NASA is gearing up to deploy a revolutionary space telescope designed to explore the cosmos in unprecedented detail.

Set for a launch no earlier than March 2 at 10:09 P.M. EST from Vandenberg Space Force Base in California, the SPHEREx mission—short for the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer—carries a price tag of $488 million and is specifically engineered for cosmological research. Its primary mission is to perform a unique brand of celestial statistics that could shed light on the universe’s nascent moments. SPHEREx will scan the entire sky using over 100 different shades of infrared light, compiling a comprehensive dataset that promises to revolutionize multiple areas of astronomy.

“This type of survey is extraordinary and quite exciting,” remarks Jo Dunkley, a Princeton University astrophysicist and member of NASA’s mission review board.

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Traditionally, astronomical surveys have either covered wide areas of the sky in only a few wavelengths, or focused narrowly on specific celestial objects to analyze light across multiple wavelengths. For instance, the camera on the Vera C. Rubin Observatory in Chile, which is expected to start operations later this year, will span the sky in six wavelength bands. On the other hand, the James Webb Space Telescope offers multiple observation modes that dissect light into numerous wavelengths but within a limited field of view.

SPHEREx introduces a novel approach. Imagine a color printer that separates an image into layers of four ink colors—cyan, magenta, yellow, and black—to create a final image. Similarly, SPHEREx uses six special filters to divide its panoramic view of the sky into 102 infrared hues.

“It’s like opening a new window onto the universe,” explains Olivier Doré, a project scientist for SPHEREx at NASA’s Jet Propulsion Laboratory and the California Institute of Technology.

The data collected by SPHEREx will be broadly relevant to all fields of astronomy, but the mission is focused on three major scientific objectives: mapping various ices in our galaxy and its neighbors, cataloging all the light emitted throughout the universe’s history, and probing the universe’s earliest moments, shortly after the big bang.

Exploring Cosmic Ices

SPHEREx will investigate myriad ices within the Milky Way and surrounding galaxies, mapping substances like water ice, frozen carbon dioxide, methanol, ammonia, and other intriguing compounds. Each substance has a unique molecular signature, or spectrum, visible in the wavelengths of light they absorb. These ice spectra will be observed with unprecedented clarity thanks to SPHEREx’s capabilities.

Historically, capturing these spectra has been challenging; prior to the JWST, only about 200 measurements of these ices existed. In contrast, SPHEREx is expected to make approximately eight million observations. This data could enhance our understanding of the complex chemical processes that bind these ices to interstellar dust grains, potentially delivering them to emerging planetary systems.

“The ices found in the interstellar medium likely seeded Earth and our solar system with water,” states James Bock, a SPHEREx cosmologist at JPL and the California Institute of Technology. “This is crucial not just academically, but also for understanding the origins of life.”

Cataloging Cosmic Light

Besides studying ices, SPHEREx will focus on the universe’s ancient, distant past thanks to its ability to detect infrared light. As the universe expands, wavelengths of light stretch, a process known as “redshifting.” The more space light travels through, the more it expands and shifts toward the red spectrum—turning it into infrared light detectable by SPHEREx.

This stretching allows astronomers to measure how far away an object is from Earth. By mapping the sky’s depth, SPHEREx adds a three-dimensional aspect to our understanding of the cosmos.

The telescope will focus heavily on areas known as the north and south ecliptic poles, observing each pole repeatedly throughout its mission. These observations aim to capture the elusive signal of all the light emitted throughout the universe’s history, which SPHEREx will analyze over time.

Previous estimates of this cosmic light likely undercount actual light production, as some galaxies are too faint or too distant to be measured accurately. SPHEREx, however, will observe the entire sky, capturing even the faintest background light often missed in other surveys.

“Even if there’s no visible star, we’ll detect the collective light emitted by all galaxies,” notes Asantha Cooray, a University of California, Irvine cosmologist and SPHEREx team member.

The mission’s ability to track how the universe’s light output has evolved over time could reveal insights into how the earliest galaxies formed and provide details about the mysterious “little red dots” observed by JWST soon after the big bang.

Focusing on Cosmic Inflation

SPHEREx’s final primary scientific goal delves even deeper into the past, to the moments right after the big bang, when cosmic inflation is thought to have rapidly expanded the universe.

“Inflation was a monumental event, expanding the universe by an unimaginable scale,” explains Bock. “Though it’s difficult to study directly due to the extreme conditions of the early universe, SPHEREx will help us understand inflation indirectly.”

SPHEREx will survey the entire sky, mapping the locations of approximately 450 million galaxies to create a vast three-dimensional cosmic map. This data will allow scientists to trace patterns in the distribution of galaxies that may still bear the imprint of the early universe, helping to support or refute different models of inflation.

“We’re effectively traveling back to the universe’s origins,” says Doré. “It’s a powerful, almost awe-inspiring ability.”

In addition to its primary missions, SPHEREx will study phenomena closer to home, such as planets, asteroids, and comets, and because it will survey the entire sky multiple times, it will also be invaluable for tracking transient events like supernovas.

“Every new way we look at the sky brings new discoveries,” Doré adds. “SPHEREx will be a true machine of discovery.”