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Meet the Cousins of Our Ancestors #1

No surviving species today is the same as a fossil or hypothetical form claimed to be an intermediate form, but living creatures preserve historical information that is otherwise lost to us in their unique adaptations and the adaptations they share with fossil/hypothetical forms. So whenever the press says a living creature is somehow “ancestral” or “primitive” it’s a furphy. A characteristic or two might retain features from long ago, but the lineages of all creatures alive today have been evolving for exactly the same length of time. Some lineages might evolve very quickly – if only to stay in the one place – but we’ve all had the same timespan to evolve in.

With that caveat consider the Ascidians or Tunicates, filter-feeders who, oddly, make a cellulose coat (‘tunic’) and, at some point in their lives, share certain features with our own Chordate/Vertebrate lineage. So who are the Tunicates? Sea-squirts are the ones we encounter most commonly, but there are a few other fascinating Tunicates who don’t just cling to rocks – Salps (Thaliacea), Doliolids, and Pyrosomes.

Salps can form incredibly large colonial masses and suffer massive die-offs when their population overloads – this happily sends carbon to the bottom of the sea to get buried, and thus form a major part of the carbon cycle.

Doliolids also form colonies, though quite differently to salps. They have a rather complicated alternating breeding system – propagating asexually part of the time, then sexually.

Pyrosomes really piqued my interest because they form huge tubular colonies – many metres long and sometimes wide enough for divers to swim into. They’re also bioluminescent.

Isn’t the natural world amazing?

A New Picture of the Early Earth

New York Times article discussing the latest evidence on the Hadean Aeon (4.5-3.8 Gya) being relatively less nasty than previously believed…

A New Picture of the Early Earth

…with the possibility of oceans, plate tectonics, even Life dating back to c.4.4 Gya. The colder, even chilly Earth that has emerged is potentially just what the Doctor ordered when it comes to Life’s Origins, as this “Discover” Magazine article explains…

Did Life Evolve in Ice?

…organic molecules concentrated into little frozen pockets inside ice do amazing things. Stanley Miller, he who created organics in a spark-gap vessel back in 1953, researched what those organics would do in ice for over 20 years. Now it seems his original samples have been doing amazing things in their vials too… New Results from a 1953 Experiment Offer Hints to the Origin of Life …forming more complicated chemicals than anyone expected. But how do those organics get enough energy to make the leap to more complexity? The Hadean was well known as “The Hell Age” because of its massive meteorite impacts, but new work reveals such events have a bright side… Devastating Meteorite Strikes May Have Created Earth’s First Organic Molecules …thus providing another means to create complex organic chemicals.

Finally the “New York Times” article above mentions a carbon isotope imbalance in ancient diamonds that might hint at Life 4.25 Gya… The Earth’s Oldest Diamonds May Show Evidence of Earliest Life. Whether that claim is verified or not will require better dating and actual microfossils before everyone is convinced.

Deuterium Fusion Rockets

Back in the 1950s a lot of work was done on the practical aspects of triggering fusion in various bomb designs and fuels. A relevant fuel is deuterium. Friedwardt Winterberg was a nuclear physicist involved in the very secret work on triggering fusion reactions without using fission bombs to create the solar-interior conditions needed for the reaction. Now some of that work has been declassified and Winterberg has put two new papers on the arXiv…

Deuterium microbomb rocket propulsion

Ignition of a deuterium micro-detonation with a gigavolt super marx generator

…which might allow nuclear fusion Orion-style rockets to launch from Earth without the fallout.

The Hobbit Challenge

We were not Alone. Less than 12,000 years ago we shared the planet with Homo floresiensis – the Hobbits. Aunty (the Australian Broadcasting Corporation) screened an updated documentary on the Hobbits, with some seriously teasing ideas… The Hobbit Enigma …which is fully downloadable. Well worth a look. It gives a voice to the sceptics as well as the believers, but makes a strong case that the Hobbits really are small-bodied, small-brained hominids unlike anything previously imagined.

