NASA’s Nancy Grace Roman Space Telescope has reached another major milestone in space. Mission teams have successfully powered up the Wide Field Instrument, a 300-megapixel infrared camera designed to survey enormous areas of the universe rapidly while still capturing extremely fine detail.
Roman’s planet-imaging system, the Coronagraph Instrument, has also completed an early checkout of its digital, electronic, and mechanical systems after waking up earlier this month.
The tests are part of a months-long commissioning process that will continue as Roman travels roughly one million miles toward its destination at the second Lagrange point, L2.
Roman’s 300-Megapixel Camera Comes Online
The Wide Field Instrument, or WFI, is designed to combine an unusually broad view of the sky with the kind of sharp detail associated with space telescopes such as NASA’s Hubble. A single WFI image will cover an area of sky larger than the apparent size of a full moon.
That combination of wide coverage and high resolution will allow Roman to carry out enormous surveys of the cosmos. Scientists plan to use those observations to learn more about planets beyond our solar system, investigate mysteries such as dark energy, and study how matter is arranged throughout the universe. Roman’s expansive and detailed observations are also expected to create a valuable dataset for many additional 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. This is a huge milestone for the team at Goddard, our industry teams at BAE Systems, Inc. and Teledyne, and our science centers,” 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 Roman’s Infrared Detectors
Before engineers could switch on the WFI, the instrument spent 10 days drying out and undergoing decontamination. During that period, its detectors were kept at a relatively warm (compared to their final operating temperature) minus 85 degrees Fahrenheit, or minus 65 Celsius.
On the morning of Sep. 11, the team shut off the instrument heater and allowed the WFI to cool to minus 225 degrees Fahrenheit (minus 143 degrees Celsius). At that temperature, engineers were able to activate Roman’s 18 infrared detectors. Together, those detectors have a light-sensitive area approximately the size of a laptop screen.
Later that evening, the team turned on the instrument’s calibration system. The following morning, engineers began sending test data through the WFI and transmitting it back to teams on Earth.
Testing Roman’s Filters and Focus
On Saturday evening, engineers turned their attention to the element wheel, which contains filters, prisms, and other optical components. The system controls which wavelengths of light reach the detectors and can separate light from cosmic objects into individual colors. This marked the first time the mechanism had been tested without gravity.
By Sunday morning, the team was testing the WFI’s focusing mechanism. That system will be critical for keeping the hundreds of thousands of images Roman is expected to capture properly focused.
Throughout these tests, the detectors continued cooling toward their final operating temperature of about minus 300 Fahrenheit (minus 183 Celsius).
The results showed that the Wide Field Instrument is functioning as expected. Roman remains on schedule to release its first science images by early 2027.
Roman’s Coronagraph Passes Early Checks
Roman’s Coronagraph Instrument is built to demonstrate some of the most advanced technology ever sent into space for directly imaging planets orbiting other stars.
The instrument combines optics, masks, self-flexing mirrors, and sensors that are designed to suppress the overwhelming glare of a star. By blocking that light, the coronagraph could allow scientists to detect the much fainter light reflected by planets orbiting nearby.
Scientists and engineers working at the Coronagraph Commanding Center at Caltech/IPAC in Pasadena, California, verified that they can communicate with every major part of the instrument. Those systems include its software, thermal controls, mechanisms, cameras, and the avionics that operate them.
In practical terms, the test confirmed that ground teams can remotely control the instrument’s various systems, including movable mechanisms that position its masks, color filters, lenses, and prisms.
Preparing the Coronagraph for Science
Engineers also verified that the coronagraph’s thermal system is functioning properly and can warm the hardware to its operating temperature, a relatively comfortable 72 degrees Fahrenheit (22 Celsius).
With the exception of its detectors, the coronagraph is intended to operate near room temperature. That design makes the system easier to test while also helping preserve the material properties required 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.”
