[HN Gopher] James Webb Space Telescope reveals Fomalhaut's disk ...
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James Webb Space Telescope reveals Fomalhaut's disk in detail
Author : gmays
Score : 288 points
Date : 2023-05-09 14:19 UTC (8 hours ago)
(HTM) web link (skyandtelescope.org)
(TXT) w3m dump (skyandtelescope.org)
| timdellinger wrote:
| A side-by-side before-and-after with the "previously best" image
| to compare against the new image would be great to see.
| Synaesthesia wrote:
| Here's on which is a composite of the ALMA (millimetre wave
| telescope) superimposed with Hubble (in blue)
|
| https://www.centauri-dreams.org/2017/05/22/best-images-yet-o...
|
| Here's just that ALMA pic
|
| https://commons.wikimedia.org/wiki/File:ALMA_Explores_Fomalh...
| Haga wrote:
| [dead]
| jakear wrote:
| Anyone know what the black blob in the center is? It's
| conspicuously left out of the labeled diagram, and doesn't seem
| mentioned in the article either. I imagine it's the central sun
| in question, but isn't it odd to never mention it?
| cubefox wrote:
| Yeah. The ability of journalists to ignore the most obvious
| questions is baffling.
| ceejayoz wrote:
| Or a magazine named "Sky and Telescope" may understand, being
| fairly niche, that its readers don't need the obvious ones
| answered.
| btilly wrote:
| That's the coronagraph that blocks out the star itself so that
| everything else is visible.
|
| https://blogs.nasa.gov/webb/2023/03/24/how-webbs-coronagraph...
| hn8305823 wrote:
| There has been a lot of confusion about this but it is
| actually overexposed pixels deleted in software. From the
| lead author of the paper:
|
| https://twitter.com/AndrasGaspar/status/1655680076103716878
| btilly wrote:
| Thanks.
|
| Silly me for believing NASA.
| kfarr wrote:
| Why make overexposed pixels black instead of white? Just to
| make it extra clear that the pixel data exceeding
| overexposure threshold is not mistaken for valid data?
| eimrine wrote:
| Additional bits of information? You cannot see what shape
| is that area if it is surrounded with a light yellow and
| you will miss some info if you'll do it after JPEG
| conversion.
| hn8305823 wrote:
| > Just to make it extra clear that the pixel data
| exceeding overexposure threshold is not mistaken for
| valid data?
|
| Saturated pixels are not necessarily "invalid" the way
| cosmic ray bit flips and stuck pixels are, but setting
| them to zero does make the other bright but not saturated
| pixels much easier to identify.
| crazygringo wrote:
| I'm baffled as well. I think it's fairly understood that
| any white pixel is always understood to be probably
| overexposed.
| dylan604 wrote:
| Black Hole Sun? There was a camera that "suffered" this
| problem, but can't remember the model to look it up.
| dudeinjapan wrote:
| Redacted by the CIA, because it contains evidence of
| extraterrestrial life.
| pfdietz wrote:
| Just think what space telescopes will be like if the Starship
| reduces cost/kg to orbit to 1/10th or less of Falcon 9's already
| low cost. They'd get very big, and it would likely make sense to
| assemble and maintain them in space by workers in space suits. It
| might even make sense to have telescopes in high Earth orbit with
| a maintenance station located nearby.
| itishappy wrote:
| Webb isn't in an earth orbit though, it's at a Lagrange point
| that humans have never visited, and it's there because that's
| where it can get the best images. I don't think Starship can
| even get there at all without orbital refueling.
| pfdietz wrote:
| Sure, and it's also there because there was no plan to ever
| repair or service it. And that was because as it was being
| planned, launch was very expensive, so no satellite beyond
| LEO (where it could not be, for heating reasons) could
| reasonably be serviced.
| vl wrote:
| But why is it at the Lagrange point in the first place?
| Wouldn't ultra-high orbit be equally enough?
