Category: Cosmos

Deuterium Fusion Starships IV

Friedwardt Winterberg’s fusion pulse driven space vehicles initiate fusion by injecting a rapid jolt of energy into the fusion target causing an implosion to high density fast enough that the fuel fuses before being blown apart and loses energy to brehmstrahlung. Vital to successful ignition is to rapidly compress the fuel to extremely high densities as well as injecting sufficient energy for the fuel ions to penetrate their mutual Coulombic repulsion barriers – normally the alike electric charges of protons repel.

But what if there’s a different way?

Leif Holmlid and colleagues have identified an ultra-dense form of deuterium about a million times denser than frozen deuterium. This Winterberg arxiv preprint discusses the implications of using such ultra-dense deuterium as a fusion target, concluding that the ultra-dense state is physically feasible and as a result it reduces the required 10 MJ impulse of energy to a mere 100 J.

Thus the new quantum-capacitor design theoretically has more than enough power (~1019 W/kg estimated) and enough energy storage (1 MJ/kg) to allow a very low-mass ignitor for pulsed fusion…

Digital Quantum Batteries, News at Technology Review and here…
Digital Quantum Batteries

…potentially allowing the construction of very compact space-craft if the ultra-dense state can be produced in large quantities. An earlier paper by Holmlid, Miley et.al. found small, ultradense clusters of deuterium in a metallic matrix. They speculated that larger amounts should actually be more stable, by making pressures on the enclosing matrix more even.

SO we may be justified in some speculation.

WARNING: RAMPANT SPECULATION WITHIN

First – flat discs of ultradense deuterium fired as fusion targets for a “fusion runway” starship launch system. Ignited by a proton beam at a convenient standoff distance and the resulting plasma directed by a Mag-Orion style field.

Second – fuel tankage maybe reduced to a tiny percentage. Very large mass-ratios may become feasible – assuming easy deuterium access. Imagine a cluster of simple pulse units which fall-away as exhausted. The BIS Moon-rocket of 1939 used such a cellular design for a mass-ratio of ~1000. Assuming 0.063 c exhaust velocity that’s a dv of ~0.43 c. Not bad for a fusion rocket. Alan Bond’s fusion rocket paper of 1972 (in the JBIS of course) assumed a 22,000 mass-ratio (i.e. x10 Vex) thus a dv of ~0.63 c.

Third – antimatter spiking of the fusion target starts making sense. Ultradense deuterium has a decent chance of reacting with the antimatter and usefully thermalising the gamma-rays from the neutral pions produced. If (a very big if) ultra-dense anti-deuterium can be made, then reacting the two together may allow something approaching the dream-goal of 0.78c exhaust velocity for an antimatter rocket.

Fourth – what would ultradense matter do to incident gamma-rays??? Could it reflect them? If we can collimate gamma-rays then black-hole and antimatter rockets become reasonable… feasible even, when we can power-up the machines to make them. Ultradense deuterium might also allow force-feeding the attometre scale black-holes of a Crane-Westmoreland blackhole rocket.

Fifth – could multilayer implosions of ultradense deuterium allow higher-level fusion, even black-hole creation? Hopefully the LHC will tell us if black-holes are easier to make thanks to higher-dimensions.

Ideas, ideas… more later.

What Knocked Uranus over?

The early Solar System was seemingly a violent place. Most versions of its formation involve massive collisions between near-planet sized objects – Mercury’s mantle was stripped by a collision, Venus’s rotation was stilled by a collision, Mars had a hemisphere almost ripped away, Earth made a Moon out of debris from a collision, and last of all Uranus was knocked over onto its side by a massive collision…

Or maybe not. New research by Jacques Laskar and colleagues, discussed at the arXiv blog, reveals another possibility – Uranus was tipped over by a lever. Not a big, long stick but a gravity lever thanks to a ‘moon’ that massed about 1% of Uranus. In Earths that’s 0.15 – a bigger version of Mars – and thus intensely interesting for another reason. There’s good reason to think that a large ‘planet’ is lurking just beyond the Kuiper Belt and its gravitational influence provides a neat explanation for the apparent “Kuiper Cliff” – the sudden end – of the classical Kuiper Belt.

