In the relatively short time that the James Webb Space Telescope has been operational, there’s seemingly no end to its list of accomplishments. And if you’re like us, you were sure that Webb had already achieved the first direct imaging of a planet orbiting a star other than our own a long time ago. But as it turns out, Webb has only recently knocked that item off its bucket list, with the direct visualization of a Saturn-like planet orbiting a nearby star known somewhat antiseptically as TWA 7, about 111 light-years away in the constellation Antlia. The star has a significant disk of debris orbiting around it, and using the coronagraph on Webb’s MIRI instrument, astronomers were able to blot out the glare of the star and collect data from just the dust. This revealed a faint infrared source near the star that appeared to be clearing a path through the dust.
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The Constant Monitoring And Work That Goes Into JWST’s Optics
The James Webb Space Telescope’s array of eighteen hexagonal mirrors went through an intricate (and lengthy) alignment and calibration process before it could begin its mission — but the process is far from being a one-and-done. Keeping the telescope aligned and performing optimally requires constant work from its own team dedicated to the purpose.
Alignment of the optical elements in JWST are so fine, and the tool is so sensitive, that even small temperature variations have an effect on results. For about twenty minutes every other day, the monitoring program uses a set of lenses that intentionally de-focus images of stars by a known amount. These distortions contain measurable features that the team uses to build a profile of changes over time. Each of the mirror segments is also checked by being imaged selfie-style every three months.
This work and maintenance plan pays off. The team has made over 25 corrections since its mission began, and JWST’s optics continue to exceed specifications. The increased performance has direct payoffs in that better data can be gathered from faint celestial objects.
JWST was fantastically ambitious and is extremely successful, and as a science instrument it is jam-packed with amazing bits, not least of which are the actuators responsible for adjusting the mirrors.
Hackaday Links: September 25, 2022
Looks like there’s trouble out at L2, where the James Webb Space Telescope suffered a mechanical anomaly back in August. The issue, which was just announced this week, involves only one of the six imaging instruments at the heart of the space observatory, known as MIRI, the Mid-Infrared Instrument. MIRI is the instrument on Webb that needs the coldest temperatures to work correctly, down to six Kelvins — we’ve talked about the cryocooler needed to do this in some detail. The problem has to do with unexpectedly high friction during the rotation of a wheel holding different diffraction gratings. These gratings are rotated into the optical path for different measurements, but apparently the motor started drawing excessive current during its move, and was shut down. NASA says that this only affects one of the four observation modes of MIRI, and the rest of the instruments are just fine at this time. So they’ve got some troubleshooting to do before Webb returns to a full program of scientific observations.
There’s an old saying that, “To err is human, but to really screw things up takes a computer.” But in Russia, to really screw things up it takes a computer and a human with a really poor grasp on just how delicately balanced most infrastructure systems are. The story comes from Moscow, where someone allegedly spoofed a massive number of fake orders for taxi rides (story in Russian, Google Translate works pretty well) through the aggregator Yandex.Taxi on the morning of September 1. The taxi drivers all dutifully converged on the designated spot, but instead of finding their fares, they just found a bunch of other taxis milling about and mucking up traffic. Yandex reports it has already added protection against such attacks to its algorithm, so there’s that at least. It’s all fun and games until someone causes a traffic jam.

