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Space

Getting Into Space, One Way Or Another 117

Posted by timothy
from the different-folks-different-strokes dept.
EccentricAnomaly writes: "David Cash has some interesting pictures of the International Space Station made with a Celestron telescope and webcam. This makes me want to get back into amateur astronomy ... in part, as a fun way to learn image processing." The resolution Cash achieved with consumer-grade equipment (Celestron Ultima 9.25 telescope and Philips Vesta Pro camera) is amazing. Demanding a slightly more visceral approach to space is "Rocket Guy" Brian Walker, who plans in the near future to launch himself to around 30 miles up in a home-brewed rocket. An unnamed reader points out the current feature on Walker over at space.com.
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Getting Into Space, One Way Or Another

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  • Futher proof people from oregon are a tad crazy :-)

    But seriously, I hope he pulls this off. I'll laugh my ass off seeing a man make a rocket with his own cash, blast himself into space and LIVE for fraction of what it would cost NASA to do the same.

    -Henry
  • by torpor (458) <jayv&synth,net> on Monday June 11, 2001 @04:06PM (#159343) Homepage Journal
    It would indeed be an incredible feat.

    Not to mention the possibility that, having successfully pulled it off, he gets swamped with cash from other space investors who want him to build private rockets just like this for those crazy enough to follow in his footsteps.

    If he pulls it off, it's the beginning of a new space race, mark my words. The 'racetrack' this time: our own backyards...

    I hope he makes it. I really, really hope he does.
  • by Moonshadow (84117) on Monday June 11, 2001 @04:08PM (#159344) Homepage
    Demanding a slightly more visceral approach to space is "Rocket Guy" Brian Walker, who plans in the near future to launch himself to around 30 miles up in a home-brewed rocket.

    All I can think is that this guy is setting himself up the bomb...

    Slashdot's getting to me.
  • by OverCode@work (196386) <overcode@gmai l . com> on Monday June 11, 2001 @04:09PM (#159345) Homepage
    My dad has gotten into this lately (using the same webcam -- the Vesta Pro is known for this). It's really fun to watch him do create his images -- he points the telescope and camera at the object, takes about 100 frames of video with the webcam, and brings the computer back inside to process the frames. He has a simple algorithm for selecting the clearest images, and he integrates the best frames into a single image with various software.

    Here's a link to his site. [hyperusa.com]

    -John

  • the faa will never let him do it.

    i hope he, in the true spirit of Amercia, does it anyway.
  • by PD (9577) <slashdotlinux@pdrap.org> on Monday June 11, 2001 @04:12PM (#159347) Homepage Journal
    I'm glad he redesigned his rocket. His old design was unstable and would have killed him. He was relying on the same thing that Goddard used in 1924 on the first liquid fuel rocket: put the nozzle at the top. Problem is, if your design isn't stable, it won't matter where the thrust comes from. Unstable rockets tumble, unless they have thrust vectoring and active stabilization.

  • by DragonPup (302885) on Monday June 11, 2001 @04:13PM (#159348)
    well, as he said in the article, if the FAA doesn't let him, he'll haul himself and the rocket south of the border to Mexico. Heh, then Mexico will have it's own space program! :-)

    -Henry
  • I always wanted a nice telescope when I was a kid, I grew up in western South Dakota, where you can get away from everything putting out light about five minutes from home.

    So how much for a good telescope and the gear to hook it up to a computer? I have two Mac laptops (iBook 2000 and G4 Titanium) so Mac solutions would be best.
  • by Tairan (167707) on Monday June 11, 2001 @04:18PM (#159350) Homepage
    Looks like the site is going down quick. There's a lot of images there! I set up a mirror over at my website [johncglass.com]

  • Wan Hu [nasa.gov] - medieval chinese rocket scientist (who may not have been exactly a rocket scientist).

    Hmm, or maybe that was Larry Walters [darwinawards.com].
    --
  • by briggsb (217215) on Monday June 11, 2001 @04:19PM (#159352)
    Why bother taking pictures of space, or trying to rocket into space? I prefer creating rifts in the space-time continuum [bbspot.com]. That's much more fun.
  • What you mean "let," white man?

    The FAA can pull his (probably nonexistant) pilot's license. The local (launch area) cops can ticket him for violating their noise ordnance. The local (impact area) cops can ticket him for littering. Unless the craft is controlled by the passenger, it isn't piloted, is it? Just a big-ass Estes going downrange.

  • Who wants to start the betting pool?
  • by ghostlibrary (450718) on Monday June 11, 2001 @04:27PM (#159355) Homepage Journal
    A Celestron "Celestar 8" with fork mount and computer s/w to help with tracking starts at around $1100. Figure $1500 to get the telescope, a good eyepiece, and software. The 9 1-4 (used in the article) is around $1500, again add a few hundred for an excellent eyepiece and for software and you still come in around $2000.

    The author just used a pretty standard webcam, so we're talking $100 here, plus $50 in mounting gear. Note that if you mount the camera in place of the eyepiece, you can skip my recommendation of getting a really good eyepiece and let the camera serve.

    You can also use any 35mm camera with a telescope, using a simple t-adapter ($40) to attach it. If you spend, oh, $500 you could get a digital SLR and then have fun using that.

    But ultimately, I say go with a C-8 and good webcam and do it for under $2000. I like the C-8s because they are highly portable, easy to set up, and fun!

    Pick up an issue of "Sky and Telescope" for prices before you start shopping, of course.

  • Unless Demon Internet have changed their policy, they shunt off any users website that gets too much traffic onto a "high-use" server which runs on a smaller pipe.

    Of course it doesn't help when there's several animated gifs on an image-laden page.

