Author: Adam

Dwarf Planet Smash-up… When?

At the edge of our Solar System is a Belt of small ice-worlds – the well-known Pluto and Charon, the unofficial Tenth Planet, Eris, and several other largish objects that the media doesn’t say much about. One of the latter is 2003 EL61, which is yet to get a real name, as the discovery code-name makes clear. It’s roughly Pluto-sized, but flattened into a football shape due to a very high rotation rate. It’s also much denser than its fellow ice-worlds, which led its discoverers to conclude it had formed in a violent collision with another ice-world. Supporting that theory are small objects in the Belt that have the same spectroscopic colour as 2003 EL61. In the Main Belt of asteroids that ALWAYS means the objects are related – for example, we have pieces of the asteroid Vesta that came to Earth as meteorites so we could check.

Computer simulations of the big smash-up support the idea, but there seemed to be no way of dating just when it occurred – bar one. Ice mixed with methane changes colour over millions of years as the methane is broken down by cosmic-rays and its break-down products recombine as “tholins” – pinkish organic material. Older ice-worlds in the Belt show these colours, indicating their icy crust once contained methane and now is diluted with a layer of tholins.

BUT 2003 EL61, and the orbitting bits of it, don’t show those tholin colours….

The Youthful Appearance of the 2003 EL61 Collisional Family

…which basically concludes that the whole group of parent body and fragments either have an anomalously low level of methane or their collision occurred less than 100 million years ago. Either conclusion is quite startling, as ice-worlds everywhere else in the Belt seem to have methane. Either the smash-up was so violent and hot that all the methane was driven off – but why didn’t the water explode as a great cloud of steam? Or the methane is there and the smash-up occurred, at the earliest, in the days of the dinosaurs. In which case a rogue dwarf-planet careened through the Belt in what is “recent time” for big planetary collisions.

“Expelled” Exposed

Here in Oz I’ve vague ideas as to who Ben Stein is, but I can only smell bullshit with his current doco. Here’s a web-site that reveals the truth and exposes the lies…

Expelled Exposed

…read it, be educated and get really pissed off at the self-righteousness that poses as Judaism/Christianity. If people want to claim to be believers in the Truth, then they should get informed and stop spouting old bullshit. God’s bigger and better than such garbage, and it’s time people believed Him with integrity.

Young Earth Creationism… a Spruce says “No!”

Young Earth Creationism is a belief in Biblical Inerrancy inspired delusion, nothing more, as it has no real evidence in its favour, bar a very particular school of interpretation of the Bible. And now we have direct proof that the world is more than a mere 6,000 years old…

World’s oldest living tree discovered in Sweden

The world’s oldest recorded tree is a 9,550 year old spruce in the Dalarna province of Sweden.

The spruce tree has shown to be a tenacious survivor that has endured by growing between erect trees and smaller bushes in pace with the dramatic climate changes over time.

For many years the spruce tree has been regarded as a relative newcomer in the Swedish mountain region.

”Our results have shown the complete opposite, that the spruce is one of the oldest known trees in the mountain range,” says Leif Kullman, Professor of Physical Geography at Umeå University.

A fascinating discovery was made under the crown of a spruce in Fulu Mountain in Dalarna. Scientists found four “generations” of spruce remains in the form of cones and wood produced from the highest grounds.

The discovery showed trees of 375, 5,660, 9,000 and 9,550 years old and everything displayed clear signs that they have the same genetic makeup as the trees above them. Since spruce trees can multiply with root penetrating braches, they can produce exact copies, or clones.

The tree now growing above the finding place and the wood pieces dating 9,550 years have the same genetic material. The actual has been tested by carbon-14 dating at a laboratory in Miami, Florida, USA.

…thus any global Flood of Noah dates to before c.7,550 BC, at the very latest. So either Noah’s Flood wasn’t global, or else it was a lot further back in time than a narrow reading of the Bible allows. Of course for a lot of Fundamentalists there is no great drama in a Flood long, long ago. A geophysicist friend of mine, Glenn Morton, believes the Bible and based on his geological knowledge places the Flood at the Messinian – c. 5.5 million BC.

