The latest update on the space telescope made me shiver. The operating temperature of the telescope's Mid-Infrared Instrument has now reached 7 kelvins.
MIRI is undergoing initial checkouts now that it has been turned on.
Since the other three instruments need to be, the temp is colder than the other two. All instruments need to reach a temperature of less than 40 K.
Most of the telescope and its instruments rely on the massive sun shield to shield it from the heat from the Sun and Earth to cool it down, as well as passive cooling, taking advantage of the frigid temperatures in deep space. Getting to the temperatures required for MIRI is not possible by passive means alone, so we have an innovative cryocooler that we use to cool the detectors so that they can see farther into theIR.
The telescope has a certain temperature and heat that would interfere with the data taken by the instrument. The entire telescope is cooled down to suppress the emissions of theIR. The distant objects can be detected without interference from the other nearby sources.
When the instrument goes from 15 kelvins to 6.4 kelvins, it's called the pinch point.
The procedure for the pinch point has been developed by the MIRI cooler team. It was a textbook execution of the procedure, and the cooler performance is even better than expected.
According to NASA, the reason the detectors need to be cold is to suppress the electric current created by the atoms in the detectors. The false impression that the detectors have been hit by light from an external source is caused by dark current. Astronomers want to find the real signals. Since temperature is a measurement of how fast the atoms in the detector are vibrating, reducing the temperature means less vibration and less dark current.
The longer IR detectors of MIRI need to be colder than the other instruments to fully remove the effect of dark current. The dark current goes up by a factor of 10 when the instrument temperature goes up.
Scientists and engineers are checking the detectors to make sure they work as expected. They are sending commands to see if it can execute tasks correctly.
Mike Ressler, project scientist for MIRI at JPL, said that they spent years practicing for that moment. When the test data came in, I was happy to see that we have a healthy instrument.
MIRI will take test images of stars and other known objects that can be used for calibration and to check the instrument's operations and function. This summer, the team will deliver the first science images from the other three instruments.
The source is NASA.
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