kirkster501

Happy New Year everyone. The party at Kirkster towers is over and just checked in to NASA - as you do 😂- and seen the port side sunshield has been deployed 👍🏻 https://blogs.nasa.gov/webb/2021/12/31/first-of-two-sunshield-mid-booms-deploys/

The positioning itself is still done by small thrusts of rocket engine lighting. The gyroscopes - and these are much more reliable than the HST's - provide the reference for a 3-D model of the sky that is constantly calibrated by the alignment of Canopus and Vega. What the JWST team do not want to be doing is slewing all over the sky between research projects. i.e M82 and then M42 and then M87, for example. The projects are scheduled scope time dependent on proximity to each other in the sky as a major factor, amongst some other things, to minimise fuel consumption.

Yep. Even Noble laureates such as Dr Mather who want to study objects that the JWST has to slew a long way to will have to wait until most of the "slew" is accomplished by the JWST's rotation around the sun in its orbit. The amount of slewing of the JWST is massively controlled and subject to huge chains of approval to minimise the use of the limited fuel. There is a Youtube video on this somewhere.

Let's meet up at the pub mate

Let's hope so Michael. Wouldn't that be wonderful? Also they will no doubt learn new ways to minimise fuel consumption too. If there is to be a refuel mission it needs to take place before the fuel runs out because when it does if will not just freeze and stay there; anything orbiting L2 without the fuel to maintain the orbit will drift off into a solar orbit into interplanetary space and at the mercy of Jupiter. Remember that JWST will be in a solar orbit, not an earth orbit.

I want to improve my planetary imaging - it sucks at present. This has not been the easiest time to do this due to the low altitude of the gas giants in the UK in recent years. Whilst technically still very difficult, planet imaging does not need the sustained hours of clear sky that DSO does making it an attractive alternative. I already dabble in lunar and solar and would like to improve on that too. Also want to get out with the Dob on the [few] clear nights to a dark sight and start to do some Herschel 250 objects. I am increasingly pessimistic on the outlook of DSO AP in the UK.

Yes. An orbit of L2 cannot be maintained without the expenditure of some fuel because the points are subject to disturbance by other solar system objects - especially The Moon and Jupiter.

Think of it like a saddle with huge, deep wells in spacetime caused by the Sun and the Earth. There are peaks and troughs in this gravity field and the peaks are L1 and L2 allowing a spacecraft to orbit them.

Not sure there is a “ranking” as such but I think the generally perceived wisdom is that the sunshield port and starboard extension phases and the subsequent tensioning is the biggest risk simply because there are hundreds of moving parts to it. Then the secondary *has* to deploy. There is zero mission if it doesn’t. No news as yet from NASA about the telescopic extension of the sunshield today so far.

Yep indeed, patience in testing, improving and testing again and again to seek out shortcomings and find out what could go wrong preemptively. They would have done this literally thousands of times before launch. I am quite confident the HW will work - it's the software where any issues, if present, will reside, IMO. It is aerospace software that would have had untold billions of Monte Carlo simulations thrown at it so it should be good. Time will tell. I see you are a STEM ambassador. Me too (computers and telecoms)

The sunshield has multiple welded seams to confine a tear to the part that was penetrated by the meteorite. The mirrors can take a reasonable amount of pitting without unduly effecting the performance. Just like a mirror in my dob, the thing can be filthy and it doesn’t stop observations. There are a lot of engineering articles online about the JWST that I’ve read. People get excited about the hardware but the JWST software (scope and ground side) comprises a third of the total development costs. People don’t realise that.

Yes, the halo orbit is tens of thousands of kilometres wide and we will see the sun lit side of the sunshield. So it should be possible to image it from the ephemeris coordinates. It will be in the plane of the ecliptic.

Me too. It is unbelievably fascinating. I’m an engineer by profession and this type of thing is incredible. “You can’t achieve great heights without taking great risks” a wise man once said.

Sunshield covers released. The big stuff starts now 😳 https://blogs.nasa.gov/webb/2021/12/30/webb-team-releases-sunshield-covers/

Not sure what you are doing wrong Laurie. Just enter the RA and Dec from JPL Horizons and enter into Stellarium or CDC and it will take you right there. You can then, after doing an initial sync or blind solve get your imaging software to take you right to JWST. In my image earlier I was a few minutes of arc off of getting JWST dead centre in the field.

Hi mate. Register all the images and use PIP or photoshop to create the GIF from them.

It takes six days to do the first half of the journey to L2 and 23 days to do the other half. This is due to it slowing down as it fights against the earth, sun and moon’s gravity. It will arrive at L2 not much faster than you could drive your car. It has no ability to slow down so the speed must never be so high that it overshoots L2 or the mission is blown. Fortunately the Ariane upper stage placed it so accurately that everything is going great in that department. The biggest test is to come, unfurling the Sun shield 😳. Fingers crossed for the next few days!

I made a video of it in DaVinci Resolve from the five still subs. See if this works on whatever Fourm software SGL is using. Conditions were dreadful but we had about 30 mins of semi clear sky. Just left of centre and slightly above the centre line. JWST.mp4

I grabbed 5 x 300s exposure last night and crated a GIF. Conditions appalling but scope aimed at where the Ephemeris said and the only thing moving is highlighted. I can't get the animated GIF to work on any website other than opening it on my computer

Tower successfully extended 😀 https://blogs.nasa.gov/webb/2021/12/29/webbs-deployable-tower-assembly-extends-in-space/

^^^indeed, scope operations are very carefully planned such that the scope is not slewing here , there and everywhere between random targets of the researchers. Target selection is extremely carefully managed so that only the tiniest whiff - literally a thimbleful - of fuel is needed to move the scope between closely adjacent objects in the sky to preserve the precious fuel.

That is correct. It can only image things that are in a cone 120-150 degrees wide centred on the sky opposite The Sun; at no point must any of the JWST telescope optics or "shadow side" components be exposed to the direct sun. This means that if it could image now it would be 60 degrees either side of Orion (i.e. opposite the Sun in the sky). When it - hopefully - opens for operations next year it will be able to observe SagA* at the centre of the galaxy. First objects are a reproduce of the Ultra Deep Field in Fornax - 160 hours of scope time! - and M82, another 80 hours.

One of these stars is JWST. I just can't get a proper 100% focus though since it's forever clouding over. Will keep trying.

Yes indeed, the accuracy of the Ariane launcher could have added years to the mission. I watched a video about this on YouTube a few weeks ago and they said it was crucial beyond crucial that the trajectory Ariane put it on was correct. It has to be placed in an exact place at an exact distance at an exact trime and a few feet per minute too fast could blow the entire mission. Let's not get too excited just yet though and hope a lot of the "twirls" and "shimmies" are not needed to get a potentially jammed sunshield opened up, thereby wasting precious fuel.

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