Rendezvous with Rama

Chaps

A C Clarke's Rendezvous with Rama had a large extraterrestrial vessel
paying a visit to our solar system, with it being spotted somewhere
out near Jupiter.

I've got two questions

1 -with current and near future technology, would we be certain to
spot something like this coming into our solar system early on, or
could it well get much closer to us without being spotted?

2 - how close could such a vessel get to Earth, without being spotted
if it tried to hide ie if it came in keeping the sun between itself
and us, and then 'hid' behind, say, Mars or Venus and they moved
closer to Earth on their orbit


Not that I'm expecting this to happen, but more a question of
scientific robustness of Science Fiction

M

On Mar 16, 8:59 am, Maurice W wrote:
Chaps

A C Clarke's Rendezvous with Rama had a large extraterrestrial vessel
paying a visit to our solar system, with it being spotted somewhere
out near Jupiter.

I recall there was once long ago a very good radio adaptation of it.

I've got two questions

1 -with current and near future technology, would we be certain to
spot something like this coming into our solar system early on, or
could it well get much closer to us without being spotted?

Depends on whether they were trying to be stealthy. It would be a
matter of luck whether one of the whole sky survey systems spotted it
assuming small asteroid size and low to moderate albedo. But if they
didn't want to be seen a 50-100 year technological advantage would
probably be enough for them to remain completely undetected. Imagine a
modern stealth plane up against WWII air defences - they would be well
below the equipment noise threshold.

And it is likely that a lot more than 100 years of technological
development is needed for interstellar travel.

2 - how close could such a vessel get to Earth, without being spotted
if it tried to hide ie if it came in keeping the sun between itself
and us, and then 'hid' behind, say, Mars or Venus and they moved
closer to Earth on their orbit

It is easier for them to hide by reflecting to us a random view of the
empty space behined them. Vey simple pasisve technology. Think of a
F-117A with no acute angles and mirror finish on all surfaces. So long
as they never reflect radar beams back to their source and leave no
engine exhaust which would be a dead giveaway they could follow a
ballistic trajectory through the solar system and be virtually
undetectable.

Regards,
Martin Brown

"Martin Brown" wrote:

Depends on whether they were trying to be stealthy.

LOL! Rama was a metallic cylinder 50 km long and 20 km in diameter;
I don't think you could get any less stealthy. ;-)

It is easier for them to hide by reflecting to us a random view of the
empty space behined them. Vey simple pasisve technology. Think of a
F-117A with no acute angles and mirror finish on all surfaces. So long
as they never reflect radar beams back to their source and leave no
engine exhaust which would be a dead giveaway they could follow a
ballistic trajectory through the solar system and be virtually
undetectable.

Indeed, but Rama was first detected by radar in the story, so we know
that it is not trying to mask itself...

On Fri, 16 Mar 2007 08:59:56 +0000, Maurice W wrote:
Chaps

A C Clarke's Rendezvous with Rama had a large extraterrestrial vessel
paying a visit to our solar system, with it being spotted somewhere
out near Jupiter.

I've got two questions

1 -with current and near future technology, would we be certain to
spot something like this coming into our solar system early on, or
could it well get much closer to us without being spotted?

No we would not be certain. There is a project called NEAT
(near earth asteroid tracking) which looks for asteroids and
comets that may pose a threat i.e. hit, earth. I'm sure someone
will correct me if I'm wrong, but I don't think they search all
the sky - just those parts that are visible from america.
Of course anyone trying to sneak up would need prior knowledge of
the planet's blind spot(s).

2 - how close could such a vessel get to Earth, without being spotted
if it tried to hide ie if it came in keeping the sun between itself
and us, and then 'hid' behind, say, Mars or Venus and they moved
closer to Earth on their orbit

It's many years (20+) since I read RvWR, but I recall that the
craft were long and thin. Given that, the cross section they present
to either a radar probe or reflected sunlight are proportionately
small, compared with their actual size.
The yanks' current stealth technology is probably good enough
to hide a small satellite in L.E.O.
If the craft came in fast and from above/below the plane of the
ecliptic (i.e. where no-one's looking) then I would expect it could
get pretty close, say to within the moon's orbit.
Maybe they're here already :-)

Not that I'm expecting this to happen, but more a question of
scientific robustness of Science Fiction

M


--
.................................................. .........................
.. never trust a man who, when left alone ...... Pete Lynch .
.. in a room with a tea cosy ...... Marlow, England .
.. doesn't try it on (Billy Connolly) .....................................

Peter Lynch wrote

The yanks' current stealth technology is probably good enough
to hide a small satellite in L.E.O.

AIUI there have been attempts at stealth LEO satellites, only partially
successful as a number of them have been tracked by "amateur" satellite
watchers.

If the craft came in fast and from above/below the plane of the
ecliptic (i.e. where no-one's looking) then I would expect it could
get pretty close, say to within the moon's orbit.
Maybe they're here already :-)

They've already landed and infiltrated most of the world's governments
and corporations. :-)

--
Hil