Soon, a new cone-shaped spacecraft will launch into space on a mission to chart the skies like never before. Called SPHEREx (for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer), the NASA mission will provide a unique all-sky 3D map of hundreds of millions of galaxies in our universe. Among several big questions the mission is poised to answer is how our universe came to be. SPHEREx will provide new clues in the quest to understand cosmic inflation, a much-studied theory that states our newborn universe expanded a trillion-trillion-fold in a fraction of a second-much less time than it takes to snap your fingers. After that initial blast, the universe continued to expand albeit at a more leisurely pace.
As mind-bending as inflation is, the theory, which was proposed by physicist Alan Guth and others in the late 1970s and early 1980s, continues to stand the test of time, making several accurate predictions about features in our universe. Now, the pressing question on most cosmologists' minds is not whether inflation occurred but how.
"If inflation is the right theory, and we think it is, then what caused it?" says Jamie Bock , the principal investigator of SPHEREx and the Marvin L. Goldberger Professor of Physics at Caltech and senior research scientist at the Jet Propulsion Laboratory. "As an analogy, think about the theory of evolution. It took people a long time to understand the mechanisms explaining how evolution works through genetic mutation, well after Darwin established the basic theory. In a similar way, inflation successfully describes our universe, but we are struggling to understand how it came about. Our approach with SPHEREx is to methodically gather data to test models of inflation."
Bock has been working on SPHEREx since 2012, two years before he and his team first proposed the mission concept to NASA . The space agency selected SPHEREX for flight in 2019 and now, six years later, the completed spacecraft is scheduled to launch into space at the end of February aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in central California. The mission is managed by JPL, which is managed by Caltech for NASA. Several groups worked together to build SPHEREx, including researchers from Caltech's campus and JPL, BAE Systems, and the Korea Astronomy and Space Science Institute. Caltech's IPAC astronomy is operating the mission's data center, which will process the data, while the data itself will be made publicly available through the NASA IPAC Infrared Science Archive.
SPHEREx's three primary goals are to explore the origins of water and organic molecules in planetary systems, the history of galaxy formation, and the mechanisms behind cosmic inflation-the "bang" in the big bang that set our universe in motion. The mission will map the sky four times over a period of two years, capturing detailed spectral information for every point, or pixel, on the sky. For each point, it will observe infrared light in a rainbow of 102 colors , ranging in wavelength from 0.75 to 5 microns.
"We will look at everything in the sky and get a spectrum for every pixel no matter what is there-comets in our solar system, planets, stars, galaxies. We expect our data set to expand our broad knowledge of the cosmos: Whatever your favorite object on the sky is, we will measure its spectrum," says Olivier Doré , the project scientist for SPHEREx at JPL.