But what are they? Two possibilities –

(i) a different evolutionary track from Australopithecus roots. Bill Jungers backs this idea, especially after he fit together near perfectly the hip bones of the Hobbit (LB-1) to the sacrum of Australopithecus afarensis (“Lucy”).

(ii) a dwarfed version of Homo georgicus – the 1.8-1.7 million year old hominids from Dmanisi in Georgia, which have much smaller brains than Homo erectus plus some post-cranial features uniquely their own.

But did the ancestors of Homo floresiensis migrate to Indonesia? Or did our ancestors migrate to Africa from Asia?

Notes:

Some links –

Were the Hobbits Cretins? …medically cretins i.e. deficient in iodine. Very unlikely as the main source of iodine, fish, were found amongst the food remains in the cave.

John Hawks’ Hobbit cretin FAQ …more reasons why that analysis is wrong.

Is the Homo floresiensis phenotype due to mutations in the PCNT gene? …a rare condition causes an otherwise normal person to grow to half-size – including an otherwise normal, but small brain. A very ascerbic Anthropology blogger’s take on the matter. Science is about scepticism…

Bradshaw Foundation page on the Hobbits …initially what drove Mike Moorwood and colleagues to Flores was 30,000 year old Asian paintings in the Kimberlies, Northern Territory.

Carnival of Space Week #73

Carnival of Space #73 is up at Alice’s Astro Info and it has some real fascinating ones.

First up – The Martian Chronicles ponders a crashed moonlet.

Second – Starts With A Bang ponders whether galaxies have more stars than bodies have cells. Has the interesting fact that human somatic cells only number about 4 trillion, with another trillion white blood cells, a trillion platelets, 30 trillion red blood cells, and a whopping 40 trillion bacterial cells living in our guts. Are you your human DNA alone???

Third – Twisted Physics discusses the Pioneer anomaly, and its possible origins in MOND.

Fourth – AstroENGINE seeks evidence of varying radioactive decay in Cassini’s RTGs. Apparently the researchers pondering varying decay think Cassini’s Pu-238 might be the wrong isotopes for the job. Not big on beta-decay, which is a neutrino susceptible weak-force mediated decay that the researchers are studying. Nice to know alpha-decay can be relied on…

Launching the Space Elevator

Recent years have seen a lot of optimistic reappraisals of the requirements for space elevators – instead of multi-billion ton structures anchored to asteroids the current designs mass less than 1,000 tons and can support 20-ton elevator cars. However there are a few problems, one of which I’ll discuss here: How to power it? If you’re observant you might notice I’ve written a few thoughts on this issue before but a few modifications of my first discussion are necessary.

Firstly, a potentially high efficiency solar-thermal conversion system is doable using a Johnson Thermoelectric converter – basically a closed-cycle fuel-cell that is aiming for an 85% of Carnot Limit efficiency. But what does that mean? Carnot efficiency is basic to thermodynamics – it’s the extractable work from a cyclical thermal process. In this case a fluid is heated by concentrated sunlight, goes through the converter then through a heat-sink, then returns to the concentrator. When it comes to dumping “waste” heat in space the hotter the heat-sink, the better. I’ve seen 600 K quoted so often it’s what I’ll assume. The Johnson converter is hoped to operate at 1300 K, thus the Carnot Limit is (1300K – 600K)/1300K or 0.5385. Thus the Johnson converter can turn 45.77 % of the heat directly into electricity, and 54.23% has to be dumped by a heat-sink to space.

How much power is needed? Assuming the 20 tons usually quoted for the ribbon-crawler, then to lift-off at a sustained 56 m/s straight up needs a lifting-power of 11 MW – which means about raw 12.2 MW electrical power with 90% efficiency in the power supply and motor systems. That means 26.7 MW of solar heat needs to be collected. If we assume the solar constant, 1365 W/sq.metre, then our collector is 19,560 sq.metres. Our heat sink, which at 600 K is radiating 7350 W/sq.m from BOTH sides (assuming a flat radiator), is 985 sq.metres. The solar collector, focussing on a converter at 1300 K, means the sunlight is being concentrated by a factor of ~120 times, thus the heavier thermal converter has an area of just 165 sq.metres (assuming all collectors and radiators are close to being perfect black-bodies.)

