During the commissioning of the James Webb Space Telescope (JWST) and the continued alignment of the main mirror, the Near Infrared Spectrograph (NIRSpec) science instrument team successfully completed the characterization of three critical mechanisms for the instrument can do its job. work.
“The NIRSpec team will continue its commissioning efforts. The whole team is very excited for the start of scientific observations,” read a statement signed by representatives of NIRSpec published Thursday (3) on the NASA blog dedicated to the observatory.
Once operational, NIRSpec will split light from targets Webb observes into what scientists call a spectrum, measuring the amount of light at specific wavelengths. This ‘fingerprint’ will allow astronomers to discover more about galaxies, exoplanets and other objects by providing information such as mass, temperature and chemical composition.
With NIRSpec, JWST can examine the spectra of up to 100 galaxies at once, making observations much more efficient, given that collecting photons of light from such distant objects will cost hundreds of hours to the observatory.
How the James Webb Telescope’s NIRpec works
According to the team, the three main mechanisms of NIRSpec are a set of filter wheels, a set of grid wheels and a set of refocusing mechanisms (RMA). The grid wheel scatters light from a target of interest through its colors (wavelengths) to create a spectrum. In turn, the filter wheel reduces contamination by blocking wavelengths outside of what scientists wish to observe. Then, the recentering mechanism adjusts the focus of the instrument.
Each of these sets has been tested separately, starting with the filter wheel, to ensure that its eight forward and rear facing positions work.
“At each position, we record a set of reference data,” NIRpec officials said. “This data showed us how well the wheel moved and how precisely it settled into each position. Between each position, we downloaded “high capacity buffer” data from the positioning sensors, and analyzed the data, which showed that the wheel moved very well, even on the first try. »
Next, engineers recorded the grid wheel assembly reference data and tested the positions in the same way, verifying that everything worked properly.
Finally, with the RMA, the engineers also carried out an initial collection of data before ordering the engine to advance “a few hundred steps from the launch position”, reveals the press release.
“After the initial movement, we command the RMA mirrors to their previous best focus position. The positive findings from this test showed us that RMA is a healthy and well-behaving mechanism,” the scientists said.
Midway through the instrument check, the main mirror alignment continues into its fourth phase, focusing on measuring and correcting small height differences between the 18 hexagonal segments that compose it.
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