Ice-wrapped Ocean Planets I

In the early 1970s John Lewis modelled the interiors of the outer planet satellites and discovered they might have sub-surface oceans of ammonia/water…

Lewis, J.S. (1971) Science, Volume 172, Issue 3988, pp. 1127-1128

Lewis, J.S. Icarus, Volume 15, Issue 2, October 1971, Pages 174-185

Abstract
Steady-state thermal models for the icy satellites are constructed in which the energy released by radioactive decay in the interiors of the satellites is exactly balanced by the net radiative loss from their surfaces. It is shown that the Galilean satellites of Jupiter and the larger satellites of Saturn, Uranus, and Neptune very likely have extensively melted interiors, and most probably contain a core of hydrous silicates, an extensive mantle of ammonia-rich liquid water, and a relatively thin crust of ices. Consequences of this model relating to the Galilean satellites and the rings of Saturn are briefly described.

The atmospheric compositions and densities of the large icy satellites and certain features of the retention of volatiles during accretion are discussed.

Thus we’ve known about these dark, inner Oceans for over 3 decades or so. Opinion, in science, is never constant without data, and some estimates of the heat-transfer via solid-state convection of ice has meant the liquid interior models have fallen out of favour – at least until more data for the oceans came to hand from Galileo and Cassini. Galileo discovered that Ganymede, Callisto and Io had detectable magnetic fields – the case of Callisto, the field seemed localised to a thin layer of salt-containing fluid just under the outer ice, enwrapping the ‘mud’ mantle below. Cassini has discovered that Titan’s outer crust is decoupled from the inner layers, probably because of a liquid mantle of ammonia/water or ammonium sulfate.

But what about other moons? Europa very probably has an ocean as its crust looks like Arctic sea-ice, and Enceladus’s geysers are hard to explain via any other cause. Further afield? Here’s an interesting paper from Paul Schenk and Kevin Zahnle…

Schenk & Zahnle, Icarus, Volume 192, Issue 1, 1 December 2007, Pages 135-149

Abstract
New mapping reveals 100 probable impact craters on Triton wider than 5 km diameter. All of the probable craters are within 90° of the apex of Triton’s orbital motion (i.e., all are on the leading hemisphere) and have a cosine density distribution with respect to the apex. This spatial distribution is difficult to reconcile with a heliocentric (Sun-orbiting) source of impactors, be it ecliptic comets, the Kuiper Belt, the scattered disk, or tidally-disrupted temporary satellites in the style of Shoemaker–Levy 9, but it is consistent with head-on collisions, as would be produced if a prograde population of planetocentric (Neptune-orbiting) debris were swept up by retrograde Triton. Plausible sources include ejecta from impact on or disruption of inner/outer moons of Neptune. If Triton’s small craters are mostly of planetocentric origin, Triton offers no evidence for or against the existence of small comets in the Kuiper Belt, and New Horizons observations of Pluto must fill this role. The possibility that the distribution of impact craters is an artifact caused by difficulty in identifying impact craters on the cantaloupe terrain is considered and rejected. The possibility that capricious resurfacing has mimicked the effect of head-on collisions is considered and shown to be unlikely given current geologic constraints, and is no more probable than planetocentrogenesis. The estimated cratering rate on Triton by ecliptic comets is used to put an upper limit of 50 Myr on the age of the more heavily cratered terrains, and of 6 Myr for the Neptune-facing cantaloupe terrain. If the vast majority of cratering is by planetocentric debris, as we propose, then the surface everywhere is probably less than 10 Myr old. Although the uncertainty in these cratering ages is at least a factor ten, it seems likely that Triton’s is among the youngest surfaces in the Solar System, a candidate ocean moon, and an important target for future exploration.

…which seems to indicate a very dramatic thermal history for Triton, with a more global melting of its crust than the apparently localised melt on Enceladus’s south pole. If so, then the sub-surface ocean is potentially very close to the surface and liable to burst through in cryovolcanic events, making the moon a very interesting target for future investigation.

