RE: starship-design: unmanned missions, AI, etc.

["L. Parker" <lparker@cacaphony.net>]

Nels,

> Regarding detection of starships from afar.  If we assume that
> starships, both alien and human, are driven by fusion rockets or some
> other engine which produces plasma exhaust (likely, in my opinion), the
> plume of relativistic plasma should be visible from quite a distance
> (i'm too lazy to do the math).  Its heat signature should be even
> brighter.  I assume any civilization that is sending out starships would
> have a large constellation of "superHubbles" of which many would be
> monitoring nearby starsystems.  Exhaust trails would give them away.
> Incedentaly, tho' i don't favor arming robot probes, a manned crew could
> save themselves from hostile craft (including other humans) by using
> their engine as a thermonuclear flamethrower.

I was referring to detecting a flyby (fly through) mission. There would be
no exhaust plume since it wouldn't be decelerating. These missions would be
relatively small craft moving perhaps at most 0.6 c, more likely only 0.3 c
so there wouldn't be much of a secondary radiation or thermal signature
either. In short, unless they just happen to catch a reflection of sun light
off of it, they won't see it, and we do know how to hide it from visual and
radar detection.

We had quite a few discussions about this some time ago. Most of us felt
that we would be able to ascertain most of what we needed to know about a
potential target system via observation from Earth or Solar orbiting
telescopes. Once a star was determined to have habitable planets and
abundant asteroid resources, a flyby probe could be dispatched to refine the
data. Many of us felt that the flyby couldn't glean enough data to make it
worthwhile and we would jump straight to either a Pathfinder or Explorer
mission.

In which case, the first ship into the system would be manned...In which
case I would favor some limited form of armament. But keep in mind that
weapons are usually fairly mass intensive and would eat into the payload
fraction. Maybe the self destruct idea is the best one. Just wipe the
computers and kill the containment field on the fusion reactors....

There are many differing viewpoints on xenopsychology and the potential
threat of aliens. Try reading Pellegrino's "Killing Star" for the xenophobic
side. I'm afraid it isn't standard SF fare, it doesn't exactly have a happy
ending.

>
> 	Good idea about the gravity assist. Also, this 'worst case' scenario is
> only valid if the probe actually returned.  A one-way robot mission
> could radio a directional signal back home.  Unless the hypothetical
> alien craft were in the proper position (in the way of earth or one of
> the other radio lobes), it would not have any idea of where earth is
> (unless it were near enough to see the dish getting turned, in which
> case our probe could probably detect it).  Besides, spacefaring aliens
> are far from the top of the danger list.  To paraphrase Douglas Adams,
> space is really big.

It is more likely it would use maser or laser signals for communication at
that distance. There wouldn't be a dish to aim.

Lee

                                                      (o o)
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Any sufficiently advanced technology is indistinguishable from magic.

Arthur C. Clarke's "Third Law"