Small interstellar payloads

Since colonization in the future is likely to accomplished by means of
sending a microscopic "seed" of self-reproducing machinery (the
"astro-chicken"), I was wondering if there has been much thought on
what propulsion system would be best to send such a payload on an
interstellar journey.

For instance, while antimatter seems like a ridiculously expensive
proposition in the human case, for an extremely small payload it seems
conceivable that it could be cost effective.

On the matter of laser propulsion, how tightly could we focus a laser
beam at an interstellar distance? What would be the effect of having
essentially no payload mass on such a system?

wrote:
Since colonization in the future is likely to accomplished by means of
sending a microscopic "seed" of self-reproducing machinery (the
"astro-chicken"), I was wondering if there has been much thought on
what propulsion system would be best to send such a payload on an
interstellar journey.
snip
On the matter of laser propulsion, how tightly could we focus a laser
beam at an interstellar distance? What would be the effect of having
essentially no payload mass on such a system?

In some ways - laser beams are better for intermediate sized payloads.
The problem is that, even with lenses on the order of hundreds of
kilometers, the sail that they are being focussed on has to be quite
large.

Dropping the payload by a factor of 100, would mean (to provide a
suitable lens) you'd need a lens of 100 times the area to focus.

A bigger laser may just be cheaper, and if it is, then there is a
certain point at which it doesn't make sense to go smaller.

alexandershepp;
Since colonization in the future is likely to accomplished by means of
sending a microscopic "seed" of self-reproducing machinery (the
"astro-chicken"), I was wondering if there has been much thought on
what propulsion system would be best to send such a payload on an
interstellar journey.
Ra--Rn--ion at greater density and much improved exit velocity is
offering perhaps 100 fold improvement over the existing Xe--ion, as
well as Ra--Rn--ion is good for way more than 1600 years w/o
refrigeration, and otherwise perfectly capable of exceeding 10% 'c'.
There's also the option of Ra--LRn--Rn--ion that's worth a bit of
phase shift energy as added trust, as this element changes from a
high-pressure liquid form of Rn becomes a vapor of fast moving hot
ions.

For instance, while antimatter seems like a ridiculously expensive
proposition in the human case, for an extremely small payload it seems
conceivable that it could be cost effective.
And don't forget seemingly lethal, although antimatter propulsion
becoming sufficiently speedy to boot, say conservatively 0.5
'c'(150,000 km/s) up to the obvious maximum of achieving 'c', whereas
colliding with so much as a dust-bunny can also become lethal.
However, a terminal velocity comet like bow-wave should help to divert
the smaller stuff.

On the matter of laser propulsion, how tightly could we focus a laser
beam at an interstellar distance? What would be the effect of having
essentially no payload mass on such a system?
Why bother to use laser as propulsion when the exchange of raw
information is so much more valuable, and it's available at the speed
of light as being worthy of nearly 300,000 km/s.

I believe 0.05 mr is doable and at best offering a propulsion worthy of
eventually achieving 0.5 'c' (150,000 km/s), although on behalf of our
deploying interstellar communication packets is where that would simply
demand a space-based laser cannon or at least a moon-based version in
order to minimize the laser beam divergence caused by our badly
polluted and otherwise H2O rich atmosphere. Ideally LL-1 and if need
be LL-2 are a couple of sufficiently nearby locations worthy of having
that laser cannon situated, with 1 TJ/ms or perhaps 1000 TJ/us worth of
photon energy potential seems a bit of a stretch but otherwise
technically doable. For the interstellar application, the given
spectrum should be configured a little different than whatever's the
prime output of our sun. Perhaps using 337 nm or of something longer
than 900 nm would become noticed better off than 532 nm.

For practice, why not try 425 nm (+/- 25 nm) or even as great as 532 nm
for accomplishing something a whole lot closer to home, like Venus?

Sorry that none of what I have to offer is of nearly scifi "VN
technology" or even all that laser sailing worthy, just plain old
conventional physics-101 and of believable hard-science at work. You
know, the same old energy-in = energy-out sort of stuff, and otherwise
doable from damn near what's off the shelf, like setting up a laser
communications platform at LL-1 or upon our moon, and always the
TRACE-VL2 platform that's specifically on behalf of the Earth/Venus
interface, along with continued and considerably more advanced
solar/TRACE research as a bonus.
-
Brad Guth (thinking pro life on Venus)

Sorry that none of what I have to offer is of nearly scifi "VN
technology" or even all that laser sailing worthy, just plain old
conventional physics-101 and of believable hard-science at work.

