Space station blues

Great. We gots ourselves a big space station. Its going to cover an acre of space. Now, I realize in the grand scheme of things, this is not very big (compared to space). But the odds of it getting hit by smallish rocks of sorts does increase.

How does the station protect itself from these smallish rocks travelling a gazillion miles an hour? I would imagine (as I really have no idea) that even the hardest of metals wouldn’t hold up “well” to a pebble travelling faster than a devil’s fart.

Shields at maximum, Captain.

Basically, the station’s got enough material (largely padding) that it can survive any small hits, as long as there aren’t two in the same place (an eventual inevitability, if it stays up long enough, but they’ll be doing periodic repairs). Meanwhile, anything large enough to kill the station on a single hit, they can track from the ground, and give enough warning for the station to take evasive maneuvers.

Wow. I find that absolutely amazing. I mean, the station’s not gonna be that nimble, and them rocks can move mighty fast. Do we really have tracking that sophisticated? I’d like to know more about this so if you have any source material please dish!!!

I’ve got no source, but I’ve heard that NASA, the USAF, and presumably other space-interested agencies can track anything the size of a baseball and up in low Earth orbit. Is that true?

I think the main problem isn’t running into a baseball-sized object. What’s more likely is a 100,000 feet/s collision with a rock the size of a dust particle, or at most a grain of sand. As Chronos said, shields exist to take this kind of damage, for a given time, for a given probability of failure. Of course these shields aren’t of the Star-Trek variety, but more like layers of metal foil with some kind of padding. The idea is to let the shield take the damage, not the station.

I’d guess that the collective cross-sectional area of all the existing satellites is more than the new space station, and they seem to do ok :slight_smile:


I seem to recall an article in SciAm that illustrated how special panels for spacecraft are created in order to protect from space debris, but I can’t seem to find it in their on-line archives…Damn.

Anyway, the tracking of objects in and of itself is not what surprises me. What does is the ability to track them far enough away from the spacecraft to be able to move the craft out of the way. Given the speed of such objects and the difficulty in moving a large craft, you’d need something that could spot 'em pretty far away AND know from that distance that a collision was imminent.

If this is for real, I’m astonished.

From the news reports I read, the new Space Station core module was finally launched (“this rocket brought to you in part by Pizza Hut”) with the bare minimum of shielding, requiring that once in operation a spacewalk be performed to add extra protection (Due to economics, timetable and launch weight considerations, also with the bare minimum of a lot of other systems). Over time, this add-on shielding has the advantage of renewability, the disadvantage of a rather risky installation method.

If we look at the experience with Mir, which although quite smaller isn’t the daintiest object in orbit either, we see a structure with a design life of 5 years held up for 13 and it was manmade mishap that almost killed it. OTOH we have seen STS skin-tiles and windowpanes with deep bullet-shot-like gouges from encounters with space debris. (In Earth orbit the danger from loose nuts, fasteners, fragments of boosters, etc. is worse than meteoroids).

Real spacecraft don’t make what we think of as evasive maneouvers, but rather changes in the inclination and altitude of the orbit. If Mir is any precedent, ISS will have attitude control (to keep the power panels pointed at the Sun and such) and a limited time orbit-maintenance capability. So it may be able to swing around to show the smallest target to the oncoming threat, and very gently add or drop a couple of miles to the orbital altitude. A really major course correction or orbit boost would likely mean using a STS or a dedicated “upper stage” as a tug.


I recall seeing a documentary on the space shuttle, whereon repairs to a pitted window revealed that a large crater in the glass had been caused by a paint chip travelling at over 17,000 miles per hour.

Well, in regards to the actual size of the space station, does this really matter when moving it?

After all, it’s in space where friction is non-existant. So the slightest thrust can move the thing a few hundred yards in a matter of minutes.

So when a metoer is picked up on radar (or whatever they use), the station would have plenty of time to move.

If you don’t care how long it takes to get there, then no. But if you want to accelerate fast, well, F=MA, or A=F/M, so yes, thhe mass of the station matters. Twice the mass, half the acceleration.

And of course, if you want to go to a higher orbit, it takes twice as much energy if the station is twice as heavy.

the more massive the orbiting object, the more it takes to change it’s angular momentum.