Gliese 436c

A new super-Earth has been announced around M-dwarf Gliese 436…

Scientists Find Smallest Exoplanet

…now the radius quoted is ~ 1.5 Earth radii. Different mixes of silicates and iron give slightly different indexes (0.272-0.268) for a power-law fit to the mass-radius curve – in this case lets take the average ~0.27, which means the planet is ~ 1.544 Earth radii. Seems the media was listening, which is unusual for a space-science story. Surface gravity would be 2.1 gee so it’s not a long-term habitable planet, but alright for visits in exoskeletons. Just 30 light-years away, so a laser-sail could reach it in ~ 100 years at 0.3 c.

Could humans get there? Another recent news item is further results from earlier studies on H2S gas induced suspended animation (SA) in mice… Rotten egg gas to Save Mars Mission …though that item doesn’t discuss further possibilities of inducing the effect via its metabolites so there’s no direct poisoning via the hydrogen sulphide itself. The research is still too basic to say what the effect on humans will be. Mice are a good start.

Let’s imagine – say the SA effect is like time-slowdown that some writers have imagined. What would that imply? Perhaps a crew could be augmented by smart AI that responds to circumstances faster than the ~ 100-fold slower crew. And what would 1 subjective year be like in induced torpor? Could muscles be used at all, or would that be too fast? Imagine crew in power-chairs controlled purely by (very slow) thoughts, with robotic arms. A normal speed person would be witness to some very strange effects, and would be a blurry figure to a time-slow crew person.

Would you go, if you could? Or some place closer, like Alpha Centauri B’s putative rocky world? That would be at least 30 years round-trip at 0.3 c. Would you risk being cut-off from the rest of humanity for so long? Good telecommunications, via laser, would allow you to keep track, but you wouldn’t be able to contribute to it without a multiyear time-lag. Could you stand the separation? Could you tolerate the same faces nearby for +30 years?

The Choices Ahead of Us

Human beings may create their successors – intelligent software, either derived from us directly or created de novo – and They may be immensely more powerful than us. One thing they might do, to capture the Sun’s light, is build a Dyson Shell. Paul Gilster’s Centauri Dreams covered a recent news bite on a search for Dyson Shells, and sparked a huge discussion…

Dyson Shells and ETIs

…to which I added a few comments. One in particular is in two parts… Part 1 Part 2

…the end of Part 2 being something I want to share further here…

In the end it seems like an aesthetic choice – do we keep planets and remake them? Do we stay human, or become Artilects? Should brute matter be remade into computronium and the Sun enshelled as in a Matrioshka Brain? Or should we be more subtle? Darwinnowed gene-brain hybrids, like us, are motivated towards exponential growth, but Transformed Humans and/or Artilects will be able to bypass all that and reach for a whole different motivation set.

Ezekiel wrote 2600 years ago “Turn from evil, and do good.” So much of society, its moral-systems and educational systems focus on the first, but there’s no clear road for what the second half is all about. What is good for us, as evolved creatures, may seem flawed and limited to beings able to reflect upon all levels of their programming. They will have all our recorded history to see the fruits of our attitudes and philosophies and there’s no telling what that might lead them to conclude.

ETIs – if They persist for billennia – will have faced the same end-point of Darwinian evolution, and will have passed Judgement on themselves as a species. Speculating on Their choice and its consequences may well help us make our own, before that choice is taken away by circumstances. At some stage we will run into the limits of social organization driven by Darwinian mechanisms, and the end of it might be catastrophic.

…the idea of impending Judgement has a lot of old religious references that I am loath to encourage. While I believe in Jesus Christ, I am unimpressed by the many and varied interpretations of his words on “the End of the Age” and I am equally dubious about present day fulfillments of the John the Elder’s Apocalypse. Christian creeds all affirm JC will come again to Judge the living and the dead, and I believe in the Resurrection of all by the Omega Point, God-as-Singularity. But there’s another “end of days” coming our way as we reach the limits of our Earth-bound existence, and contemplate the creation of intelligence fundamentally different to our own.

Some approach the task with fear. They imagine to create intelligence will be animating the “Image of the Beast”, foretold in the Apocalypse. I don’t think so. If we create new minds we will only be fulfilling the Image of God within us. Yet we must be very careful not to infect this new life with the blight in our own souls from our evolution’s necessities.

