APOD: A Large Space Station Over Earth (2010 Apr 14)

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APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by APOD Robot » Wed Apr 14, 2010 7:46 am

Image A Large Space Station Over Earth

Explanation: The International Space Station is the largest object ever constructed by humans in space. The station perimeter now extends over roughly the area of a football field, although only a small fraction of this is composed of modules habitable by humans. The station is so large that it could not be launched all at once -- it is being built piecemeal with large sections added continually by flights of the Space Shuttle. To function, the ISS needs huge trusses, some over 15 meters long and with masses over 10,000 kilograms, to keep it rigid and to route electricity and liquid coolants. Pictured above, part of the immense space station was photographed out of a window by a member of the visiting Space Shuttle Discovery STS-131 crew. Visible in the foreground is Japan's Kibo research module, while a large truss is visible toward the left. On the far right, a crescent Earth slices through the blackness of space.

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radtech21

Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by radtech21 » Wed Apr 14, 2010 8:59 am

"That's not a moon, it's a space station." :P

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neufer
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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by neufer » Wed Apr 14, 2010 10:29 am

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Truss, n. [OE. trusse, F. trousse, OF. also tourse; perhaps fr. L. tryrsus stalk, stem. Cf. Thyrsus, Torso, Trousers, Trousseau.]

1. A bundle; a package; as, a truss of grass. Fabyan.
Bearing a truss of trifles at his back. - Spenser.

2. A padded jacket or dress worn under armor, to protect the body from the effects of friction; also, a part of a woman's dress; a stomacher.
Puts off his palmer's weed unto his truss, which bore The stains of ancient arms. - Drayton.

3. (Surg.) A bandage or apparatus used in cases of hernia, to keep up the reduced parts and hinder further protrusion, and for other purposes.

4. (Bot.) A tuft of flowers formed at the top of the main stalk, or stem, of certain plants.

5. (Naut.) The rope or iron used to keep the center of a yard to the mast.

6. (Arch. & Engin.) An assemblage of members of wood or metal, supported at two points, and arranged to transmit pressure vertically to those points, with the least possible strain across the length of any member. Architectural trusses when left visible, as in open timber roofs, often contain members not needed for construction, or are built with greater massiveness than is requisite, or are composed in unscientific ways in accordance with the exigencies of style.
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Truss, v. t. [F. trousser. See Truss, n.]

1. To bind or pack close; to make into a truss. Shak.
[His hood] was trussed up in his wallet. - Chaucer.

2. To take fast hold of; to seize and hold firmly; to pounce upon. [Obs.]
Who trussing me as eagle doth his prey. - Spenser.

3. To strengthen or stiffen, as a beam or girder, by means of a brace or braces.

4. To skewer; to make fast, as the wings of a fowl to the body in cooking it.

5. To execute by hanging; to hang; -- usually with up. [Slang.]
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Art Neuendorffer

MLB forever

Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by MLB forever » Wed Apr 14, 2010 11:10 am

So now ! Who can identify the landscape ? :lol:

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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by owlice » Wed Apr 14, 2010 11:17 am

lol!!
To skewer; to make fast, as the wings of a fowl to the body in cooking it
ACK!!!
A closed mouth gathers no foot.

Astronut

Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by Astronut » Wed Apr 14, 2010 11:20 am

WOW! What a veiw, But WATCH that first step!!

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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by neufer » Wed Apr 14, 2010 12:51 pm

couette wrote:
To skewer; to make fast, as the wings of a fowl to the body in cooking it
ACK!!!
WHOOO do you truss :?:
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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by biddie67 » Wed Apr 14, 2010 12:54 pm

(( good laugh .... ))

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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by neufer » Wed Apr 14, 2010 12:58 pm

Astronut wrote:What a veiw, But WATCH that first step!!
Indeed!
http://www.deseretnews.com/article/1,5143,590045106,00.html wrote: 'I before E' rule is rife with exceptions
By Bill Sones and Rich Sones, Ph.D.
Published: Monday, Feb. 23, 2004 8:04 a.m. MST

Question: "I before E except after C." What thanks do schoolkids owe the originator of this famous mnemonic device for spelling words like "receive," "deceive," "conceive," "conceit," "ceiling"?

Answer: No thanks at all for this anCIEnt, unsCIEntific, ineffiCIEnt, insuffiCIEnt and defiCIEnt rule!

NEIther should kids try to rule-spell "finanCIEr," "soCIEty," "juiCIEr," nor anything in the group of "EIght," "bEIge," "nEIghbor," "codEIne," "protEIn," "rEIgn," "sEIze," "thEIr," "wEIgh" and "wEIrd."

There are well over 100 such exceptions, says David Crystal in "The Cambridge Encyclopedia of the English Language," with IE following C, or EI following just about anything it chooses.

