Comments by "H. de Jong" (@h.dejong2531) on "James Webb Just Turned On Its Camera To Look At Its First Target" video.

  1. not quite. They moved the mirrors all the way to an end stop, in a position where the mirrors are supported. This helps prevent damage during launch. After launch, they had to move the mirrors about 12 mm from their end stops to get to their operational location.
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  2. it's too warm to reach its final performance, but this early work can be done at a higher temperature.
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  3. The telescope isn't run by the government, but by a university. Astronomers from all over the world can request observations. The whole process is far too public to hide anything.
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  4. A telescope more advanced than this one will have to be invented and developed first. JWST is the state of the art at the moment.
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  5. You're assuming nobody is working on that? Or that the JWST team is the only group capable of doing anything about our climate crisis?
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  6. What military uses would there be for a telescope that cannot look at Earth?
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  7. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  8. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  9. Most of that is done passively: anything in space that's not in direct sunlight, will radiate heat with very little resistance. If you take care to block incoming sunlight, this will get you close to 30K.
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  10.  @s.muller8688  it's true. Only one instrument (MIRI) has an active cooling system: MIRI will be cooled down to 6 K. The other instruments and the mirrors rely on the sunshade only.
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  11. There were a few requirements for the star used for calibration:   1. the star must be isolated, with no bright stars nearby.   2. the star must be visible from JWST's position (it can see only 30% of the sky at any given time).   3. the star must not be too bright. Interesting targets will be looked at later, when calibration is complete.
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  12. NIRCam has been switched on, it's being used to align the mirrors. So it's taking pictures, just not scientifically usable ones.
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  13. There were a few requirements for the star used for calibration:  1. the star must be isolated, with no bright stars nearby.  2. the star must be visible from JWST's position (it can see only 30% of the sky at any given time).  3. the star must not be too bright.
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  14.  @merkridge8780  Those are reasons, not excuses.
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  15.  @merkridge8780  You've clearly never been involved in a complex project. Every complex machine requires commissioning; even at a much simpler level than JWST it can take months to commission a machine. The JWST team has spent years retiring every possible risk. But there are things you can't do before launching the telescope into orbit, and one of those tasks is aligning the mirrors. This will take time. Those are just the facts of life.
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  16.  @merkridge8780  I'm saying (again) they are not excuses, they are reasons. You should read up on the difference between the two.
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  17. They really do have cameras: 3 of the 4 instruments are imaging devices. They may not be visible-light cameras, but they are cameras.
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  18.  @phillipbrown2896  He's right in that the images won't look like Hubble's. They're closer to the thermal imaging systems we use on Earth: these use colors to indicate temperature. There are a few different ways to map IR images to visible-light images, depending on what information you want to emphasize. These are the JWST instruments: Near-Infrared Camera, or NIRCam. Near-Infrared Spectrograph, or NIRSpec. Mid-Infrared Instrument, or MIRI, a combination camera and spectrograph Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph , or FGS/NIRISS, a combination camera and spectrograph
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  19. The calibration images will be released when calibration has finished.
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  20. try this one about MIRI: https://www.youtube.com/watch?v=3_JhKI6Z7CI
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  21. Better video: https://youtu.be/AOI4vDWsRhE?t=2364
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  22. JWST does carry cameras. These are the 4 instruments on JWST: Near-Infrared Camera, or NIRCam. Near-Infrared Spectrograph, or NIRSpec. Mid-Infrared Instrument, or MIRI, a combination camera and spectrograph Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph , or FGS/NIRISS, a combination camera and spectrograph.
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  23. Ground-based systems can't observe at all at the wavelengths JWST is designed for: our atmosphere absorbs these wavelengths.
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  24. Every photo that's not done using photosensitive film is 'created by a computer'. That doesn't make those photos any less real.
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  25. JWST's resolution is too low to see the moon lander, let alone the flag. To resolve the lander from Earth, you need an optical telescope with a diameter of about 50 meters; JWST is further from the Moon than we are. However, the Lunar Reconnaissance Orbiter photographed the Apollo landing sites: https://www.youtube.com/watch?v=Pnhnx95LkCc
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  26. The calibration images haven't been published yet. I suspect they want to wait until calibration has finished, to prevent people coming to the wrong conclusions.
