Sizing Up the Daedalus Interstellar Spacecraft 191
astroengine writes "How big would an interstellar spaceship need to be? New artwork of the British Interplanetary Society's 1970's Project Daedalus by the non-profit organization Tau Zero Foundation gives the impression that the fuel economy for a nuclear pulse propelled vehicle might be a bit steep."
Re:Spaceship? (Score:2, Interesting)
Or you could start with a small female crew, and thousands of "genetic samples". (Semen and eggs)
Re:Automation has a long long way to go (Score:4, Interesting)
I think you'll find that we can do that [wikipedia.org], if by "we" you mean the human race. IKAROS has passed Venus, and is still going strong.
Re:Nuclear fission propulsion (Score:4, Interesting)
Freeman Dyson published a paper called "Interstellar Transport" (Physics Today, October 1968, p. 41–45) on how to build an Orion spaceship to get to Alpha Centauri [wikipedia.org], so yes, it could carry enough fuel for interstellar travel. Your other two points are correct though.
Re:Spaceship? (Score:5, Interesting)
And if it were to be manned it wouldn't be a return trip so to allow for a sufficient genetic variation the crew needs to be at least 1600 individuals.
Otherwise the risk of genetic degradation would be too great.
Depends on what "too great" means. The Hutterite community in North America, a closed religious community, was founded around 1700 with a founding population of about 400 that was already highly inter-related (compared to world-wide human genetic diversity) and has now increased to 50,000. Genetic studies do show a measurable penalty in fertility and fitness with this high level of inbreeding, but the community is doing quite well nevertheless.
What is more there is evidence of major human populations developing from even smaller founder groups PLoS Biology, June 2005, On the Number of New World Founders: A Population Genetic Portrait of the Peopling of the Americas [plosbiology.org] asserts that "Taken together, the analyses in this study suggest a recent founding of the New World Amerind-speaking peoples by a small population of effective size near 70"
Now the lack of diversity in the immune system of the American Indians later led to an epidemiological calamity when diseases from the Old World were imported 10 or 15 millenia later, but this is an avoidable hazard for interstellar colonists.
But the key difference with a space mission is that there is much we can do to avoid genetic disorders and promote genetic diversity:
* Select colonists (or colonist couples) for genetic diversity,
* Use sperm/ova banks to import gentic diversity,
* Use genomic screening to screen out lethal genes (which can be applied in a number of ways).
These techniques can make inbreeding problems go away entirely.
Re:From the article: A major drawback (Score:2, Interesting)
The obvious trick would be to include a mass driver that shoots planetary probes. At the appropirate point of approach start shooting probes backwards, killing as much of the approach velocity as possible. With any luck and perigee/perihelion burns, perhaps the probes could achieve stellar orbit and send back more data.
That would be a good trick, maybe "nano-probes" that could be "shot" at 12.499999% of the speed of light in the opposite direction so they will be slow enough to be captured in orbit by the star?