| areoform wrote:
| The coldhead of one of these sensors (MIRI) functions
| optimally at temperatures _less_ than 7@K (i.e. 7@ above
| absolute 0). The other sensors run at temperatures under
| 40@K.
|
| For reference, the melting point of nitrogen is, 63@K.
|
| Any sunlight at all would overwhelm this sensor and
| severely reduce the operational lifetime (and results!)
| of the telescope.
|
| At L2, the telescope has the sun and the Earth behind a
| layered sunshield. It's easier to maintain position there
| and to have both objects always in the sol-ward direction
| while looking outwards.
| pfdietz wrote:
| There are telescopes on Earth that cool their detectors
| (not optics, though) well below that temperature. The
| SPT-3G at the South Pole, for example, has detectors at
| 3K.
| Valgrim wrote:
| The cryocooler assembly on the JWST is one of the coolest
| marvel of engineering ever built (pun intended).
| Tuna-Fish wrote:
| Because it is an infrared telescope, and in earth orbit
| there are three very bright infrared sources that would
| mess up the instruments or heat up the telescope too much
| if they ever shone on the sensitive parts. (Sun, Moon and
| Earth.) When the telescope is placed in the Sun-Earth L2,
| all three sources are always very close to each other in
| the sky, and you can shield against all three with a
| single directional sunshield.
| cubefox wrote:
| I always thought L2 was chosen for Earth to cover up the
| sun. But apparently Earth covers it only to 84%.
|
| https://www.quora.com/Is-the-L2-point-of-Earth-in-a-
| permanen...
| bagels wrote:
| It needs solar power
| Tuna-Fish wrote:
| Because the JWST is not at the L2, but in a halo orbit
| around it, Earth in fact never covers the Sun at all from
| its point of view. They are just always fairly close to
| each other.
| cubefox wrote:
| Interesting!
| sjburt wrote:
| It's so the sun and the earth will always be in the same
| direction and both can be hidden behind the sun shield.
| dylan604 wrote:
| That's not the main reason. Webb is viewing wavelengths
| where it has better viewing by being that distance away
| from the Earth. Putting Webb in similar Hubble orbit would
| diminish its abilities. If you want to build bigger visible
| wavelength platforms, then this might be a discussion to
| have with Starship capabilities.
| pfdietz wrote:
| Yes, and it has better viewing at that distance because
| close to Earth, thermal radiation from the Earth would
| make it too warm.
| dekhn wrote:
| the cost of launching a scope is not the bottleneck.
| pfdietz wrote:
| High cost of launch prevents economical repair (especially in
| high orbits), which requires extreme reliability. It also
| creates incentive for extreme weight reduction. Both these
| drive up the cost of a satellite. At low launch cost, there's
| no reason a space telescope should be much more expensive
| than a terrestrial telescope of the same size.
| spenczar5 wrote:
| No, that goes way too far. Radiation hardening and heat
| dissipation are really difficult problems that remain for
| any space telescopes.
|
| (I'm at the University of Washington Department of
| Astronomy, and work on telescope software).
| pfdietz wrote:
| With sufficiently cheap launch, you get radiation
| hardening with shielding. The goal is to use off the
| shelf hardware as much as you can. If things break,
| that's why we have servicing, just like on terrestrial
| telescopes.
| AnimalMuppet wrote:
| The cost of rolling a truck to a terrestrial telescope is
| several orders of magnitude smaller than the cost of
| servicing a telescope in space. From that difference
| flows a greater emphasis on reliability for a space-based
| scope.
| dekhn wrote:
| Do you work in the field of space? I don't mean to be
| dismissive but claiming that space telescopes cost about
| the same as terrestrial scopes if you subtract out the
| launch costs and can maintain them with crews, isn't really
| consistent with what I've heard from space telescope
| astronomers.
| sebzim4500 wrote:
| No, but the mass and volume constraints are. See how much
| effort went into making JWST fold up and how hard they had to
| try to get the mirrors to be light enough.
| pfdietz wrote:
| That's where in-space assembly comes in.
