archive: SETI FW: [ASTRO] Re: The Habitat

SETI FW: [ASTRO] Re: The Habitat

Larry Klaes ( )
Wed, 14 Oct 1998 12:46:00 -0400

From: Philip Chien
Sent: Tuesday, October 13, 1998 11:14 PM
Subject: [ASTRO] Re: The Habitat

There was a gag about a couple on a colony spaceship in bed saying "Let's
make a kid, and he better be a good pilot because he's got to land this

Colony spaceships going to other solar systems will certainly be a
challenge, but sociological will be minor in comparison with the
engineering challenges.

Consider the tens of thousands of immigrants who traveled from Europe or
Asia to North America before regular two-way travel - on risky trips with
little chance of ever returning or communicating with their families ever
again. A very small percentage made the return trips to their native
countries, the rest effectively wrote off their previous lives when they
emigrated. Anybody who made the journey before the 19th century (more
reliable ships, transatlantic cable) certainly took more risks and was more
separated from their families and culture. From that sense an interstellar
system habitat isn't that difficult.

If Gerard O'Neil-style space colonies ever become a reality then it seems
logical that one of those colonies would eventually become the first to
leave the solar system. They wouldn't have extremely strong ties with
'mother Earth' anyway (just as somebody who moves 1000 km. from home may still communicate and occasionally visit but is for the most part a
transplant settled in their new location). And a self-sustaining colony
with an existing infrastructure (social, economic, etc.) wouldn't have that
far a leap to make to convert their earth-orbiting (or outer solar system?)
colony spaceship in to an interstellar spacecraft.

As far as who goes it would have to be individual choice. Find enough
people with the right skills you need, cajole others to join the journey,
kick out anybody who doesn't want to go, and make whatever other deals you
need. The final mix will include adventurers, nuclear families -- like any
other emigrant ship. Large sign-up bonuses are not likely to be important
incentives (where would you spend it?) but other forms of incentives could
be used to attract the appropriate skills - just like any other job.

The typical 2nd or 3rd generation colonist would have about as much
interest in returning to Earth as a typical North American nth generation
immigrant has of going back to some ancestor's original country. Certainly
an interest in where mom or grandfather came from - but not any longing
desire to go there.

Communications with mother Earth is quite feasible - although it would be
of a restricted nature. A modulated high power LASER could send constant
communications from Earth to the colony. While there's no practical way
for the interstellar travellers to specify specific pieces of information
there's an easier solution - just transmit everything (or as much as
practical). The travellers would get older and older news as they got
further and further away but would be able to still receive news. It would
have more bandwidth than current forms of communications, and would be more practical than the Pony Express or many other forms of distributing the

The key challenge would be complete self-reliance without any way of
obtaining spare parts, or other critical systems. At least when the
European explorers came to North America they could be assured that there
was air to breathe, water, and other things necessary for life.

As far as destination is concerned a nearby star is not the only
possibility. If the journey's already planned which will take 50 to 100
years to complete, another 25 to 50 years makes little difference.
Certainly if the NASA Origins program finds a nearby solar system with
Earth-like planets that would be the most logical goal.

As far as what to do when you get to another solar system, that depends on
what you want to do, and the type of propulsion.

If you use a high thrust short-duration propulsion system (chemical
rockets) then you can brake in to orbit around the other solar system and
explore a bit (say 100 years or so). With enough local resources you could
refuel your propellant tanks and then decide whether to go back to Earth or
go on to another system. In an extreme case you could bring enough
equipment along to build a clone of your habitat and each of the two
habitats could then take a different journey. (This eventually leads to
the SETI Ferimat(?) paradox)

With a low thrust long duration propulsion system (ion propulsion) you'd
have to accelerate until you're half way to your destination and then turn
around and deaccelerate the rest of the way if you wanted to enter orbit
around the destination solar system.

In either case I'm assuming the habitat has enough propellant to handle
whatever's required to deaccelerate in to the destination system.

The obvious alternative if you don't have enough propellant is to slingshot
through the solar system, collecting whatever remote sensing data you can
given the limited amount of time there, (like the Pioneer and Voyager outer
planet flybys) and aim your trajectory so you can point yourself towards
another solar system of interest.

If you're incredibly lucky - or talented in your choice of interstellar
trajectories - you may be able to find a permutation where you make flybys
of several of the planets in your destination system and the star in a
manner which permits you to get 'captured' by that solar system, or even a
trajectory which reverses your course and aims you back towards the Earth.
(a couple of well placed black holes here and there, a can-do engineer
named "Scotty" and almost anything's possible)

Simon Hastie said

> Actually there are four books:
> all of them are great, you should read them.

Well the first Rama book is incredible - Arthur C. Clarke at his prime. I
believe it's supposed to be made in to a movie.

As far as the rest they were written by Gentry Lee and had little
involvement by Clarke. While interesting, I'd hardly call them "great"
(IMHO of course) and certainly don't count them in my list of Clarke books.

"Songs of a Distant Earth" is another excellent Clarke novel which involves
interstellar travel with a large population, however it uses 'deep sleep'
instead of multi-generations to cover the interstellar distances.

Philip Chien, KC4YER

Earth News
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