Two astronomers from the University of Arizona will participate in a new space mission that will help astronomers understand both how our universe evolved and how common are the ingredients for life in our galaxy’s planetary systems.

NASA's Explorer program recently selected the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer, or SPHEREx, mission, a planned two-year mission funded at $242 million, not including launch costs. Elisabeth Krause and Tim Eifler, who both joined the UA as junior faculty members last fall,  are part of the project that is targeted to launch in 2023.

SPHEREx will survey hundreds of millions of galaxies near and far, some so distant their light has taken 10 billion years to reach Earth. In the Milky Way, the mission will search for water and organic molecules – essentials for life, as we know it – in stellar nurseries, regions where stars are born from gas and dust, as well as disks around stars where new planets could be forming.

Krause, assistant professor of astronomy and physics at the UA, is a mission co-investigator. Eifler, assistant professor of astronomy, is a SPHEREx collaborator.

SHEREx will map galaxies across much of the universe to study the universe’s earliest moments of rapid expansion after the big bang, a period of time called “inflation.” Krause will use SPHEREx to better understand the physics behind the brief period of time following the big bang, when the universe expanded from microscopic to cosmic scales in less than a nanosecond.

By collecting the spectra – individual components of light – of more than 300 million galaxies, SPHEREx will seek to gain insights into the origin and history of galaxy formation. The space telescope will be able to see a broader range of colors than any other survey telescope, including the Large Synoptic Survey Telescope, or LSST, which will begin observing in 2020. Both telescopes will map the entire sky, but the LSST can only see visual light.

"SPHEREx can observe galaxies in the infrared light spectrum," Eifler said. "Hence, its observation window nicely starts where LSST’s ends."

Eifler’s role is to determine the best way to combine the data from the two surveys. Utilizing both visual light, which LSST will see, and the infrared light from SPHEREx, astronomers will be able to better define how far away the Milky Way’s neighborhood galaxies are, and how fast they are traveling through space. Understanding the dynamics of our galactic community enables scientists to look back through the history of the universe, to investigate how galaxies form and evolve.

Every six months, SPHEREx will survey the entire sky using technologies adapted from Earth satellites and Mars spacecraft. The mission will create a map of the entire sky in 96 different color bands, far exceeding the color resolution of previous all-sky maps. It also will identify targets for more detailed study by future missions, such as NASA’s James Webb Space Telescope and Wide Field Infrared Survey Telescope.

"This amazing mission will be a treasure trove of unique data for astronomers,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “It will deliver an unprecedented galactic map containing ‘fingerprints’ from the first moments in the universe’s history. And we’ll have new clues to one of the greatest mysteries in science: What made the universe expand so quickly less than a nanosecond after the big bang?”

NASA's Astrophysics Explorers Program requested proposals for new missions in September 2016. Nine proposals were submitted, and two mission concepts were selected for further study in August 2017. After a detailed review by a panel of NASA and external scientists and engineers, NASA determined that the SPHEREx concept study offered the best science potential and most feasible development plan.

NASA's Explorer program, managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, is the agency's oldest continuous program, designed to provide frequent, low-cost access to space using principal investigator-led space science investigations relevant to the Astrophysics and Heliophysics programs in NASA’s Science Mission Directorate. The program has launched more than 90 missions, beginning in 1958 with Explorer 1, which discovered the Earth’s radiation belts. Another Explorer mission, the Cosmic Background Explorer, which launched in 1989, led to a Nobel Prize.

For the next four years, the SPHEREx team will be designing, building and testing the space telescope. The California Institute of Technology and the Jet Propulsion Laboratory will develop the SPHEREx payload. The spacecraft will be supplied by Ball Aerospace. The Korea Astronomy and Space Science Institute will contribute the non-flight cryogenic test chamber. The data will be made publicly available through the Infrared Processing and Analysis Center. The SPHEREx team also includes scientists at the University of California, Irvine, The Ohio State University, the Harvard-Smithsonian Center for Astrophysics, Arizona State University, the Rochester Institute of Technology, the Argonne National Laboratory and Johns Hopkins University.