http://antwrp.gsfc.nasa.gov/apod/image/0307/earthsat_fu.gif

The Satellites that Surround Earth
Illustration Credit: P. C.-W. Fu & A. Hanson (Indiana), P. Frisch (Chicago), NASA

Thousands of satellites orbit the Earth. Costing billions of dollars, this swarm of high altitude robots is now vital to communication, orientation, and imaging both Earth and space. One common type of orbit is geostationary where a satellite will appear to hover above one point on Earth's equator. Geostationary orbits are very high up -- over five times the radius of the Earth -- and possible only because the satellite orbital period is exactly one day. It is usually cheaper to place a satellite in low Earth orbit, around 500 kilometers, just high enough to avoid the effect of Earth's atmosphere. The above animated sequence starts by showing the halo of Earth's satellites, including the ring at geostationary, and finishes by zooming in on the only one currently hosting humans: the International Space Station.

Does this post have a point or is this your version of "the word of the day"?

We causually throw around the words of put a satellite in orbit, LEO, the space station, ect. No one ever considers what is already there on our level. It is a nice way to show the space overhead is pretty crowded already.

How many of these are equipped with high powered lasers?

Originally posted by Wrong Robot
How many of these are equipped with high powered lasers?

Only the ones manned by sharks. You know the ones with frikkin' laser beams attached to their heads,...

One must always laugh at the idea of a crowed orbit. I don't know how many satellites there actually are. Ill assume 20000. If you dropped all these on the earth you would have one for every (aprox) 22500SKM. Thats a lot of land to cover if you had to find one (150 by 150km). In space the density is even less, and with satellites usually smaller then cars you have a very few needles in a very large hay stack.
Maybe in a thousand years there might be a millions satellites, then we might say that, theres a crowed sky..

Arent they getting worried about the potential problems if a satellite gets shattered by debris, and this snowballs into a massive hailstorm that takes out many satellites? Theres already a fairly large amount of debris up there besides the satellites. Chances are nothing will happen for years, but the European GPS system is going ot go up at some point, and theres still more satellites being launched.

It's the very small pieces of debris that post the real challenge in space travel and for satellites. A paint chip about the size of a postage stamp crashed into a space station (or something of sorts) at the speed of 10 miles a second and caused a crack in the window. Anything bigger or heavier would have done double damage.

well no doubt anything moving that fast is gonna do some dmg. but thats why i belive the outer shell should be made of a material that would bend at such strain not break and under that outer coating would be an absorption type material which would act to absorb the bend metal and cushion the impact. but with glass its not very easy. being able to see through it and it being able to take a hit are serious matters in space a crack in space can turn into a hole and then basicaly crush the ship. sad thing is most of the debris up in space is by us on our space missions. funny huh

Originally posted by ydoc16
well no doubt anything moving that fast is gonna do some dmg. but thats why i belive the outer shell should be made of a material that would bend at such strain not break and under that outer coating would be an absorption type material which would act to absorb the bend metal and cushion the impact. .... funny huh

Have you done ke = 1/2mv^2 at school yet?

Very small items moving very fast have massive kinetic energy. It's just impossible to built flight bodies that can withstand them.

Let's do some maths, .... a nut, say weighing 40gr (grains) travelling at 3 miles per second. (15840 fps), yields 22,290 ft.lbs of energy. Which is about twice as powerful as a .50cal BMG projectile, which are used to shoot up lightly armoured battlefield vehicles. So you'd need heavy armour. Tanks in space?

Of course, that energy is for a small nut, that may just fall off a rocket or satellite. If was the whole bolt, you'd have even more mass. If it was in a more eccentric orbit, even more speed.

But back in 1996, the French 'Cerise' satellite was hit by a fragment of space debris the size of a suitcase (part of the separating nosecone of an Ariane rocket deploying another satellite) at 31,000mph (8.6 mph). Don't know the weight of the pbject , but I'm guessing a couple of pounds, so that gives us ,er, 64million ft.lbs, which is why it vapourised the boom holding the gyros.

It is impossible to make satellits to withstand that sort of impact. In fact pointless, as even if it survived, it would be knocked out of it's correct orbit.

i didnt say withstand the impact i said absorb the impact into the shell absorption is alot different then withstanding a strike. if someone punches me in my face i withstand the blow and fly back.(given that you dont abosrb the blow by letting your face slide to the side)
if someone puches me in my gut i keel and absorb the blow and go nowhere. a crude analagy but it shows my point

Originally posted by ydoc16
i didnt say withstand the impact i said absorb the impact into the shell absorption is alot different then withstanding a strike. if someone punches me in my face i withstand the blow and fly back.(given that you dont abosrb the blow by letting your face slide to the side)
if someone puches me in my gut i keel and absorb the blow and go nowhere. a crude analagy but it shows my point

What semantic difference do you think 'withstand' and 'absorb' make in this context? Any?

Your 'point' wrt a punch to the stomach is missing the physics at work by a mile., especially as you admit you 'fly back' if punched, ....

Ever played pool? A ball hits another ball, and both end up moving. The balls are strong enough to 'withstand' the impact, but the stationary ball ends up getting pushed away.

Now, take that stationary (geostationary?) object standing on a near frictionless environment (orbit?), and slam an implulse into it. Is it going to;

a; pick up momentum like the afore mentioned pool ball, and have it's orbit changed,

or

b; fold over reacting to the blow to the stomach by reacting against the force, throwing bodyweight around to maintain the balance it has on it's legs which contact on a plane and exhibit friction?