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  27. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  28. Anyone interested in the actual images can see them here: https://www.youtube.com/watch?v=QlwatKpla8s
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  29. There were a few requirements for the star used for calibration: 1. the star must be isolated, with no bright stars nearby. 2. the star must be visible from JWST's position (it can see only 30% of the sky at any given time). 3. the star must not be too bright.
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  30. Photos of the ISS usually show the ISS in bright sunlight. The exposure time is far too short to show stars.
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  31. The only editing they'll do is the 1:1 mapping of infrared wavelengths to visible-light colors (which you need for images to be viewable at all).
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  32. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  33. we're not looking at the point where the Big Bang occurred. We're looking at stars 13.5 bn lightyears away, so we can see them as they were 13.5 bn years ago.
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  34. Nope, real mission and real data.
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  35. You never know. Several imaging techniques developed by NASA for space telescopes have found their way into medical imaging devices (X-ray, MRI, CT, etc).
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  36. JWST does have cameras. 3 of the 4 instruments are imaging systems.
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  37. The title is correct though: NIRCam has been switched on, it's being used to align the mirrors.
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  38. The electronics are powered by a solar panel on the sun-facing side of the spacecraft. You're right, heat from the electronics is a potential problem, so the spacecraft had to be designed to efficiently remove heat, and to insulate the instruments from the computers.
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  39. No, it's not broken. JWST was designed so that the mirrors would have to be aligned after launch. This was inevitable for several reasons: 1. the size of the telescope meant it had to be folded 2. the telescope had to be launched at room temperature, but is designed to work at ~30K. This means the telescope will shrink after launch.
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  40. Real images. JWST has 3 infrared cameras, so they'll have to do some mapping of IR wavelengths to visible colors to produce visible-light images.
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  41. That's a load of nonsense. We have known Earth is a sphere for 2200 years. The only conspiracy is the one that started the 'flat Earth' meme. There is no evidence that Earth is flat. On the contrary, all our observations indicate Earth is a sphere. You can measure this yourself using simple surveying equipment. We have a horizon. When you get farther away from an object, it will disappear below the horizon. This is correctly predicted by the 'Earth is a sphere' hypothesis, and it disproves the 'Earth is flat' hypothesis. The 'Earth is flat' hypothesis is full of holes and cannot be maintained by anyone who applies scientific rigor and logic.
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  42. Status page: https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
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  43.  @gedstrom  There's also a blog (search for NASA JWST blog), YT won't let me paste that link here...
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  44. nope. Lots of real images.
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  45. None of the images in the video have been made by JWST. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  46. Space around Earth isn't really cold though. Every m^2 of space around us receives more sunlight than we get on the hottest day of the year.
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  47. In order to calibrate, one of the instruments has to be used. So the title is correct: the first images have been taken.
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  48. First, you need to ask yourself what kind of resolution you need to take an image of an entire hemisphere (12,000 km diameter) and be able to zoom in to where you can see people (1.5 m). That's 8 million pixels for 12,000 km. How many cameras do you know that have a resolution of 64 terapixels? That's right, none. So with current technology, you can't zoom in from an entire hemisphere to a single human. Not that a 64 Tpx image would convince you, you'd just move the goalposts again. So instead of making impossible demands, how about we examine your beliefs instead? On a flat Earth, there would be no horizon. That fact alone shows Earth can't be flat. Here are a few other bits of evidence that show Earth cannot possibly be flat: https://www.youtube.com/watch?v=o_W280R_Jt8 and https://www.youtube.com/watch?v=pL1b9khYH5Y Getting back io imaging Earth, we have geostationary weather satellites that take images of the entire hemisphere every 10 minutes, see for example https://youtu.be/zoMRwyNhqJ4 And a few more: Earth from space: https://www.youtube.com/watch?v=JVBlQ31FzJU and Earth from the moon: https://www.youtube.com/watch?v=iTNTfSxP0HQ and images of Earth, incl Moon and Earth in one shot: https://www.youtube.com/watch?v=xPM2kITNtTs
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  49. Hubble orbits Earth in about 2 hours, so it has to be rotated to keep the object in view, that's done by reaction wheels. The motion of Earth around the Sun is slower, but can also be compensated for by reaction wheels.
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  50. Yes. They have started taking images for mirror calibration this week.
