NASA's SPHEREx maps water ice in space
- NASA said on April 15 that its SPHEREx space observatory mapped water ice across the Cygnus X star-forming complex, turning infrared spectra into a chemical map of one of the Milky Way’s busiest nurseries. - The new maps span regions more than 600 light-years across and trace water ice alongside polycyclic aromatic hydrocarbons, with the strongest ice lining up with the densest dust lanes in Cygnus X. - SPHEREx is built to survey the whole sky in 102 infrared wavelengths four times in two years, extending ice studies far beyond earlier one-target-at-a-time observations. (nasa.gov)
SPHEREx reads space in infrared colors the eye cannot see, and NASA says those colors now reveal giant reservoirs of water ice in Cygnus X. (nasa.gov) The April 15 release from NASA and the Jet Propulsion Laboratory showed water ice spread across parts of the Cygnus X star-forming region more than 600 light-years wide. A companion study appeared the same day in *The Astrophysical Journal*. (nasa.gov) (jpl.nasa.gov) Instead of a standard picture, SPHEREx makes a spectrum, a kind of barcode of light, at many positions across the sky. In Cygnus X, that let researchers map the 3-micron signature of water ice and compare it with features from polycyclic aromatic hydrocarbons, or PAHs, carbon-rich molecules seen in interstellar clouds. (jpl.nasa.gov) (arxiv.org) The maps show the strongest water-ice signal where dust is thickest, supporting the idea that ice forms on tiny dust grains and survives because the dust blocks ultraviolet radiation from nearby newborn stars. NASA compared those grains to particles in candle smoke. (nasa.gov) (jpl.nasa.gov) That matters because astronomers think much of the universe’s water is made and stored in these frozen coatings before it is carried into comets, planets, moons, and young planetary systems. SPHEREx is designed to track not only water ice but also carbon dioxide and carbon monoxide ice across broad stretches of the Milky Way. (astropix.org) (jpl.nasa.gov) SPHEREx is short for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer. NASA launched it on March 11, 2025, and the mission plan calls for all-sky surveys every six months, for a total of four full-sky maps over two years. (science.nasa.gov) (jpl.nasa.gov) NASA says the observatory will observe the sky in 102 infrared wavelengths, more than any previous all-sky survey, giving researchers a uniform data set instead of piecing together narrower observations from different telescopes. (jpl.nasa.gov) (iopscience.iop.org) The Cygnus X result is one of the first public examples of that approach: a chemical map built over a huge field, not a close-up of a single source. The research team said the near-infrared maps are among the largest of their kind yet assembled. (nasa.gov) (arxiv.org) SPHEREx was built for three jobs at once: mapping galaxies, probing the early universe, and surveying ices in the Milky Way and Magellanic Clouds. In the ice program alone, researchers say the mission is set up to collect spectra for nearly 10 million preselected sources. (iopscience.iop.org) (arxiv.org) The Cygnus X maps do not answer where Earth’s water came from by themselves. They do show SPHEREx starting the census NASA designed it to make: where cosmic ice sits, what shields it, and how widely it is spread. (nasa.gov)