Hmm, which is the more apt analogy?

So, even if you could could make an armoured satellite, it would get pushed out of it's orbit. What don't you understand about this?

And please, no pointless analogies about you getting beaten up.

i didnt say amoured satalite maybe you still dont understand that a tanks is armoured i am talking more like a new minvan that crumpels when hit and no you analagy about the pool balls was wrong in the fact that the pool balls do not absorb the kinetic energy they transfer it from 1 ball to another if you line of two balls and hit them with the another the 1st ball will fly off the second will move to the 1sts location and the 3rd to the seconds.
is that good enough for you? and i never said satalites altoght you assumed wrong not reading the previous posts
i was talking about large objects such as space stations and ships
things that are equiped with thruster and could make the nessacry adjustments with the thrusters.

if obect A hits nasa space shuttle at 10 miles per second and its the size of a bolt pierces hull and kills the crew becuase they didnt see it coming.

if obeject A hits the shuttle made to abosrb the impact shuttle gets away with a dent in the side of the ship and getting knocked (depending on the direction and place it hit the shuttle) back. and has to readjust with the thrusters.

(by sargentlard
It's the very small pieces of debris that post the real challenge in space travel and for satellites. A paint chip about the size of a postage stamp crashed into a space station (or something of sorts) at the speed of 10 miles a second and caused a crack in the window. Anything bigger or heavier would have done double damage.)

ydoc16, crumple zones, like on a 'minvan' ( I presume you mean minivan') absurd! I think maybe you just dont understand the energy involved here, and the concentrated force. I did the maths, did you not pay attention?

A small nut has nearly twice the power of a .50cal BMG round. Does that not mean anything to you? Absorb all of that energy with deformation? And harmlessly emit it as heat (deformation disperses energy as heat, before you question this too.) leaving so little momentum transfer that thrusters could sort out the rest?
And this isn't armour? How do you protect the solar panels? They are a large surface area, and made of fragile material. Cover them in your magic padding? Would they still work ????? So your magic padding has to be transparent to sunlight too, it gets better!

The thread was about satellites, not space stations btw (how many satellites vs space stations in orbit?), so saying you were talking about space stations with thrusters than could adjust their orbits is some post facto attempt to draw the debate.

Your fantasizing about things which just aren't feasible kid, and digging yourself in deeper. Get a physics book, go read it, and get back to me.

NASA at one time developed an impact shield for probes. I am not sure that it was ever actually used on a probe but am sure that the idea was tested.

Basically it was a layered approach with some space between the layers. This was only designed for micrometorites as the larger stuff was just hopeless to try and shield the craft from.

exactly wet 1 lol things larger then metorites are hopeless to protect against this guy keeps thinking i talking about things that at that speed nothing could be proteted against.

The do make crumple zones of sorts for spacecraft. They call them "whipple shields". The concept is that for small particles (much smaller than a nut, and more the size of paint particles) they can absorb the impacts. They have an outer skin, so when the particle hits the skin it breaks up as it goes throught the skin. The inner skin then absorbs the impart of the now much smaller impacts.

It's not quite armor, but there is some protection for spacecraft from orbital debris

http://stardust.jpl.nasa.gov/tech/aerogel.html

Whipple Shielding is far from common, as far as I'm aware, only used on satellites that plan cometary intercepts, and used on habitation modules for the ISS.

It's not a 'crumple zone' as ydoc16 describes, but a sacrificial layer, which is vapourised by, and vapourises small incoming objects, leaving a hole in the protective shield.

We never used it on the satellites we used to build, ours were just covered with thermal foil.

ydoc16, in your 'example', 'object A' was a 'bolt'. Your own words, sonny, and shuttles (quite obviously from the recent Columbia disaster) aren't made to withstand damage. If it could be done, it would be done, it's quite simple.

will you stop trying to refer what my theorys come from no i was not thinking about the columbia disaster. if you must know i got the idea along time ago when my friend who was small at the time shot me with a bb gun in the leg my pants folded in to the bb and it did not pierce thru and fell off before it ever touched my leg that was a very small object moving slowly. now you know where i got the idea from stop using your super mind to come up with wrong answers.

ydoc16, it was you who first mentioned the shuttle, in your 'object A' analogy. I was merely pointing out that the shuttle doesn't have any protection, and that the recent disaster shows have fragile it is.

So you got the idea from being shot in the leg with a BB gun, which produces maybe 2 ft.lbs of energy, and then extrapolate this to an object with 22,000+ ft.lbs of energy.

A bit of a leap!

Like I say, if it could be done, it would be done, greater minds that yours are working on this stuff every day.

it was an example you moron can you do me a favor and shut the hell up. they have in fact made kevlar sheets that absorb the impact of a bullet that act in the same manner as my PANTS did i dont base anything i say on theory or conjectur only proven fact you sitting here picking my sentances apart is annoying and i wish you would leave me alone if i knew where the ignore button is on these forums was trust me youd be on the list.

p.s. if there is a ignore list can someone show me how to add this guy besides him.

Wet1

Have you seen this before?

http://liftoff.msfc.nasa.gov/RealTime/JTrack/3D/JTrack3D.html

Click the link “J-Track 3-D” and it will open up a real time satellite-tracking applet. You can zoom in and out, find particular satellites and get a variety of views. You can also use it to see which satellites have gone or will be going over your location.

that realy is a good viewer of the sattalites think you for posting it

:bugeye: And if you want to keep track of exactly where they are at any given time this (http://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/JavaSSOP.html) will tell you. :rolleyes: