James Webb Space Telescope gets all shook up – launch delayed again The European Space Agency has delayed the launch of the James Webb Space Telescope until December 22 so that it can undergo additional testing following an incident that sent unintended vibrations through the observatory. The James Webb Space Telescope – an international collaboration between NASA, ESA and the Canadian Space …
A good measure of a man is how he calls his machine's errors. My favourite is Xerox's mispuff.
Technologically, the 914 is so complex (more complex, some Xerox salesmen insist, than an automobile) that it has an annoying tendency to go wrong, and consequently Xerox maintains a field staff of thousands of repairmen who are presumably ready to answer a call on short notice. The most common malfunction is a jamming of the supply of copy paper, which is rather picturesquely called a “mispuff,” because each sheet of paper is raised into position to be inscribed by an interior puff of air, and the malfunction occurs when the puff goes wrong. A bad mispuff can occasionally put a piece of the paper in contact with hot parts, igniting it and causing an alarming cloud of white smoke to issue from the machine; in such a case, the operator is urged to do nothing, or, at most, to use a small fire extinguisher that is attached to it, since the fire burns itself out comparatively harmlessly if left alone, whereas a bucket of water thrown over a 914 may convey potentially lethal voltages to its metal surface.
Probably the same as when we were trying to get the 75" TV up the stairs to the first floor living room, on its end and one step at a time to clear the ceiling. We accidentally dropped it down the first step on to the concrete floor when getting it on to its end. There was a lot of swearing, but by a miracle the glass didn't break. Now its on the wall you can see the chassis is very slightly dented at one corner. Fingers crossed the stored up stress is going to make it go crack just after the warranty is out.
NASA? Mere beginners compared to the century-long experience of the UK's wonderful British Railways Excuses Department. Their responses to delays and cancellations of trains ranged all the way from:
"Leaves on the line"
to
"The wrong kind of snow"*
*(Absolutely true, except maybe the name of the 'Excuses Department'.)
Showing my ignorance here, but could some kind engineering type pease explain to this (pure-ish) mathematician type what a 'clamp band' is? And is 'unplanned release' a euphemism for destructive failure, or merely the sort of thing my shoelaces tended to do before I started tying them with a reef knot rather than a granny knot?*
* see https://mathworld.wolfram.com/SquareKnot.html for a topological explanation
Well said. More sensitive to space radiations it's poised to observe as well as more sensitive to being handled roughly, as there is no plan in place for service once it flies. It's a good approach to measure twice, especially in view of the optical anomaly the Hubble was sent upwards with.
> preparing to attach the telescope to the launch vehicle adapter, a "sudden, unplanned release of a clamp band"
So basically, they dropped it.
However, I suspect that the JWST will be subject to a great deal more vibration¹ during launch, so is this incident playing down the event?
[1] especially if this is still an issue:
the August 2020 launch and the previous Ariane launch in February 2020, the separation of the faring induced vibrations into the payload stack well above acceptable limits
Certainly the vibration during launch would probably shake your back teeth out!
However NASA are simply following standard procedures developed over the last 50 years. Basically they have a list of planned actions and events that will occur while they are mounting the satellite on the launcher; if anything not on this list occurs, they immediately check everything to make sure that the satellite is still intact and fully operational.
On the one hand, it could be an overabundance of caution over an unplanned jolt of a $10B project. On the other hand, it's been tested for the sorts of vibration expected during launch, which are of known frequency, duration, magnitude and vectors. This "ding" may have been outside any or all of the parameters of what they tested for.
Geez, isn't it time to give up on monoliths and launch a larger swarm based telescope
Swarm telescopes are dependent on optical interferometry, which is a pain to get working correctly. Only a handful have ever been functional, and even fewer are working. This means the process of operating a swarm of optical-infrared-UV satellites isn't as simple as slapping some 1-meter telescopes on a Starlink chassis, launching 60 on a Falcon 9, and then laughing as old school astronomers are left in the dust. Rather, it'd likely be an effort of several decades with one or more pathfinder missions proving out the technology.
Besides requiring the novelty of optical interferometry, a swarm of astronomical satellites focusing (hah) on multiple, small platforms would lack the total "light bucket" capacity of a single, large telescope. For example, while the Navy Precision Optical Interferometer can resolve the shapes of oblate stars and geosynchronous satellites it does so with just six 50-centimeter telescopes. (Currently supplemented by 4 non-interferometric 1.8m "outrigger" telescopes, with plans to add 1-meter interferometric optics). That's a grand total of 11.3 square meters of collection area (mostly in the outriggers). The James Webb has 33 square meters of collection area. That's just better at seeing faint, distant objects than a swarm with less collection area.
Ultimately, yes, a swarm of large telescopes in space could be awesome but, for now, monolithic and segmented telescopes like Hubble and James Webb are easier to implement.
"1,500,000km (930,000 miles) beyond Earth's orbit"
could confuse some that think of orbit as circling the planet whereas in this case the orbit referred to is the earth's orbit round the sun. *
though I think technically it will still be in orbit around earth just that the orbital period will be one year and so remain roughly inline with the sun and earth.
* that's what I did and was going to comment that it implies there is only orbit round earth and manged to understand the sentence just before making a fool of myself !!!
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