The camera that will serve as the eye of the Roman Space Telescope has been switched on. The observatory, which will soon begin mapping the cosmos with unprecedented detail, has activated its 300-megapixel Wide Field Instrument, or WFI, on September 11. Every system has checked out as expected. The telescope’s planet-imaging system, the Coronagraph Instrument, also passed early tests of its digital, electronic, and mechanical systems after waking up earlier this month.
As Roman moves roughly one million miles toward the second Lagrange point, L2, during its months-long commissioning process, the milestone arrives. Both instruments are performing as expected, and the telescope is on track to release its first science images by early 2027.
The 300-Megapixel Eye
The WFI is a 300-megapixel infrared camera built for surveying vast stretches of the universe quickly, while still managing to capture extremely fine detail. One WFI image alone covers an area of sky larger than the apparent size of a full moon. That pairing of wide coverage and high resolution will let Roman carry out enormous surveys of the cosmos.
Researchers hope to draw upon those observations to gain insight into worlds outside our solar system, probe mysteries such as dark energy, and examine how matter is organized throughout the universe. Roman’s comprehensive and detailed observations are also expected to produce a valuable dataset for many further scientific studies.
“After years of effort to build and test the instrument on the ground, we now have confirmation that it is operational in space,” said Josh Schlieder, the Wide Field Instrument scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “There is much to do, but we are on our way to groundbreaking science.”
Cooling Out
Engineers let the WFI sit for 10 days as it dried out and was cleared of contamination before turning it on. During that time, its detectors stayed at a warm minus 85 degrees Fahrenheit, or minus 65 Celsius.
The team switched off the instrument heater early on the morning of Sep. 11, letting the WFI cool to minus 225 degrees Fahrenheit (minus 143 degrees Celsius). Once it reached that temperature, engineers had enough cold to turn on Roman’s 18 infrared detectors, which together make up a light-sensitive area roughly the size of a laptop screen.
On the evening in question, the instrument’s calibration system was activated. The next morning, engineers started sending test data through the WFI and sending it back to teams on Earth.
First Light
On Saturday evening, the team turned its focus to the element wheel, a component that holds filters, prisms, and other optical parts. That system is what decides which wavelengths of light make it to the detectors, and it can take light from distant objects and split it into individual colors. It was the first time the mechanism had been tested without being pulled by gravity.
By Sunday morning, the team had begun testing the WFI’s focusing mechanism. That system will be essential for ensuring the hundreds of thousands of images Roman is expected to capture remain properly focused.
During the course of these tests, the cooling of the detectors progressed toward their target operating temperature, approximately minus 300 Fahrenheit (minus 183 Celsius).
The test results demonstrated that the Wide Field Instrument is performing as designed, and the telescope remains on track to release its first science images by early 2027.
The Coronagraph Test
The Coronagraph Instrument, built by Roman, is a demonstration of some of the most advanced technology ever sent into space for directly imaging planets orbiting other stars. It combines optics, masks, self-flexing mirrors, and sensors designed to suppress the overwhelming glare of a star, allowing scientists to detect the much fainter light reflected by nearby planetary systems.
A dedicated ground control facility operated by IPAC at Caltech in Pasadena, California, served as the Coronagraph Commanding Center for the test. From there, scientists and engineers confirmed they can communicate with every major system of the instrument, including its software, thermal controls, mechanisms, cameras, and the avionics that operate them.
In practice, the test confirmed that ground teams can remotely guide the instrument’s various systems, including its movable mechanisms, which position its masks, color filters, lenses, and prisms.
Keeping It Warm
The thermal system of the coronagraph was verified to work as intended by engineers, who confirmed that it can warm the hardware to its operating temperature, a relatively comfortable 22 degrees Celsius — or 72 degrees Fahrenheit.
Except for its detectors, the coronagraph is built to run at close to room temperature. This choice eases testing while also aiding the material properties demanded by its deformable mirrors.
“Now that this test is complete, we’ve been decontaminating: sitting idle with our detectors warm so anything that’s stuck to the surface, such as water or trace chemicals, will tend to leave it,” said Eric Cady, an optical engineer leading commissioning efforts for the Roman Coronagraph at NASA’s Jet Propulsion Laboratory in Southern California. “This will continue for 30 days, with occasional stops to do other early calibration activities.”
The Path Ahead
As Roman journeys around one million miles towards L2, the second Lagrange point, the commissioning process will proceed.
- The WFI will complete its remaining alignment and calibration steps as the telescope moves toward L2.
- The Coronagraph Instrument will complete its remaining calibration steps during the same period.
- Teams will monitor both instruments throughout the journey to ensure they remain stable.
- The first science images are expected to be released by early 2027.
Key Facts Box
- Camera: 300-megapixel Wide Field Instrument (WFI)
- Detectors: 18 infrared detectors, light-sensitive area approximately the size of a laptop screen
- Cooling: Final operating temperature of about minus 300 Fahrenheit (minus 183 Celsius)
- Coronagraph: Thermal system warms hardware to 72 degrees Fahrenheit (22 Celsius)
- Schedule: First science images by early 2027
What Comes Next
The early tests show that Roman’s two key instruments are behaving as expected. The WFI’s 18 detectors cooled to their target temperature and recorded test data without issue. The Coronagraph’s remote control system confirmed teams can move its masks, filters, lenses, and prisms from the ground.
The telescope’s journey to L2 will take months, and the commissioning process will continue throughout that time. Roman’s instruments will be fine-tuned as the telescope travels, with teams watching for any changes that might require adjustments.
The first science images are scheduled for early 2027. The team’s confidence is justified, and the telescope’s path toward science operations is clear.
Source material: “NASA just powered up Roman’s massive 300-megapixel camera,” ScienceDaily.
Get the Notebook.
The day's best stories and every fresh verdict, in plain English, in your inbox by seven. One email a day, no more.