James Webb: A $10bn machine in search of the end of darkness

[weltweit]

James Webb: A $10bn machine in search of the end of darkness

The biggest space telescope ever built is ready to show us the first stars to light up the cosmos.

www.bbc.co.uk

Equipped with a 6.5m-wide (21ft) mirror and four super-sensitive instruments, Webb will stare for days at a very narrow spot on the sky to detect light that has been travelling through the immensity of space for more than 13.5 billion years.

"We think there should be stars, or galaxies, or black holes maybe beginning at 100 million years after the Big Bang. There won't be many of them to find at that time but the Webb telescope can see them if they're there, and we're lucky," the US space agency (Nasa) researcher te..

 

[editor]

The scientists are beyond terrified about the launch. Fingers crossed!

 

[editor]

It's HUGE!

 

[weltweit]

10 billion dollars it has cost ..

Launching from French Guyana. (wonder why)

 

[weltweit]

Has to run very cold because it detects in Infra Red and a local heat source could confuse the telescope.

 

[2hats]

10 billion dollars it has cost ..

Launching from French Guyana. (wonder why)

The ESA contribution is (mainly) the launcher. JWST has been built around Ariane 5 (it the was the only reliable launcher option with a wide enough fairing to accommodate JWST at the time of mission design; still is the only one with a wide enough fairing - Falcon's is too narrow).

 

[weltweit]

Webb will stare for days at a very narrow spot on the sky to detect light that has been travelling through the immensity of space for more than 13.5 billion years.
"They will be just little red specks," says JWST senior project scientist and Nobel Prize winner John Mather.
"We think there should be stars, or galaxies, or black holes maybe beginning at 100 million years after the Big Bang.

 

[weltweit]

Comparison with Hubble



Wonder why its predicted lifetime is so much less than Hubble?

 

[Fez909]

Wonder why its predicted lifetime is so much less than Hubble?

I don't think Hubble's predicted lifetime was 31 years - it's just how long it has lasted. It was expected to be long disused.

 

[8ball]

I don't think Hubble's predicted lifetime was 31 years - it's just how long it has lasted. It was expected to be long disused.

Done pretty well considering the initial massive disappointment with the mirror.

 

[moochedit]

Comparison with Hubble

View attachment 301143

Wonder why its predicted lifetime is so much less than Hubble?

Short awnser is it will be located much further away from the earth making servicing missions impractable.

Why NASA’s James Webb Space Telescope Will Never Live As Long As Hubble

Hubble's still going strong after 31+ years. James Webb will never make it that long.

www.forbes.com

 

[8ball]

Short awnser is it will be located much further away from the earth making servicing missions impractable.

Why NASA’s James Webb Space Telescope Will Never Live As Long As Hubble

Hubble's still going strong after 31+ years. James Webb will never make it that long.

www.forbes.com

Further than Mars?
Where's Elon Musk when an actual job needs doing?

 

[2hats]

Wonder why its predicted lifetime is so much less than Hubble?

Original HST mission lifetime was ~15 years. Individual instruments (modular, replaceable) had lifetimes of about 5 years.

JWST lifetime limiting factor is the on-board hypergolic fuel needed to stationkeep in the L2 halo science mission orbit in the face of N-body perturbations. Sufficient reserve is also required to dispose of it at end of mission (to Earth-trailing heliocentric orbit). HST never required fuel as the low Earth orbit is relatively stable by comparison (and accessible for periodic reboost by visiting space shuttle).

Pointing of both is managed by reaction wheels.

 

[2hats]

Further than Mars?

L2 halo orbit about 4 times further away than the Moon in the opposite direction to the Sun. Less than 1/36th the distance to Mars when that's closest to Earth.

 

[NoXion]

Maybe the next space telescope after James Webb will be one in a similar orbit that can be refuelled. Which is why I really hope that the launch and deployment of the JWST goes smoothly, touch wood.

 

[2hats]

Maybe the next space telescope after James Webb will be one in a similar orbit that can be refuelled. Which is why I really hope that the launch and deployment of the JWST goes smoothly, touch wood.

All the forthcoming planned space telescopes are targeting Sun-Earth L2 halo orbits.

