A new NASA space observatory is scheduled to launch into orbit Thursday on a lofty mission to map more than 450 million galaxies.
The SPHEREx mission (short for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer) will map the entire sky four times over two years, offering scientists a chance to study how galaxies form and evolve, and providing a window into how the universe came to be.
“It’s going to answer a fundamental question: How did we get here?” Shawn Domagal-Goldman, acting director of the astrophysics division at NASA headquarters, said in a recent news briefing.
SPHEREx is scheduled to lift off Thursday no earlier than 10:09 p.m. ET from Vandenberg Space Force Base in California.
The cone-shaped spacecraft — along with four suitcase-sized satellites that NASA will deploy at the same time on a separate mission to study the sun — will launch atop a SpaceX Falcon 9 rocket.
The $488 million SPHEREx mission, which has been in development for about a decade, is designed to map the celestial sky in 102 infrared colors — more than any other mission before it, according to NASA.
Infrared instruments in space are ideal for piercing through dust and gas to see some of the universe’s oldest stars and galaxies, which would otherwise be obscured from view. (Colors in the infrared range are not visible to people, however, because infrared light has longer wavelengths than the eye can detect.)
Using a technique called spectroscopy, scientists can split the infrared light from stars and galaxies into different colors, similar to how sunlight hitting a prism separates into a rainbow of visible hues. An object’s spectra can reveal many useful characteristics, including its composition, density, temperature and motion.
The SPHEREx observatory will use its spectrometers to survey the sky in three dimensions and measure these characteristics in hundreds of millions of galaxies, said Jamie Bock, principal investigator of the SPHEREx mission and a professor of physics at the California Institute of Technology.
Bock said these observations could unlock answers about galaxy formation and enable the observatory to investigate the origin of water and other organic materials in our Milky Way galaxy.
“In splitting up the light, we can use that to determine the distance to galaxies, to build up that three-dimensional map, and we also see the fingerprints of water,” Bock said.
Tracing the origins of water could not only help scientists figure out how life evolved on Earth; the work might also yield clues about where key ingredients for life may be found elsewhere in our galaxy.
“This is a new capability, and with any new capability comes the potential for discoveries and surprises,” Bock said.
In charting the celestial sky, the SPHEREx mission will also tackle one of astronomy’s most enduring mysteries: What happened in the first moments after the Big Bang that created the universe around 13.8 billion years ago.
One theory, proposed in the late 1970s and early 1980s, suggests the universe underwent a remarkable trillion-trillion-fold expansion in the first fractions of a second after the Big Bang. The theory, known as cosmic inflation, has been used to explain the universe’s flat geometry and lack of curvature, and as a possible reason for how some of the largest structures in the universe — galaxies and clusters of galaxies, for instance — came to be.
But astronomers have long struggled to piece together what drove cosmic inflation or why it happened in the first place. The SPHEREx mission could test the theory in new ways, since determining the precise distribution of hundreds of millions of galaxies would help scientists hone in on the physics of cosmic inflation and how such a rapid expansion may have occurred.
“What SPHEREx will do will test certain models of inflation by tracing out in three dimensions hundreds of millions of galaxies over the entire sky,” Brock said.
Domagal-Goldman said the SPHEREx mission’s study of galaxies, cosmic inflation and the origins of the universe could advance humanity’s understanding of fundamental physics.
“We’re very privileged in the long story of the human existence on this planet to live at a time where we can actually answer questions about the universe,” he said.