    Get those mirrors up quick...
    --
  • I'm floored by the webcam footage. It still looks like Zapruder was running the cam, but when you consider the range (I KNOW he used a telescope, okay?) it's damn impressive.

    I've got a Logitech and an IBM-the damn thing looks like a miniatire of one of their PS2s, and the image quality in my living room isn't much better. He did good work.

  • You forgot "Oh, and avoid Meade like the plague. It's the Packard Bell of telescopes!"

    FP
  • These pictures are also pretty durn cool. I esp. like the Jupiter and Saturn pictures.

    But, I wonder... can anyone tell me what this "stacking" process is?

  • Yes, it'd be all together too sensible for the Slashdot crew to implement a semi-mirror system, in which the text for the website comes from the original source, but where the images are drawn from a Slashdot cache.

    It's just cruel and abusive to subject someone's little ISP/account to the teeming hordes. More often than not, I'll wager, it causes overwhelming surcharges to the poor sucker who gets the attention.

    I'd *never* want a site of my own to come under the Slashdot gun. It'd just cost way the hell too much.


    --
  • by tedtimmons (97599) on Monday June 11, 2001 @04:38PM (#159361) Homepage
    Here's my mirror of that site, on a fairly large connection:

    http://www.perljam.net/misc/iss/www.djcash.demon.c o.uk/astro/webcam/webcam.htm [perljam.net]

    -ted

  • by egomaniac (105476) on Monday June 11, 2001 @04:46PM (#159362) Homepage
    Did you guys catch that the ISS was tracked *by hand*? Admittedly, only about twenty frames out of a 50MB AVI actually included the ISS, but hey that's still pretty amazing.

    It can be tough enough (as an amateur, at least) to find and track a planet when you already know its precise coordinates. Finding the ISS by hand, I'd imagine, takes some impressive cojones.
  • by technos (73414) on Monday June 11, 2001 @04:46PM (#159363) Homepage Journal
    You take ten or twenty pictures right in a row, assign them all a translucency value (20 images, each is only 5% opaque) and stick them on top of each other, lining up some specific feature or by simple edge detection. Minimizes atmospheric effects and effects from the CCD camera.
  • by small_dick (127697) on Monday June 11, 2001 @04:48PM (#159364)
    Proving once again that a single man, with guts, can make a huge impact on the earth.


    Treatment, not tyranny. End the drug war and free our American POWs.
  • Proving once again that a single man, with guts, can make a huge impact on the earth.

    Or, also likely, that one man with a large hunk of mass (such as a rocket) can make a huge impact into the Earth.

  • Of course, The site is still perfectly functional....
    ---------------------------------- --
  • sigh...

    That goes into copyright issues, as well as a pile of stuff such as how is space.com going to pay for the bandwidth they do use when slashdot robs their content and doesn't put up the ads.

    Besides, /. is slow enough when it's just serving text and a few tiny images. You might slashdot slashdot if you throw a pile of images into the mix.

    You can always host your pictures on geocities and move the blame from you to them...

    -------

  • by Anonymous Coward
    I don't know where you get your information, I'd much rather have the higher accuracy and stability of the Meade LX200 series than any Celestron, even an Ultima. Of course, if you were really serious you might research the hobby a little more. Assuming you want to take photos of more than the ISS, you'd get much better resolution and contrast with a field flattened refractor, or even a long focal length newtonian on a stable tripod/pier.
  • Yep. We left europe, asia, and africa to get away from the likes of you, and crossing an ocean just want far enough. You followed us. Now we'll try agan.
  • by John Carmack (101025) on Monday June 11, 2001 @05:14PM (#159370)
    The FAA regs (FAR 101) used for model/high power rocketry specifically refer to "unmanned rockets", not "unpiloted rockets", so it isn't at all clear how something like this is regulated.

    I have sent a query to the FAA about getting waivers for the manned rockets my team is working on, but it got booted up to Washington a couple weeks ago, and I haven't heard back yet.

    John Carmack

  • What I find more problematic is his use of fiberglass as his general building material (capsule, etc.). I am pretty sure the epoxy will catch fire from the air resistance, if nothing else. Also, that peroxide fuel he's using decomposes into hot steam and oxygen. This is better than outright burning fuel, but it still could have pretty nasty effects on the engine and nozzles (high speed corrosion, etc.), if they not made of the right materials...

    I do hope he has considered and dealt with these sorts of nit-picky issues. An close-to-full-scale engine test, at least, might be a good idea.
    --

  • Try one of these...

    http://www.globaldialog.com/~obsessiontscp/OBHP. ht ml

    That thing would make a great lawn ornament, dont you think? Right alongside the pink flamingos.

    McDoobie
  • There are two major problems amateur astronomers have to deal with: sensitivity and atmospheric turbulence.

    Often the objects an astronomer is trying to photograph are very faint, and they might not reliably register on the CCD. Stacking up (adding together) a bunch of image frames allows even the faintest readings to show up.

    The other problem is turbulence. Temperature differentials in the atmosphere can cause optical distortion. By taking hundreds of frames of the same object, you have the luxury of selecting the least distorted frames for processing.

    Basically, integration/stacking lets you extract as much detail as possible out of a large set of imperfect images.

    -John
  • Thanks for the info. I've spent about all I can spend on TVs and computers...so why not spend money on something new ;)

    Oh...Mod me down, I'm offttopic :).
  • No, we're trying to get still farther from Europe, since we met you coming the other way 'round. (Australia).
  • And as you'd expect you can get much better images of satellites if you use computer-guided tracking. See for example these images. [meridiancontrols.com]

    Pretty impressive stuff being done with off-the-shelf equipement these days.

