I do my own research. Really. I do.

[winneganfake]

Look, google is going to take far too long to find this kind of stuff with the time I have available, so here's to hoping that someone either knows this, or knows it well enough to make a definite answer:


1. So, um, just how big a blast would it take to make the atmosphere ring like a bell?


2. Failing that, is it theoretically possible to have an object in high semi-geosynchronous orbit (figure a month minimum for it to make a single orbit around the planet) that can maintain that orbit for a long period without the use of attitude or positioning jets? And yes, it has to be semi-geosynchronous- the thing must fully orbit the earth, but do so at a slow rate of speed.

A League of Extraordinary Bastards sticker to the first one who can definitively answer both, if they want it.

Comments

[anarchangel23.livejournal.com]

I'm no expert, but:

1) I'm not sure if that would be a function of the blast size. I would suspect it would have more to do with resonant frequencies, but I'm not sure if even that is possible, or what frequency would be required.

2)I'm pretty sure that all orbits decay and thus require attitude/positioning jets. I'm sure there's an orbital distance which would allow your rate of rotation, but I'm not sure what it is.

So, I'm no expert, and thus, can provide no helpful answers :)

[inaurolillium.livejournal.com]

All orbits decay eventually, but with the right relationship between mass, altitude, and orbital period, it can take a very long time.

[anarchangel23.livejournal.com]

Yeah, I was assuming the question was related to a very long time period... such as if they were abandoned by humans for thousands of years... what sort of scale are we talking here for decay from a very stable orbit?

[inaurolillium.livejournal.com]

Ultra-long-term-stable orbit? Well, for an orbital period of roughly a month, at an average altitude of 384,400 km, you're looking at a mass of 7.347673×10^22 kg. (That would be the Moon.) If you're willing to have it closer to the Earth than that, it can be less massy, but it will also have a shorter orbital period.
A cube of solid gold of that mass would be a bit more than a third of a kilometer on a side. Make it dense enough and it'll shrink. The problem you've now got is that it's massy enough to fuck with the tides.
But making a seriously massy object isn't the only way to provide a long-term-stable orbit. Put an object at the L5 point, and it only needs enough mass to provide sufficient inertia to compensate for debris strikes. You can also avoid the tidal problem, since whatever pull your satellite might exert comes from the same direction as the moon. It might, however, be visible to the naked eye, if it's large enough. And you retain the same orbit period as the moon.

[anarchangel23.livejournal.com]

I've been away from physics too long, I keep having all these "duh, of course" moments! Thanks :)

[inaurolillium.livejournal.com]

You're welcome. I haven't done much physics in a good long time, either, but I do keep reading SF, and just enough of it is solid on the science part to keep my brain in shape.

[inaurolillium.livejournal.com]

Geosynchronous means that it orbits the earth in 24 hours (geo=earth, syn=same, chrono=time, "taking the same time as the Earth" to orbit/rotate), remaining in space above the same spot on the earth throughout its orbit, so you're NOT talking about a geosynchronous orbit, even semi-. And yes, it is absolutely possible for an unpowered object to remain in the same orbit for long periods. Look at the moon, for example. All it takes is the correct amount of mass for the orbit chosen. High, slow orbits require fairly massy objects -- again, the moon comes to mind -- but as long as it's closer in than the moon, it can have less mass. Also, remember that the moon isn't all that dense (for a lump of rock), and that a very dense object could have sufficient mass at a much smaller size. There's also the L5 point -- a point directly between the centers of gravity of the moon and earth, at which the gravitational pulls even out. It is VERY easy to stick an unpowered satellite there, which is why people want to put a colony there, and within certain parameters, it doesn't actually matter how much the thing masses.

[winneganfake.livejournal.com]

Ok, that answers that- it's a good answer, too, just unusable for what I need, which is and accidental knocking of a not-so-massy object (like a communications satellite) up into the kind of orbit I described, and still having close enough range to broadcast some kind of cohesive signal. L5's too far off for that, unfortunately (not for the signal, but a random accident that sent something that far would make it impossible for the sat to stop itself, even with using all of its reaction mass.)

Anyways, first full solution, so the LXB sticker is yours, if you want it.

[inaurolillium.livejournal.com]

What project is this for, out of curiosity?

[winneganfake.livejournal.com]

Sorry, but it's tedchnically NDA'd at this point. Or rather, it's not NDA'd, so I'm not sre what I can and can't say about it yet. I can get away with saying its a different twist on tthe old post-apocalyptic genre, but that's about it.

hmmm

[typhonset.livejournal.com]

1. Insufficient cohesive surface tension (http://en.wikipedia.org/wiki/Surface_tension). The effect would be a whopping "thump", stunning humans, vaporizing ambient moisture and killing small animals.

2. The fifth Lagrangian point (http://en.wikipedia.org/wiki/Lagrangian_point), as mentioned above, could allow a massive object to 'park' in an orbit.

Re: hmmm

[winneganfake.livejournal.com]

Actually, a whopping thump is just about the effect I'm after, so long as it can get somewhere close to the proverbial "sound heard 'round the world." type of effect. It's close enough that with a little handwaving, it can work. Thanks!

L5's good, but it's too high for what I had in mind. That solution to this whole thing is looking to be far too much trouble as it is, so I think I'm leaving that line of query to die out.