VN technology is hard science, particularly the CAD/CAM route.
Interstellar travel is a long way off admittedly. In fact CAD/CAM tells
us that any robot worth having, any robot that can perform household
tasks and assemble flatpacks is a potential VN.

on 1 Mar 2006 20:32:11 -0800, sez:
` Since colonization in the future is likely to accomplished by means of
` sending a microscopic "seed" of self-reproducing machinery (the
` "astro-chicken"), I was wondering if there has been much thought on
` what propulsion system would be best to send such a payload on an
` interstellar journey.

` For instance, while antimatter seems like a ridiculously expensive
` proposition in the human case, for an extremely small payload it seems
` conceivable that it could be cost effective.

` On the matter of laser propulsion, how tightly could we focus a laser
` beam at an interstellar distance? What would be the effect of having
` essentially no payload mass on such a system?

If it's really microscopic, consider ionizing it and using an ion
accelerator in orbit. The accelerator may need to have large spacial
extent, but consider it constructed like the projected designs for the
TPFT - discrete segments held in alignment dynamically. Each segment
provides its +/- pull/kick, independently solar powered. Large mass
relative to a single molecule can mean a long time getting the
projectile up to speed, but with lots of space to play with, you can
have large insulating distances allowing a very large charge to be
deposited on it, which compensates somewhat. Infrastructure cost will
be quite large compared to your suggested options, but may give better
performance. Any photon pressure scheme takes a long time to build up
velocity, during which time the flux impacting the target shrinks as
the target flees. This can be compensated for by building focussing
devices, but the size required for these to be effective over the
distances required rapidly becomes impractically huge.

A question arises then about the design requirement. How much of a
hurry are you in? The simplest goal is simply to exceed solar system
escape velocity with vast numbers of probes, preferably billions,
dispersed widely. This may take millions of years to achieve
successful "seeding", but could be relatively easy to accomplish. If
you want results sooner, the scale of the enterprise expands steadily
to heroic proportions with desired velocity. Recall though, that you
have to get your probes to land intact. Being microscopic, their
primary braking option is solar wind at destination system, so
it's not clear that pushing velocity up to near c gets you any
advantage.

By the way, I would say the seed pellet contents will be more
likely to be bio-engineered or bio-mechanically hybrid, rather
than nanomachinery. A zygote is an incredibly efficiently compressed
information carrier. We will be more likely to piggyback on this
existing technology rather than build from scratch...


--
================================================== ========================
Pete Vincent
Disclaimer: all I know I learned from reading Usenet.

I have no doubt that "VN technology is hard science" because, my
LSE-CM/ISS is actually highly based upon employing robotics of a
sufficient AI form of applied VN technology. Unfortunately, most of
humanity can't hardly grasp much of anything unless it's related to
protecting their sorry butt.

People do have difficulty assembling their flatpacks. I think if
someone like IKEA did the research, not to produce a VN machine but a
flatpack assembler they would get a payback. The Pons Assinorum is in
fact the flatpack.

Compared to the naysayism of our NASA, IKEA might even be VN technology
overkill.

A "flatpack assembler" sounds perfectly interesting and it's certainly
of what's doable without going all that much robotic postal.

What's the maximum individual deployment capability of "flatpack"
tonnage that can be gotten into the LL-1 orbit, say if given a month to
get it there?
-
Brad Guth

What's the maximum individual deployment capability of "flatpack"
tonnage that can be gotten into the LL-1 orbit, say if given a month to
get it there?

I have descibed thisd as the Pons Assinorum - The bridge of asses. This
means that having done FP assembly we can chart a route. We need our
PA, the next thing we need is a replicatable route with all the
components CAD specified. Now everytingh that goes into space today is
CAD specified, it is difficult to concieve of anything that isn't.

The question that should be asked is the weight of seed, and seed
replication rate. There may in fact be a tradeoff between these two
things. Mass production is very efficient in producing a large volume
of widgets but to mass produce you need factories for every part and an
enormous seed weight. To some extent we have to think of how things
were done in the pre industrial age. Not quite we do have electricity
and the high precision of robotic motion. Not available in the Middle
Ages.

In article ,
pete wrote:
A question arises then about the design requirement. How much of a
hurry are you in? The simplest goal is simply to exceed solar system
escape velocity with vast numbers of probes, preferably billions,
dispersed widely. This may take millions of years to achieve
successful "seeding", but could be relatively easy to accomplish...

Bear in mind that the probes will be taking cosmic-ray damage while in
transit, and won't have energy available for in-flight repairs. A century
is unlikely to be a problem, but transit times of millions of years will
leave few to none of the probes functional at the destination. This is
one disadvantage of going really small...
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

I said a Pons Assinorum. Hubble is more complicated than a wardrobe but
complexity means nothing to AI. All you need is a bigger memory. Also
an IKEA system could quite esily replace the gyros on Hubble.