Comments on: Doomsday in space? Maybe not.

By: Chance

Chance — Tue, 27 Jun 2006 18:39:33 +0000

Just another example of the liberals who would have us cut-and-run from the alien fleet menace. We’re fighting them in space so we don’t have to fight them here.

By: shubber Ali

shubber Ali — Mon, 26 Jun 2006 22:38:44 +0000

Prove what? The non-existence of a fictitious threat that you think my tax dollars should be wasted to defend against?

The onus is on YOU to prove they exist.

Otherwise, the following argument has as much validity:

we should spend precious space $ to defend against the impending invasion by the space alien fleet which is due to attack soon by building a giant fleet of space laser platforms.

Prove that the space alien fleet does NOT exist. Don’t tell me that you can’t find it, prove to me it DOESN’T EXIST.

I think that most would agree that I should prove it does exist…

By: Kevin

Kevin — Mon, 26 Jun 2006 07:43:18 +0000

Prove it.

By: Shubber Ali

Shubber Ali — Sun, 25 Jun 2006 19:47:59 +0000

What stops some amateur group or unfriendly government from launching a handful of parasitic microsats and sending some to GEO? What trajectories could be used?

That they don’t exist yet..?

By: Paul Dietz

Paul Dietz — Sun, 25 Jun 2006 14:55:48 +0000

Charles: explosions above the latitude at which magnetic fields lines connect to the magnetotail would cause the plasma to rapidly escape. Explosions at low latitude would trap the plasma at low altitude.

The concern would be explosions at latitudes between these. There is a latitude where the magnetic field lines go out to the position of GPS satellites, for example.

The explosions would probably have to be thermonuclear to really have a significant effect. Starfish was a 1.4 megaton explosion. The stored magnetic energy in the external portion of the Earth’s magnetic field is about 200 megatons, so to get significant plasma beta (ratio of plasma pressure to magnetic pressure) you’d need rather hefty explosions (although damage to satellites could occur even at lower average beta.)

By: Kevin Parkin

Kevin Parkin — Sun, 25 Jun 2006 08:08:09 +0000

a few thoughts on this:

1) The US military is increasingly reliant on commercial satellites. I presume these are unhardened.

2) The Galaxy IV failure (http://en.wikipedia.org/wiki/Galaxy_IV) suggests to me that picking a small number of key satellites can have a sufficiently crippling effect.

3) What stops some amateur group or unfriendly government from launching a handful of parasitic microsats and sending some to GEO? What trajectories could be used? Could we even track something the between the size of a coke can and a shoe box in the vicinity GEO? If there were already something there, how would we know?

By: Charles Phillips

Charles Phillips — Sun, 25 Jun 2006 02:19:54 +0000

The results of the early US and Soviet out-of-atmosphere tests (the US series including STARFISH comes to mind, and the Soviets launched a bunch from Novaya Zemla to the regions of the open magnetic field lines) indicate there would be more limited problems. The results of such an explosion at the altitude of a satellite with a low apogee/perigee would be devastating to satellites such as the Space Station but would not be harmful to most other satellites. The sun-synchronous NOAA satellites might be at some risk, but the Iridium and other medium height satellites would be unaffected. All geosynchronous satellites would be well above the effects.

Most geosychronous satellites are armored against charged particles anyway, since they can be assumed to be outside of the Earth’s protective magnetic shield at some point in their operational lives.

For a low latitude explosion, the cascade of charged particles would be trapped in a band of latitudes about the equator – and would spread around the world in a belt. The particles would have a hard time crossing magnetic field lines in general.

For an explosion above the Arctic or Antarctic, the charged particles would be quickly ducted either into the atmosphere or out into the magnetotail.

I would not want to be an astronaut on the Station – and some low altitude satellites would be fried – but the most probable nuclear explosion in near space would not directly affect our economy. Other than increasing defense budgets again.

By: Paul Dietz

Paul Dietz — Sat, 24 Jun 2006 00:17:37 +0000

And it doesn’t even have to reach orbital altitude — just the charged particles do. Exploding the bomb at high magnetic latitude, above the atmosphere, will cause the electrons and positrons to spiral out to much higher altitude.

By: Edward Wright

Edward Wright — Fri, 23 Jun 2006 22:09:31 +0000

> However, as the witnesses at the hearing pointed out, most major communications satellites are
> not in LEO but in GEO, which is much harder to reach (the exceptions are the ORBCOMM, Iridium,
> and Globalstar satellite constellations), while navigation satellites are in MEO, which is also difficult to reach.

A nuclear weapon doesn’t have to reach GEO or MEO. All it needs to is reach orbital altitude, not orbital velocity.