    --Seen

  • by thogard (43403)
    FAA doesn't own the airspace. They are only involvoed with civil aviaion and rockets don't fit that. FAA is also not required to be involved with military or police or state activites. Your situation is that there will be lots of people with no authority to say no that won't say yes. Groups that could approve it are the DOD, NASA, USAF, secret three letter types, FAA, the state aviaion board, the state police. If any of those approve it, the others don't have any grounds to disapprove it. Your best bet is ask for some SBIR money from NASA.
  • Hmmmm. 3 degrees absolute, near-complete vacuum, hella long walk to the corner pharmacy......or Los Angeles and New York City.

    It's a no-brainer!

    --
  • by 6EQUJ5 (446008) on Monday June 11, 2001 @05:47PM (#159379) Homepage

    "... goes to -- Brian 'Rocket Guy' Walker!"

    Maybe David Cash can capture the Kodak moment when Brian goes up on Challenger Two.
  • "Never seen a red flapjack before."
    --Gimlet the Dwarf.

    --
  • Is this about Timothy McVeigh?

  • by RennieScum (118197) on Monday June 11, 2001 @06:07PM (#159382) Homepage
    Walker knew he wanted to go into space; he also knew he didn't have the "right stuff." No one with dyslexia and attention deficit disorder gets picked to be an astronaut.

    So should he be building rockets then?!?

  • Do you have any idea what kind of lift capacity this would take?!
  • by Alatar (227876)
    Don't worry, if the FAA can't find anything to object to, they'll find a regulatory agency that will, or perhaps they will merely draft a new rule to fit your case. My suggestion would be to make a donation to your local congressman and send a letter to his office to have him make a call to the appropriate government agency on your behalf.
  • by goingware (85213) on Monday June 11, 2001 @06:25PM (#159385) Homepage
    When I was in junior high and high school I ground, polished and figured several telescope mirrors. I did a 6 inch, then a 10 inch, and finally an 8 inch.

    The 6 inch had a decent figure but I didn't know I could send it away to be vacuum aluminized, so I chemically deposited silver on it using chemicals I bought at the University of Idaho [uidaho.edu] chemistry stockroom. Take my advice, it's much better to get a mirror aluminized.

    I hurried a bit too much on fine grinding the 10 inch and wasn't happy with it, so I tried again with my 8 inch and was much more patient, and got excellent results from it (1/10 wave according to Chabot Amateur Telescope Maker's Workshop's Paul Zurakowski).

    Grinding telescopes and being a sciency kind of guy led me to study astronomy at CalTech [caltech.edu] where I assisted CalTech astronomer Jeremy Mould in observing the the Palomar 60 inch and 200 inch telescopes - the experience of a lifetime for an amateur astronomer.

    It's been about 18 years since I last worked any glass but I just bought an 8 inch plate glass kit from Dan Cassaro [jacksonville.net]. You can buy Pyrex kits and optical glass (suitable for lenses) from Newport Glass [newportglass.com].

    I'm starting to write about the telescope I'm about to work on here [geometricvisions.com].

    If you are in the San Francisco Bay Area check out the Eastbay Astronomical Society's Chabot Amateur Telescope Maker's Workshop [eastbayastro.org] (there's an observatory there too, it's in Oakland), Fremont Peak Observatory [fpoa.net], which has a 30 inch reflector that's open to the public, with regular gatherings of amateurs who bring their telescopes up there, and the San Francisco Sidewalk Astronomers [sfsidewalk...nomers.org] - the Sidewalk Astronomers set up telescopes on city sidewalks and introduce people to astronomy by inviting them to look through their scopes.

    You can get books on astronomy, and importantly, the specifics of how to actually grind and polish a telescope from Willman-Bell [willbell.com] and Newport Glass [newportglass.com].

    Check out this guy who made a ribbed mirror blank [tms-usa.com] by cutting out a pattern from one disk of glass with a water jet and fusing it to a solid sheet in a furnace.

    Visit Google's index of Amateur Telescope Making [google.com], particularly http://www.atmpage.com [atmpage.com].

    If you want to get into amateur telescope making, take advantage of an immensely valuable resource that wasn't available to me when I was a kid - subscribe to the ATM List - here's the FAQ [jacksonville.net].


    Mike [goingware.com]

  • What's wrong with the idea of simply putting a solid-fuel rocket on the back of, let's say, a LearJet?
  • What? How dare he. It's not In AD 2101 yet...
  • What? How dare he. It's not IN AD 2101 yet...
  • Rather funny you should ascribe that quote to Churchil, who was himself half American, and furthur is on record as having great admiration for the US.

    Read his bio. Make up your own mind.
  • Not content to roam away from Europe to the 'New World'

    Wait, I though it was Europeans who became restless with and roamed away from Europe to the New World? Crud... damn biased history books!

    I wonder how long it will be before someone like Rocket Man attaches a GPS system and a accute steering to a rocket and makes an intercontinental missle. It's not illegal to fire a few dozen exploding cans of Spam over to the County of Hampshire, is it?

  • Screw buying a telescope, and grind your own mirrors. The blank will cost you about $50-100 for a decent quality blank. Grinding the blank into the right shape will a take you about 40-60 hours at most. Silvering the blank shouldn't be much and the materials to mount the mirror and hold the secondary and eyepiece shouldn't cost more than a hundred or so. You can buy a good secondary from fisher scientific for a hundred, and the eyepeice can be purchased also. The mount and tracking stuff can be purchased off the shelf. So I figure total costs shouldn't run more than $1000.

    Plus when you grind your own mirror, you can really get a high quality surface on it and can test it and get rid of small imperfections. It's a lot cheaper than buying a high quality 6-10 inch scope.

  • Alas, Uncle Sam sez no go.

    See, the majority of GPS chipsets and firmware (and off the shelf units) don't work so hot above certain altitudes and speeds. (as I recall anyway) Reason: Uncle Sam doesn't like people using GPS for ICBM guidance.

