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NASA's SPHEREx Mission Maps Interstellar Ice in Milky Way Star-Forming Regions

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NASA's SPHEREx Mission Maps 'Interstellar Glaciers' in the Milky Way

NASA's SPHEREx mission has produced an unprecedented, large-scale map of interstellar ice within the Milky Way galaxy. The observations, detailed in a study published in The Astrophysical Journal, cover regions spanning more than 600 light-years across within giant molecular clouds, areas where stars are born. The mission's data reveals the spatial distribution of icy molecules, including water, carbon dioxide, and carbon monoxide, attached to microscopic dust grains.

Mission Overview and Capabilities

The Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx) observatory launched on March 11, 2025. It is managed by NASA's Jet Propulsion Laboratory.

  • Primary Goal: To map the chemical signatures of various types of interstellar ice across the entire sky via a large-scale spectral survey.
  • Technical Capability: The observatory observes the sky in 102 distinct colors, each representing a different wavelength of infrared light. This allows it to identify specific molecules by the wavelengths they absorb.
  • Survey Progress: By late 2025, SPHEREx had completed the first of four planned all-sky infrared maps.

Key Findings and Observations

The study analyzed data from molecular clouds in the Cygnus X star-forming region and the North American Nebula.

Ice Detection: SPHEREx mapped water ice, carbon dioxide, and carbon monoxide. In mission data, water ice appears as bright blue structures that overlay dark lanes of interstellar dust.

Location and Formation: The ice was found inside giant molecular clouds. The findings support the hypothesis that interstellar ice forms on the surfaces of tiny dust particles, which researchers state are no larger than particles found in candle smoke.

Environmental Shielding: Dense regions of dust within these clouds appear to shield the ices from intense ultraviolet radiation emitted by newborn stars.

Observation Method: Unlike previous methods that relied on light from individual bright stars to reveal ice, SPHEREx detects ice by observing diffuse background infrared light shining through entire dust clouds along the galactic plane. This allows it to see the spatial distribution of ices within the clouds.

Comparative Analysis: The mission can detect varying relative amounts of different ices, such as water and carbon dioxide, which are understood to respond differently to environmental factors like ultraviolet light and heating.

Scientific Context and Researcher Statements

Researchers involved in the study provided context for the findings.

Ice as a Cosmic Reservoir: Researchers state that these ice reservoirs are where most of the universe's water is believed to be formed and stored. They note that the water in Earth's oceans and the ices found in comets and on other celestial bodies are understood to originate from such interstellar regions.

"These vast frozen complexes are like 'interstellar glaciers' that could deliver a massive water supply to new solar systems that will be born in the region." — Phil Korngut, instrument scientist for SPHEREx at Caltech and study coauthor.

"When looking along the galactic plane... there's a lot of diffuse background light shining through entire dust clouds, and SPHEREx can see the spatial distribution of the ices they contain in incredible detail." — Joseph Hora, lead author and astronomer at the Center for Astrophysics | Harvard & Smithsonian.

"We can investigate the environmental factors that contribute to different ice formation rates across large areas of interstellar space. The SPHEREx mission's 'big picture' view provides valuable new information you can't get when zooming in on a small region." — Gary Melnick, study coauthor and astronomer at the Center for Astrophysics.

Mission Management and Data Accessibility

  • Construction: The telescope and spacecraft bus were built by BAE Systems in Boulder, Colorado.
  • Science Analysis: Science analysis of SPHEREx data is conducted by a team of scientists at 13 institutions across the United States, South Korea, and Taiwan. The team is led by Principal Investigator Jamie Bock (Caltech) and Project Scientist Olivier Doré (JPL).
  • Data Processing: Data from the mission is processed and archived at IPAC at Caltech in Pasadena, California.
  • Public Access: The complete SPHEREx dataset is freely available to the scientific community and the public.

Background and Objectives

SPHEREx is the first infrared mission specifically designed to find icy molecules across the entire sky through a spectral survey. While other space telescopes, including NASA's James Webb and Spitzer telescopes, have detected similar molecules, they have not conducted a survey of this scale.

The mission aims to help answer fundamental questions about the cosmos, including the origins of water and the chemical processes that deliver molecules considered essential for life to newly forming planets.