So just how did a tiny thing like a “Macho-Mars” knock over a planet almost 15 times as big as Earth? Chaos. That and the migration of Uranus and Neptune from where they formed – between about 10 and 15 AU – to where they are now, at +19 and +30 AU respectively. How did they migrate? After they formed a large, heavy disk of unaccreted material still surrounded them. Close, hyperbolic flybys of this material gradually tugged the planets away from the Sun, with some nudging from Jupiter and Saturn, themselves caught in an unstable gravitational resonance a few hundred million years after formation… well maybe. There are various issues involved with timing that are yet to be resolved. Just how quick after formation was the migration is a major unresolved issue.

But the principle remains. With a big enough lever, even an Ice Giant can end up flat on his… side

Mars, Europa & Titan… Hopes for Life

The old SF Solar System had native alien races on just about every body. A prime example is Edmond Hamilton’s “Captain Future” series which featured human races on most moons and all the planets – we were all related by common descent from interstellar travellers from Deneb.

By 1960 those hopes were largely dashed by advances in spectroscopy and radio telescopes – even the most ‘hospitable’ planet, Mars, seemed bare of anything but scabby lichens.

By 1976 – in the wake of “Viking” – even lichens seemed a long shot.

But Mars didn’t wait for us to go visit to get rock samples. Billennia ago bits of Mars were blasted into space and ever since they’ve rained down as the occasional meteorite. In 1996 the Antarctic discovered meteorite, ALH 84001, became famous because microscopic traces looked like bacteria and its chemistry indicated it would’ve been palatable to life at some point in time past. Since then the argument for, and against, this claim has oscillated back and forth. Now new analysis has revived the ‘for case’…

Fresh claim for fossil life in Mars rock

…so who knows? But not really SF material, chiefly because life is probably common between the two planets anyway, due to the meteorite trading that occurs with every big impact. Mars life, as interesting as it will be, is in all likelihood akin to Earth-life.

Further afield are two more interesting prospects for “life as we don’t know it”, Europa and Titan. Titan is in the news again because of the discovery that acetylene is far more abundant in its methane lakes than anyone first imagined, up to 1% in solution…

Icy moon’s lakes brim with hearty soup for life

…which is great news for acetylene-powered life. But I don’t expect such life to be visible without a microscope either. Or rather individually I don’t expect to see it. However bacterial colonies and their traces can be large and colourful… something for a Titan rover to look out for around the lakes.

“I think the results are very exciting and further support the possibility for life on Titan,” says Dirk Schulze-Makuch of Washington State University in Pullman, one of the scientists who proposed the possibility of acetylene-eating life in 2005. “Titan should be one of the two top targets for future astrobiology missions, the other being Mars.”

Dirk’s webpage is here.

If we want ‘alien fish’ then we need an oxygenated ocean. Europa could have a complex biosphere because it probably has just such an oxygen-rich environment. Richard Greenberg has been studying Europa for some time and believes it provides a huge variety of habitats…

Thin Ice Opens up Opportunities for Life on Europa

…the tidal flexing of the ice shell means a flow towards the surface and away on a daily basis, keeping things stirred up and interesting for any life. Europa is also bathed in radiation from Jupiter’s magnetosphere which produces oxidants in its icy shell, which in turn get buried and drawn down into the ocean below…

Europa’s Oxygenated Ocean… Discovery News

…so the situation isn’t so hopeless in our Solar System as it once seemed. There’s enough oxygen to sustain about 3 million tons of sea-life. Doesn’t sound like much, but it’s nothing to sneeze at. There really might be fish – alien, unearthly ones – swimming beneath the crazed ice-shell of Europa.

A Captured Moon?

Most workers in the cosmogony business take it for granted that the Moon formed from the remnants of an impact between the early Earth and a Mars-mass object, usually called ‘Theia’. But that’s not the only theory. Throughout the 1970s and 1980s, in parallel to the Big Impact research effort, Robert Malcuit of Denison University was working on a Capture theory for the Moon’s origins, in an effort to explain its curious refractory rocks and the odd pattern of maria on its nearside face.

