Tuesday, November 09, 2010

Thinking about Rocks

So, throwing a spacecraft at the Asteroid Belt, with the asteroids on average being a million kilometres apart, your chances of hitting one are not exactly high, which is why the spacecraft we have sent out that way got through unscathed. However, what is an asteroid? From what I can gather they are the objects we can see through our telescopes and have counted. Beyond that the number is estimated and estimations vary widely. I also have to wonder what we can see. I’m guessing that objects the size of a football or a pea aren’t picked up. The chances of something the size of the Pioneer or Voyager craft hitting one of these was probably negligible, but they’d certainly have to be taken into account if you’re presenting a profile 5 kilometres across and travelling at 20,000 kilometres per hour.


Jonathan said...

Hi Neal,

There was a Horizon programme on the subject of the asteroid belt on just last week. iPlayer link here:


Wraitholme said...

It would seem that the term you want is 'Meteoroid', being an object 'smaller than an asteroid' but still floating around in space.


Depending on who's definition you subscribe to, that means that an asteroid is bigger than either 10m or 50m.

Since millions of them hit the atmosphere every day, the assumption is high that there's a huge number of the things floating around out there... allowing for the big gravity well we're sitting on that's probably distorting the distribution, I'm guessing.

20000 kph is, if my math serves me right, around 5kps. Wikipedia suggests that some meteoroids can get up to 26kps. 30kps is very painfully fast to hit anything, let alone rocks with the possibility of interesting metals in them.

I think I'd want a hardfield or some Prador exotic metals between me and the front of the ship :P

Found a couple more sites of possible realworld interest... much slower speeds, but relevant nontheless:



Neal Asher said...

Thanks Jonathan, I'll take a look at that when I get the bandwidth (that is, when Caroline stops watching Poirot).

Wraitholme, I guess you could call this particular post thinking out loud, but also to see what might feed back. I think the point is that the Asteroid belt consists of everything from dust up to the large objects that have been found there.

The next two are not Polity book, by the way - they're much closer to home.

Djehuty said...

Fantastic website I've perused a lot:


It helped me out when I was creating a roleplay about hard space combat.

Neal Asher said...

Thanks for that, Djehuty, it certainly looks worth a perusal.

Neal Asher said...

Enjoyable program that, Jonathan. Interesting to learn about that asteroid detected heading towards Earth and then actually impacting as predicted. Interesting too to learn the theory that water on Earth was delivered after its formation. I think I already see the SF story of a comet or ice asteroid being found in the future with some three-billion year old space drive fitted... Cheers!