NASA's $4B Roman telescope nears launch, eyes 2,500 worlds

NASA's Nancy Grace Roman Space Telescope, a $4 billion flagship observatory, is on track to launch Sunday, August 30 at 7:26 a.m. EDT aboard a SpaceX Falcon Heavy from Launch Complex 39A at Kennedy Space Center, with a backup opportunity the following Monday. Already sealed inside the rocket's fairing, the telescope moved into the SpaceX hangar at the pad complex this week, where teams will mate it to the Falcon Heavy in the coming days ahead of a Launch Readiness Review on Friday, August 28.

Once launched, Roman will spend roughly 30 days cruising to the Sun-Earth Lagrange point L2, about 1.5 million kilometres from Earth, joining Webb in an orbit shielded from the Sun's heat and light.

The telescope's case for existing rests on a single design choice: a primary mirror the same 2.4-metre size as Hubble's, paired with a camera that captures a field of view at least 100 times larger. That combination lets Roman survey the sky up to 1,000 times faster than Hubble while matching its sharpness and infrared sensitivity, the only practical way to attack questions that require watching enormous numbers of objects at once rather than one target in detail.

The exoplanet payoff is the more concrete number. NASA expects Roman's Galactic Bulge Time Domain Survey, staring at the crowded center of the Milky Way and watching roughly 100 million stars for brightness changes over hundreds of days, to find about 2,500 planets through a technique called gravitational microlensing. That method reaches worlds current surveys systematically miss: planets smaller than Mars, and ones orbiting far enough from their stars to sit at Jupiter- or Saturn-like distances rather than the tight orbits the more common transit method favors.

The telescope's other headline goal is dark energy, the roughly 68 percent of the universe's total content that is inferred from cosmic acceleration rather than observed directly. By tracking how that acceleration has changed over billions of years across huge volumes of sky, Roman is built to test whether dark energy's influence is shifting over time, or whether the anomaly instead points to a breakdown of general relativity at the largest scales.

This article was updated with new detail on the Launch Readiness Review, current processing status and the mission's specific exoplanet and dark energy science goals.