Of course, in hindsight, one can see the Capture origin idea was eclipsed by the simulation successes that Big Impact theorists have had, and the fairly strong direct geochemical evidence for kinship between Earth and Moon rocks. However not everything is so easily explained by the Big Impact and it’s by no means a ‘proven’ theory of Moon origin, merely a very good one. Science advances by distinguishing betweening good competing theories via experimental tests. But what discriminates between possible events that occurred about 4 billion years ago?

More later.

Relevant links…

MSNBC: Controversial moon theory rewrites history

Robert Malcuit’s page at Denison U…

2007 GSA Meeting…

Science News report from 1987…

Denison U Magazine piece 2007…

Discovery Channel News 2009…

NASA ADS entry on ‘Robert Malcuit’…

ADDENDUM:
Abstracts from the GSA 2009 meeting…

A RETROGRADE PLANETOID CAPTURE MODEL FOR PLANET VENUS: IMPLICATIONS FOR THE VENUS OCEANS PROBLEM, AN ERA OF HABITABILITY FOR VENUS, AND A GLOBAL RESURFACING EVENT ABOUT 1.0-0.5 GA AGO

A PROGRADE PLANETOID CAPTURE EPISODE ABOUT 3.95 GA AGO: IS THIS MODEL COMPATIBLE WITH THE INFORMATION FROM HADEAN- AND ARCHEAN-AGE DETRITAL ZIRCON CRYSTALS?

Beyond the Desert Earth…

Long, long after Earth has dried up it may end up locked tidally into facing the Sun on one side and the Cosmic Heatsink on the other, forever. What would such an Earth be like?

Earth: 7.5 Billion AD

…a description of an end-state scenario described by Jeffrey Kargel in 2003 (“New Scientist” article… “Hell on Earth” ), best seen in this graphic…

(a larger version can be found here… graphic) Basically one side of the Earth is a magma ocean at 2500 K, while the other is covered in the deepest, coldest night at 33 K. In between is an annular ocean surprisingly of liquid water. An ocean between silicate rain and argon snow. What strange remains might be scavenged from the strata of the Earth that many aeons beyond our day? What would we leave behind?

“Noise”

Harry Stubbs aka ‘Hal Clement’ was the Grand Master of alien planet building with such classic creations as Mesklin, Dhrawn and Tenebra. His last creation, prior to his passing in 2003, was Kainui in his novel “Noise”, which I finished reading yesterday. Kainui, as the name implies, was settled by Polynesians and the protagonist is a Moari from Earth who has come to Kainui to study its languages and their evolution on a new planet. Hal Clement books are known for their memorable alien characters, but in “Noise” the planet itself is the alien encountered. Not in a “Solaris” sense of being a unitary alien mind, but because it is so alien an environment, one to which the Polynesian colonists have had to adapt to.

Kainui is the inhabited member of a binary planet, which in turn orbits a pair of M class stars. It masses just 0.44 Earths, but has a radius of 1.15 Earths, thus a surface gravity of just 0.33 gee. The density is just 0.29 of Earth’s because the planet is covered in 2900 kilometres of ocean, which is liquid for much of its depth, but supercritical near the magma of the core. As a result of such intimate contact with the core, the global ocean is in a continual state of violent agitation, a constantly lethal din of underwater shock-waves which can kill any unprotected human much as dynamite in a pond kills fish. Also the atmosphere is filled with electromagnetic noise from endless storms, lightning filling its clouds and waterspouts are a continual hazard. Fortunately the endless spray of ions means no lightning can reach the ground – any charge leaks away too quickly – but above about 100 metres lightning becomes a risk. The atmosphere is bereft of oxygen and there’s no land or native life – how do the colonists survive?

All cities are afloat and dependent on a nanotechnological pseudolife ecosystem for food, oxygen, freshwater and metals – the latter two related by metal ions being accumulated by the removal of salts from the seawater. Vast pseudolife “fish” harvest ions and water deeper down, closer to the core, then rise for solar energy accumulation and tapping of their produce by humans. Due to the lack of long-range communications the planet can only be navigated, not mapped, and so the “fish” float freely, their bounty claimable by any who encounter them. People set out for months, years at a time of sailing the open ocean in search of promising “fish” and profitable trading with other crews and cities, usually in a small crew of adult sailors and young apprentices hoping to earn their adulthood through meritable sailing skills.