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  51. JWST will observe at wavelengths where SOFIA does not work, because the water vapor in the atmosphere absorbs most infrared light. SOFIA's resolution is also a lot lower than JWST's, and JWST can observe 24/7 while SOFIA rarely manages to make more than one 8-hour flight a month.
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  52. Asteroids are rare enough that the chance of that happening is astronomically low (10^-9).
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  53. They don't use active cooling for the mirrors: they're relying on heat radiation. That's part of why it takes so long to cool down.
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  54. They've started calibrating the mirrors this week.
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  55. 'Sun-like' means it has a similar mass and composition as the Sun. Stars that are much larger or smaller behave differently.
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  56.  @coffeeisgood576  Have a look at this: https://www.youtube.com/watch?v=_RIYnXMJ0hI "sun-like star" is shorthand, astronomers have a more exact method of classifying stars. Our sun is a G2-class star.
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  57.  @coffeeisgood576  I know. When an astronomer uses the word 'sun-like', he is talking about a G-class star.
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  58. no, that hasn't been published yet.
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  59. You want the timing to be accurate, because when one mirror is out of phase with another, the signal from those 2 mirrors would cancel each other out.
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  60. it hasn't been released yet.
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  61. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  62. JWST will start doing science in 6 months. Mirror calibration and cooldown will take until then. All JWST images will be published.
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  63. the raw data from all of JWST's instruments will be published. Many of JWST's images will be of objects we've imaged before, which provides a way to check the JWST data. Any astronomer can apply for observation time on JWST.
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  64.  @kevin-ng8md  There are good reasons photos of Earth look different. The Earthrise photo taken by Apollo 8 was done with a consumer camera. This is a pretty good match to what the naked eye would see. Many modern whole-hemisphere photos are made by weather satellites. These are not built to match naked-eye images: the latest weather satellites (GOES-R) have a camera that records in 16 bands across the visible and IR spectrum. It has red and blue filters, but no green, so the visible-light images made by these satellites look different to what you're used to. For details on this camera, see https://www.youtube.com/watch?v=n_S8d_1KVhU
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  65. ​ @kevin-ng8md  As for recreating a globe map: It's impossible to create an accurate representation of a 3D object (like a globe) in 2D. There are lots of different ways to map the 3D object to a 2D object (these are called map projections), each projection has its own errors, see https://www.youtube.com/watch?v=kIID5FDi2JQ
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  66.  @kevin-ng8md  The early origins of the universe and the Big Bang are derived from data from all kinds of instruments, most of which are not operated by NASA. Some of these observations were done long before NASA was even established: the fact that most galaxies are moving away from us was established in 1910. This was measured using ground-based telescopes around the world.
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  67.  @kevin-ng8md  There are a few exceptions: the Andromeda galaxy is moving towards us, for example. A few thousand galaxies are moving towards us, the rest (billions) are moving away from us.
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  68.  @kevin-ng8md  The pyramids don't seem to be lined up to any stars. sunset on the winter solstice falls above the Pyramid of Menkaure as seen from the Great Sphinx of Giza. And the corners of the Great Pyramid of Giza also align well with the cardinal directions — north, south, east, and west. But no alignment to stars has been found, even when we calculate where the stars were at the time the pyramids were built.
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  69. JWST won't be at the edge of the galaxy, it is at the Sun-Earth L2 point, which is 1.5 million km away from Earth. It arrived at this destination a few weeks ago.
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  70. The astronomy community has already proposed a successor (LUVOIR), this will be another flagship project that will take 20 years to develop and build.
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  71. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  72. The benefit is that we'll find out more about how the universe works, how it came to be and if we're alone.
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  73. First science operations are in June, they're using one of the science instruments to adjust the mirrors.
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  74. You can see JWST through a telescope and verify that it is indeed orbiting L2. During the Apollo program, amateurs saw the Apollo spacecraft through their telescopes and verified that they were orbiting the Moon. If your username is 'Truth matter', why do you believe in claims for which there is no evidence?
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  75.  @truthmatters5536  Why can't we see the Apollo landers on the moon from Earth: https://www.youtube.com/watch?v=A2FnbzR2ox8 to summarize: it's a lot easier to see a spacecraft against the black background of space than against the bright background of the Moon. This is basic physics.
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  76. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  77. no. It was launched on December 25. They're adjusting the mirrors now.