News Bites of note

A lot happens when you’re not blogging.

Titan may harbour an ocean beneath its icy crust – either a mix of ammonia and water, or ammonium sulfate…

Titan harbours a hidden ocean

…of course this has been modelled for years, but now Cassini has provided real data in the form of slips in rotation rate due to the crust slipping around (very slightly) on a well lubricated layer, an internal ocean. If it’s ammonium sulfate this could power some very vigorous vulcanism on the surface, explosive eruptions due to trapped clathrates suddenly decomposing. Would make exploring some regions very exciting indeed.

Another interesting piece is Alan Bond and Dr. Mark Hempsell have decoded an old Sumerian astronomical text and have concluded it is referring to an impact in the Alps on 29 June 3123 BC (Julian calendar) – the source of the Phaeton myth and the destruction of Sodom and Gomorrah tradition… maybe…

Kofels Impact Decoded

…people are a bit shy of committing to this one, as a cursory glance at comments around the Web seem to indicate. Cuneiform is pretty tough to decipher, not least because we’re not always sure what the ancients were on about. Interesting implications for the Bible tales – if true, then Abraham either heard about the tale, or else lived a lot further back in time than currently imagined.

Finally, the Large Hadron Collider has attracted the attention of worry-warts who think it might make world-gobbling strangelets or mini-Black Holes. Penn and Teller say it so succinctly… “BULLSHIT!”

My fifth child born today

12:56 AM my fifth child was born, in a very quick labour. We had arrived at the hospital just an hour earlier. He, and Mum, are doing well. He’s 3 weeks early, but already 8 lb 2 oz, so he would’ve been big at full term – I think his ideas on full term were more modest, thus an early arrival.

Some Planetary Science news bites…

The latest issue of Astrobiology is out and a few abstracts caught my eye…

Acetylene as Fast Food: Implications for Development of Life on Anoxic Primordial Earth and in the Outer Solar System

…acetylene, as any welder knows, is quite unstable and thus energy-rich. On a cold, cold world like Titan that’s a BIG plus.

Cyanobacterial Emergence at 2.8 Gya and Greenhouse Feedbacks

…a Hypothesis paper from Ken Caldeira, and co-workers David Schwartzman and Alex Pavlov, discussing the evidence for a shift in Earth’s greenhouse atmosphere from a primordial heavy CO2 atmosphere of about 1 bar pressure, to a methane dominated greenhouse with just 0.1 bar CO2. The Earth is believed to have cooled down substantially at this time, but were still a scorching 60 C – a long time would pass before it cooled enough for multicellular life, which needs temperatures under 40 C.

The 2008 Lunar and Planetary Sciences Conference is coming in March, and the abstracts are already up – detailed enough to be almost mini-papers. This one discusses the mass of the Solar Nebula Disk that the planets eventually formed from…

MASS DISTRIBUTION AND PLANET FORMATION IN THE SOLAR NEBULA

…the Minimum Mass Solar Nebula’s mass distribution has various implications for the formation of the planets. A new idea discussed by the paper is that the Ice Giants and Saturn all formed somewhat closer to the Sun, then migrated out. This explains a lot of features, like the Late Heavy Bombardment, the Kuiper Belt, and the formation time of the Ice giants is under 10 myr, as required by the observed gas loss time of young-stars. A perfect fit is found if Neptune and Uranus actually changed places (as happens in 50% of simulations of their migration) and both were within 15 AU of the Sun.

The outer margins of the Nebula were photo-evaporated by large O-B stars in the Sun’s birth nebula. The largest of those probably lived for less than 5 myr, then exploded as supernova and seeded the Sun’s Nebula with short-lived radioactives like Al-26. Enough heat is generated by Al-26 to melt any asteroid over 10 km in diameter, so long as those early planetesimals formed quickly enough – signs of localised melts in meteoroids is an important way of dating the age of formation of the asteroids. Main Belt Asteroid 3 Vesta is covered in basalt from eruptive volcanism once powered by Al-26 decay heating, and a whole family of smaller bodies are spalled off bits of Vesta.

