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James Webb is fully deployed

nasa.gov

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Re: James Webb is fully deployed

#461

Post by z3t4 »

bigiain wrote: post #388
dmead wrote: post #354

Earlier quoted context omitted.

Literally every other nasa mission is filmed like this now. 10 billion and we can't even get visual confirmation it's doing well. And yes. Hubble being deployed was a big deal.

How much electrical power do you want to devote to this feel-good PR selfie camera? According to the mission director SmarterEveryDay interviewed on his YouTube channel recently, the James Webb Space Telescope is so sensitive it could detect the heat signature of a bumblebee at the distance of the moon. I’m pretty sure if you asked the astronomers if you could put a 5 Watt webcam on the dark side of their sun shield…

If it could see a bumblebee on the moon could it detect a while on Jupiters moons ? Can anyone do the calculations ?

Re: James Webb is fully deployed

#462

Post by Retric »

bmitc wrote: post #418
claaams wrote: post #415

Earlier quoted context omitted.

The point of the telescope is to capture IR light from space, if the telescope itself were generating IR light itself it would disrupt the sensor and data that it collects. Part of why its going to take so long for it to begin operating is that it needs to cool down to ultra cold temperatures before beginning operation.

Who said anything about generating infrared light? And I don't know what your last sentence is in reference to. Yes, it needs to cool down. Why is that relevant to this discussion other than what's already mentioned about that being a downside to operating cameras? From the article so people can just debate NASA's own reporting: > Although infrared or thermal-imaging cameras on the cold side could obviate the need fo…

First it’s possible to send up a camera that would be sensitive enough to use starlight to capture images on the dark side. However, those things aren’t light and would come at the cost of less propellant for minimal gain. Adding a tiny camera and a tiny light at the same time would also be possible but there really isn’t anything worth looking at via a single camera.

As to using infra red camera, they simply don’t work on objects the same temperature as the camera. NASA could have sent one up with a cooling system to look at the cold side of the sunshade, but again weight and pointlessness means it’s just wasteful.

Re: James Webb is fully deployed

#463

Post by jacquesm »

mturmon wrote: post #358
freeflight wrote: post #346

Earlier quoted context omitted.

> the telescope is aimed at the dark and away from the sun To be more specific; It's "parked" in an orbit [0] that constantly puts Earth between the sun and James Webb. So it's not only aimed away from the sun, Earth is also acting as a planetary scale sunscreen for it. [0] https://en.wikipedia.org/wiki/Lagrange_point

JW does indeed circle that Lagrange point, but it is definitely not in Earth’s shadow. The JW orbit semi major axis (about the L2 point) is order of 500,000 km. The radius of Earth is about 6500 km. Thus, the shadow of the Earth is extremely small compared with the excursions of JW.

Besides the sun being so stupendously large that the L2 point isn't in the direct shade cone anymore. At the orbit it is in full sunshine as though the Earth isn't there.

Re: James Webb is fully deployed

#464

Post by moffkalast »

willis936 wrote: post #350
freeflight wrote: post #346

Earlier quoted context omitted.

> the telescope is aimed at the dark and away from the sun To be more specific; It's "parked" in an orbit [0] that constantly puts Earth between the sun and James Webb. So it's not only aimed away from the sun, Earth is also acting as a planetary scale sunscreen for it. [0] https://en.wikipedia.org/wiki/Lagrange_point

Actually JWST orbits around L2 at appreciable altitude. The unique aspect of the orbit is that it is never in the shadow of the Earth or moon. It guarantees consistent solar power and thermal load. https://jwst-docs.stsci.edu/jwst-observatory-characteristics...

Given that this does not really give the orbit any real significance in terms of being shaded by the Earth from the Sun, is there another reason it's there?

I guess it gives you a very stable position for observations, but why not just put it in solar orbit then? Then again this is kind of a solar orbit that happens to stay close to the Earth at all times so that's a plus for comms.

Re: James Webb is fully deployed

#466

Post by moffkalast »

z3t4 wrote: post #461
bigiain wrote: post #388

Earlier quoted context omitted.