How big is 19,560 square metres? Almost 5 acres – if it was two circular collectors they would have a diameter of 158 metres each. Big, but doable with large inflatables, which is easy to do in space. However for about 60 km or so the crawler isn’t in space, and inside the atmosphere, with ravenous winds, big solar collectors aren’t practical. So what to do?

Current designs assume high powered lasers, but the efficiency of lasers is dreadful – less than 20% of wall-socket power becomes laser beam energy. Assuming the 12.2 MW at the crawler, about 85% conversion efficiency from laser light, then the crawler’s laser light receivers are taking a beating of ~14.4 MW of laser energy, and the ground base is pumping 72 MW of electrical power into the lasers on the ground – or worse, depending on atmospheric absorption. Still the laser receivers don’t have to be really huge – if they’re dissipating the waste heat at 500 K, then twin receivers would only 20 metres in diameter each.

But what if we can get above the atmosphere before inflating the collectors? To power that climb – 60 km – we need a sufficiently energy dense power source to do the job. First question: could it be done with a petrol engine? As air thins out in a hurry it would need oxygen tanks for at least part of the trip – a big part probably. Also the power the engine would need to supply would be over 13,000 horsepower, which would be quite an impressive engine. Obviously it would be a gas turbine as that’s the only design regularly built at such power-levels – they’re frequently used to provide peak power by electrical utilities in the multi-megawatt range. At 35% efficiency thermal efficiency and 90% power conversion efficiency then the 13,000 hp of electrical power means a 42,000 hp gas-turbine… which is starting to get seriously heavy. Good-bye 20 ton crawler.

So what about EEstor ultra-capacitors? According to Wikipedia’s latest update on EEstor they’re now claiming about 2.5 MJ/kg energy density. If we assume 0.9 efficiency electrical-to-mechanical power efficiency and 0.9 from battery-to-motor then a 60 km trip at 56 m/s straight up needs 14.55 GJ of energy – some 5,820 kg of capacitors. Not bad and improved by a “booster crawler” that carries the main crawler to the desired height, then rolls back down while regeneratively braking and recouping some of the power.

So, if EEstor’s claims pan out, then the Solar-powered space-elevator might just be viable.

News Bites 26 August 2008

Sky survey yields new cosmic haul …including a new Inner Oort Cloud member – making two, the first being Sedna.

Solar plane makes record flight …stays aloft 3 days by recharging lithium-sulfur batteries via very light-weight solar cells. It cruised at 18 km up (temp -70 C, pressure 0.075) and is hoped to be a battle-theatre “Eye in the Sky” or a civilian comms-platform. The company is hoping for 5 year flight-times for a large version – carrying 450 kg versus the 2 kg payload on this bird.

An end to spaghetti power cables …MIT demos power transfer via magnetic induction resonance with 90% efficiency over 1 metre. Enough to get rid of cables in the home.

Stellar Still-births …brown dwarfs are aborted stars – low mass objects perturbed out of a trinary birth-nebula. Thus they’re a cosmic class of their own.

Genome of simplest animal reveals ancient lineage, confounding array of complex capabilities …placozoans, Trichoplax, share a lot of genes and introns with both cnidarians and bilaterians, even us humans. And there’s at least 13 species now distinguished by these researchers… something to update all the web-pedias which still say there’s just one, plus a maybe. Not so, and a quick Google reveals a few papers to that effect since 2003… come on people! Pick up your game!

Exploding Chromosomes …because DNA has one charge along its length it can’t be wound up tight without some help. In humans it’s histones, big molecules, but in dinoflagellates it’s just sodium and calcium ions. A neat trick with some lessons for the prehistory of genomes.

One Man’s Crater Quest …a New Jersey native, Daniel Connelly, is trying to interest professional geoscientists in a gigantic crater smack bang in the middle of Australia. Problem is it’s a bit hard to see. He’s been roving the Outback trying to gather evidence – he’s convinced and has convinced his wife, a physician, but the pros aren’t biting yet.