    Now the RUSSIAN system (called GLONASS [www.rssi.ru]) would be a better bet. Only catch is that it isn't quite as accurate as GPS.

    However if you are just trying to hit a county it would probably do just fine...

  • As this is the first thing i've heard of a private company/individual trying to launch some kind of rocket or whatever you want to call it into space, it brings up an interesting question. Who owns the rights to space?

    Almost all the "property?" on earth seems to be owned by someone. But as technology advances, and can see a whole bunch of problems in the future when someone other than a gov. agency wants to settle on the moon- etc. etc. etc.

    I can't wait to see how the world governments handles this- but it will probably go through the stages that most gov. invloved legal issues do...
    activist groups...protesting...bashing...laywers...money... interpretation of the constitution...and so on.

  • by cr0sh (43134) on Monday June 11, 2001 @07:51PM (#159394) Homepage
    I noticed that he redesigned the whole thing too, recently - after getting a lot of email from "rocket scientists". I know I sent him at least a couple of emails, and I am sure others did as well. BTW - IANARS!!!

    But, perhaps what this shows is that we can have an effect on the Rocket Guy's plans - so maybe we should start sending him other ideas as well - maybe it can be a "group guided" effort, hmm?

    Worldcom [worldcom.com] - Generation Duh!
  • I'm looking forward to the streaming video of his burning lawn dart crashing into the Earth, then the '12 Hooters girls' bounce over and pour champagne on his still-smoldering body.Darwin award, indeed.Alex
  • by Dutchie (450420) on Monday June 11, 2001 @08:27PM (#159396) Homepage Journal
    At work, we discussed the chance of Walker succeeding. Basically, his assumption is that by putting the thrust in the top of the rocket, he'll create some sort of pendulum effect. I even emailed him, asking him if he had any mathematic calculations to back this story up, but he said he had no such calculus at the time, yet he went on to talk about the pendulum.

    However, a pendulum always has a force acting on it that's directed upwards. This is because the pendulum hangs on a wire *attached* to something that's fixed. If the pendulum would be attached to something that makes fairly random movements however (much like Walker's rocket, 'attached' to the athmosphere pretty much), the pendulum would not swing all that well and the point of attachment could easily end up being below his rocket, making the rocket point to the White house for example, and kill that arrogant Texan oilbaron. Now THAT would be funny.

    • Imagination is more important than knowledge.
  • I find this could be of some concern too, but it does one well to remember that while the US spent millions on finding an acceptable re-entry coating, the Russians discovered that it required nothing more than a mixture of epoxy and oak sawdust to achieve the same results.

    Sometimes simpler is better.

    ---
  • at least give a url slashdot ppls

    http://www.rocketguy.com/ [rocketguy.com]

  • by goingware (85213) on Monday June 11, 2001 @08:37PM (#159400) Homepage
    Here are the basics of how you grind a telescope mirror. There are many variations. You definitely want to get a book. I used:

    and one other I can't find anymore. There are other good books.

    The stubby Celestron [celestron.com] and Meade [meade.com] telescopes that are popular with amateur astronomers who prefer to purchase their instruments are of a type called a "schmidt-cassegrain". This has a nearly flat corrector plate in the front, that actually has a shallow fourth-order curve ground into it to correct spherical aberration, a deep prolate spheroidal primary mirror, and a convex secondary mirror mounted on the back of the center of the corrector plate.

    It's the convex secondary that makes the telescope a cassegrain. The 200 inch on Palomar is a cassegrain. I don't have a schmidt-cassegrain to show you but here's how an ordinary cassegrain is laid out [atmpage.com].

    The use of the schmidt corrector plate allows one to make the telescope very short, with a small ratio of focal length of the primary to its diameter, without making images away from the center of the field blurry.

    This is an advanced kind of design for an amateur to make oneself, although many amateurs have. Here's how one guy made a schmidt corrector plate [atmpage.com].

    The typical amateur starter scope is the "newtonian reflector" [atmpage.com]. This has a concave parabolic mirror at the back end of the tube, and a few inches inside its focus is an optically flat mirror at 45 degrees. The optical path shown in the diagram is for the light from a single star, an image is formed from light sources spread across a small angle, and a small image is formed at the focal plane where it's examined by the eyepiece (a high-power magnifier) or photographed with film, a CCD or I guess even a webcam.

    If you make a parabolic mirror with too short a ratio of focal length to diameter (the f-number, like the f ratio on a camera lens), then the images away from the center are blurred. This is called "coma". A parabola only focuses light perfectly if it's parallel to its axis and tilting the beam introduces coma. A ratio of 1 to 4 is about the shortest you can make it - f/4. My 6 inch is f/8, my 10 inch is f/3.5, and my 8 inch is f/6.

    Having a longer focal length gives you greater magnification. Having a shorter one gives you a wider field of view, within the limits of the coma. Having a shorter focal ratio also makes it easier to fit in a car, an important consideration for making the scope enjoyable. Those Celestrons are nice because they'll easy fit in the trunk of a car or even in airline luggage (with a hard case) but it comes at the expense of a fancier design.

    For the first homebuilt scope one usually grinds the primary and buys the flat diagonal mirror from a vendor. More advanced amateurs make their flats too but again optically flat surfaces are hard to make.

    Making a primary that doesn't have too short a focal ratio is not too bad because the grinding process naturally makes a sphere. You grind a sphere of the right radius of curvature, fine grind through successively finer grits, then polish. You then use an optical test to get the mirror perfectly spherical, then deepen the center to move from a sphere to a parabola of revolution, testing carefully as you go.

