Among the proposals to visit the Alpha Centauri system "Breakthrough Starshot" seems promising, at 0.2 C. I'd rather inject something into orbit, though; and nobody is undoing a 0.2 C delta-V once in motion. Instead, let's shoot thither: a big lumbering colony-ship, at A.
Phase one is to get a crew out to an outer-system orbit where there's a very large asteroid waiting, outside an ice giant's gravity-well. Neptunian Trojans look good for that.
Next: hollow out a Rama. If the crew run low on metallics, then supply from Jupiter's Trojan asteroids. At first it can be a pre-Rama; we're going to be kicking this thing around.
When ready, and satisfied that this massive thing can support a colony: evacuate said colony, except for crew and a big sperm/egg bank. Next time the planets align (mostly Venus): rocket the colony into the inner Solar System, for the gravity boost.
Our own personal Rama curves into a fast trajectory toward the Alpha Centauri system. The next worry is to decelerate - and to figure out which trajectory of A/B is the most worthwhile decelerating TO. "Breakthrough Starshot" will have given to Rama some information; Rama itself will learn more as it gets closer.
Once there's a reasonable trajectory plotted, set Rama's course and get into that orbit. At A/B expect said orbit to be horrendously elliptic, at first. But that's a big success considering where we started! [NOTE 1/6: If there be a colony ship en route to A/B, expect Earth to zoom a flyby thither and also at Proxima, and deliver pertinent information in advance.] About twenty years out from Centauri is also a good time to start birthin' those babies.
An initial orbit around A (sometimes called Rigil-Centaur) with 2:3 resonance against B - called Ẓalīmān, or "Tolimán" - should work for stability. Tolimán orbits at 79.91 of our years. The Plutonian resonance yields period of 119.9 years on the outside. Rama will need to store the energy it takes from A on its fry-by.
The new youngsters will settle the vast empty (or rocky) spaces of Rama and, also, will pilot craft to bring more resources INTO Rama. Rama's orbit can be adjusted to swing by the richest of these deposits. I suggest the Hilda, which skates by WHAT WOULD BE Tolimán's L5-3 IF IT HAD THEM. A Hilda would have a year of 53.27 of our years.
The Ramaeans build habitats of their own orbiting A and Tolimán, proper. The aim is to build more Ramas from Centauri's own asteroids and comets. At least one of these can be sent over to Proxima, as well.
UPDATE 1/6: The Centaur's Foot is 1.21 times the mass of Ẓalīmān. Their Librations 4 and 5 are unstable when this ratio is less than 24.96. (Similarly, A/B together only offer 16.3 times the mass of Proxima.) Maybe I can blame Hop. Anyway I don’t expect a happy hunting ground in any of these stellar Librations. The Hilda orbit itself, however . . .
ANNOTATION 1/11: The notion of using a century-ship has been questioned, first by Alastair Reynolds and then more forcefully by Kim Stanley Robinson. I recall other short-stories about the longterm effects of a closed system on a human population. KSR has been questioned, himself.
I side with KSR only this far: to vet a Rama biosphere in Solar System conditions first, before rocketing the thing into a century-long trajectory. The Neptune L4 outpost needs to prove it can sustain at least one generation of human citizens and maybe more. Also, Chung at Project Rho is right: there is going to be regression-to-the-mean. the Solar System must enforce some local eugenics upon the Rama, on the outset. Those in the later generation less-suited for this trip will need to be taken off this rock and replaced with cooler heads.
No comments:
Post a Comment