How much electrical power do you want to devote to this feel-good PR selfie camera? According to the mission director SmarterEveryDay interviewed on his YouTube channel recently, the James Webb Space Telescope is so sensitive it could detect the heat signature of a bumblebee at the distance of the moon. I’m pretty sure if you asked the astronomers if you could put a 5 Watt webcam on the dark side of their sun shield…

If it could see a bumblebee on the moon could it detect a while on Jupiters moons ? Can anyone do the calculations ?

Well it can allegedly make photos of Jupiter that would be comparable of doing them during a close flyby, but that's likely not good enough for something of that sort. You'd have to see things through kilometers of ice.

Re: James Webb is fully deployed

#467

Post by yreg »

JohnBooty wrote: post #349
dev_tty01 wrote: post #345

Earlier quoted context omitted.

Yes, I get all of that, but they still missed an excellent PR opportunity. NASA really could have built some engagement showing images of the deployment process, even if the images wouldn't have direct scientific benefit. Good PR leads to improved funding which leads to more science.

I just want to make sure I understand. Your position is that they should have added significant complexity to a maneuver that was already the most complex of its kind. A maneuver with $10 billion and two decades of work on the line. In order to make the first 30 days of a 10+ year mission marginally more entertaining. You propose this while fully aware that the "entertainment" in question consists of things unfolding…

I doubt adding a tiny camera is adding a significant complexity.

Re: James Webb is fully deployed

#468

Post by older »

awb wrote: post #379
mywacaday wrote: post #238

What I love about this project is that I had an active worry about its success, very few things in life inspire that kind of emotion. Well done to all involved, a true lifetime achievement. Can't wait for the images!

The cost: 23 years and $10B The benefit: “JWST’s instruments are designed to make discoveries across the spectrum of astronomy — ranging from the worlds and mini-worlds in our own solar system to alien planets circling distant stars, from the supermassive black hole at the center of our own Milky Way galaxy to the edge of the observable universe.” ( https://www.geekwire.com/2021/high-cost-high-risk-high-hopes... ) Ex…

So it is cheaper than most of recent Olympics. More benefit as well.

Re: James Webb is fully deployed

#469

Post by willis936 »

moffkalast wrote: post #464
willis936 wrote: post #350

Earlier quoted context omitted.

Actually JWST orbits around L2 at appreciable altitude. The unique aspect of the orbit is that it is never in the shadow of the Earth or moon. It guarantees consistent solar power and thermal load. https://jwst-docs.stsci.edu/jwst-observatory-characteristics...

Given that this does not really give the orbit any real significance in terms of being shaded by the Earth from the Sun, is there another reason it's there? I guess it gives you a very stable position for observations, but why not just put it in solar orbit then? Then again this is kind of a solar orbit that happens to stay close to the Earth at all times so that's a plus for comms.

That's exactly what L2 is. Otherwise the orbits of JWST and Earth would have different periods. It's handy to be able to have constant high speed communications and not need large antennas with blackouts.

It also is handy to keep the closest IR sources (Earth and moon) in the same direction as the sun at all times so there is never a point where you have a significant IR source above the sun shield.

Re: James Webb is fully deployed

#470

Post by repler »

voidfunc wrote: post #419
JohnBooty wrote: post #208

Earlier quoted context omitted.

Great blog post from NASA themselves explaining it: https://blogs.nasa.gov/webb/2022/01/06/why-doesnt-webb-have-... the post is really not very long and I would suggest getting it straight from the horse's mouth, but for those not willing to devote a click here are arguably the most relevant bits! "deployment surveillance cameras would not add significant information of value for engineering teams commanding the spac…

Once again scientists miss the entire point. It is about marketing and making people interested. It makes it easier when you go back five years later and ask for more money if people can see the multi-million dollar toy they paid for.

How often do you look at exterior photos of the Hubble?

Secondly, do we collectively as smart people honestly care what the ivermectin crowd thinks about exploring the cosmos?

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