From: Terry W. Colvin (fortean1@mindspring.com)
Date: Tue Mar 05 2002 - 21:22:41 MST
One Lifetime Is Not Enough for a Trip to Distant Stars
By NATALIE ANGIER
< http://www.nytimes.com/2002/03/05/science/space/05TRAV.html >
Nobody knows why our early ancestors decided to get off their knuckles
and stand upright. Maybe they just wanted a better view of the stars.
And when sky gazers finally realized that the heavenly lights were not
the footprints of the gods, but rather millions of blazing stars like our
Sun writ far, they began to wonder, How do we get there? How can we leave
this world and travel, not merely the 238,000 miles to the Moon, or 35
million miles to Mars, but through the vast dark silk of interstellar
space, across trillions and trillions of miles, to encounter other stars,
other solar systems, even other civilizations?
According to a group of scientists for whom the term "wildly optimistic
dreamers" is virtually a job description, it will indeed be very
difficult to travel to other stars, and nobody in either the public or
private sector is about to try it any time soon. But as the researchers
see it, the challenge is not insurmountable, it requires no defiance of
the laws of physics, so why not have fun and start thinking about it now?
At the annual meeting of the American Association for the Advancement of
Science, held last month in Boston, scientists discussed how humans might
pull off a real-life version of "Star Trek," minus the space Lycra and
perpetual syndication rights.
They talked about propulsion at a reasonable fraction of the speed of
light, a velocity that is orders of magnitude greater than any space ship
can fly today, but that would be necessary if the light-years of space
between the Sun and even the nearest star are ever to be crossed.
They talked about the possibility of multigenerational space travel, and
what it might be like for people who board a space ship knowing that
they, their children, grandchildren and descendants through 6, 8 or 10
generations would live and die knowing nothing but life in an enclosed
and entirely artificial environment, hurtling year upon year through the
near-featureless expanse of interstellar space.
They talked about how big the founding crew would have to be to prevent
long-term risks of inbreeding and so-called genetic drift. They talked
about how the crew's chain of command would be structured, what language
people would most likely speak, and what sort of marital and family
policies might be put in place.
And they talked about food, all of which would have to be grown,
cultivated and synthesized on board.
"One thing is almost certain," said Dr. Jean B. Hunter, an associate
professor of biological and environmental engineering at Cornell. "You'll
have to leave the steak, cheesecake and artichokes with hollandaise sauce
behind."
Many of the subjects raised during the session were so fanciful that at
times it felt like a discussion of how to clone a unicorn, and indeed
half the presenters moonlight as science fiction writers.
Nevertheless, the researchers argued, human beings have shown themselves
to be implacable itinerants, capable of colonizing the most hostile
environments.
Dr. John H. Moore, a research professor of anthropology at the University
of Florida, compared a theoretical crew of spacefaring pioneers to groups
of Polynesians setting out tens of thousands of years ago in search of
new islands to populate.
"Young people with food and tools would set out in large flotillas of
canoes," he said. "Nobody knew if they would ever come back, the trade
winds went in only one direction, and many of them perished in the ocean."
Yet over time, the Polynesians managed to colonize New Zealand, Easter
Island and Hawaii.
Still, no human migration in history would compare in difficulty with
reaching another star. The nearest, Alpha Centauri, is about 4.4 light-
years from the Sun, and a light-year is equal to almost six trillion
miles. The next nearest star, Sirius, is 8.7 light-years from home. To
give a graphic sense of what these distances mean, Dr. Geoffrey A. Landis
of the NASA John Glenn Research Center in Cleveland, pointed out that the
fastest objects humans have ever dispatched into space are the Voyager
interplanetary probes, which travel at about 9.3 miles per second.
"If a caveman had launched one of those during the last ice age, 11,000
years ago," Dr. Landis said, "it would now be only a fifth of the way
toward the nearest star."
Dr. Robert L. Forward, owner and chief scientist of Forward Unlimited, a
consulting company that describes itself as "specializing in exotic
physics and advanced space propulsion," argued that rockets and their
fuel would be so heavy that they would prevent a starship from reaching
the necessary velocity to go anywhere in a sane amount of time. He
envisions a rocketless spacecraft that would be manufactured in space and
equipped with an ultrathin, ultralarge sail, its span as big as Texas but
using no more material than a small bridge. A beam of laser light or
high-energy particles from a source on Earth, in space or perhaps on the
Sun- drenched planet of Mercury would be aimed at the sail, propelling it
and its attached module to as much as 30 percent the speed of light - or
about 55,000 miles per second.
At that pace, said Dr. Forward, a crew would reach Alpha Centauri in
under 50 years.
"You could get a bunch of 16-year- olds, train them and then send them
out at the age of 20," he said. "They'd have a long, boring trip, reach
Alpha Centauri when they're in their 60's or 70's, do some exploring, and
send everything they learned back home."