|
| It's kind of sad that the one real thing the Space Station
| demonstrated, assembly of large space structures, has been
| abandoned in the name of feeding the pork pipeline with
| SLS.
| tsimionescu wrote:
| Given that SLS works and Starship has failed pretty
| spectacularly so far (engines failing off the gate and in
| flight, launch site damage, failed to detonate on
| demand), I think it's about time to stop saying SLS is
| just pork.
| cubefox wrote:
| SLS may be further ahead in development (though the
| version that launched is far from the final one), but it
| is much worse than Starship in nearly every other aspect.
| This is consensus in the space community, it has been
| discussed to death.
|
| Edit:
|
| The most significant thing Starship is bad at is
| launching and landing humans. Human launch systems like
| Falcon 9/Dragon or SLS/Orion have both a launch abort
| system and a highly reliable "blunt capsule" method of
| landing humans back on Earth. For Starship, both
| launching and landing humans is much more dangerous, as
| it doesn't have a launch abort system and it uses a
| complex maneuver ("belly flop") in order to land.
|
| Starship will need to do a lot of unmanned satellite
| launches to prove a safety level acceptable for humans.
| Or people transfer to and from Starship in space, as in
| Artemis 3, and start/land with a different rocket.
| pfdietz wrote:
| SLS basically has a single purpose: funneling money to
| particular contractors. There is no objective in space
| that couldn't be done more cheaply with F9 and FH, given
| propellant transfer and some in-space assembly.
| GolfPopper wrote:
| > _Given that SLS works_
|
| A cost of $27,000,000,000 per launch, and a launch rate
| of 1 per 132 months is a generous definition of "works".
| And that's where SLS is right now.
| cubefox wrote:
| I think it is "just" 4 billion per launch, though of
| course this doesn't include the development costs.
| Regardless, the costs are staggering compared to Falcon
| 9, Falcon Heavy, Vulcan, or Starship.
| dylan604 wrote:
| How did China lift their space station?
| basementcat wrote:
| Modules were launched on Long March 5B rockets.
| https://en.m.wikipedia.org/wiki/Tiangong_space_station
| https://en.m.wikipedia.org/wiki/Long_March_5
| adgjlsfhk1 wrote:
| Space assembly for a telescope is way harder than the
| ISS. Telescope mirrors need to be aligned to within a few
| nanometers of each other, compared to the ISS which just
| needs airtight seals (so ~1mm + O-ring tolerance).
| nordsieck wrote:
| Why do you say it's been abandoned?
|
| SLS will be delivering segments of Gateway after the
| first 2 are delivered by Falcon Heavy.
| pfdietz wrote:
| ISS involved assembling segments that could be lifted on
| the Shuttle. Continuing that would involve lifting
| segments that could be lifted on F9 or FH. There would be
| no need for something as large as SLS.
| nordsieck wrote:
| > the cost of launching a scope is not the bottleneck.
|
| Starship isn't just about price, but also fairing volume. And
| fairing volume is one of the major factors that drives
| telescope design.
|
| It's even possible that SpaceX would do a limited run
| hammerhead fairing for the right price.
| cubefox wrote:
| Not sure a larger fairing would be compatible with the
| current tower. Though they could use landing legs, then it
| doesn't have to be caught mid flight.
| nordsieck wrote:
| > Not sure a larger fairing would be compatible with the
| current tower.
|
| I'd imagine that a hammerhead fairing would mean an
| expended 2nd stage. There's just too much custom work
| that would have to be done (for example with the heat
| shield) to really make it work.
|
| But if the cost is reasonable (I'm guessing ~$25 million
| for an upper stage), that isn't a bad price to pay to get
| access to a 12m fairing.
| cubefox wrote:
| I think 25 million USD is too optimistic, since the
| Starship upper stage has six raptor engines, and the
| Falcon 9 upper stage has only one Merlin engine, but a
| launch price of around 60 million US dollars.
