James Webb Space Telescope reveals Fomalhaut's disk in detail
skyandtelescope.org
skyandtelescope.org
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 )
Nah. It is comparing a distance with a distance.
Besides I assume more people reading my comment are familiar with the concepts of radius/diameter than the meaning of astronomical units. But now, thanks for your clarification, even the geometrically challenged will have the correct mental model. You never know.
> On the same scale, Pluto is 78 AU and Voyager is 320 AU.
Have to disagree. You take your pocket tape measure, carefully hook the end of the tape on the Sun and slowly walk to Pluto. You read what it says. That is a distance.
Then you walk to the disk, hook one end of the tape on one side (carefully, since it is made of dust) and walk to the other side. That is a distance.
Where do I hook my tape measure to measure 78 AU for Pluto? Orbits are not real. You cannot kick them, you cannot lick them, you cannot hook a tape measure on them.
“See where that planet is? Now imagine how far it will be in 124[1] years in a sun fixed coordinate system!” does not quite have the same impact on me as “See that blob? It is huuuge!”
Doubling the number with Voyager makes even less sense. You cannot even say that you are measuring the antipodal points of its orbit, since it is not orbiting the Sun. So the “diameter” of what are you even talking about there?
1: half of Pluto’s orbital period.
FTFA, quoted by you above: “The outer ring is about 240 astronomical units in diameter.”
Pluto’s orbit is 60-98 AU in diameter. Voyager 1, if it were orbiting the sun, would have an orbital diameter of 320 AU.
By that measure then, you carefully hook your tape measure to Fomalhaut and slowly walk out to the outer ring, whereupon your ancient eyes perceive the distance to be 120 AU, not 240 AU (since 240 AU is the diameter). A given rock in the outer ring is therefore less distant from Fomalhaut than Voyager is from the Sun.
That's all the parent is saying, and I agree with them - I, too, know the difference between radius and diameter but a quick read of your comment left me thinking that Fomalhaut's outer ring is orbiting further away from Fomalhaut than Voyager is from the Sun.
It's clearer to compare a radius to a radius, is all.
The OP wasn't comparing a diameter to a radius, he was comparing one line to another line: the diameter of the outer ring (line going from one end to the other passing through the middle) and the distance between Pluto and the Sun (line between two points). The fact that Pluto orbits the Sun is just a coincidence for the purposes of this comparison.
OP was mathematically correct, just a bit unclear. We really don't need to spend so much time on this.
(240 AU is 32 light hours)
Though out of fashion, the various power laws of Bragg, Richardson, Armellini building on the Titius–Bode rule come to mind, namely that there may be physical reasons to see orbital patterns emerge consistent with some sort of power law.
Below data includes candidate planets/disks still being verified.
Our Sun: - Mass 1 M - Inner Planets: 0.39 AU to 1.52 AU - Inner Disk (Asteroid Belt): 2.1-3.2 AU - Gas Giants: 5.2 AU to 30.06 AU - Outer Disk (Kuiper Belt): 30-55 AU
Formalhaut: - Mass: 1.92 M - Hot Disks: 0.21 AU to 1.08 AU - Inner Disk: Around 8-12 AU - Outer Disk: Previously around 133-158 AU but now suggesting around 120 AU? (Surrounded by a larger halo)
Vega - Mass: 2.135 M - Planet: 0.05 AU - Inner Disk: Around 8 AU - Outer Disk: Around 80-120 AU (Surrounded by a larger dust halo)
Epsilon Eridani: - Mass: 0.82 M - Inner Disk: Around 3 AU - Planet: 3.48 AU - Potential Additional Disk: Around 8-20 AU (and may revise inner disk & planet) - Planet: 40 AU - Outer Disk: Around 35-75 AU
Proxima Centauri - Mass: 0.1221 M - Planets: 0.03 - 0.05 AU - Hot Disk: 0.4 AU - Inner Disk: 1-4 AU - Planet: 1.5 AU - Outer Disk: 30 AU
HR 8799 - Mass: 1.43 M - Inner Disk: Less than 16 AU - Planets: 16.25 AU, 26.67 AU, 41.39 AU, 71.6 AU - Outer Disk: 135-360 AU
Beta Pictoris - Mass: 1.75 M - Planet: 2.7 AU - Inner Disk: 6.4 AU - Planet: 10 AU + Potential Planetary Belts: 14/16, 28/30, 52, 82 AU - Outer Disk: 130 AU (Surrounded by a larger disk/halo)
55 Cancri - Mass: 0.905 M - Planets: 0.01-0.7 AU - Speculated Planets: 0.9-3.8 AU - Planet: 5.9 AU - Disk: Around 40 AU (Would be interesting if a second disk around 4 AU)
Tau Ceti - Mass: 0.783 M - Planets: 0.1-1.334 AU - Planet: 3-20 AU - Disk: 35-50 AU (Would be interesting if a second disk around 3-5 AU)
I guess that's just one of those cosmic coincidences.
https://blogs.nasa.gov/webb/2023/03/24/how-webbs-coronagraph...