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  78. When you have to align 18 mirrors to be in sync to within a few nanometers, the process is inevitably going to take time. Cooling down the mirrors and instruments is also a slow process, because it's mostly done passively.
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  79.  @manoo422  And your expertise in aligning mirrors to a precision of less than 1 wavelength of IR light is what, exactly?
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  80. No, they are positioning the mirrors at the moment. Science observations will start in June.
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  81. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  82. Real images of Earth coming up: we have geostationary weather satellites that take images of the entire hemisphere every 10 minutes, see for example https://youtu.be/zoMRwyNhqJ4 And a few more: Earth from space: https://www.youtube.com/watch?v=JVBlQ31FzJU and Earth from the moon: https://www.youtube.com/watch?v=iTNTfSxP0HQ and images of Earth, incl Moon and Earth in one shot: https://www.youtube.com/watch?v=xPM2kITNtTs
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  83. it takes 6-7 seconds, communication is done via radio.
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  84. Images will be published in a few days.
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  85. Images are here: https://www.youtube.com/watch?v=QlwatKpla8s
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  86. The first camera has been started up already, they are using it to position the mirrors. Science observations will start in June.
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  87. they have started taking images for mirror calibration this week.
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  88. Taking images is part of the mirror alignment process, so yes, the first images have been taken. They'll be a blurry mess so they aren't being published yet.
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  89. Yes, at least if they're not too far away. But they'll only be visible as a single pixel.
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  90.  @johnc735  yep. Even that will be an advance on what we have now: even the largest telescopes we have can only see a small number of exoplanets directly. Most of the exoplanets we've discovered have been found through indirect methods (when the planet passes in front of its star, we can measure the difference in brightness of the star), we've never seen them.
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  91. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  92. ​ @ottom.3094  You haven't looked at a Hebrew dictionary then. Nasa: A primitive root; , in a great variety of applications, literally and figuratively, absolutely and relatively: – accept, advance, arise, (able to, [armour], suffer to) bear (-er, up), bring (forth), burn, carry (away), cast, contain, desire, ease, exact, exalt (self), extol, fetch, forgive, furnish, further, give, go on, help, high, hold up, honourable (+ man), lade, lay, lift (self) up, lofty, marry, magnify, X needs, obtain, pardon, raise (up), receive, regard, respect, set (up), spare, stir up, + swear, take (away, up), X utterly, wear, yield.
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  93.  @ottom.3094  Look up at the sky tonight. You can see satellites passing overhead. There are about 4000 operational satellites, which supply us with data that are impossible to fake.
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  94.  @ottom.3094  Of course there are interruptions and signal loss. The people who notice that are the satellite's operators, not the general public (with a few exceptions, like TV broadcast satellites). Space junk is a problem, and satellites have to be built to keep working despite the occasional hit. Most of the debris is microscopic; a Whipple shield offers good protection against that. Large pieces of space junk and large near-Earth asteroids are tracked, and satellites sometimes have to maneuver to avoid a collision.
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  95. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  96. Try this video: How JWST orbits the L2 point: https://www.youtube.com/watch?v=ybn8-_QV8Tg
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  97. JWST did receive first light this week, according to the NASA JWST blog. They've started calibrating the mirrors.
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  98. The first calibration images haven't been released yet.
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  99. They have started taking images for mirror calibration this week. Science-quality images will take a while, yes.
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  100. nope. All images will be released. Any astronomer can request observations, the list of observations is public, and all images are stored on a public website.
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  101. It won't be operational for another 5+ months, but they have started taking images for mirror calibration this week.
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  102. The first camera has been started up already, they are using it to position the mirrors. Science observations will start in June.
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  103. It's pointless to aim JWST at Earth: Earth's atmosphere absorbs the infrared wavelengths that JWST observes at. So you get a view of the water vapor in the atmosphere, like this: https://www.youtube.com/watch?v=g0dIpgqPOcw
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  104. JWST will start doing science in 6 months. They have started taking images for mirror calibration this week.
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  105. JWST downlink speed is 3.5 Mbit/s. Images will be downloaded in batches, on the same day they were made.
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  106. We're spending far more on fixing hunger than this telescope has cost.
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  107. It is correct though: NIRCam has been switched on. It's being used to calibrate the mirrors.
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