    The way I ground my mirrors was with pyrex mirror blanks on plate glass tools. Initially each is flat. They are both pretty thick, my 8 inch is about 1.25 inches thick, to stiffen them so they don't lose their figure. You have to have a figure that is perfect to about 1/8 of a wavelength of visible light in variation across the whole face of the glass, so any bending is disastrous. The 1/8 wave limit is the same for mirrors of all sizes so it's much harder to figure larger ones - best to start small. I would recommend an 8 inch for a first mirror. I have heard of people doing much larger first telescopes though.

    What you do is sprinkle some granulated silicon carbide and water on the tool, place the mirror blank face down on it and push it back and forth until the silicon carbide ("carborundum") breaks down. (This is the same abrasive as you find on black wet-or-dry sandpaper, only in free-flowing powdered form). Then you add more abrasive and water and repeat. When too much mud builds up you wash it off and add more abrasive again.

    To grind a concave curve into the mirror blank you place it on top, face down, grind with long strokes and have it hanging mostly off the side. Also you put pressure on it, either pushing hard or putting weights on it. This concentrates the grinding action in the middle and a shallow sphere develops.

    Every few strokes you rotate the mirror a little, and once a minute or so you rotate the tool a little, with the idea that every part of the mirror gets ground over every part of the tool in every direction.

    These days it has become popular to "hog out" a mirror with a metal ring tool, like a pipe cap as I'm about to try, then after rough grinding you make a fine-grinding tool out of small bathroom tiles mounted in dental stone or portland cement. This is in part because it's getting harder to get telescope making kits, unfortunately because it's so easy to buy a Celestron people don't make their own as much anymore. So people conserve the glass just for the mirrors and make the tile tools instead.

    Be aware, before you say "well it's easier to buy a Celestron", that the price of a telescope goes up astronomically with increasing diameter - my 8 inch kit was $78 including shipping, I'll probably spend a few hundred to make a nice clock-driven mount, but the 10 meter telescope on Mauna Kea cost $90 million! If you know how to make your own, it is within your reach to grind your own 20 inch, which will have astounding views, but few of us could hope to afford to purchase a twenty inch commercial scope.

    I know people who have ground 30 inch scopes and I know of some amateurs who are now figuring a 67 inch mirror!

    Anyway it takes several hours of work to rough grind your mirror, more if you're doing a short f/number, less if you have a higher one, also less for smaller mirrors and more for larger ones. My 6" f/8 was about as deep as the thickness of an american dime, I don't know a little more than a millimeter.

    Then you fine grind, grinding for a few hours with successively finer grades of abrasive. Usually you rough grind with 80 mesh silicon carbide - it is graded by sieving it through a mesh with 80 wires in it (same as the sandpaper sizes). Then you grind with #120, #220, #320, #400 and then several very fine grades of aluminum oxide whose sizes are given in microns.

    The idea is that each finer grade erases the pits left by the previous grade. Between each grade you must scrupulously clean yourself, the mirror and tool and your work environment lest a coarse particle get into a finer stage and cause a scratch.

    With each grade the mirror and tool surfaces will become more and more accurately spheres, within the limits of the sizes of the grits. This is because a sphere is the only shape that allows two surfaces to be placed anywhere against each other in any position or rotation (a flat surface is the limit of this as the radius goes to infinity). If there are any high spots, they will get more pressure and grind off quickly; any low spots will miss out on grinding and the surrounding surface will come down to match.

    Then you polish. You make a "pitch lap", using either another dental stone base or the glass grinding tool, covered with refined, thickened pine pitch. You cut channels in the pitch with a knife or mold them in with a silicone mold. Then you cover the pitch lap with a suspension of cerium oxide in water, or else ferrous oxide (same as rust but finely powdered - "jeweler's rouge"). Then again you stroke the mirror on the pitch lap.

    During fine grinding and polishing you use shorter strokes, and alternate which is on top, the mirror or the tool, to keep the depth constant. You also stroke a little side-to-side, in a W pattern. This evens everything out.

    To test the mirror you use the Foucault test [atmpage.com] or the Ronchi Test [uoregon.edu]. The foucault test appatatus I link to is much fancier than you need, although nicer to use - you can do it all with your naked eye and the tester, you don't need a camera.

    In each test you use a light emanating from a pinhole or narror slit just to the side of the center of curvature of the mirror. The image of the pinhole or slit will form an equal distance to the other side, where you can place a knife edge (Foucault) or screen (Ronchi) across it and hold your eye there and look at the mirror.

    It's kind of hard to explain but each of these has the effect of dramatically magnifying deviations from spherical surfaces in the mirror. A dramatic demonstration is to have someone hold their hand in the beam - you can see the distortion in the beam caused by the warm air rising from their hand.

    You can easily make out a bump or hollow that's a fraction of a wavelength high on the glass.

    Then you make your mirror perfectly spherical by preferentially polishing off the high spots. If you did the fine grinding and polishing well you won't have to work hard to do this.

    Unfortunately what we want is a parabola, not a sphere. This must have a precisely controlled error in each test. This is a little more than I want to get into, but basically your preferentially polish out the center of the mirror so it's deeper in the middle than appropriate for a sphere by a little bit. Get it just right and you have a parabola, and your mirror will focus perfectly.

    Then you package it securely and send it off to one of the people who does vacuum aluminization. They clean the mirror extremely well, place it in a high vacuum, and evaporate aluminum off of tungsten wires. The aluminum vapor sticks to your glass and you have a telescope mirror.


    Mike [goingware.com]

  • by deathcow (455995) on Monday June 11, 2001 @08:41PM (#159401)
    The celestron 9.25" scope he used has a good reputation amongst amateur astronomers.