The only way to impose a degree of order on this muddle is to relate spellings to grammar and pronunciation, such as exceptions involving affixes (agencies, seeing, absenteeism) or proper names (Einstein, O'Neill, Leicester), or how the IE/EI is sounded, such as in an unstressed syllable of "ancient."
Art Neuendorffer

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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by biddie67 » Wed Apr 14, 2010 1:05 pm

(( still laughing )) That man sure keeps one on their toes ...

I can't help but wonder, when in the future of space-based urban sprawl, what the favored designs of condos, individual homes, space-golf resorts, gambling resorts aka Las Vegas, traffic routes and the like will will look like. The above will be remembered as "the good ol' days".

This structure, as man's first venture into a near-space-based livable structure, was well thought out and built as pieces could be carried there and assembled. But it has always looked as ungainly as all get out.

Have there been any 2nd thoughts as to how the design could have been better?

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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by owlice » Wed Apr 14, 2010 5:13 pm

"I before E except after C."
The article left off the rest, which is "or when sounding as a as in neighbor and weigh," which takes care of some of the exceptions.

Including "agencies," "seeing," and proper names as "exceptions" is just stupid. They can rail all they want, but the phrase is still a handy guideline.
A closed mouth gathers no foot.

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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by bystander » Wed Apr 14, 2010 6:07 pm

owlice wrote:Including "agencies," "seeing," and proper names as "exceptions" is just stupid.
Yes, changing y to ie in plural forms, past tense and past participles of verbs is common. Seeing may be an exception, but for a different reason. Forming the present participles or gerunds of verbs ending with e are usually formed by dropping the e (placing, changing, trading).

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Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by owlice » Wed Apr 14, 2010 7:42 pm

bystander wrote:
owlice wrote:Including "agencies," "seeing," and proper names as "exceptions" is just stupid.
Yes, changing y to ie in plural forms, past tense and past participles of verbs is common. Seeing may be an exception, but for a different reason. Forming the present participles or gerunds of verbs ending with e are usually formed by dropping the e (placing, changing, trading).
Aren't all "ee" verbs -- agree, pee, flee, free, tree, and so on -- treated the same way? It's not just see. Off the top of my head, I can't think of an exception. (You may be using see as the example for this whole category, so we may be saying the same thing. :ssmile: )
A closed mouth gathers no foot.

Guest

Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by Guest » Fri Apr 16, 2010 7:35 pm

I can't resist asking why the ISS needs such heavy trusses. Since the inertial loads on the assembly are very low, the main threat to rigidity seems to be thermal cycling. Have we lifted all that material just for thermal mass? From what I've seen, the solar panels are seldom aimed within ten degrees, and the components should be fine either independently or with compliant joining. A rigid assembly of thin shells attached to a strong, rigid truss, with cyclic thermal stress sounds risky.

DonLund

Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by DonLund » Sat Apr 17, 2010 5:07 am

Guest wrote:I can't resist asking why the ISS needs such heavy trusses. Since the inertial loads on the assembly are very low, the main threat to rigidity seems to be thermal cycling. Have we lifted all that material just for thermal mass? From what I've seen, the solar panels are seldom aimed within ten degrees, and the components should be fine either independently or with compliant joining. A rigid assembly of thin shells attached to a strong, rigid truss, with cyclic thermal stress sounds risky.

I speculate that the reason for a stiff truss is minimize vibration amplituds of ISS structure, which because of its size will iinherently respond at low freequency to any exciting forces such as maneuvering , docking, etc. Such vibration would not damp out quickly like it would due on earth due to air friction, could persist for a long time and interfere particularly with docking. Ideally, the ISS should be a rigid body, next best is the stiffest practical structure.

Guest

Re: APOD: A Large Space Station Over Earth (2010 Apr 14)

Post by Guest » Sat Apr 17, 2010 6:46 pm

I speculate that the reason for a stiff truss is minimize vibration amplituds of ISS structure, which because of its size will iinherently respond at low freequency to any exciting forces such as maneuvering , docking, etc. Such vibration would not damp out quickly like it would due on earth due to air friction, could persist for a long time and interfere particularly with docking. Ideally, the ISS should be a rigid body, next best is the stiffest practical structure.
Thanks for the reply, I'll grant that the amplitude would go down, and the average frequency would go up. I'm not sure how much longer a tuning fork vibrates in a vacuum, but it does decay. Aramid fiber is an excellent material for wound pressure vessels, such as the modules, and is popular for armour as well. It also features high hysterisis, so it wouold dampen vibrations faster than metal in air by quite a bit, IMHO. It should not be difficult to minimize the docking impact with a bumper and shock absorber, and isolate each section with a flexible connection, so that a random impact would not send damaging vibrations elsewhere.
Bob Stuart