Gocek.Henr@PARC-MAXC.ARPA (01/06/84)
Someone recently commented that manned, interstellar flights would be made before the turn of the century. I agree that the technology will be available, and the question of "Why?" doesn't bother me. The problem is that, assuming that faster-than-light travel is not available, by the time the space travellers get anywhere in their 20th century ship, they will have been passed by 21st century travellers using more advanced, 21st century transportation systems. The early travellers would waste several years, only to arrive at an already established colony. It's one thing to test out hardware in orbital missions or earth-moon missions, but missions that never return are another story. That's why it was feasible to send Mercury crafts into space, rather than simply waiting for the space shuttle. Interstellar travel is a situation where I think we should wait for reasonable technology. The first oceanic crossing wasn't in a canoe. The first manned, deep space crossing shouldn't be in a primitive craft either. Gary
REM%MIT-MC@sri-unix.UUCP (01/08/84)
From: Robert Elton Maas <REM @ MIT-MC>
Minor point, in the early days of sailing we didn't have radio, so
there as no way a fast ship overtaking a slower ship en route could
find it to pick up its crew. Instellar travel will be different.
There's no reason the crew of the first instellar ship need be left
adrift by the second ship. The first crew can enjoy the first voyage
while they're still young, instead of waiting forever for the "It's
Tuesday, we must be passing Vega" high-speed ship, then in their old
age join the crew of the second-generation <technology> ship. This
assumes they are going in the same dirction. If not, your original
complaint is invalid, since a canoe traveling to North America will
get there faster than a sailing ship headed to India will get to NA,
so the effort won't be wasted.
Now on to my main point...
I'm not totally disagreeing with you, but I have some amendments to
your thesis:
Date: Fri, 6 Jan 84 13:15 EST
From: Gocek.Henr@PARC-MAXC.ARPA
It's one thing to test out hardware in orbital missions or earth-moon
missions, but missions that never return are another story. ...
Interstellar travel is a situation where I think we should wait
for reasonable technology.
(1) There's a general fallacy involved here, although it only slightly
applies here, but I'll cover it first: There's no point in spending
effort on anything this year because next year we'll have better
technology and the same amount of effort can get much more
accomplished. This would be partly valid if effort were a
"non-renewable resource" like petroleum. But effort is a "renewable
resource", so if we do no work this year at all, we've totally wasted
this year's quota of effort, wheras if we "waste our effort/time"
working inefficiently this year at least we'll get a little
accomplished, even if it seems small when we look back from next year,
it's better than nothing. Even if it were a non-renewable resource
like money, there are flaws in the argument. From a capitalist view,
even though work we do this year is less productive than work we wait
to do with better technology, everybody else is more productive next
year too, so by the law of supply and demand the monetary value of
work next year will be less, so it turns out the return on investment
is the same now as next year. Thus private industry might as well
spend money to make products&services to sell now, even though it
seems they'd get more done if they wait. From a holistic view, if
everybody waits until next year to invest money in new works, because
the same money will accomplish more useful work next year, nobody will
be doing the bootstrapping work this year that will make next year's
technology possible, so in fact next year we won't have the new
technology we were waiting for. Thus government MUST continue to
invest money in pushing the frontiers even if it seems the money would
be more effectively spent using better technology next year.
(2) Now regarding interstellar flight: In the case of unmanned probes,
your thesis doesn't apply. (Since you were writing about manned trips,
I'm not contradicting you, yet, but see section 3 below.) When the
Voyager was first proposed, I started to think "why bother sending
Voyager out past Saturn to Uranus and Neptune using this cruddy
chemical-rocket technology, when in five years the ion rocket will be
developed and it can get there in half a year, overtaking the Voyager
somewhere between Saturn and Uranus, with much better computers and
instruments, grossly improving on Voyager's images of Saturn and
passing Voyager before it even gets to Uranus? But then I thought,
well it's nice to take out insurance, just in case the ion rocket takes
longer to develop than expected and the super-Galileo has to use
chemical rockets too, so launched in 1981 the super-Galileo doesn't
get to any of the planets before the Voyager does. Little did I know
it'd be worse than my worst fears, the planetary program would be
slashed almost out of existance, the Voyager 2 being several years
past Saturn, almost to Uranus, by the time the Galileo is launched
with chemical rockets in 1985 or 1986 or ..., and the super-Galileo
never even getting considered. The Voyager 2 may in fact be the only
spacecraft to reach Uranus during my lifetime.
