NASA Launches Roman Space Telescope to Study Dark Energy and Exoplanets

"Roman will investigate dark matter, dark energy and the structure of the universe itself, and accelerate the future of discovery of potentially habitable planets outside our solar system," NASA Administrator Jared Isaacman said, as reported by CNN.

The telescope, about the size of a tour bus, is named for Nancy Grace Roman, NASA's first chief astronomer and the "Mother of Hubble." It has Hubble-like sharpness but a field of view at least 100 times larger, allowing it to image huge swaths of the sky at once. Its primary mirror is about the same size as Hubble's but at 80 percent less weight, reflecting technological advances since Hubble was built in the 1970s, Axios reported.

Roman will be placed at the Sun-Earth Lagrange point 2, or L2, where the combined gravity of Earth and the Sun allows a stable orbit with minimal fuel. The journey will take more than three months, during which engineers will check the telescope's focus, pointing and calibration. "It's basically like our time to kick the tires and just make sure that the focus is right, the pointing is right," NASA integration and test scientist Jeremy Perkins told NPR.

The mission's central goal is to probe cosmic mysteries. The telescope will map normal and dark matter by measuring how gravity subtly bends light across great distances, using a technique called microlensing. It will also hunt for dark energy, the force believed to drive the accelerating expansion of the universe, by cataloging Type Ia supernovae, the "standard candles" whose predictable brightness reveals how fast distant galaxies are receding. Roman will pursue a second dark-energy method by surveying galaxy distributions to detect baryon acoustic oscillations, or the fossilized imprint of sound waves in the early universe, and a third by using microlensing to fill in the cosmic distribution of matter, according to The Conversation and Scientific American.

In addition, Roman is expected to identify more than 100,000 new exoplanets by watching for dips in starlight as planets cross their stars, and about 1,000 more through microlensing, NASA said. The telescope carries a coronagraph instrument that blocks starlight and will test direct imaging of planets, a technology intended for future missions hunting Earth-like worlds.

Roman will beam back about 1.4 terabytes of raw science data daily using a refrigerator-sized high-gain antenna. NASA will make the data immediately available to scientists and the public through a cloud-based system called Roman Nexus. "Roman's database at the end of its prime mission after five years is going to be bigger than your standard music streaming platform," Perkins said.

The observatory is the product of an unusual lineage. NASA began planning the $4.3 billion telescope 15 years ago when the National Reconnaissance Office offered NASA a surplus surveillance satellite, NPR reported. After substantial modifications, that satellite became the core of Roman. The telescope is 42 feet long and more than 14 feet wide, with a 300-megapixel near-infrared camera designed, among other tasks, to study the three-dimensional distribution of dark matter, The Conversation reported. While Hubble has covered a limited portion of the sky over three decades, NASA anticipates Roman will image more than 50 times that area in its first five years, according to USA Today.

Roman's planned surveys include a year-long look through the Milky Way's galactic bulge, building a vast catalog of objects, plus dedicated surveys for dark matter and dark energy. The telescope will also study rogue planets, isolated black holes, starquakes and planet-forming disks, the Houston Chronicle reported. "Almost regardless of what your scientific interest is, Roman is probably already planning to take observations," Julie McEnery, Roman's senior project scientist, said in July.

Scientists are eager for Roman's data. Nearly three decades after dark energy's discovery, astronomers are increasingly questioning the standard cosmological model, and Roman's three complementary methods for probing dark energy could clarify whether its effects change over time, Scientific American wrote. As Perkins put it, the mission will also catch "all the things that we are not expecting to see... one-in-a-million things" that make the mission unique.