NASA switched on Roman's 18 infrared detectors at minus 143 Celsius in cruise to L2

The switch-on NASA described is mostly a cooling schedule. The instrument spent 10 days drying out and decontaminating with its detectors held at minus 65 Celsius ^[5]. On the morning of 11 September the heater went off, the camera fell another 78 degrees to minus 143 Celsius, and engineers activated its 18 infrared detectors ^[6][17]. Those detectors kept cooling through the rest of the tests, toward an operating point of about minus 183 Celsius, 40 degrees below the temperature at which they first drew power ^[11][18].

Three hundred megapixels across 18 detectors works out to roughly 16.7 megapixels each ^[19], and NASA puts their combined light-sensitive area at about the size of a laptop screen ^[7]. One exposure covers more sky than the apparent size of a full moon ^[4].

The calibration system came on that evening, and the next morning engineers began pushing test data through the instrument and down to Earth ^[8]. On Saturday evening they turned the element wheel, which holds the filters and prisms that decide which wavelengths reach the detectors, for the first time without gravity ^[9]. Focus came next, on Sunday morning, using the mechanism that has to hold the hundreds of thousands of images Roman is expected to take ^[10]. NASA says the results show the instrument functioning as expected ^[12].

"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 ^[13]. He added: "There is much to do, but we are on our way to groundbreaking science" ^[14].

The coronagraph is the harder instrument to read from this. It combines optics, masks, self-flexing mirrors and sensors meant to suppress a star's glare so the far fainter light reflected by an orbiting planet can be detected ^[15]. NASA describes the checkout so far as covering its digital, electronic and mechanical systems ^[2][20]. The agency's summary says the coronagraph is working as expected ^[21]. Contrast, the measurement the instrument was flown to produce, depends on optical steps later in a commissioning process NASA calls months long ^[3].

For proposal writers and pipeline builders, the content of this milestone is a shorter risk list. The camera powers on in flight, reaches temperature, moves its mechanisms in weightlessness, and returns test data ^[6][9][8]. The surveys those detectors are meant to feed are aimed at exoplanets, dark energy, and the arrangement of matter across the universe ^[16]. NASA says first science images remain on track for early 2027, with commissioning continuing over the roughly one-million-mile cruise to the second Lagrange point ^[12][3].