|
| But NASA would pay much more than that if it means they
| can launch a telescope with a big mirror that doesn't
| need to be folded in. The main problem I see is that they
| would likely also have to pay for the entire development
| of the new upper stage, which would be much higher than
| the pure launch cost. Since NASA already has JWST, I'm
| not sure they have much interest in a big new space
| telescope currently. Other than that, it's not clear what
| a super large payload fairing would be required for.
| nordsieck wrote:
| > The main problem I see is that they would likely also
| have to pay for the entire development of the new upper
| stage
|
| I don't see why they'd need to do a full 2nd stage.
|
| I'm sure a limited run fairing (especially a complicated
| one like a hammerhead) will be expensive - certainly
| quite a bit more than the $5 million per unit cost of the
| Falcon fairings. But ultimately a fairing just isn't that
| complicated, and SpaceX has a lot of experience with
| them.
| cubefox wrote:
| Well, the aerodynamics are different and the launch abort
| system would probably have to be somewhat different too.
| The structural integrity could also be quite different.
| Of course it won't be a completely new upper stage, as it
| is just a modification, but a few test launches are
| probably required.
| dylan604 wrote:
| >I'm guessing ~$25 million for an upper stage
|
| that'll be initial cost submitted. once it is approved
| and work begins, that number will double, triple, or more
| before it is completed.
| cubefox wrote:
| I can't find it now, but about a year ago there was an article
| by some professors with an extensive analysis what Starship
| could do for space science.
|
| Their point was that Starship has a big _potential_ to
| significantly reduce cost by enabling the development of
| devices that are less optimized for size and weight. For
| example, the extremely expensive JWST could have been built
| with a much cheaper, non-foldable mirror, since the Starship
| fairing has a quite large diameter.
|
| But they also argued that there is an unfortunate tendency in
| science to overoptimize everything, which leads to exploding
| cost. So it is well possible that scientists won't use Starship
| to reduce the cost of their spacecrafts, but to optimize them
| for maximum performance like they did before, e.g. by designing
| complex foldable mirrors which barely fit into the Starship
| fairing.
|
| So I guess if they do that, Starship would enable an _even
| stronger_ cost explosion than in the past, not a cost
| reduction. More available mass and size means more opportunity
| to spend money on complex engineering. The launch costs
| themselves are not a significant factor here.
| vl wrote:
| Interesting consideration:
|
| Starship is monolithic right now, ie it's unclear how it can
| unload payload of its own size. There are no bay doors a-la
| shuttle.
|
| I guess they will have to do tilt-away nose section or
| something.
| cubefox wrote:
| From the official Starship users guide:
|
| > The Starship payload fairing is a clamshell structure in
| which the payload is integrated. Once integrated, the
| clamshell fairing remains closed through launch up until
| the payload is ready to deploy. An example sequence of
| payload deployment is shown in Figure 3. To deploy the
| payload, the clamshell fairing door is opened, and the
| payload adapter and payload are tilted at an angle in
| preparation for separation. The payload is then separated
| using the mission-unique payload adapter. If there are
| multiple payloads on a single mission, a rotating mechanism
| can be provided to allow each satellite to separate with
| maximum clearance. Once separation is confirmed and the
| payload(s) have cleared the fairing, the payload fairing
| door is closed in preparation for Starship's return to
| Earth.
|
| Figure 3: https://i.stack.imgur.com/D3MYv.png
|
| Full PDF:
| https://www.spacex.com/media/starship_users_guide_v1.pdf
| pfdietz wrote:
| Or, it means teams and organizations that can't control cost
| don't make the discoveries, and are weeded out.
| simonh wrote:
| Cost control is largely about correctly predicting costs.
| So teams that correctly predict costs will select lower
| performing but affordable instruments. Teams that fail at
| that may well under predict costs, over engineer their
| systems and end up with super expensive but super capable
| systems.
| echelon wrote:
| Forget everything else, we need to build _THIS_ :
|
| https://www.youtube.com/watch?v=NQFqDKRAROI
|
| A telescope array that can use our sun's gravitational lens
| would enable us to resolve the surfaces of extrasolar planets.