    You've all seen the big blue Meade scopes, the 8", 10" and maybe a 12" down at "Nature Store" and places like that. All those scopes (all these are SCT's, or Schmitt Cassegraine Telescopes) and the Celestron SCT's have a pretty mediocre reputation for quality. However, people say the 9.25" model is a winner. It has a differently designed set of mirrors than the other common SCT's available.

  • by IronChef (164482) on Monday June 11, 2001 @08:44PM (#159402) Homepage

    Neat pictures, but if you are into astrophotography... why not a real camera? Or a good digital camera? Seems like a shame to waste $1-2k of telescope on a $100 imaging unit.

    Would this guy's story have made the front page if it didn't use a webcam?
  • Great point, Deathcow. You deserve a "5 Informative".

    Here are some more astropics from the Celestron 9.25" scope:

    Weatherman's 9.25" pics [weatherman.com]

  • It doesn't at all count for copyright issues: content is regularly cached by @home, AOL, MSN and every other big-name ISP so that their customers receive it quicker.

    It would be a simple matter to *not* cache the banner advertisements, which would allow the site to continue its ad revenue.

    Slashdot is usually pretty darn quick for me. I can't say the same for the poor sites that get slashdotted.



    --
  • See, the majority of GPS chipsets and firmware (and off the shelf units) don't work so hot above certain altitudes and speeds. (as I recall anyway) Reason: Uncle Sam doesn't like people using GPS for ICBM guidance.

    The real reason is much more mundane. If they artificially cap the speed at 90mph (150km/h) or so, they can drop the prices on consumer-grade GPS units and make a smaller unit profit on scads more units, without cannibalising sales for the sleek aerospace units, which generate a much larger unit profit on fewer units.
  • So should he be building rockets then?!? Why not?
    is coffeine or nicotine addiction more suitable?
    Disorders doesn't mean somebody's dumb.
  • The things I were most impressed with about this guy after reading the space.com article was that he was receptive to ideas not of his own origin. Which is something you *generally* don't see of someone who is of the mentally unstable, kook or crazy inventor type. Case in point: "Due to the advice of many real rocket scientists who have been in contact with Rocket Guy the design has gone through some major re-working." (IMHO NASA scientists frustrated with job politics are probably helping him.) Another is the fact that *this guy does not give up*. The tank-pressurizing people wanted $50,000 per tank. Walker rolls his eyes. "Military contractors. So I'm going to do my own tanks." Which, as a programmer, is an attitude I definitely dig. And finally, if the US govt. gives him problems: The FAA says they'll ask to see both Walker's flight plan -- to make sure no other craft are heading into the same airspace -- and his plans for the rocket before issuing a permit. Walker doesn't care if they say no. "I'll just haul it down to Mexico." In other words, screw you, I *am* gonna do this like it or not! :)
  • Actually, the Vesta Pro can be had for as little as $20, so it's definitely worth hacking up and experimenting with.

    To get better quality, you'd have to buy a considerably more expensive camera; probably $500+, at least. That's not appealing to a low-budget amateur (this IS just a hobby for many astronomers). Even then, there's no guarantee your results would be better. A "professional" grade camera may very well use the same CCD chip as something like the Vesta.

    -John
  • No one owns space. A while back, all of the superpowers (at the time) agreed that space (and I don't remember what definition...how far up they decided) would have the same openness as international waters.

    -Legion

  • Who makes a sub-$500 T-mount digital SLR? Are you missing an extra 0 on that amount? (Not trolling, really curious---I'd love to be able to use my f and t mount lenses on even a prosumer digital SLR.)

    ----
  • ... owns me. Not really, but I admire and respect him massively. His statements on individuality, the nature of role models, and self-determination are rare and precious these days. That, in addition to what he's actually DOING - he amazes me. I wish him the best.

  • On one hand, I totally admire you. On the other hand, I wonder what it sounds like at singles bars when you say to women "you know, I can grind my own telescope mirror". :)
  • I can understand the desire to keep things cheap, the article just didn't come across that way somehow.

    A "professional" grade camera may very well use the same CCD chip as something like the Vesta.

    Heh, no way. :) I have had a series of digital cameras of various prices and I know that that *none* of them would have been bettered by a $20 webcam. For reference, here [dpreview.com] are some pics from a $500 Canon digicam. Show me where to get that quality for $20 and I'll buy ten of them!
  • no, no, no. Tasco is the PB of telescopes. Meade is not that bad. For the truely serious, there are 20-30" techtrons.
  • Grinding is a very difficult task. It isn't that hard to learn, but takes a good while and is easy to screw up. It would probably be easier to buy the mirror and build the telescope, or buy a decent scope secondhand from somebody who doesn't know how to use it.
  • I truly don't know enough about photography to know if this would even be remotely useful for you, but my Sony DSC-S30 (retail value ~$380) has a 37mm threaded lens mount. It doesn't have a removable lens, though, which I'm guessing is what you'd want.

    A 37mm to T-ring adapter works for astrophotographical purposes, but I don't know (actually, I doubt) if you could do anything constructive with your nice lens on top of the standard lens (f=6.1-18.3mm).

    Ref: http://home.att.net/~scopetronix/digitalcam.html

    --
  • Sidewalk Astronomers set up telescopes on city sidewalks and introduce people to astronomy by inviting them to look through their scopes.

    If you are at all interested in astronomy, look into a local astronomy club. I've been involved with the Atlanta Astronomy Club [atlantaastronomy.org] for the past five years, and the members are very knowledgeable and friendly. There are all kinds of people doing pretty much any kind of astronomy you can imagine. The Google list is here [google.com].

  • And good luck and GodSpeed to him, the world needs more people to take a risk. Without peopel like him well be stuck on Earth for the next 50 years.
  • Is life so bad in America that the airless vacuum of space is preferable to another day in that cultural wasteland ? Or is it simply that Americans cannot tolerate their fellow countrymen, since they are all so egotistical ?