Silly me for believing NASA.
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.
When using a coronagraph, it's possible that that value is all over the place (diffraction around edges, noise, etc) but you know any data "under" the coronagraph is bogus and you know which pixels are covered, because you know how the device was made, so you can mark them as bogus yourself.
The actual value in the data isn't black (0,0,0), it'll be some obviously special value that won't otherwise happen, because black is a valid value.
I suppose the idea that not-misleading data trumps aesthetically-pleasing data continues then to the press release image, even though a solid white central spot would look more familiar to people who have accidentally included the sun in a photo.
>The 23.0 µm coronagraph of MIRI uses a classic Lyot mask to achieve high contrast imaging near bright sources. The mask is rather large, providing an inner working angle (IWA) of ∼ 3.3λ/D, i.e., ∼ 2. Our data is the first complete reference PSF subtracted set of observations taken with JWST using this mode.
There's some residual light and diffraction effects around the Lyot mask which they have manually deleted.
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
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).
Here's the book's bibliography, in case you're wondering about the science:
EDIT: nevermind, they are listed here: https://impacts.to/credit.html
(I'm at the University of Washington Department of Astronomy, and work on telescope software).
You don't service cubesats, you just learn from your past mistakes and launch more.
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.
SLS will be delivering segments of Gateway after the first 2 are delivered by Falcon Heavy.
Eventually someone with a brain is going to notice, SLS will be canceled, and decades of federal jail time will ensue for the criminals who perpetuated this fraud upon the American people.
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.
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.
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.
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.
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.
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.
that'll be initial cost submitted. once it is approved and work begins, that number will double, triple, or more before it is completed.
It’s amazing how wrong facts are asserted with absolute certainty here on HN.
That was what you responded to. Since when the upper stage is the payload? Which facts are you asserting?
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.
https://www.quora.com/Is-the-L2-point-of-Earth-in-a-permanen...
Putting it at L2 gives a more consistent thermal environment and means it doesn't have to repoint as often, but doesn't really make it any cooler. (After all, it's just barely past the Earth) At equilibrium the hot side of the Webb is around 300K. (80F)
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.
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.
> 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
That is a hilarious statement.
https://www.usaspending.gov/agency/national-aeronautics-and-...
Pretty sure there is no space organization which comes close.
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.
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.
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.
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%.
Awfully coincidental it happens to cost just slightly less than than the competitors.
No, that's just you stupidly confusing price and cost.
There is downward pressure, we're just hitting physical limits on what can be done with chemical rockets.
The mere existence of the Starship design, which doesn't break any physical laws, shows your claim is nonsense.
Obviously wrong how? I saw that Musk was claiming that launch costs for starship will be around $1-2 million at some point - probably after hyperloop launches as a "5th mode of transport" in Neverland.
Orbital dockyards and asteroid mining would be in reach if Starship delivers on its (admittedly pretty steep) promises.
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?
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:
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.
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?
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.
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.
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).
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.
A problem with this idea was that this part of space looked vacant, so it seemed unlikely that two objects had managed to crash into each other. The team’s discovery of the intermediate debris belt has now proffered a solution.
“We now know there’s stuff there,” Dr. Christiansen of the NASA archive said. “OK, so it’s a collision — we can finally put that to bed.”
Cataclysmic melees are not just transpiring close to the star. What looks like a vast maelstrom of dust within the outer belt may be the ghost of another gargantuan impact.
“That’s just cool,” Dr. Christensen said. “What is it? It’s very tantalizing.”
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...
> 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?
Nope, just something behind the ring.
Here's a famous system: https://en.wikipedia.org/wiki/HR_8799
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]
But yeh, if I weren't a nitwit, the scale's completely wrong (and it should be hoovering up the ring in short order besides).
Hubble: https://en.wikipedia.org/wiki/File:NASA%27s_Hubble_Reveals_R...
Edit: the above quote is from NASB Proverbs 30:20.
This is the way of an adulterous woman: She eats and wipes her mouth, And says, “I have done no wrong.”