| We could resolve surface features as small as 10 km across at a
| distance of 100 light years.
|
| JPL is actively investigating this. It's incredibly promising.
| cubefox wrote:
| Yeah, though I have some doubts as to how certain it is that
| it would really produce results that impressive. Maybe this
| is quite speculative. There could be tiny inaccuracies which
| reduce the image quality substantially.
| tonyg wrote:
| Beautiful. Thank you for that link.
| moffkalast wrote:
| LUVOIR's planned to launch on Starship or something of its
| size.
| macspoofing wrote:
| >Just think what space telescopes will be like if the Starship
| reduces cost/kg to orbit to 1/10th or less of Falcon 9's
| already low cost.
|
| Falcon 9 is around $60 million/launch (though when contracted
| by NASA or the military, launches tend to be 2x-4x the price).
| This is pretty much inline with what you get from Arianespace,
| and Roscosmos. There is no path to reduce price by another
| order of magnitude. We've pretty much hit the limit on what we
| can do with chemical rockets.
| wolfram74 wrote:
| Or, since there's no downward pressure on price, it's equally
| valid to say we've hit the limit of what we can do with
| capitalism in the current ecosystem.
| pfdietz wrote:
| Price won't approach cost until there's another competitor
| with similar costs. But China is heading strongly in that
| direction, working on a F9 clone (and perhaps more than
| one; there are many quasi-private launch efforts there).
| I'm sure Musk knows F9's life as a money-printing machine
| is finite.
| macspoofing wrote:
| >Or, since there's no downward pressure on price, it's
| equally valid to say we've hit the limit of what we can do
| with capitalism in the current ecosystem.
|
| There is downward pressure, we're just hitting physical
| limits on what can be done with chemical rockets.
| pfdietz wrote:
| Please stop with this nonsense. It's obviously wrong.
| pfdietz wrote:
| Falcon 9's price is a bit below its competitors. But
| remember, cost != price. There is not much reason for SpaceX
| to reduce the price further, if demand is sufficiently
| inelastic.
|
| There is room to reduce cost much further. Discarding the
| second stage is a large cost. The propellants used by F9 cost
| $200K/launch, according to Musk. With full reusability costs
| should fall at least another order of magnitude.
| macspoofing wrote:
| >There is not much reason for SpaceX to reduce the price
| further, if demand is sufficiently inelastic.
|
| Or they can't, because there are physical limits to the
| chemical rocket technology.
|
| >There is room to reduce cost much further. Discarding the
| second stage is a large cost ... with full reusability
| costs should fall at least another order of magnitude.
|
| Reusability is not a panacea. Falcon 9 is partially
| reusable and it is not significantly (if at all) cheaper
| than the competition. There is no evidence that full
| reusability will provide an order of magnitude cost
| decrease in prices. Fully reusable rockets imply that
| you're cutting into your cargo space (because you have to
| ship extra fuel for the decent), and maintenance is
| expensive and time-consuming. Don't get me wrong, there may
| be costs savings there, but not 10x, more like 10%.
| jansan wrote:
| The most stunning and accessible comparison between Hubble and
| James Webb for me is still the pillars of creation images. A few
| weeks ago I was in the planetarium at the U.S. Space & Rocket
| Center in Huntsville where they faded from the Hubble image into
| the James Webb image. That was truly a sight to behold. In
| general the presentation there was one of the best I have ever
| seen.
|
| Edit: I think this video is exactly what they showed. Of course,
| in this case the bigger your monitor the better.
| https://youtu.be/f8q8ZIXf_Rw?t=67
| casenmgreen wrote:
| Can't view. Stuck in the Cloudflare verification loop.
| quakeguy wrote:
| It's a brave new web.
| NoMoreNicksLeft wrote:
| I feel cheated... I glance at the image, see that bulge in the
| ring and was immediately excited that they had captured the
| visual image of an exoplanet (even if it was going to be a large
| brown dwarf).
