NASA's Roman Space Telescope Launches Sunday to Revolutionize Cosmic Discovery

On Sunday morning at Kennedy Space Center, a SpaceX Falcon Heavy rocket will carry into orbit a telescope that will fundamentally alter how we see the universe. The Roman Space Telescope, a $4.3 billion observatory, launches at 7:26 a.m. EDT bound for a gravitational waypoint a million miles from Earth, where it will spend the next five years collecting more data about the cosmos than humanity has ever gathered before.

The telescope's most striking feature is its speed. Roman's 300-megapixel wide-field camera will scan the sky 1,000 times faster than the Hubble Space Telescope, collecting so much information so quickly that it will gather in a single month what Hubble managed to accumulate over an entire century. To put the scale in perspective: a single full-resolution image from Roman would require half a million 4K television screens to display in their entirety, or would cover 45 city blocks. Over its five-year mission, Roman will downlink 2,500 terabytes of data—roughly what Hubble collected across three decades of operation. NASA Administrator Jared Isaacman called it a tool that will "give the Earth a new atlas of the universe."

The telescope's mirror has an unusual origin story. NASA received it as a donation from the National Reconnaissance Office, the agency that oversees classified spy satellites. Two identical mirrors, each 7.9 feet wide and weighing 410 pounds, were originally built for a classified reconnaissance project that was later canceled. Rather than let them sit unused, the mirrors were given to NASA. They are the same size as Hubble's primary mirror, ground to near-perfect specifications—though those specifications were designed to focus on Earth, not the distant cosmos. Engineers had to fundamentally recalibrate the optics and redesign supporting structures to make the mirror work at the ultra-cold temperatures of deep space. Project manager Jackie Townsend described the process as receiving "a set of well-tested parts" but having to "start over and make it our own." The second donated mirror remains unused; NASA has no plans or funding to build a second flagship observatory.

Roman is named for Nancy Grace Roman, NASA's first chief astronomer, who spent her career advocating for space-based telescopes and was instrumental in developing Hubble. She is often called "the mother of Hubble." The new telescope will be stationed at Lagrange Point 2, the same gravitational equilibrium point where the James Webb Space Telescope orbits, roughly a million miles away on the far side of Earth from the Sun.

The mission's scientific ambitions center on two of the universe's deepest mysteries: dark matter and dark energy. Dark matter is the invisible substance that holds galaxies together and accounts for most of the mass in the cosmos. Dark energy is a repulsive force that has been accelerating the expansion of the universe for the past five billion years. Roman will study how these forces have shaped the structure of the cosmos over time. But the telescope may also resolve one of cosmology's most troubling puzzles: the Hubble Tension. When Hubble was launched in 1990, scientists could only estimate the universe's age as somewhere between 10 and 20 billion years old. Hubble measurements of supernovae allowed researchers to calculate the rate of cosmic expansion—the Hubble Constant—with precision, yielding an age of 13.8 billion years, accurate to within 1 percent. But separate observations of the cosmic microwave background radiation, the faint afterglow of the Big Bang itself, produced a slightly different number. This mismatch suggests something fundamental is wrong with the current model of how the universe works. Project scientist Julie McEnery explained that the discrepancy indicates "the model that connects those two things might not be quite right." She added that Roman will likely demonstrate that "our standard model is wrong, and set ourselves on a path to figuring out how our universe really works."

Beyond dark matter and energy, Roman will revolutionize exoplanet discovery. The telescope carries a second instrument: an advanced coronagraph equipped with deformable mirrors that can block out a star's glare to detect the faint light reflected from orbiting planets. Vanessa Bailey, the coronagraph instrument scientist at the Jet Propulsion Laboratory, said the telescope will be capable of detecting planets roughly 100 million times fainter than their host stars. "We are hoping to see a Jupiter twin around a nearby star using visible light reflected from its cloud tops for the first time," she said. By analyzing that reflected light, researchers may determine the chemical composition of planetary atmospheres. About 6,200 exoplanets have been discovered to date using smaller instruments like NASA's Kepler Space Telescope. Roman is expected to discover more than 100,000 exoplanets over just 18 months of dedicated observations.

The mission includes three core survey programs. The High-Latitude Wide-Area Survey will map 12 percent of the entire sky, cataloging a billion or more galaxies to understand how dark matter and energy have shaped cosmic structure. The High-Latitude Time-Domain Survey will repeatedly image the same regions to capture transient events—supernovae, radiation from stars falling into black holes, what McEnery called "things that go bump in the night." The Galactic Bulge Time-Domain Survey will focus on the Milky Way's core, searching for tens of thousands of exoplanets through a technique called microlensing, in which gravity from intervening objects magnifies the light of distant stars. A fourth program, the Galactic Plane Survey, will map 20 billion stars across the disk of the Milky Way, providing the most complete portrait of the galaxy ever captured. It will take three to four months after launch to commission the spacecraft, calibrating instruments and testing systems before science operations begin in earnest. Even with a donated mirror, the total cost to taxpayers will be $4.3 billion to build, launch, and operate the telescope for its five-year primary mission.