Professor of Physics and Astronomy Ryan Hickox served on a national committee of astrophysicists that just released plans for three core surveys that NASA’s Nancy Grace Roman Space Telescope team will conduct after it launches.
The surveys were designed to investigate some of the most profound mysteries in astrophysics while enabling expansive cosmic exploration.
“Roman will be truly revolutionary in that it provides astoundingly sharp and sensitive views of the cosmos over extremely large areas,” Hickox says. “A single picture with the Hubble Space Telescope or James Webb Space Telescope covers only a tiny patch of the sky. In contrast, Roman’s field of view is 100 times larger and it is able to move between fields 10 times faster, so you get Hubble-like images but with surveys 1,000 times faster. These extraordinary high quality images will be useful for a broad range of science from the solar system to the whole universe.”
The telescope is targeted to launch by May 2027, with the team working toward a potential launch as early as October 2026.
“I'm especially excited about the fact that we'll detect hundreds of millions of galaxies, which will give us an unprecedented picture of how galaxies like the Milky Way grow along with their black holes and dark matter halos over cosmic time,” Hickox says.
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. (Infographic courtesy of NASA’s Goddard Space Flight Center)
The Roman Observations Time Allocation Committee (ROTAC) asked the science community to detail the topics they’d like to study through each survey and selected committees of scientists across many organizations to evaluate the range of possibilities and formulate three compelling options for each.
Hickox also served as co-chair of the committee that defined the details of the largest research program, the High-Latitude Wide-Area Survey. This survey will combine the powers of imaging and spectroscopy to unveil more than a billion galaxies strewn across a wide swath of cosmic time. With this survey, the Roman telescope will look far from the dusty plane of the Milky Way galaxy, looking up and out of the galaxy rather than through it to get the clearest view of the distant cosmos.
The distribution and shapes of galaxies in the telescope’s enormous, deep images can help illuminate the nature of dark energy—a pressure that seems to be speeding up the universe’s expansion—and how invisible dark matter, which the telescope will detect by its gravitational effects, influences the evolution of structure in our universe.
“As we move forward, the High-Latitude Wide-Area Survey committee and ROTAC will continue to provide guidance to the Roman project as they implement the plans for these ambitious observations to start after the planned launch in one to two years,” Hickox says.
The High-Latitude Time-Domain Survey will observe the same region of the cosmos repeatedly. Stitching these observations together to create movies will allow scientists to study how celestial objects and phenomena change over time periods of days to years. This survey can probe dark energy by finding and studying exploding stars which allow scientists to measure cosmic distances and trace the universe’s expansion.
Finally, the Galactic Bulge Time-Domain Survey will look inward to provide one of the deepest views ever of the heart of the Milky Way galaxy. The Roman telescope’s crisp resolution and infrared view can allow astronomers to watch hundreds of millions of stars in search of microlensing signals—gravitational boosts of a background star’s light that occur when an intervening object passes nearly in front of it.
The same set of observations can reveal “rogue” planets that drift through the galaxy unbound to any star, brown dwarfs (“failed stars” too lightweight to power themselves by fusion the way stars do), and stellar corpses like neutron stars and white dwarfs. Scientists could discover 100,000 new worlds by seeing stars periodically get dimmer as an orbiting planet passes in front of them, events called transits. Scientists can also study the stars themselves, detecting “starquakes” on a million giant stars, the result of sound waves reverberating through their interiors that can reveal information about their structures, ages, and other properties.
Ryan Hickox with PhD student Stephanie Podjed, left, and Kelly Whalen, Guarini ’23 (now a NASA postdoctoral program fellow) in front of the Roman Space Telescope at the Goddard Space Flight Center in January
Just as the Roman surveys were defined by a community process, their data will be freely available immediately to any astronomers in the world.
Hickox’s research group at Dartmouth, including postdocs, graduate students, and undergrads, will make extensive use of the survey data for studying the evolution of galaxies, black holes, and large-scale structures.
“I also look forward to using Roman images in my courses to inspire and educate the next generation of astronomers,” Hickox says. “We can’t wait to use Roman observations and see what secrets the universe has in store for us.”