by a sea of stars It currently shines before the scientific eyes of the James Webb Space Telescope. In just two months, scientists a million miles away on Earth will use the new observatory to detect distant, unknown planets from subtle changes in these starbursts.
To date, only 5,000 of these distant worlds, commonly called exoplanets, have been detected; Scientists estimate that our galaxy is home to 100 billion. Exoplanets lurk in many nearby corners of our galaxy, some occasionally making their presence known to highly sensitive observatories by passing in front of their parent star and dimming its light from Earth’s perspective.
The space telescope is almost ready for the task. There are only 200 milestones left to complete before Webb’s next-generation instruments reach their full observing capabilities. The telescope team has whittled down to this number in the last five months from an initial list of more than 1,000 tasks. In this last stage of the commissioning run, the teams will become familiar with the essential details of how the instruments work. Only after Webb’s devices prove their capabilities will they be left “loose in the Universe”.
Webb Near Infrared Camera
The James Webb Space Telescope will use its incredibly sensitive Near Infrared Camera, or NIRCam, to find more alien worlds. Teams from three space agencies — NASA, the Canadian Space Agency and the European Space Agency — gave an update Monday on the status of each of Webb’s four new imaging instruments, including the progress of NIRCam, which is considered the Webb’s main image generator.
The telescope is a newcomer to space, having launched during the last days of 2021. It still needs about two more months to be ready for its official “first light.” Showtime for science observations is scheduled to start sometime this summer, in June or July. Webb’s team will release the first official images as a package called ERO, or “Early Release Remarks.”
NIRCam deflected light from the surrounding universe last week so its mission team can calibrate its moving parts to finally take real data on a star’s periodic dimming of light, which could indicate the presence of a previously unknown planet.
“We’ve already issued nearly 15,000 commands to NIRCam,” Marcia Rieke, the instrument’s principal investigator and regents professor of astronomy at the University of Arizona, said at a news conference Monday. “Everything impeccably.”
looking for exoplanets
Rieke’s team strives to provide high-quality images in all wavelengths of light to astronomers searching for exoplanets. To that end, “we have already taken more images like the one that had been released, but using all of the NIRCam filters,” Rieke said.
NIRCam can perform some specialized maneuvers to detect these distant worlds, and the team has begun testing these designs. One important use, called time-series observations, “is when one takes a very long series of exposures to track what’s happening during the transit of an exoplanet,” the term for that dip in light caused by a planet passing through. the side of a star that faces Earth.
Rieke’s team has already witnessed a transit of exoplanets. “When an exoplanet comes between us and its parent star, and we see the little dimming of the parent star’s light, we can analyze that and learn about that exoplanet. We’ve already done the first demonstration of that, and now we’re looking at the data.”
“We have shown that we can load, into the installation, the correct command and the correct time sequence to capture one of these transits. So that’s the first step. More to come.”
Successfully noticing these intermittent signals requires NIRCam to sit in a configuration long enough to stabilize its moving parts.
“For time-series observations, we want to start far enough in advance of the actual transit that any disturbances in it, with the detectors or anything on the instrument, have died down,” he said, explaining that detection involves “measuring very, very small changes in the signal.
“So when you get to the target and you start taking data, you let everything settle and then you can start acquiring the data that you’re really going to count on,” Rieke said. This process can vary from 30 minutes to several hours. It depends on the type of star. “And of course once you hit the target, you don’t disturb anything. You leave the filter settings, everything as it was.”
Preliminary tests of Webb’s NIRCam have already “surprised” Rieke.
“This is like a whole new world,” she says. “Just unbelievably beautiful.”
