NASA’s Roman Telescope to Launch with First Active Coronagraph for Exoplanet Imaging
Scheduled for launch as early as the end of next month, the Nancy Grace Roman Space Telescope will carry a 300-megapixel camera and an innovative coronagraph designed to suppress starlight with unprecedented precision.
NASA’s Nancy Grace Roman Space Telescope is scheduled to launch as early as the end of next month, marking a significant milestone in astronomical instrumentation. The mission will carry the first space-bound “active” coronagraph, an instrument designed to suppress starlight using shape-shifting mirrors with 48-by-48 checkerboards of actuators. This technology aims to directly image Jupiter-like exoplanets and potentially Earth-like worlds, building on the legacy of previous observatories while introducing new capabilities for direct detection.
The active coronagraph utilises two deformable mirrors, each featuring a 48-by-48 checkerboard of actuators beneath a thin glass sheet. These actuators can deform the mirror surface by up to 0.5 micrometers in increments as small as 10 picometers to cancel out unwanted light waves. The system uses “silicon grass” masks—microscopic spikes designed to trap photons and prevent them from bouncing back toward the detector. This approach represents a shift from the stationary blocking systems used in earlier telescopes, allowing for active wavefront control that measures and suppresses leftover light before each observation.
Compared with current space-based coronagraphs, the system is expected to improve sensitivity to exoplanets against the glare of their host stars by a factor of up to 1,000. This enhanced sensitivity will enable astronomers to see smaller, dimmer, and more close-in exoplanets, including mature gas giants similar to Jupiter in our own solar system. Unlike the hot, young Jupiters currently visible, these mature planets reflect their parent star’s light rather than emitting their own heat, making them significantly more challenging to detect against stellar glare.
In addition to the coronagraph, the telescope carries a 300-megapixel wide-field camera capable of capturing images 100 times larger than Hubble’s widest exposures at similar resolution. This instrument is expected to detect around 100,000 new exoplanets, primarily through gravitational microlensing, while also helping astronomers study the mysterious identities of dark matter and dark energy. The sheer volume of data generated by these capabilities is expected to keep scientists engaged for decades, with researchers describing the leap in observational capacity as moving from interviewing a handful of people to conducting a global census.
The technology aims to improve sensitivity to exoplanets against stellar glare by a factor of up to 1,000 compared to current space-based coronagraphs. While Roman will not resolve planets into solid globes, the ability to analyse the wavelengths of light from these point sources will provide insights into atmospheric chemistry and surface conditions. The mission serves as a critical stepping stone for future observatories, such as the proposed Habitable Worlds Observatory, which aims to separate the light of an Earth-like planet from that of a sunlike star.
The launch timeline remains subject to variability, with the mission targeted for the end of next month. Engineers and scientists will initially focus on verifying the coronagraph’s ability to maintain starlight suppression as the spacecraft moves through space and experiences temperature changes. The success of this instrument could redefine the direct imaging of exoplanets, offering a new chapter in the search for worlds beyond our solar system.