|
| Nope, just something behind the ring.
| Vox_Leone wrote:
| >I glance at the image, see that bulge in the ring and was
| immediately excited that they had captured the visual image of
| an exoplanet (even if it was going to be a large brown dwarf).
|
| I was under the same impression. Upon a second look it became
| clear that blob is roughly 8 AU in diameter [judging by the
| overall scale]
| Synaesthesia wrote:
| A visual of an exoplanet is still beyond the possibility of
| anything but a REALLY big telescope (100m)+
| hotshot1001 wrote:
| Actually we've imaged many exoplanets, but typically ones
| that are much larger than Jupiter.
|
| Here's a famous system: https://en.wikipedia.org/wiki/HR_8799
| jl6 wrote:
| If I may take advantage of the presence of knowledgable people in
| this thread...
|
| The JWST is located at the L2 point. Does that mean L2 is now
| "taken", or could it make sense to host multiple telescopes and
| spacecraft at or near that point?
| mnw21cam wrote:
| There's already multiple telescopes there, including the Gaia
| telescope. See
| https://en.wikipedia.org/wiki/List_of_objects_at_Lagrange_po...
| itishappy wrote:
| In short, it orbits the L2 point. There's plenty of room for
| more!
|
| Here's a 20s YouTube video that should clear things right up:
|
| https://www.youtube.com/watch?v=6cUe4oMk69E
|
| Here's an article with additional info:
|
| https://webb.nasa.gov/content/about/orbit.htm
| samstave wrote:
| What does the F2300C and F2550W mean? Focal length?
| dekhn wrote:
| They are "mask" which only allow some wavelengths so you can
| see different structure.
|
| https://en.wikipedia.org/wiki/Coronagraph
| xioxox wrote:
| They are the filters used in the observation. Telescopes use
| filters to select a range of light wavelength/frequency to be
| observed. See http://svo2.cab.inta-
| csic.es/svo/theory/fps3/index.php?id=JW... to see their
| properties.
| causi wrote:
| _It reveals an inner belt, akin to the solar system 's asteroid
| belt but dustier and more extended; an intermediate belt; and a
| previously imaged outer belt that's analogous to our Kuiper
| Belt._
|
| How could something analogous to our Kuiper belt possibly
| reflect/emit enough light to be visible as a cloudy ring? There
| is no way it isn't orders of magnitude more massive than the
| Kuiper belt.
| cl42 wrote:
| I was going to ask the same thing -- maybe someone more
| astronomically inclined has an answer to this...
|
| If one were to take a phot of our solar system, would our
| asteroid belt really be dense enough to show up in any
| wavelengths?
| bbojan wrote:
| Maybe because it's still gas and dust, whereas if the same mass
| coalesces into large objects it's much less reflective?
| eimrine wrote:
| Are there any previous images of the same object from a
| superexpencive telescops of previous generations to compare James
| Webb's advance from other telescops?
| coldpie wrote:
| Wikipedia has a number: https://en.wikipedia.org/wiki/Fomalhaut
|
| Hubble:
| https://en.wikipedia.org/wiki/File:NASA%27s_Hubble_Reveals_R...
|
| ALMA: https://www.eso.org/public/images/eso1216a/
| krisoft wrote:
| > The outer ring is about 240 astronomical units in diameter.
|
| That is huge. Just reference for those who don't feel
| "astronomical units": One astronomical unit (AU) is (roughly) the
| Earth-Sun distance.
|
| Distances to compare with: Pluto is ~39 AU away from the sun.
| Voyager 1, the furthest probe of humanity right now, is ~160 AU
| away from the sun.
|
| So in other words: that is mind-bogglingly large.
|
| (If you want to read more about astronomical units:
| https://en.wikipedia.org/wiki/Astronomical_unit )
| mwcremer wrote:
| Comparing diameter to radius is a little misleading, the ring
| is actually closer than Voyager, at 120 AU. On the same scale,
| Pluto is 78 AU and Voyager is 320 AU.
