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Mapping Andromeda & Triangulum

One Roman survey will take spying on the neighbors to the extreme, creating the most detailed mosaics ever of two of the closest big galaxies to the Milky Way: Andromeda and Triangulum. Roman will observe each galaxy repeatedly, ultimately mapping more than half a billion stars in 3D and monitoring how they move and change over time.

That will help astronomers reconstruct how the galaxies formed and evolved, including how they’ve interacted with each other over the course of billions of years. Astronomers will better understand how stars are born, live, and die in galaxies beyond our own.

The survey will also probe each galaxy’s dark matter underpinnings. This mysterious material doesn’t emit light or interact with normal matter except gravitationally, yet it accounts for the vast majority of the universe’s mass. Watching how gravity guides the movement of stars in these galaxies will help astronomers trace the distribution of both normal and dark matter in exquisite detail.

NASA's Kepler space telescope, shown in this artist's concept, revealed that there are more planets than stars in the Milky Way galaxy. NASA's Nancy Grace Roman Space Telescope will extend Kepler's legacy by covering the same area in even sharper detail, which is sure to unearth many more planets and other objects.

Kepler Revisited

As NASA's first dedicated planet-hunting mission, the Kepler space telescope searched a slice of our galaxy for Earth-sized planets. Now, Roman is set to retrace Kepler's footsteps, covering the same area in even sharper detail.

The Roman-Kepler Legacy Survey will capture detailed images of all 200,000 objects Kepler observed, including over 4,000 stars that may host planets. And Roman’s more powerful view will reveal things Kepler was unable to see, adding up to about 17 million stars and brown dwarfs — in-between objects that are too heavy to be classified as planets, but not quite massive enough to become stars.

The survey will also probe Tatooine-like worlds that orbit pairs of stars. These stellar couples are so close that they easily blur together, which is why we need a crisp view like Roman’s to tell them apart.

This image from NASA's Hubble Space Telescope captures what looks like a galactic glitter bomb in the night sky. Called 47 Tucanae, this stellar collection is one of about 150 globular star clusters in our Milky Way galaxy. While previous telescopes have only observed small pieces of it at a time, Roman will capture it in its entirety in a single snapshot. In about one week of observation time, NASA’s Nancy Grace Roman Space Telescope will survey this cluster and three others covering a total area that would take NASA’s Hubble Space Telescope around 18 years to cover, while matching its resolution.

Globular Cluster Survey

Roman’s globular cluster survey will take the most complete inventory ever of stars in four relatively nearby groups of ancient, densely packed stars: M4, NGC 6397, 47 Tucanae, and Omega Centauri. 

In just one week of observation time, Roman will survey a total area that would take NASA’s Hubble Space Telescope around 18 years to cover, while matching its resolution. That will help astronomers tally up and map their hundreds of thousands of stars while identifying very faint objects, like brown dwarfs.

This is a Hubble Space Telescope view of a portion of GOODS-South, the southern field of a large deep-sky study by several observatories to trace the formation and evolution of galaxies. The image shows a rich tapestry of 7,500 galaxies stretching back through most of the universe's history. The farthest galaxies, a few of the very faint red specks, are seen as they appeared more than 13 billion years ago, or roughly 650 million years after the big bang.

Baby Galaxies

The GRACE (Grism Reionization and Cosmic Evolution) Survey will spend about 2.5 weeks peering far into the universe’s past to hunt for some of the earliest galaxies. Its main goal is to shed light on how the cosmos transitioned from being filled with an opaque gas to becoming crystal clear, allowing light to travel across the universe.

This is the era when the first galaxies began lighting up the cosmos. The GRACE survey aims to find ten times more of the earliest known galaxies than all other telescopes have discovered to date. Scientists will be able to see how galaxies, stars, black holes, and the cosmic web evolved from the dawn of the universe to the present day.

The eXtreme Deep Field, or XDF, was assembled by combining 10 years of NASA Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra Deep Field. NASA’s Nancy Grace Roman Space Telescope will conduct a similar observation covering a patch of sky more than 140 times larger.

Extreme Deep Field 

The RXDF (Roman eXtreme Deep Field) will stare deep into a small patch of sky, essentially collecting a cosmic core sample. This mega-exposure will be similar to but more than 140 times larger than Hubble’s eXtreme Deep Field. 

And instead of taking a single snapshot, Roman will repeat the observations over time. Stitching together a detailed time-lapse of a relatively large chunk of the early universe will help astronomers track how the earliest galaxies, black holes, and other structures formed and changed across cosmic history. The observations could also catch some of the first supernova explosions and show how they shaped the early cosmos.

NASA’s Nancy Grace Roman Space Telescope’s three main observing programs, highlighted in this infographic, will enable astronomers to view the universe as never before, revealing billions of cosmic objects strewn across enormous swaths of space-time.

All of this is in addition to Roman’s three core surveys and first announced bonus survey, which will transform our view of the universe. Follow along with Roman’s road to launch at nasa.gov/roman, and virtually tour the Roman observatory here.