NASA powers up Roman telescope’s 300-megapixel infrared camera

NASA’s Nancy Grace Roman Space Telescope has activated its main scientific camera in space, marking a significant step toward the observatory’s planned first science images in early 2027. The Wide Field Instrument, known as WFI, is a 300-megapixel infrared camera built to map vast regions of the universe while preserving fine detail.

The telescope’s separate Coronagraph Instrument has also passed an initial examination of its electronic, digital and mechanical systems. Together, the developments show that two of Roman’s central instruments are responding as planned during a commissioning programme expected to last several months.

ScienceDaily reported the milestones, which are taking place as Roman travels about one million miles toward the second Lagrange point, or L2. The observatory’s destination is a region of space where it will carry out its long-term investigations.

A wide view with sharp detail

Roman is designed to occupy a middle ground between the broad surveys possible with some observatories and the detailed views associated with NASA’s Hubble Space Telescope. One image from WFI will span more sky than the apparent area of a full Moon, giving scientists an unusually large field of view in a single exposure.

That capacity matters because many of Roman’s investigations depend on examining enormous numbers of objects and large sections of the cosmos. Researchers intend to use its observations to study planets outside the solar system, explore dark energy and examine the distribution of matter across the universe.

The survey data will also be useful beyond those primary goals. Because the instrument will collect extensive, detailed observations, scientists expect the resulting archive to support many other investigations as well.

Before WFI could be switched on, engineers spent 10 days drying and decontaminating it. During that preparation, its detectors were held at minus 85 degrees Fahrenheit, or minus 65 Celsius. That temperature was warmer than the level required for normal operation.

On the morning of September 11, the heater was turned off and the instrument was allowed to cool to minus 225 Fahrenheit, or minus 143 Celsius. Engineers then activated its 18 infrared detectors. Their combined light-sensitive surface is approximately comparable to a laptop screen.

The calibration system was powered up later that day. Test data began moving through the instrument the following morning and was transmitted to teams on Earth for examination.

Testing the camera’s moving parts

The commissioning work then moved to WFI’s element wheel. This mechanism carries filters, prisms and other optical components, selecting the wavelengths that reach the detectors. It can also divide light from astronomical objects into separate colours, providing information that a simple image cannot.

The wheel was tested without the effects of gravity for the first time on Saturday evening. Engineers began checking the focusing system the next morning. Maintaining focus will be essential because Roman is expected to produce hundreds of thousands of images during its mission.

While these activities were under way, the detectors continued cooling toward their eventual operating temperature of about minus 300 Fahrenheit, equivalent to minus 183 Celsius. The test results indicated that WFI is performing as expected.

Josh Schlieder, WFI scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said the successful activation confirmed years of work on the ground. He credited teams at Goddard, BAE Systems and Teledyne, as well as the mission’s science centres, and described the achievement as a major milestone.

Roman’s search for nearby planets

The Coronagraph Instrument is intended to demonstrate technology for directly observing planets orbiting other stars. Such planets are much dimmer than the stars they circle, making them difficult to see with conventional imaging.

Roman’s coronagraph combines optics, masks, deformable mirrors and sensors to reduce the glare from a host star. If the system performs as intended, it could make it possible to detect some of the faint light reflected by planets around nearby stars.

At the Coronagraph Commanding Center at Caltech/IPAC in Pasadena, California, teams confirmed communication with all of the instrument’s major components. The checks covered software, thermal controls, mechanisms, cameras and avionics. Engineers also showed that ground controllers could operate movable parts that position masks, colour filters, lenses and prisms.

The thermal system was tested as well, including its ability to warm the hardware to 72 Fahrenheit, or 22 Celsius. Most of the coronagraph is designed to operate at about room temperature, apart from its detectors. Keeping it relatively warm simplifies testing and helps retain the material characteristics needed by its deformable mirrors.

The coronagraph is now undergoing a 30-day decontamination period, during which its detectors remain warm so water and trace chemicals can leave their surfaces. Engineers will occasionally pause that process for additional early calibration work.

Roman’s successful instrument checks do not mark the end of commissioning, but they remove important early uncertainties. The mission remains on schedule to publish its first science images in early 2027.