Admittedly, the astronauts would not make it home themselves. "It's a
lifetime job," Dr. Forward said. "But it could be done in a single
generation."
For longer journeys, designed with multigenerational crews in mind, an
onboard engine and fuel source would be required, perhaps something
powered by nuclear bombs, or the combining of matter and antimatter in a
reaction that converts both substances into pure energy.
However the ship is propulsed, the researchers agree that it must be
comfortable for long-distance travel. That means creating artificial
gravity by gently rotating the craft; a spin no greater than one or two
revolutions per minute would suffice.
It might also mean calling upon architects with Disney-esque
sensibilities.
"The inside of one of these long- duration space habitats might feel like
the inside of a shopping mall," Dr. Landis said. "Malls are carefully
designed to use space efficiently, yet to give you the feeling that
they're more spacious than they are."
And malls, of course, are a great place to bring the family. In Dr.
Moore's view, the good old-fashioned family is the key to success in
space.
"Over the past several decades, space scientists and writers of science
fiction have speculated at length about the optimum size and composition"
of an interstellar crew, he said. They have imagined platoons of Chuck
Yeager-type stalwarts grimly enduring all hardships, or teams of bionic
and vaguely asexual crew members overseeing freezers of embryos that can
be defrosted and gestated as needed.
"Some of the scenarios proposed so far are downright alarming from a
social science perspective," Dr. Moore said, "since they require bizarre
social structures and an intensity of social relationships which are
quite beyond the experience of any known human communities."
In deciding how to organize a star mission, Dr. Moore looks to the most
"familiar, ubiquitous, well-ordered and well-understood" of social forms,
the human family. "Virtually every human society in history has been
structured along kinship lines," he said, "from small-scale foraging
societies to empires comprising millions of people."
Lines of authority and seniority in a family are reasonably clear, and
when they're not, well, there's always the time-out chamber.
In Dr. Moore's rendition, all recruits for an interstellar odyssey would
be guaranteed the opportunity, though not the requirement, to marry and
have children. Mate choice would be part of the bargain as well, with the
population cannily structured so that each cohort of individuals, on
reaching sexual maturity, would have about 10 potential partners of a
similar age to select from.
Dr. Moore and his colleagues have developed a computer simulation called
Ethnopop, in which they asked how large the crew must be in order to
maintain genetic variability over time while still allowing crew members
a choice of sex partners. They determined that a founding crew could be
as small as 80 to 100 people and stay viable for more than a thousand
years, assuming that two rules were followed: women waited until they
were in their mid-30's or so before having children, and they had only a
couple each. Counterintuitive though it may seem, said Dr. Moore, delayed
childbearing and small families are known to help maintain genetic
variability in a closed population.
Genetic diversity may be essential, but Dr. Sarah G. Thomason, a
professor of linguistics at the University of Michigan, argued that the
same could not be said for language. "You want everyone to be able to
talk to each other as soon as they're on board," she said.
As Dr. Thomason sees it, the likeliest lingua franca for a starship will
be ó gracias a Dios ó English. After all, she said, English is the
language of the international air traffic control system, the scientific
community and the educated class generally. English is the official
language of 51 of the 195 nations of the world, and it is the second
language of many others.
Yet, while crew members will be expected to speak English, their accents
are likely to be quite diverse, and the English that their children and
grandchildren end up speaking will have a rhythm and texture of its own ó
Space English. And though Dr. Thomason believes that the basic structure
of Space English is not likely to change much from that of the mother
tongue, teenagers will, of course, invent words of their own and drop
words of scant use. "I can imagine the loss of words like snow, rivers,
winter, mosquitoes, if they're lucky," she said.
Another arena that will test the limits of human ingenuity is space
cuisine. Without livestock on board or supply ships to restock the
pantry, crew members will have to be entirely self-sufficient. Dr. Hunter
of Cornell envisions crops grown in hydroponic gardens, in which plants
are suspended in troughs like rain gutters, and water and fertilizer are
trickled slowly over their roots. Among the possible food groups are
wheat, rice, sweet potatoes, beans, soy, corn, herbs and spices.
In addition, space-minded agronomists are exploring the marvels of
microbes. Plants take weeks to grow, but yeastlike micro-organisms
replicating in vats can be used to churn out significant quantities of
carbohydrates, sugars, proteins and fats in a matter of hours. Of benefit
to a community in which recycling is not just a personal virtue but a
public necessity, micro-organisms can live on the carboniferous waste
products of plants and people.
"There's a protein product called quorn, which is made from filamentous
mold," Dr. Hunter said. "Not to make a joke of it, but it does taste like
chicken."
Some clichés, it seems, are truly universal.
Copyright 2002 The New York Times Company
--
Terry W. Colvin, Sierra Vista, Arizona (USA) < fortean1@mindspring.com >
Alternate: < terry_colvin@hotmail.com >
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