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See where Webb is on the way to L2 orbit; https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html F
by Maxburn 5y ago
See where Webb is on the way to L2 orbit;
https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
Fun to see where it is on deployment.
It's also interesting to me that the mirror appears to be fully exposed to space unlike Hubbell. If anyone knows something about that design choice I've like to hear it.
- wmf 5y agoIf the optical path was enclosed the JWST would probably be too big to fit on any existing rocket.
- Laremere 5y agoFactors I can think of: 1. Bigger mirror = better. Enclosing a mirror requires mass and volume, limiting mirror size. 2. The L2 orbit is unstable. Far less risk of being hit by debris than low Earth orbit. 3. Webb's sun shield blocks the primary light pollution angle. Hubble would need more protection from all angles due to the Sun, Earth, and Moon.
- anonAndOn 5y ago4. Any variations in temperature in the mirror array affect geometry/optics
- Maxburn 5y agoI was just reading that after L2 insertion it's going to take five months to get everything cooled off and aligned properly. Amazing.
- jacquesm 5y agoCooldown has already started with the deploying of the sunshield from it's launch position, even before it is unfolded fully and stacked properly the delta is already a whopping 60 degrees Celsius across a bit over two meters.
- latchkey 5y agoMaybe we will get lucky and find out something like this announcement.
- Maxburn 5y agoDid not realize the light pollution angle, that's a major one. I also had no idea L2 was unstable and found a little discussion on it. https://space.stackexchange.com/questions/284/why-should-the-james-webb-space-telescope-stay-in-the-unstable-l2 https://space.stackexchange.com/questions/284/why-should-the...
- miohtama 5y agoHere is a good video about the stability of L1 - L5 points https://youtu.be/7PHvDj4TDfM https://youtu.be/7PHvDj4TDfM
- terramex 5y agoHubble needed to hide mirror because it is passing from sunlight into shadow every 47 minutes and mirror has to be protected from thermal stress. Also Earth emits some light even on night side that would interfere with observations. JWST's mirror is always in shadow and stray light from sides will not be a problem at L2.
- Maxburn 5y agoThat makes a lot of sense, thanks.
- y4mi 5y agoIf you're interested in a more indepth view of how it's supposed to work, Real Engineering did a video about it recently. No idea if what they're saying is true however, I've no knowledge about the domain. https://youtu.be/aICaAEXDJQQ https://youtu.be/aICaAEXDJQQ
- 19870213 5y agoMain reason I heard was that enclosing it would be preferable, but then it wouldn't fit in any currently in use fairing.
- jacquesm 5y agoI've been glued to that page since the launch. The temperature delta just came online so you can now see the 'top' and 'bottom' temperature. In the end it will be several hundred degrees difference, which given the distances involved is extremely impressive.
- Maxburn 5y agoThe explore all deployments section is worth a read too. Wealth of info on the whole site and it's designed really well. Clearly catering to the education / general public good will with this site. https://jwst.nasa.gov/content/webbLaunch/deploymentExplorer.html https://jwst.nasa.gov/content/webbLaunch/deploymentExplorer....
- vikingerik 5y agoFascinating that it's already covered 40% of the distance, but it's only on day 4 out of 30. That makes sense once you realize that its radial velocity needs to slow to zero when it reaches L2. I'd love to see the shape of how the velocity curve slows.
- Maxburn 5y agoThey link to this which shows the gravity gradients in play. I could have sworn they charted the velocity involved but I can't find it now. https://upload.wikimedia.org/wikipedia/commons/3/36/Lagrangian_points_equipotential.png https://upload.wikimedia.org/wikipedia/commons/3/36/Lagrangi...
- the_milkdromeda 5y agoi've been checking for the past few days and it looks like JWST is available now in NASA's little 3D space model. you can literally it in the solar system model now too! https://solarsystem.nasa.gov/solar-system/our-solar-system/overview/ https://solarsystem.nasa.gov/solar-system/our-solar-system/o...
- Maxburn 5y agoAnother neat site from NASA, thanks!