All in all Hal Clement has created an alien yet believable world inhabited by ‘alien’ people who are still familiar enough to care about. Kainui, in light of the multitude of Super-Earths and Hot-Neptunes discovered since 2003, is representative of many planets beyond our Solar System – Clement’s tale seems uncannily prescient in that light.

A Moistened Moon II

Over at the Planetary Society blog Emily Lakdawalla gives us a more detailed account of just how and what was found on the Moon…

The “Water on the Moon” Hoopla …part 2

…which explains a lot of the current ambiguity in the data. So is there another data point that might help resolve the issue?

The Bone-Dry Moon Might be Damp …discusses research on volcanic glass found in the Apollo moon-rocks and regolith samples. Apparently the glass has 50 ppm water, but lost ~95% during eruption, thus originally had ~750 ppm, which is close to Earth’s mantle value and the high end of the new observations. So the Moon has (some) water. Of course 0.075% doesn’t sound like much, but if all the water in the Moon’s mantle erupted then it really would have seas and a steam atmosphere. For comparison, Earth’s oceans, all 1.35E+9 km3 of them, represent just 0.15% of the Earth’s mantle’s volume and 0.05% of its mass.

AfterLives

Mankind’s first Science-Fiction, tales of visionary quests, let humans tread the pathways of the Immortals, gods and heroes. More recent varieties of SF have often focussed on the not-too-far-off here-and-now, but Big Stories and big themes lure even the hardest of hard SF writers back towards the eschatological and metaphysical. All sorts of “after-lives” have been imagined by SF writers, great and small. Alan Boyle, at his Cosmic Log, has pointed readers to the curious little collection of AfterLife tales by neuroscientist David Eagleman, Sum: 40 Tales From the After Lives. Other After-Life possibilities have been described…

(i) Resurrection as a Cyborg – One of the earliest versions of this SF trope, aside from “Frankenstein”, is a curious set of short stories about a Professor Jameson, by Neil R. Jones, who orbits his coffin in space and is revived by intelligent robots some 40 million years in the future to join them in a series of adventures. “Brain in a Vat” stories have followed ever since.

(ii) Resurrection on another planet – Most famously the late Phillip Jose Farmer‘s Riverworld series, upon which 36 billion people are resurrected via high technology – though no one at first knows this – and struggle to survive-in-style by taking charge of the resurrection machinery. Humans have ‘souls’ called wathans, but these are non-conscious when detached from the body, which has to be reconstructed by mass-creation technology that converts energy into matter.

(iii) Resurrection via Time-Travel – The Light of Other Days, a mind-blowing collaboration by Stephen Baxter and Arthur C. Clarke, uses wormhole-based time-viewers to record the lives and DNA of every person who has ever lived, and every foetus ever miscarried or aborted, and then nanotechnology to ‘resurrect’ them. Fortunately the human race, enhanced by wormhole direct-neural links, has figured out how to move en masse to other planets, to accomodate the resurrectees.

(iv) Souls as particles – Bob Shaw, in his Orbitsville trilogy and several short stories, pondered the possibility that the ‘soul’ might actually be a new kind of particle, a ‘mindon’, created by complex living matter. In the Orbitsville trilogy this idea has cosmological implications that explain much of the mystery of the alien Dyson Spheres.

(v) ‘Soul wave’ – SF is about asking “what if…” and David Brin rather cleverly asks “what if the old Jewish myths of ‘golems’ could be for real?” in his book Kil’n People. Duplicates of living people in clay, animated by a high-tech copy of an individual’s “soul-wave”, have transformed society. One Person can now do the job of a multitude, though with the drawback that one’s ditto only lasts for a short time before turning back into inert clay slop. And what’s the status of a ditto whose flesh-and-blood original has died? Are they legally alive? And where do “soul waves” go after?

(vi) What if “Death” is some kind of predator that only you can see – and avoid? Or the Angel of Death is an alien? Ian Watson poses these conundra in his tale Deathhunter, which is now 28 years old, but still enjoyable, especially the twist at the end. Nothing is as it seems in Watson’s AfterLife.

