JWST deployments challenge

 Sunshield 

107 pins or membrane release (non-explosive) devices, consists of springs and magnets

 

These pins were designed to keep all 5 layers of the sunshield tidy for launch. With the completion of this deployment, all of them have now been successfully released.

 

NASA

the unfolding is similar to how parachute unfold ( by wind), or sails rigging on a sail boat, via strings or ropes.

The unfolding and tensioning of the sunshield involved 139 of Webb’s 178 release mechanisms, 70 hinge assemblies, eight deployment motors, roughly 400 pulleys, and 90 individual cables totaling roughly one quarter of a mile in length. The team also paused deployment operations for a day to work on optimizing Webb’s power systems and tensioning motors, to ensure Webb was in prime condition before beginning the major work of sunshield tensioning.

11:59 a.m. EST Tuesday(4 Jan 2022), the sunshield was fully tensioned and secured into position, marking the completion of the sunshield deployment

 Temperatures on the Sun/hot side of the sunshield will reach (design spec) a maximum of approximately 383K or approximately 230 degrees F (110 degrees C) and on the cold mirror/instruments side of the sunshield, a minimum of approximately 36K or around -394 degrees F(-247 degrees C)

Scientific payload of JWST:

NIRCam

NIRSpec

MIRI

FGS/NIRISS

The (active) cooling system for MIRI includes a Pulse Tube precooler and a Joule-Thomson Loop heat exchanger. This allows MIRI to be cooled down to a temperature of 7 kelvins during operations in space.

Weak lens, wavefront sensing

Optical design status

ellipsoidal primary, hyperboloidal secondary, and ellipsoidal tertiary

Secondary mirror:

NASA declined to tell us which company made the blurred-out part, saying that information is an International Traffic in Arms Regulations issue. (More on this jargon in a moment.)

However, we know Northrop Grumman is the prime contractor that designed the spacecraft, and Ball Aerospace built the secondary mirror.

Lon Rains, a Northrop Grumman representative, declined to comment further and asked us to direct our questions to NASA. Ball Aerospace did not immediately respond.

Why is the back of a mirror on a taxpayer-funded scientific observatory considered an "arm" that must be regulated?

 

Probably because of spy satellites.

After all, if your telescope can see as sharply as Hubble, yet resolve objects 10 to 100 times dimmer — as JWST should be able to do — that could be useful for peering down at human activity on Earth. And the US government wants to maintain any edge it can over the militaries of countries like China and Russia.

Third mirror:

Stationery

Corrects astigmatism and field curvature.

In this YouTube video (02:05), it's bit misleading of role of tertiary mirror

The fine steering mirror. It is hexagonal segmented, U guess it works as baffle to restrict stray lights

Beginning about 77 days after launch, MIRI’s cryocooler will spend 19 days lowering the temperature of the instrument’s detectors to less than 7 kelvins.

HST ACS vs JWST NIRCAM

Cryo testing

JWST PSF   

Spied library

Two opd

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