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Getting Into Space, One Way Or Another
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.
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
"Useless organic meatbag" -HK-47
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.
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
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.
Here's a link to his site.
-John
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
"Useless organic meatbag" -HK-47
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.
/. is a commercial entity. goto slashdot.com
Wan Hu - medieval chinese rocket scientist (who may not have been exactly a rocket scientist).
Hmm, or maybe that was Larry Walters.
--
Why bother taking pictures of space, or trying to rocket into space? I prefer creating rifts in the space-time continuum. That's much more fun.
Who wants to start the betting pool?
All Troll + "offtopic" mods are meta moderated as "Unfair", because you abused the system.
http://www.perljam.net/misc/iss/www.djcash.demon.c o.uk/astro/webcam/webcam.htm
-ted
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.
ZFS: because love is never having to say fsck
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.
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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.
Treatment, not tyranny. End the drug war and free our American POWs.
See my user info for links.
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.
All Troll + "offtopic" mods are meta moderated as "Unfair", because you abused the system.
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
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).
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!
--
--
"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
"... goes to -- Brian 'Rocket Guy' Walker!"
Maybe David Cash can capture the Kodak moment when Brian goes up on Challenger Two.
So should he be building rockets then?!?
...Time is the best teacher, unfortunately it kills all of its students.
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 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 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. You can buy Pyrex kits and optical glass (suitable for lenses) from Newport Glass.
I'm starting to write about the telescope I'm about to work on here.
If you are in the San Francisco Bay Area check out the Eastbay Astronomical Society's Chabot Amateur Telescope Maker's Workshop (there's an observatory there too, it's in Oakland), Fremont Peak Observatory, 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 - 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 and Newport Glass.
Check out this guy who made a ribbed mirror blank 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, particularly http://www.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.
Mike
-- Could you use my software consulting serv
What's wrong with the idea of simply putting a solid-fuel rocket on the back of, let's say, a LearJet?
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) 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...
"There's no secret. You just press the accelerator to the floor and keep turning left." -- Bill Vukovich
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
A winner is you!
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.
- Amateur Telescope Making by Albert Ingalls
- How to Make a Telescope by Jean Texerau
and one other I can't find anymore. There are other good books.The stubby Celestron and Meade 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.
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.
The typical amateur starter scope is the "newtonian reflector". 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 or the Ronchi Test. 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
-- Could you use my software consulting serv
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.
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.
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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 are some samples, unfortunately without captions, and here 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.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.