| tambourine_man wrote:
| As a layman I get the feeling that JWST is showing us more
| detailed things we'd already seen than brand new ones. I remember
| being moved by the Hubble deep field, where a long exposure
| revealed that what looked like an empty patch of the sky was
| anything but.
|
| Are we reaching the point of diminishing returns of what a
| reasonably sized (for our current rockets) space telescope can
| see?
| retrac wrote:
| > Are we reaching the point of diminishing returns of what a
| reasonably sized (for our current rockets) space telescope can
| see?
|
| In terms of sensitivity, yes. Collecting more light needs more
| light-collecting material, which ultimately means more mirror,
| or detector, surface area. Little more gain to be had there.
| We're not going to see much more that's really, really faint.
|
| But we're just getting started with resolution. Apertures can
| be synthesized in software. Theoretically, a handful of space
| telescopes, orbiting the Sun, linked together, could have an
| angular resolution equivalent to that of a physical telescope
| with a mirror the same diameter of the orbit. Not the light
| sensitivity (since the "mirror" is mostly empty space), but it
| would have the ability to distinguish between two points like
| such a giant telescope would.
|
| This has been done with radio astronomy already; things have
| just recently gotten fast enough for aperture synthesis at
| infrared wavelengths; optical is probably not too far behind.
| adgjlsfhk1 wrote:
| I think optical is pretty far behind. EHT was already dealing
| with 100s of TB of data per telescope. Going to visual turns
| that into ~10s of PB. I think the more likely advance is some
| way of doing space based radio wave interferometry.
| potamic wrote:
| They did discover several galaxies beyond redshift 11 that
| Hubble cannot see. I'm not in the field, but venturing a guess
| here that they might want to prioritise getting images of known
| objects first, because there must be so much active research
| that can immediately benefit from the new detail. Over time I
| hope they will dedicate time for some wild hunches like Hubble
| did and open up something yet unknown.
| hn8305823 wrote:
| The Hubble deep fields take many days/weeks/months of exposure
| time. The deep fields released from JWST so far have been just
| hours long...
|
| There are a lot of different proposals being rapidly shot in
| these early year(s) of the telescope. Later on there will
| certainly be longer exposures.
| tambourine_man wrote:
| I'm eager to see what JWST can do with more than 48h of
| exposure. It should be amazing. I'm wondering why they're
| choosing to shot other stuff before.
| adgjlsfhk1 wrote:
| Because telescope time is expensive. If you do a 1 week
| deepfield, you can't use the telescope for anything else
| for 1 week. You get more discoveries earlier by doing all
| of your hour long shots first.
| BurningFrog wrote:
| JWT doesn't have much more detail than Hubble, but it observes
| infrared frequencies, which is a whole new view of the
| universe.
| nologic01 wrote:
| Discovering brand new things at a constant rate is probably not
| a realistic expectation. The 20th century has been an
| extraordinary journey for astronomy that cannot possibly
| continue indefinitely (same with other parts of fundamental
| science). We went from barely a sense what our galaxy is about,
| to discovering an extraordinary number of exotic astronomical
| objects by progressively expanding the window into radio,
| x-ray, gamma rays, gr waves etc.
|
| But I don't think its true that future astronomers / space
| telescopes are condemned to boring hires pictures of known
| stuff. The excitement is not in the visual impression but in
| what it might tell us about the universe. In the end what
| matters is whether we understand what is happening (e.g., in
| this instance how planetary systems like our very own are
| forming). So while the visual impression might not alter much,
| the quantitative detail may be fixing the physics or even
| prompting completely new theories. Remember sometimes even the
| stuff you don't see can bring about a revolution (dark matter,
| dark energy).
| soulofmischief wrote:
| JWST is an infrared scope of a magnitude never before employed.
| Astronomy is more about collecting data than anything else,
| pretty images are a welcome side-effect. JWST will be extremely
| beneficial for deep-space exploration. It's worth reading
| about!