    Let me tell you a little story about history. Once upon a time, there was a country in mainland Europe. They elected a guy to the top job who had a funny mustache and only one testicle. This guy wanted to kill my parents, and a dozen or so million people with last names like my parents'.

    There was another country floating just off the coast of Europe. This country elected a guy to the top job who was determined to appease the aforementioned nutless wonder at all costs. And then there were a few more countries which set up puppet governments to do whatever the euunich said for them to do.

    So there's something in the American mindset that there's always something better if we just go and actually look for it. That brought us out of Europe, Africa, Asia, South America, etc, saving us and our children from having to live with the likes of you.

    Some people are happy with taking a stream of sewage and calling it a river, or are happy with having no power themselves. Some people like living in apartments and being dependent on public transportation for their whole lives. Some people like to fork over two-thirds of their paychecks. Some people can't stand the thought of even the very existence of a wilderness big enough to get lost in. Heh. In my state, they don't last long west of I-25.

    So, you're damn right we're restless. There's ALWAYS ALWAYS ALWAYS a better way, if man only has the drive and the imagination to find it and learn it.

  • This is just plain sweet. It's good to see someone in the US going back into space.

    I mean, if NASA doesn't really care about Aeronautics or Space, someone has to. It's good to see that this guy is into it enough to actually do something with it.

    Yeah, the FAA is going to shit bricks. They're more Administration than Aviation anyway. And he's in the PNW, home of some genuine silliness. Some crystal-wearing posie sniffer is probably going to stumble on this, think "rocket=missile=weapon=nuclear," and go truly apeshit and try to chain herself to the rocket.

    But just the same, this needs to be done.

    So, where does he want the donations sent? I'm not an engineer, and the only physics I know are the ones involved in firearms and traffic accidents, but I have a few buck to throw in.

  • That bit at the top would make sense, but you didn't enter the war until 1942 or something stupid like that (when the Japanese performed an excellent raid on Pearl Harbour). We'd already been fighting for 3 years (and beat off the german air force).
  • Here's a suggestion: Why not actually go and read a history book (not one produced in the US) and see if you get a different perspective.

    You mean one spouting some revisionist view of World War 2, the kind that's so popular with many Europeans these days? You people do so love to rewrite history to suit yourselves, especially when there's any sort of humiliation involved....

    Max
  • Oh no, we tolerate our fellow countrymen just fine. It's the fact that we have to share the planet with a bunch of arrogant Europeans that drives us to explore space.

    Sadly, moving to a new continent proved only to be a stop-gap measure. By creating the internet we managed, much to our dismay, to bring European hubris and ego right back into our living rooms.

    It's no wonder private citizens are looking for a way to leave the planet.

    Max
  • Hmmm... Robert Goddard's rockets were designed as Walker's - the nozzle placed at the top, with the fuel tank below, and they worked quite fine (for that time)... As long as you have control of what's up and down (preferrably a hopefully failsafe N-version system consisting of a combination of hardware [gyro] and software [computer together with radio triangulation]), then you can steer in the correct direction. Or blow up the rocket in case it starts pointing towards your neighbour - what do I know... Anyways - I think it doesn't matter very much if the engine is located at the top or the bottom - it's a design issue, but there could be other problems, like the wear that would result from the engines exhaust flowing over the other parts of the rocket - THAT could be a problem...
  • Strikes me that what they did to McVeigh stinks of "Cruel and Unusual Punishment."
  • No, curel and unusual punishment would have been tying him in a phonebooth and blowing it up...
  • by jesterzog (189797) on Tuesday June 12, 2001 @03:50AM (#159427) Homepage Journal

    You could go and buy an expensive telescope, but unless you're really devoted to what you're doing you might find that you don't use it after a few months. You'll probably just find that it's bulky, heavy and awkward to carry around. Especially if you don't have anywhere convenient to set it up.

    I'm currently the membership secretary of a local society. We have a deal with a local science shop to sign up new members as they buy telescopes. If we can't get these people and drag them in, they're usually no longer members after a year because they never really got involved enough in astronomy to understand how to find things and enjoy it properly.

    They look through it a few times expecting to see a brilliant time-lapsed artificial-colour image out of a book or magazine, then get very dissappointed when it's just a faint, barely visible blur. To really appreciate seeing most things involves lots of time to sit down and observe something, learn what it looks like, and having looked long enough you'll slowly start to see new things.

    You can almost never look at a galaxy and see a brilliant image in ten seconds. You have to look at lots of galaxies and understand how to look at them, and then they start to look like brilliant images - but albeit in a way that most people don't see.

    It's also a bit offputting that it gets so cold at night and you usually have to be organised and know how to define what you're doing to survive out there for hours without getting bored and cold. There are only so many things you can find without knowing what to look for, and there's only so much that a book can teach.

    I'd recommend first finding and joining a local astronomy club or society. Turn up to the meetings, get to know some people, and look through other people's telescopes. Going observing with other people is lots of fun. It's not just a social thing, you also get to learn from other people how to do and enjoy nearly everything. Then you get to show them things afterwards.

    Arrange to borrow telescopes if and when you can so you can get a good idea of what sort of thing suits you best. It might sound boring at first, but I reccommend getting a small one to start with. There's heaps of things you can see with small telescopes when someone's there to show you how and where to look. Often there's more to see, because the things you look at are much more common an obvious.

    Don't bother with a motor drive and expect to use it much. If you want to just key in positions and let the scope find stuff for you, you're missing out on lots of experience that is valuable for nearly everything else. Learn the constellations and star names, because they're the first part of using a star map to find your way around the sky.

    Have fun.


