Author Topic: NASA - James Webb Space Telescope - Discussion and Updates  (Read 180686 times)

Offline Nomadd

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #520 on: 08/01/2017 11:40 PM »
 How long would BepiColombo have to wait if it missed it's window?

Offline zubenelgenubi

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #521 on: 08/03/2017 04:59 PM »
How long would BepiColombo have to wait if it missed its window?

I don't know, given that this mission's flight path is about as far as possible from a simple Hohmann transfer orbit--7 years of solar electric propulsion on a delta-v EVVMMMMMM gravity assist trajectory.  (M = Mercury, V = Venus, E = Earth)

Here are some, if not all of the previous launch windows, taken from the BepiColombo thread:
August 2013
July 2014
August 2015
"mid-2016"
January 2017
? 2018
October 2018
« Last Edit: 08/03/2017 05:00 PM by zubenelgenubi »
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Online LouScheffer

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #522 on: 08/03/2017 05:21 PM »
How long would BepiColombo have to wait if it missed it's window?
The first two flybys are Earth and Venus.  Earth is always in the same position relative to Earth, so that's not a constraint.  But to get to Venus with about the same state, you'll need to start when Earth and Venus are in the same relative positions.  That happens every 19.6 months.  This agrees with the last launch window slip, which was January 2016 to October 2018.

So the next similarly good trajectory will be about 19 months later, or June 2020, more or less. 

EDIT:  forgot 2018 is next year already.   Fixed the date.
« Last Edit: 08/04/2017 12:44 AM by LouScheffer »

Online pippin

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #523 on: 08/04/2017 12:03 AM »
2020

Online LouScheffer

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #524 on: 08/04/2017 01:56 AM »
How long would BepiColombo have to wait if it missed it's window?
The first two flybys are Earth and Venus.  [...]
So the next similarly good trajectory will be about 19 months later, or June 2020, more or less. 
From the paper BEPICOLOMBO TRAJECTORY OPTIONS TO MERCURY IN 2016 AND 2017, there are other options in addition to waiting for the same planetary configurations to repeat.  They can modify the phase to the Earth flyby, or sometimes go direct to Venus.  Given all these options, it looks like windows are typically 6 months apart or so, though there was a one year gap in 2016-2017.  So a detailed analysis would be needed, but most likely it would not require waiting the full 19.6 months.

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #525 on: 08/09/2017 07:10 PM »
Sunshield Layers Fully Integrated on NASA’s James Webb Space Telescope

Quote
The five sunshield layers responsible for protecting the optics and instruments of NASA’s James Webb Space Telescope are now fully installed.

Northrop Grumman Corporation in Redondo Beach, California who designed the Webb telescope’s optics and spacecraft bus for NASA’s Goddard Space Flight Center in Greenbelt, Maryland, integrated the final flight layers into the sunshield subsystem. The team is now folding and stowing the layers, in preparation for deployment tests in August.

The sunshield layers work together to reduce the temperatures between the hot and cold sides of the observatory by approximately 570 degrees Fahrenheit. Each successive layer of the sunshield, made of kapton, is cooler than the one below. All layers were installed and tested in June and July 2017 at Northrop Grumman Corporation’s Space Park facility in Redondo Beach.

“This is a huge milestone for the Webb telescope as we prepare for launch,” said Jim Flynn, Webb sunshield manager, Northrop Grumman Aerospace Systems. “The groundbreaking tennis court sized sunshield will shield the optics from heat and assist in providing the imaging of the formation of stars and galaxies more than 13.5 billion years ago.”

"All five sunshield membranes have been installed and will be folded over the next few weeks," said Paul Geithner, deputy project manager - technical for the Webb telescope at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The Webb telescope’s sunshield will prevent the background heat from the sun from interfering with the telescope’s infrared sensors. The five sunshield membrane layers, designed and manufactured by the NeXolve Corporation in Huntsville, Alabama, are each as thin as a human hair. Because the sunshield is the size of a tennis court, it helps solidify the Webb telescope as the largest ever built for space. The sunshield, along with the rest of the spacecraft, will fold origami-style into an Ariane 5 rocket.

The Webb telescope is the world’s next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope ever built, the Webb telescope will observe distant objects in the universe, provide images of the first galaxies formed and see unexplored planets around distant stars. The Webb Telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

https://www.nasa.gov/feature/goddard/2017/sunshield-layers-fully-integrated-on-nasa-s-james-webb-space-telescope

Online Phillip Clark

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #526 on: 09/06/2017 03:04 AM »
Excellent programme from the BBC World Service radio about the James Webb Space Telescope.

http://www.bbc.co.uk/programmes/w3csvnv2

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #527 on: 09/06/2017 11:21 AM »
Excellent programme from the BBC World Service radio about the James Webb Space Telescope.

http://www.bbc.co.uk/programmes/w3csvnv2

Thanks for the link.

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #528 on: 09/08/2017 07:08 PM »
Quote
Jeff Foust @jeff_foust
Scolese: JWST has survived a gov’t shutdown, derecho, snowstorm, and now hurricane. Hope when it goes to Calif. there’s not an earthquake.
5:32 pm · 8 Sep 2017

https://mobile.twitter.com/jeff_foust/status/906193506007269376

Quote
Jeff Foust @jeff_foust
Scolese: lost only a couple days of testing at JSC. Still on track for late 2018 launch, pending resolution of launch schedule conflicts.
5:44 pm · 8 Sep 2017

https://mobile.twitter.com/jeff_foust/status/906196606642466817

Offline catdlr

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Re: NASA - James Webb Space Telescope - Discussion and Updates
« Reply #529 on: 09/21/2017 11:23 PM »
Aligning the Primary Mirror Segments of the James Webb Space Telescope

James Webb Space Telescope (JWST)
Published on Sep 21, 2017

Engineers at NASA’s Johnson Space Center in Houston used light waves to align the James Webb Space Telescope’s mirror segments to each other, so they act like a single, monolithic mirror in the cryogenic cold of the center’s iconic Chamber A.

Part of the Webb telescope’s ongoing cryogenic testing in Chamber A at Johnson includes aligning, or “phasing,” the telescope’s 18 hexagonally shaped primary mirror segments so they function as a single 6.5-meter mirror. All of these segments must have the correct position and correct curvature; otherwise, the telescope will not be able to accurately focus on its celestial targets.

https://www.youtube.com/watch?v=2dh41uouutU?t=001

Tony De La Rosa

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