatively modest budget of $488 million, SPHEREx represents a cost-effective yet scientifically ambitious mission that could reshape our understanding of the universe. If successful, it will not only enhance our knowledge of cosmic history but also guide the next generation of astronomical discoveries.
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