NASA’s Nancy Grace Roman Space Telescope has completed pointing tests and captured its first coronagraph starlight following an August 30 launch. The spacecraft proved it can hold steady to better than 1/100,000 of a degree as it travels toward its destination at the second Lagrange point.
Fine Guidance System Validation Tests
Before the coronagraph could look outward, engineers had to prove the observatory could remain motionless against the vacuum of space. Between September 15 and 21, mission teams evaluated Roman’s fine guidance system during a rigorous series of pointing trials. On September 15, Eric Cady — the JPL optical engineer in charge of bringing the coronagraph online — mentioned that staff were remaining inactive with detectors kept warm to allow any residual surface moisture or trace chemicals to dissipate.
The spacecraft’s attitude control system handles initial pointing, while the fine guidance system checks the guide star positions roughly four times per second and commands tiny adjustments to counter any drift.
Every Roman observation relies on its ability to stay precisely pointed at the correct region of space long enough to collect an image, which can take from minutes to hours for a deep exposure.
Begoña Vila
Those pointing tests confirmed that the observatory can maintain stability better than 1/100,000 of a degree. NASA likened that precision to holding a laser steady on a U.S. dime from roughly 150 miles away. The system maintained stability for up to eight hours during coronagraph tests.
Coronagraph Instrument First Light
With pointing stability verified, the mission paired the guidance system with the Coronagraph Instrument on September 22 and 27. The coronagraph’s purpose is to showcase cutting-edge methods for masking stellar brightness so that astronomers can detect much fainter planets and debris disks surrounding nearby stars.
The instrument’s first target in the Large Magellanic Cloud exhibited some electronic noise because detectors were deliberately held warmer than their final operating temperature to prevent contamination. Even so, the initial telemetry met expectations.
This observation confirms that the instrument can produce a focused image.
Vanessa Bailey, the Roman Coronagraph Instrument scientist at NASA’s Jet Propulsion Laboratory
Bailey also noted at a press briefing on August 29 that astronomers used coronagraphs more than 100 years ago to create an artificial eclipse to study the sun’s corona. Brandon Creager, the coronagraph’s lead mechanical engineer at JPL, has worked on the instrument since 2018.
Comparison With Hubble and Webb
Named after Nancy Grace Roman — often described as the mother of the Hubble Space Telescope and NASA’s first chief of astronomy — the new telescope shares its 2.4-meter primary mirror lineage with the Hubble Space Telescope.
| Telescope | Primary Mirror Diameter | Field of View Advantage |
|---|---|---|
| Hubble Space Telescope | 2.4 meters | Standard baseline field of view |
| Nancy Grace Roman Space Telescope | 2.4 meters | Up to 200 times larger than Hubble’s |
| James Webb Space Telescope | 6.5 meters | Narrower field of view, optimized for deep infrared sensitivity |
Its Wide Field Instrument captures patches of sky up to 200 times larger than Hubble’s capacity. Duke University physicist Dan Scolnic, serving as co-principal investigator of the Roman Supernova Project Infrastructure Team, and Michael Troxel, who leads Duke’s SPACE Initiative, noted that Roman can accomplish in one year what Hubble would require a thousand years to survey.
Journey to Lagrange Point 2 and Upcoming Schedule
At L2, the observatory joins the James Webb Space Telescope and the European Space Agency’s Euclid Telescope in a stationary orbit relative to the Sun and Earth.
Science operations are expected to commence by early 2027, including planet searches via microlensing and the transit method.