(vii) End of the World as Gateway to the Other World – which has several variants. On the one hand is the Omega Point scenario, in which the collapsing Universe allows an infinite number of experiences to be experienced in a finite ‘time’. William Shatner (James T. Kirk to “Star Trek” fans) has written a series of novels (“Quest for Tomorrow”) in which the protagonist has a direct line to the Omega Point, who may (or may not) be God. Thus Heaven is in the final fractions of a second – yet infinite in experienced time – of a collapsing Cosmos. Alternatively, the Big Crunch might be hostile to life, and Life might need to escape this Universe to live forever, as in Charles Sheffield’s tale Tomorrow and Tomorrow.
Another variant is the idea of the End of the Earth as a Gateway, which features in Brian Stableford’s The Walking Shadow. A complicated tale, which sees Paul Heisenberg, a professional ideologue, “jump” unexpectedly through time by becoming a silver statue in a kind of time-stasis in front of a whole stadium of people. This causes others to follow suit, ultimately journeying to the end of all life on Earth as-we-know-it billions of years from now, then travelling beyond it after Earth has been taken over by “Third Phase Life”.

More to come…

A Moistened Moon

The Moon is ‘wet’.

That’s the latest conclusion of a trio of observations by various spacecraft over a decade (here, here, here, here.) The question is: just how wet? Not very, but a whole lot more than we once thought. A thin layer of water molecules coats the whole surface of the Moon, at least part of the day, and more may well be found towards the Lunar poles. The colder the surface, the longer it sticks, and it’s very, very cold in the permanently shadowed polar craters – down to just 35 K… colder than Pluto! There, it’s hoped, the water has ‘stuck around’ for billennia and slowly accumulated to substantial amounts.

So, the Moon has water. And there are signs of more within the Moon, evidenced by hydrated minerals around new craters. That really throws that cat in amongst the pigeons, as current Moon-formation models have the Moon condensing largely from vaporised rock after Theia smacked into the Earth. Robin Canup, Moon-maker extraordinaire, commented that the current modelling doesn’t have enough resolution to really tell if bits of the collision that became the Moon were cool enough or not for water to be retained.

Science-fiction, of course, has featured underground water on the Moon for over 100 years – H.G.Wells mentions seas within the Moon in his “First Men in the Moon” and Herge has Tintin discover ice in a cave, are two famous examples. “Moon Zero Two” – a daft movie from 1970 – also mentioned, in passing, that the Moon Colony got its water from hydrated minerals underground. A silly movie for a lot of reasons, but it had some redeeming features, including a portable computer (!) which was quite a leap for 1970.

Digressions aside, what does it mean for the development of the Moon? Water – especially its hydrogen component – features heavily in a lot of industrial chemistry as well as sustaining life-as-we-know-it. A slew of processes become easier when there’s available water. But it’ll need to be heavily recycled because of the difficulty of gathering together significant amounts of moon-water. Learning to do that might teach us some useful tricks down here on Earth too.

Classic Freeman Dyson papers online…

Freeman Dyson, for a Physicist without a PhD, has done some utterly cool and amazing things during his long career. One paper he wrote 41 years ago, based on his “Project Orion” experiences from 50 years ago, is this…

Interstellar Transport …watch out, as it’s an 18 Mb pdf. In the paper he introduces us to the fusion-bomb propelled starship, which is probably the best use of fusion bombs anyone has ever suggested. In the years since his design has served as a baseline for all further discussion, with newer versions merely tinkering with fusion ignition itself. Potentially a fusion-bomb starship can reach 0.1 c, thus making Alpha Centauri a 44 year one-way trip.

Another classic is his discussion of the very long term future of Life in the cosmos, albeit Life that has become very large “Black Cloud” style dispersed entities…

Time Without End

…he covers life into the mind-bogglingly remote period of 10^(10^76) years, which is an unimaginably large number, but not infinite. Yet even infinity might not be enough time to exhaust physical Life’s potential in his analysis. More recent cosmological speculation modifies his conclusions, but the certainty with which we can skein so far ahead is much less than often imagined.

More Dyson material is available online here and there throughout the Web, a select few at this webpage…

Dyson at Wisdom Portal

…which is a testimony to his appeal across ideologies. Infectious optimism.