| digging wrote:
| > Are we reaching the point of diminishing returns of what a
| reasonably sized (for our current rockets) space telescope can
| see?
|
| No, not as far as I know (also a layperson). It's just that
| we've already seen the incredible leap of "there's nothing
| here" -> "there's things here". The JWST is still a massive
| leap in capabilities, but you aren't going to be as impressed
| at seeing intricate structures inside a galaxy that once
| appeared smooth. The JWST is truly a new era of exploring the
| early universe, but it might not have the same "wow" factor.
| thangalin wrote:
| Years ago, for my Impacts Project, a scientific illustrator
| created a similar image (page 7):
|
| https://impacts.to/downloads/lowres/impacts.pdf#page=7
|
| The middle of the disc has our star having burned away everything
| close by, leaving an empty area behind, which the JWST cannot
| show because of the blindingly bright star. Each of the rings in
| the illustration represents paths for our rocky planets (yet to
| have fully formed).
| joshmarinacci wrote:
| What is this project? It looks amazing. Will it be a printed
| book?
| isoprophlex wrote:
| Incredible, my kids will love this..! Thanks!
| thangalin wrote:
| Thanks! The illustrators did an incredible job and the
| physical book itself is in lay flat format.
|
| https://impacts.to/
|
| Here's the book's bibliography, in case you're wondering
| about the science:
|
| https://impacts.to/bibliography.pdf
| sph wrote:
| Care to name your illustrators? I love the work they have
| done.
|
| EDIT: nevermind, they are listed here:
| https://impacts.to/credit.html
| dekhn wrote:
| that's just stunning
| jp42 wrote:
| If JWST can do these amazing discoveries and detailed images, I
| wonder what kind of discoveries we make when starship can launch
| way bigger telescope than JWST. Future is Awesome!
| digging wrote:
| Manufacturing the JWST was already extremely challenging. Not
| saying we can't do bigger, but payload size isn't the only
| limiting factor.
| sebzim4500 wrote:
| Manufacturing the JWST would be a lot easier if it weren't
| for the mass/volume constraints.
| digging wrote:
| Perhaps, because of all the moving parts. How big is
| Starship though? I don't expect a telescope bigger than
| JWST could go up completely unfolded and expect to be
| perfectly resilient to launch forces. In addition, even if
| we had the option of a solid mirror, manufacturing such a
| massive mirror to perfect smoothness would be a feat.
| Piecemeal mirrors are probably easier in some ways because
| if one section is flawed, it can be replaced.
| Cthulhu_ wrote:
| Bigger is one option, but more of them is another; combining
| the data from multiple telescopes at, say, 10km apart
| effectively turns them into a telescope with a 10km diameter
| (see e.g. the event horizon telescope that made the first image
| of a black hole: https://eventhorizontelescope.org/ )
| rqtwteye wrote:
| You get the resolution but not the light capturing capability
| of a big telescope. The event horizon telescope had to do a
| lot of machine learning trickery to get an image. Also, as
| far I understand, it's much more difficult to do this at the
| wavelength of visible light.
| PopePompus wrote:
| The EHT has used machine learning techniques, but those
| were not required to get an image that shows the shadow of
| the black hole. Just using the "clean" algorithm for
| deconvolution yielded an image showing the shadow, and that
| algorithm has been in use for radio interferometry for over
| 40 years, and has nothing whatsoever to do with machine
| learning.
| rqtwteye wrote:
| I watched a presentation by a researcher that worked on
| the EHT. She pointed out that there was a lot of machine
| learning to rule out wrong pictures. It's not simple
| interferometry.
| isoprophlex wrote:
| Interesting comment below the linked article:
|
| > Lots of asymmetries involved. The star is off-center toward the
| lower right, same direction as the partial arc. The major ring
| could be elliptical, rather than circular. It also varies in
| brightness around the circumference.
|
| I'm a complete layman, but could this explain the high deviation
| from circular orbits of our own outer planets? IIRC this was
| something of an unexplained issue?
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