Day: February 20, 2009

SKYLON in the News…

Cosmos Magazine has a news bite on SKYLON which reports older news about SKYLON and funding of an engine study by the ESA. Goods news, but no breakthrough. At least the word is out there.

Here’s something to consider: SKYLON’s development is likely to be roughly $10 billion. How does that affect price-tag for LEO services? If 30 SKYLONs are made and each flies 200 times before replacement, then the development cost divided over all those 6,000 flights is $1.67 million, or $139/kg. If 300 SKYLONs are built then it’s just $13.9/kg. That’s development cost, to which we add per unit cost, per flight costs, and fuel costs, then profit. SKYLON uses 66 tons of hydrogen and 150 tons of LOX for propellant, which costs ~ $250,000 total adding $20.8/kg to the bill. Then there’s vehicle costs incurred due to wear and tear of the components of the cryogenic system, SABRE ejector ramjets, landing gear, RCS and avionics every flight. I’m not sure what the best estimate of those would be, but let’s assume roughly comparable to the fuel costs. Thus the bill is up to $55.5/kg. If a SKYLON costs ~$200 million per unit – expensive jet-fighter value – then that’s $1 million per flight over its lifetime, which adds $83.3/kg. That seems excessive and might go down with large production volumes. Perhaps we can halve it. Thus SKYLON might cost $100/kg to deliver payload to LEO.

How much payload do 300 SKYLONs need to carry to LEO to drive costs down? All up they represent 720,000 tons of payload lofted on 60,000 flights. If a 1 GW SPS masses 3,000 tons, including the GEO delivery system for its subcomponents, then 240 GW of SPS power could be installed. To power the whole world to the tune of 24 TW then 30,000 SKYLONs making 6,000,000 flights will be needed. Larger LEO cargo vehicles would reduce this somewhat. The Star-Raker SSTO, designed in the late 1970s as a ramjet/rocket hybrid, was designed to deliver 120 tons per flight, thus reducing the fleet or the flight numbers ten-fold. Alternatively Space-Elevators may eventually be developed, but that’s totally dependent on materials and laser advances that are unpredictable. SKYLON, I would submit, can get the job done.

A Numerical Testbed for Hypotheses of Extraterrestrial Life and Intelligence

[0810.2222] A Numerical Testbed for Hypotheses of Extraterrestrial Life and Intelligence.

The study in question by Duncan Forgan. It uses pretty standard assumptions based on Panspermia, Habitable Zones (Stellar & Galactic), plus some stochastic guesstimation of the emergence and fate of ETIs. Even assuming they last as long as their stars once they spread to all the planets of their system, there aren’t too many in the Galaxy.

Of course the question then is: what happens if They proceed to colonize other systems?

At “The Habitable Zone” a Belgian amateur astronomer, Raoul Lannoy, frequently gives us space-optimists a space-pessimist take on things. Recently Raoul brought up a Space Review piece on mass colonization of space – i.e. billions leaving Earth to inhabit the rest of the Solar System and beyond. Mark Eby had this to say… Mark’s response …essentially that in human history small bands of intrepid wanderers have been the ones to spread far and wide, beyond the ancestral range.

Unless a star-system is being evacuated then mass colonization seems rather more difficult than it is worth. As independent New Beginnings for the human race, Star Colonies would have great practical and symbolic value, helping preserve humanity against system-scale collapses from whatever cause might destroy a system. Spread across the Galaxy our species would seem protected against the largest known energetic events in the Universe… except, so far spread, we wouldn’t remain the same species for very long in cosmic terms. We’d undergo divergent evolution, unless a deliberate policy of genetic mixing was pursued. Even more rapid divergence would occur if the pioneers were those posited small bands – the so-called Founder Effect
 would result in rapid fixation of any new alleles and genes while the effective population was small. Each new band settling into a different system would be a species divergence point unless more colonists followed.

Keeping those small intrepid bands in mind, once settled and grown strong, we have to ask if they will then spawn a new band of intrepid pioneers eager to venture further into the Galaxy. Geoff Landis modelled such a process as a discrete percolation process, which spread into the Galaxy not as an inexorable wave, settling every star system, but as dendritic filaments that left large unoccupied voids between them. This suggests our Galaxy could be well settled and we could still be left alone, as per the Fermi Paradox.

Alternatively They’re here and They’re watching us, but keeping quiet in any frequency we can scan. An old saying is that perfectly coded signals should be indistinguishable from noise…

ER1470 Reconsidered II

A bit over a year ago a poster by Dr. Timothy Bromage on the craniofacial development of the hominid ER 1470 received a lot of press because his reconstruction made the hominid look more ape-like. Bromage wasn’t the first to reconstruct ER 1470 like that – Alan Walker had reconstructed it differently to his colleague Richard Leakey along Australopithecine lines – but Bromage’s team were the first to use laser-scanning and 3-D manipulation of the skull to fit it according to known developmental principles. A surprise result was the small estimate of 526 cc for the brainpan’s volume versus the previous estimate of c.750 cc. Now a new paper by Bromage and colleagues estimates a volume closer to 700 cc, thus closing the discrepancy between the two.

When looking for this newer paper by Bromage, which he had said was forthcoming, I found an awful lot of Creationist propaganda using his work’s relatively tentative conclusions as some sort of definite “evidence” against concluding the species represented by ER 1470 is a human ancestor. But the affinities of a single skull is largely irrelevant to that question and the baseless propagandising should disgust any honest seeker of the truth.