What Comes After James Webb and WFIRST? Four Amazing Future Space Telescopes

The Hubble Space Telescope has been in space for 28 years, producing some of the most beautiful and scientifically important images of the cosmos that humanity has ever taken. But let’s face it, Hubble is getting old, and it probably won’t be with us for too much longer. NASA’s James Webb Space...

www.universetoday.com

 

[weltweit]

According to google

James Webb Space Telescope/Launch date
22 December 2021

 

[Storm Fox]

I was looking to find this page

Launch - NASA Science

Webb Launch Slideshow The image below is a SLIDESHOW. Hover over the image to reveal the controls and see the image titles. Click the image to go to a Flickr detail page with more info and the ability to download the image at various resolutions (lower right down arrow). View the entire...

jwst.nasa.gov

And it had a link to the URL below stating launch has just been pushed back to no earlier than the 24th Decemeber

Webb Space Telescope Launch Date Update – James Webb Space Telescope

blogs.nasa.gov

 

[2hats]

Currently no earlier than 1220UTC, 24 December (troubleshooting a communications issue between the payload and the pad prep room communications kit). Update due tomorrow.

 

[manji]

Launch pushed back to 24 Dec Faulty cable responsible for latest James Webb Space Telescope launch delay

 

[weltweit]

from the OP BBC article

"We think there should be stars, or galaxies, or black holes maybe beginning at 100 million years after the Big Bang. There won't be many of them to find at that time but the Webb telescope can see them if they're there, and we're lucky," the US space agency (Nasa) researcher tells a special edition of Discovery on the BBC World Service.
It's an astounding idea that you might still be able to witness such a thing. But that's the consequence of light having a finite speed in a vast and expanding cosmos. If you keep probing deeper and deeper, you should eventually get to retrieve the light from the pioneer stars as they group together into the first galaxies.

 

[weltweit]

Discovery - The James Webb Space Telescope - BBC Sounds

A new giant space telescope that will show us the first stars that shone in the universe

www.bbc.co.uk

BBC Inside Science - The James Webb Space Telescope - BBC Sounds

A new giant space telescope that will show us the first stars that shone in the universe.

www.bbc.co.uk

 

[Steel Icarus]

Slight nerd annoyance at Alpha Centauri being described as the nearest star outside our solar system. It isn't; it's not a star, it's a trinary star system

 

[WouldBe]

I don't see how it will work. It has to rely on light coming into it. But the universe is expanding. Presumably not at the speed of light. So any light from the first stars will be well ahead of us. The only way we could see that light is it if reflects of something, but what?

 

[8ball]

I don't see how it will work. It has to rely on light coming into it. But the universe is expanding. Presumably not at the speed of light.

Faster than the speed of light, because the universe is in the region of 14 billion years old, and the known universe is is about 93 billion light years in diameter.

 

[WouldBe]

Faster than the speed of light, because the universe is in the region of 14 billion years old, and the known universe is is about 93 billion light years in diameter.

Sounds a bit fishy as nothing is supposed to travel faster than the speed of light.

 

[8ball]

Sounds a bit fishy as nothing is supposed to travel faster than the speed of light.

Indeed, it is weird.
I was just kidding about stuff moving faster than the speed of light, but the age and diameter of the universe are things you can check me on.

 

[Signal 11]

Sounds a bit fishy as nothing is supposed to travel faster than the speed of light.

Nothing is supposed to travel through space faster than the speed of light. That's not what the expansion of the universe is -- it's space itself expanding, so something far away enough will be receding from us faster than the speed of light.

 

[8ball]

Nothing is supposed to travel through space faster than the speed of light. That's not what the expansion of the universe is -- it's space itself expanding, so something far away enough will be receding from us faster than the speed of light.

And if you believe that, I've got a two hundred foot bridge to sell you.
Extra cheap, cos 14 billion years ago it was only twenty foot.

 

[Signal 11]

So any light from the first stars will be well ahead of us.

No. When we see something in the early universe, it took that amount of time for the light to go from where that object was then to where we are now, which includes the extra distance due to the expansion of the universe.