NASA’s SPHEREx Probe Maps Unprecedented Interstellar Ice Region in the Milky Way

NASA’s SPHEREx probe has recently mapped an unprecedented distribution of interstellar ice in the Milky Way, discovering an extensive ice region stretching over 600 light-years within giant molecular clouds. These regions, composed of gas and dust, are the cradle of stars, and the ice they contain is a key raw material for forming the chemical basis of life. The related research has been published in the latest issue of The Astrophysical Journal.

One of the core scientific goals of the SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) mission is to map the chemical characteristic spectra of various interstellar ices, including water ice, carbon dioxide ice and carbon monoxide ice. Scientists believe that these ices, attached to the surface of cosmic dust particles, are the largest reservoir of water in the universe, and the ice on Earth’s oceans, comets and other celestial bodies may originate from such regions.

China News Network reports that interstellar ices play a crucial role in the origin of life, as they can serve as the precursor for synthesizing key components of DNA and RNA. In this study, scientists from institutions including the California Institute of Technology and the Harvard-Smithsonian Center for Astrophysics used SPHEREx to conduct in-depth observations of star-forming regions such as Cygnus X in the Milky Way.

With its powerful infrared spectral capability, the probe penetrated the dense dust bands that are completely opaque in visible light, revealing the spatial distribution of different ice molecules in unprecedented detail. Observations show that ice abundance is highest in the densest dust regions, supporting the mainstream theory that interstellar ice forms on the surface of tiny dust particles and is protected by dense dust from the intense ultraviolet radiation of newborn stars.

Launched in March 2025 and managed by NASA’s Jet Propulsion Laboratory, the SPHEREx space telescope is the first mission specifically designed for all-sky infrared spectral surveys. It can observe the sky at 102 infrared wavelengths, enabling precise identification of the “chemical fingerprints” of different molecules. By the end of 2025, it had completed the mapping of the first all-sky infrared map.

Unlike devices such as the James Webb Space Telescope, which conduct in-depth observations of specific sky areas, SPHEREx provides a macro “big picture” perspective. This allows scientists to systematically study the environmental factors affecting ice formation rates in large areas, such as comparing the response differences of water ice and carbon dioxide ice to different environmental stimuli, such as ultraviolet radiation or changes in dust temperature.

The distribution and abundance of these ices are directly related to how many volatile substances necessary for life future planetary systems born in those regions can obtain. Ralph Kaiser, a researcher at the University of Hawaii, noted that interstellar ices are vital to exploring the origin of life, as they can generate complex organic molecules under cosmic conditions.

This discovery is only the beginning of the SPHEREx mission. Its continuous observations will provide crucial data for understanding a series of fundamental issues, such as the structure of the Milky Way, the physics of star and planet formation, and how life-essential molecules are transported to new worlds.