Earth and Sun – a merged future…
Posted on Wednesday, January 30, 2008 – 06:49 am:   
Found this really interesting update on what the Sun is going to end up like in a few billion years – and whether Earth will end up in a decaying orbit ploughing through red-hot solar material.

Distant future of the Sun and Earth revisited (pdf format file)

Table of important phases of the Sun…

Phase Age/Gy L/L¡Ñ Teff/K R/R¡Ñ MSun/M¡Ñ
ZAMS 0 0.7 5596 0.89 1
present 4.58 1 5774 1 1
MS:hottest 7.13 1.26 5820 1.11 1
MS:final 10 1.84 5751 1.37 1
RGB:tip 12.17 2730 2602 256 0.668
ZA-He 12.17 53.7 4667 11.2 0.668
AGB:tip 12.3 2090 3200 149 0.546
AGB:tip-TP 12.3 4170 3467 179 0.544

First thing to note is that the official Main Sequence ends in about 5.42 billion years – but contrary to its TV depiction the Sun won't suddenly balloon into a humungous Red Giant. For about a billion years it will be bigger, brighter, but cooler than today, about bright enough to warm Mars to nice temperatures. This remains relatively stable. Then it will slowly swell as the core contracts until it peaks at ~ 12.17 Gyr of age, some 7.59 billion years from now.

A good time to move to the outer planet moons will be during the Helium Main Sequence – lasts about 100 million years, and the Sun will be ~ 54 times brighter. While a Red giant the Sun will lose ~ 1/3 its mass, and the planets will orbit ~ 1.5 times their present orbits to conserve angular momentum. Except Mercury and Venus, which get swallowed. The Galilean Moons will receive as much sunlight as Earth currently does, while Titan will get as much as Mars, during the Helium Main Sequence – though how well they will survive the Sun's climb to Red Gianthood is debatable.

The acronyms need some explaining:
ZAMS – Zero Age Main Sequence, the Sun at year zero
MS – Main Sequence, the Sun burning hydrogen in its core. About 10 billion years.
RGB – Red Giant Branch, the tip of which is its peak luminosity
ZA-He – Zero Age Helium Main Sequence, the Sun burns hydrogen in a shell around a helium burning core.
AGB – Asymptotic Giant Branch, the death-throes of the Sun,as it really runs out of fuel, throws off mass, and becomes a white dwarf.

And what of Earth? If its orbit isn't modified then it will be engulfed when the Sun hits its RGB maximum. The main cause will be due to tidal interactions with the bloated Sun's atmosphere, not merely drag with its outer layers.

At the Sun's RGB-tip the Habitable Zone will be beyond 52 AU. Which is roughly where Neptune will be, thanks to RGB mass-loss. What's left of the Kuiper Belt will form a vast band of comets across the sky as their volatiles boil away.

Jupiter's moons will experience about x45 Earth's present heat levels, Saturn's moons about x13, so none of them will remain as they are before hitting more clement weather on the He MS. But even at those energy levels their mass-loss won't be fast – Callisto & Ganymede will probably end up much like Europa, while Europa might keep much of its ocean.

Once the Sun's Core explodes and it heaves itself onto the He MS, then Jupiter might have some decent real estate orbitting it. In the table the symbol for the Sun (a circle with a dot in the middle) didn't transliterate from Unicode to WordPress.

So L/LiN is the luminosity in present Solar luminosities.

Similarly R/RiN, MSun/MiN, are the radius and mass in present day solar values.

Teff/K is the effective temperature of the Sun in Kelvin.

As you can see the Sun only gets a bit hotter, but then gets much cooler. Inside the Sun the Core rises in temperature as it shrinks – it needs +100 million degrees to turn helium into carbon/oxygen. That super-hot core, some 54% of the Sun's mass, is much smaller than the present Sun and so hot that it causes the outer layers to swell into a bloated red-giant. At the end of the AGB the last outer layer is blown away, exposing a white dwarf, hotter than any normal star. But it's no longer producing energy from fusion and rapidly cools to more star-like levels.

Ultimately all that carbon will crystallise – from the Core outwards gradually the Sun's corpse will become a gigantic diamond, solidifying totally perhaps a trillion years from now.