What is SPHEREx? NASA’s ambitious mission to unravel Big Bang mystery scheduled to launch between 2024 and 2025

SPHEREx will survey hundreds of millions of galaxies near and far, some so distant their light has taken 10 billion years to reach Earth


                            What is SPHEREx? NASA’s ambitious mission to unravel Big Bang mystery scheduled to launch between 2024 and 2025
(NASA/JPL-Caltech)

How did the universe begin? While many scientific theories have tried to answer this question, the widely accepted explanation is the big bang theory. But what exactly happened at our universe’s birth and how did it take the shape we observe today? NASA’s ambitious mission SPHEREx – Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer – which will help scientists unravel the mysteries of the universe, is one step closer to reality.

According to NASA, the mission has officially entered “Phase C,” which implies that the agency has approved preliminary design plans for the observatory, and work can begin on creating a final, detailed design, as well as on building the hardware and software.

A map of the universe in over 100 colors

SPHEREx will help scientists determine how our universe evolved. Managed by NASA’s Jet Propulsion Laboratory (JPL) in Southern California, SPHEREx is scheduled to launch as early as June 2024, and no later than April 2025. The mission was selected in 2019. 

SPHEREx will survey the sky in optical as well as near-infrared light which, though not visible to the human eye, serves as a powerful tool for answering cosmic questions. It will survey hundreds of millions of galaxies near and far, some so distant their light has taken 10 billion years to reach Earth. Astronomers will use the mission to gather data on more than 300 million galaxies, as well as more than 100 million stars in our own Milky Way.

It will survey hundreds of millions of galaxies near and far, some so distant their light has taken 10 billion years to reach Earth (Getty Images)

By creating a map of the universe in more than 100 colors, the mission will let scientists learn about the formation of galaxies and search for life-sustaining molecules in the clouds of material where stars and planets form. “Its instruments will detect near-infrared light, or wavelengths longer than the light visible to the human eye. During its two-year mission, it will map the entire sky four times, creating a massive database of stars, galaxies, nebulae (clouds where stars form), and many other celestial objects,” reveals NASA. 

About the size of a subcompact car, the space telescope will use a technique called spectroscopy to break near-infrared light into its wavelengths, or colors, just like a prism can break sunlight into its component colors, creating a rainbow. Spectroscopy data can reveal what an object is made of because individual chemical elements absorb and radiate specific wavelengths of light. It can also be used to estimate an object's distance from Earth, which means the SPHEREx map will be three-dimensional. SPHEREx will be the first NASA mission to build a full-sky spectroscopy map in near-infrared, and it will observe a total of “102 near-infrared colors.” “That’s like going from black-and-white images to color; it’s like going from Kansas to Oz,” explains Allen Farrington, the SPHEREx project manager at JPL.

SPHEREx it will map the entire sky four times, creating a massive database of stars, galaxies, nebulae (clouds where stars form), and many other celestial objects (Getty Images)

According to researchers, astrobiologists studying the potential habitability of extrasolar planets will benefit from the data returned by SPHEREx. This data will also be used to narrow down targets for further study by future telescopes like the James Webb Space Telescope (JWST) and Wide Field Infrared Survey Telescope (WFIRST). 

What are its key goals?

The fundamental questions it will tackle are the origin of the universe, the origin and history of galaxies, and the origin of water in planetary systems. 

The first goal is to look for evidence of what happened less than a billionth of a billionth of a second after the big bang. “In that split second, space itself may have rapidly expanded in a process scientists call inflation. Such sudden ballooning would have influenced the distribution of matter in the cosmos, and evidence of that influence would still be around today. With SPHEREx, scientists will map the position of billions of galaxies across the universe relative to one another, looking for statistical patterns caused by inflation. The patterns could help scientists understand the physics that drove the expansion,” say experts.

The second objective is to study the history of galaxy formation, ranging from the first stars to ignite after the Big Bang, all the way to present-day galaxies. SPHEREx will do this by studying the faint glow created by all the galaxies in the universe, allowing scientists to understand how the first galaxies initially formed stars.

The first objective is to look for evidence of what happened less than a billionth of a billionth of a second after the big bang (Getty Images)

The final aim is to look for water ice and frozen organic molecules, the building blocks of life on Earth, around newly forming stars in our galaxy. “Water ice gloms onto dust grains in cold, dense gas clouds throughout the galaxy. Young stars form inside these clouds, and planets form from disks of leftover material around those stars. Ices in these disks could seed planets with water and other organic molecules. In fact, the water in Earth's oceans most likely began as interstellar ice,” notes NASA. It adds, “Scientists want to know how frequently life-sustaining materials like water are incorporated into young planetary systems. This will help them understand how common planetary systems like ours are throughout the cosmos.”

A collaborative effort

Before entering Phase C, the SPHEREx team completed a preliminary design review in October 2020. The SPHEREx team is scheduled to spend 29 months building the mission components before entering the next mission phase when those components will be brought together, tested, and launched. The scientific analysis of the SPHEREx data will be conducted by a team of scientists located in 10 institutions across the US, and South-Korea.

The mission’s principal investigator is James Bock of the California Institute of Technology (Caltech) in Pasadena. Caltech is working with JPL to develop the mission payload. Ball Aerospace in Broomfield, Colorado, will provide the SPHEREx spacecraft and mission integration. The Korea Astronomy & Space Science Institute in Daejeon, Republic of Korea, will contribute test equipment and science analysis.

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