NASA’s Nancy Grace Roman Space Telescope is set to transform our understanding of the Milky Way’s hidden structure. While telescopes like Hubble and Webb reveal glittering stars and galaxies, Roman will focus on the less sparkly—but equally vital—components: gas and dust that form the interstellar medium.
One of Roman’s most ambitious efforts, the Galactic Plane Survey, will map roughly 20 billion stars across our galaxy—four times more than have ever been mapped before. These observations will pierce through dusty regions and create the most complete 3D picture of our galaxy yet.
Solving a Milky Way Mystery.
For decades, astronomers have struggled to visualize the far side of our galaxy. Dense dust clouds act like cosmic fog, blocking shorter wavelengths of light, such as blue light, and leaving us with an incomplete map.
Roman will cut through that fog using infrared light, which penetrates dust more easily. By comparing starlight distortions with the properties of the stars themselves, astronomers can determine how dust alters light—unlocking critical clues about dust grain size, composition, and distribution.
“With Roman, we’ll be able to turn existing artist’s conceptions of the Milky Way into data-driven models,” said Catherine Zucker, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian.
Galactic Life Cycles Written in Dust.
The interstellar medium isn’t just space filler—it is the birthplace of stars and planets. Dust and gas clump into molecular clouds, which collapse to form new stars. Those young stars, in turn, send out winds that shape future planetary systems.
As NASA scientist Josh Peek explains:
“Dust carries a lot of information about our origins and how everything came to be. Right now, we’re basically standing on a really large dust grain—Earth itself was built from countless tiny grains that grew together.”
Roman will identify newborn star clusters and distant star-forming regions, expanding on discoveries from past missions like the retired Spitzer Space Telescope.
Mapping the Milky Way’s Spiral Arms.
The Milky Way’s spiral arms—its traffic-jam-like patterns of stars, dust, and gas—remain a puzzle. Do they trigger new star formation, or simply gather material without sparking it?
By combining 3D dust maps with star velocity data, Roman will help astronomers test competing theories and reveal how these galactic “traffic jams” evolve.
A Legacy for Generations.
Roman’s massive survey of the galactic plane will not only solve current mysteries but also leave behind a treasure trove of data. Processed results will be made publicly available through the Roman Research Nexus and the Barbara A. Mikulski Archive for Space Telescopes.
“People who aren’t born yet are going to be able to do really cool analyses of this data,” said Peek. “We have a beautiful piece of our heritage to hand down to future generations.”
Looking Ahead.
The Nancy Grace Roman Space Telescope is currently scheduled to launch no later than May 2027, with an earlier target possible as soon as fall 2026. Managed by NASA’s Goddard Space Flight Center, in partnership with JPL, Caltech/IPAC, and other leading institutions, Roman is poised to redefine our view of the Milky Way.
This mission won’t just map stars—it will unveil the hidden architecture of our galaxy, bringing us closer to understanding how the Milky Way, and ultimately our own solar system, came to be.