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STS-67 ASTRO-2 UV observatory
When I try to explain the Big Bang Theory to my granddaughter, I start with Edwin Hubble’s discovery that the universe was expanding. If it is expanding now, then in the past the universe had to have been smaller, denser and hotter. The start of the expansion is what we now call the Big Bang. If there was a Big Bang, there would be left over cosmic background radiation. For that, I’ll show her a paper model of the COBE space telescope by John J available on jleslie48.com/gallery_models.html. When it comes to evidence of primordial helium, I couldn’t find a paper model of the ASTRO-2 UV observatory that was on the STS-67 mission. Therefore, I decided to design and build a model of the UV telescope that could fit into AXM’s 1:144 scale or Fortezza’s 1:100 scale model of the space shuttle Endeavour.
The UV observatory would include the pallet and associated Igloo (power supply for instrument on the pallet), the Instrument Pointing System (IPS), the Hopkins Ultraviolet Telescope (HUT), the Wisconsin Ultraviolet Polarimeter Photometer (WUPPE), the Ultraviolet Imaging Telescope (UIT), the star tracker, the Optical Sensor Package (OPS), and Integrated Radiator System (IRS). To complete the payload visible in the space shuttle cargo bay, the model will also include the Extended Duration Orbiter (EDO) pallet as well as 2 Get Away Special or Hitchhiker Program (GAS) canisters. I started with the HUT to see if it was possible to build the spectroscope, shutter doors, and other details inside the telescope. I am pleased to report that it can be done. Next, I will try to build the WUPPE. |
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#2
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Nice start to your model and I (and I am sure others) like all the explanation. Looking forward to seeing more of the model and learning more about the telescope.
Regards Kevin
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Normally the most advanced tech I use is a pencil. |
#3
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Wow, Henry. From jet airliners to these teeny scale models that's quite a shift. Sounds, and looks, fascinating.
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This is a great hobby for the retiree - interesting, time-consuming, rewarding - and about as inexpensive a hobby as you can find. Shamelessly stolen from a post by rockpaperscissor |
#4
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Hi Elliot,
There are similarities between the two. Notice that I used a “handhold” (part 30) to guide the primary mirror into position within the telescope tube, the same way I maneuver formers into place inside aircraft fuselages. I forgot to mention that of the 3 UV telescopes, the HUT (Hopkins Ultraviolet Telescope) was designed to measure primordial helium or intergalactic medium (IGM) which the Hubble telescope could detect but not measure. The WUPPE (Wisconsin Ultraviolet Polarimeter Photometer) was designed to measure the polarization of ultraviolet light in bright stars and extended nebulas that are difficult or impossible targets for Hubble. The UIT (UV Imaging Telescope) had a much wider field of view than the Hubble and was used to survey the UV populations of entire galaxies or star clusters. The WUPPE was a Cassegrain design whereas the HUT and UIT were Ritchey–Chrétien designs, same as the Hubble telescope. Both designs have a secondary mirror that reflects light from the primary back down through a hole in the primary mirror to the focal point behind the primary mirror. Now that I have to do my own design work, I couldn’t help but wonder about a small part attached to the primary mirror. Was this part unique to UV telescopes? The part in question turned out to be a light baffle around the hole in the primary mirror. More questions revealed that the Hubble telescope had one too. Even though I had built the paper model of the Hubble telescope available from HubbleSite - Hand-held Hubble - Paper Model, expert, I didn’t remember building a light baffle in front of the primary mirror. Fortunately, Ton Noteboom designed the Hubble paper model so the interior telescope could be slid out of the exterior shroud. Sure enough, there was a primary baffle that I had forgotten. And there was also a baffle around the secondary mirror, which I did not recognize when I built the model. Which raised yet another question. Did either the HUT, WUPPE or the UIT have a secondary baffle? From the drawings that were available on the internet, it does not appear so. Next, the UIT, star tracker, the cruciform, IRS and OSP Last edited by hjlyuen; 02-22-2018 at 05:07 PM. Reason: forgot something |
#5
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it's a good project !
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#6
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I forgot to attach the patterns for the HUT and WUPPE. The patterns are in 1-144 scale so the finished model can fit into AXM’s model of the Endeavour. It may look like a lot of wasted space but the extra wide margins allow the patterns to be resized 144% so it can fit into Fortezza's 1:100 scale model and even 200% for 1:72 scale models.
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#7
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Thanks a bunch
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#8
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The light baffles had me intrigued. Then I remembered I used to have a 500 mm catadioptrictelephoto lens, which is basically a Cassegrain design. After some searching, I found the lens and peered into the tube with the help of a flash light. Sure enough, there were both a primary and a secondary light baffle, now that I know what to look for. And therefore in commemoration of this moment of discovery, my UIT model will have both a primary and secondary light baffle as shown in the drawings that I found on the internet. Actually, part 42 in the model is, from front to rear, a stack up of an image stabilizer, secondary mirror, and light baffle. On the HUT, there is a spectroscope instead of an image stabilizer. Honestly, no one will ever see any of this because the telescope tubes are so small and everything inside is black.
Meanwhile, there is part 61. It is very reflective, mounted on the outside of the UIT sunshade, to the left of the single head star tracker. I cannot find any information on its name or its function. Apparently, there are two star tracking systems on ASTRO-1 and 2. The space shuttle can maneuver so that the telescope is pointing within a couple of degrees from the target. The one with 3 heads (OSP or Optical Sensor Package) mounted on top of the IRS (Integrated Radiator System) then takes over and sends data to the ISP (Instrument Pointing System) which in turn makes small movements to keep the telescopes with +/- 1.2 arc seconds of the target. The other one with a single head and looks like a long tube mounted on the side of the UIT is used by the image stabilizer mention above. Finally, the UIT is a little different from the HUT and WUPPE in that the drawings appear to show 4 instead of 3 vanes on the secondary mirror and the main light baffle appears not to have any supporting vanes. Next: the co-axial mount with all 3 telescopes, the Optical Sensor Package and Integrated Radiator System, followed by the Instrument Pointing System, and pallet. |
#9
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The 3 UV telescopes and the co-axial mount is finally done along with the Optical Sensor Package and Integrated Radiator System. Next is the Instrument Pointing System which is going to be challenge to build as it is basically a lattice of small diameter tubes which I will have to roll by hand.
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#10
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Nice detailed work, can't wait to grab the rest of
parts to complete the model. |
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