Eventually of course some advanced-technology ship will overtake any
of our various early travelers (Pioneer 11, Voyagers 1 and 2). But
during that first part of the trip the early craft will arrive first
and chart the course for the later craft as well as provide scientific
information that helps us design the instruments and helps us plan the
observation program of the later craft. Examples: Pioneer and Mariner
gave a crude view of the planets, allowing us to pick landing targets
on Mars for Viking and optimum viewing targets for Voyager. In
particular Pioneer showed Saturn to be a lot more interesting visually
than we thought it'd be, prompting us to invest in good cameras on
Voyager. Pioneer and other craft were purturbed by the gravity of
things it passed by, and measuring its trajectory gave us better
knowledge of the orbits and mass of the satellites so the trajectory
of Voyager could be planned better. Voyager in turn gave us enough
information that Galileo will use an elaborate gravitational-assist
programme to make each looping orbit in a different place to gather
maximal information with minimum fuel consumption. The first
interstellar probe with proper instrumentation will provide valuable
information about the Oort cloud and other possible hazards to later
faster-moving craft. -- Other advantages of spacecraft out there, even
if moving slowly: With telscopes far beyond Pluto, we'll be beyond the
obscuring effect of "zodiacial light" (dust in the Solar system) so we
can get truly accurate measurements of our galaxy, and furthermore our
base for triangulation will be larger so we can directly measure the
distances to stars much further out than we can now, furthermore the
relativistic purturbation of the Sun will be reduced so our paralax
(triangulation) measurements can be more correct. We'll be able to
measure the distance to nearby stars more accurately too, so as to
accurately plan later trips by advanced craft. Also the scientific
knowledge we gain in this early stage of interstellar exploration,
both the geometry of our galaxy and the physics of the Oort cloud an
vicinity, may be useful in understanding what we're dealing with so
our later ships can take appropriate instead of useless instruments,
and so those ships won't have to take unnecesary precautions about
imagined but non-existant interstellar hazards yet can still take
prcautions against real hazards discovered by the early ships.
Recall how Voyager 1 found the rings of Saturn less dangerous than
expected so Voyager 2 could "shoot the rapids" and thus gain more
info, while one of the probes found Jupiter's environment to be much
more dangerous than expected, and nearly got its electronics fried, so
later craft could keep their distance.
(3) When we decide that we need people to make on-the-fly (real-time)
decisions, because our artificial-intelligent computers are complete
idiots compard to the task needed, the above argument applies to
manned craft. The first manned craft will act as a survey ship to
scout for dangers later craft will want to avoid, and to scout for
interesting things to report back which may modify/influence the
programme of later ships. But you say "how can we send a crew on a
one-way trip, in virtual isolation?", how can we subject our crew to
cruel and unusual punishment? Well, the fun-life of most people
consists mostly of (a) TV, (b) interaction with friends&co-workers and
office machines (including computers) at work and around the home, and
(c) travel to see new and interesting things. Well, TV can be beamed
to the crew, with only a month or so delay for Oort-cloud journeys,
and with a large crew in a full closed-ecology system all of (b) would
be provided. The only problem is (c), where instead of traveling to
random places the crew is taking one very long trip to one kind of
place. I guess we'll have to get the kind of crew that doesn't want to
visit Paris or Rome every so often except by vidiophone/telepresence,
and will instead be content at spending the rest of their lifetimes
exploring the Oort cloud. Perhaps their children will be picked up by
a later-generation <technology> craft and moved to a colony around
another star, or perhaps back to Earth to find their "roots", or
perhaps to a later-generation <technology> space probe traveling at
relativistic speed to explore a nearby cluster of stars in person.
Perhaps their children (original crew's grandchildren) will be picked
up again to make a colonization voyage at very-relativistic speeds to
M13. Perhaps their children (ggc of original crew) will be picked up
yet another time to embark upon colonizing the Magenellic clouds.
(Z) We wouldn't want to promise the first crew they'd be on their way
to Alpha Centauri, knowing full well they'd arrive 1000 years after a
faster ship has goten there and established a colony. But each
generation <technology> of ship could be used to send more crews a
little bit further into the Universe, pushing the frontier a bit
further outward and exchanging all the latest information with Earth
and with other crews on other ships in different directions at the
same time. The time from when they start out until they are overtaken,
would not be wasted.