    ===
  • Indeed!
    Guy 1: It should be any minute from just above that tree.
    Guy 2 (with binoculars): Right...
    Guy 1: THERE IT IS - WOW!
    Guy 2: Where?
    Guy 1: I didn't think it would move so fast - amazing.
    Guy 2: Is it above the tree yet? Where??
    Guy 1: No - it's above that house now.
    Guy 2: Which One???

    etc... etc.... etc....

    Oh - and no, I wasn't the guy with the binoculars
  • Note the sequence of ISS images -- some are blurry, but one in the sequence is sharp.

    Ground based telescopes are limited by convection cells that roil the image. Anybody who's looked at a planet through a small telescope pushed to the limits of its usable magnification has seen this.

    However, there are brief instnaces where you happen to be looking through a patch of stable atmosphere, as can be clearly seen in the image sequences -- one is much clearer than the others. Ron Dantowitz from the Boston Museum of Science discovered the technique of using individual video frames (actually he used half frames from an NTSC CCTV camera) to get unprecedented resolution images of satellites from small telescopes. For instance he has taken ground based pictures of the shuttle where you can see whether the cargo bay doors are open or closed. He put images of spy satellites on the web and got a prompt visit from some NSA spooks who wanted to know how he got them. The cool thing about this is that works in broad daylight, so you don't have to be up freezing your butt off after midnight.

    here [skyshow.com] are some samples, unfortunately without captions, and here [mos.org] are a few with captions.

    The ISS pictures in the article were even better; perhaps the state of the art has advanced, or the observer was lucky.

  • Some people are happy with taking a stream of sewage and calling it a river, or are happy with having no power themselves. Some people like living in apartments and being dependent on public transportation for their whole lives. Some people like to fork over two-thirds of their paychecks.
    You're talking about New Yorkers, right?

    "What are we going to do tonight, Bill?"
  • He's only going 30 miles up? What's the point, then? It's not even edge of space. (Space being defined somewhat arbitrarily at 50 miles).
  • I have recently bought a telescope, a skywatcher newton 130mm F5 on a EQ3 mount and accessories, for the price I paid (392$CAN) I can assure you it is a fantastic piece of equipment! You can see some pictures on my website and links where I bought it.
    --
  • It's difficult, but not unreasonable, because we do have precise coordinates. Want to have a pretty good idea of where the ISS is right now? Here is a state vector [celestrak.com], and this [celestrak.com] or this [stk.com] software will let you propagate that vector. The really difficult part in the whole process isn't tracking, it's getting escape velocity out of your nerf [thinkgeek.com].
  • I was reading in a recent Sky & Telescope about a German teenager who got some pretty good pictures of the ISS + shuttle with a 4 inch (!) 'scope and a webcam. Found his website here [nbci.com].
  • in french and english, explain everything on webcam for astronomy, how to setup various model, special driver to allow long exposures, "blackening" the CCD and remove this "black" image from the image you've taken, etc, very very good site here at astrocam http://www.astrocam.org/ (don't know why but i cannot put the link with a A tag)
    Another site with special webcam for astronomy is SAC [nbci.com]
    --
  • well, a SBIG or a Apogee CCD camera can cost more than 1-2k$, the SBIG ST8 is something like 7k$, and a apogee CCD can cost more than 10k$ for sure
    --
  • Isn't french Ariane private? Also heard about this project about launching rockets from an oil platform placed exactly on the equator - believe it was private as well...
    mind you, might be wrong
  • I found the whole grinding process to be fairly simple. The hardest part was getting the imperfections out. Then again I had an experienced friend helping me. He's graduated to bigger scopes now. I think his other scope is the 10 meter one at Keck.

  • On the other hand, I wonder what it sounds like at singles bars when you say to women "you know, I can grind my own telescope mirror". :)
    Uh, yeah, many take it as evidence of unabashed Geekness.

    While there are some women who grind telescope mirrors, it still seems to be a largely male activity, and while my wife encourages it, she thinks it's a pretty odd thing to get excited about.

    I read a lot on the ATM list about how wives tend to think their ATM husbands are pretty weird for making telescopes.

    On the other hand, I am married, so it can't be all that unattractive to the opposite sex. Probably best something not to put forward on the first date though.


    Mike [goingware.com]

  • This is true, but not the cap I'm thinking of. You are correct in that the consumer models are artificically capped at around 100mph, BUT there is also an altitude cap on all civvie units that prevents them working above some height (which I can't recall right now.)

    I was working with some motorola GPS DSP chipsets/firmware a while back and there was some info on this stuff.

  • It's not as stupid as you think, the first telescopes grew out of eyeglass making.

    While you could make a telescope this way, you wouldn't get one with a very wide objective lens, so it wouldn't capture much light.

    Also, you have the problem that the lens is made out of only one kind of material (plastic these days), so you have the problem of chromatic aberration - any one kind of lens material refracts light of different wavelengths differently, so you can't get all the colors in focus simultaneously and you get colored fringes around your stars, or just blurring of larger objects.

    Mirrors work by reflection, and reflect geometrically, so they don't suffer from chromatic aberration. I think this is what Newton was after when he invented the newtonian telescope.

    A lens suitable for astronomy needs at least two components, and needs to be made of glass of precise characteristics, and free of internal defects, and their are four surfaces to grind and polish, and further you can only support them at the edges. So it's impractical to make large quality refractor lenses - the biggest is the Yerkes observatory 40 inch.

    Modern observatory instruments are all mirrors, I think the biggest single mirror is the 236 inch in Russia, and you can also compose a mirror out of numerous smaller mirrors, and the biggest one of those is the Keck 10 meter on Mauna Kea, Hawaii which has thirty mirrors in it.


    Mike [goingware.com]

An Ada exception is when a routine gets in trouble and says 'Beam me up, Scotty'.

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