The cratered lunar face preserves the song
Of bolide roller derbies eons past
But while the cold dead moon remembers long
The rains of Earth reshape the surface fast.
Did impacts peak four billion years ago?
Or taper off through geologic time?
Archean rocks are analysed to know
micaceous balls were hot glass in their prime.
This impact melt was blasted into space
By comets larger than the dino's doom.
Thus diminution models must replace
The cut-off LHB has us presume.
Can cratering effect how cratons grow?
Tectonic orogens changed status quo.
Geology 42 747
I'm a geochemist. My main interest is in-situ mass spectrometry, but I have a soft spot in my heart for thermodynamics, poetry, drillers, trees, bicycles, and cosmochemistry.
Wednesday, November 26, 2014
Thursday, November 20, 2014
The wrong kind of Bang
In science education and popularization, there is a delicate
balance that must be struck between overcomplicating and oversimplifying.
Insufficient simplification can result in overly obtuse deviation into
secondary details, which confuse and distract the readers and derail the flow
of the prose. Excess simplification can
be wrong. And this is where the Medium
article by Ethan Siegel of “Starts with a Bang” fame has ended up.
Dr. Siegel argues that the recent Philae
comet lander would have more successful if it had been powered with a 238Pu
RTG device instead of solar panels.
However, his simplified argument ignores the reality of 238Pu
fuel production, the definition of “we”, and the nature of comets.
238Pu is a byproduct of the nuclear arms race
between the USA and the USSR .
It is created by neutron activation of 237Np, which in turn is a
byproduct of 239Pu production for nuclear weapons. With the nuclear
arms deals of the 1980’s the superpowers stopped building nuclear weapons by
the tens of thousands, and the cheap source of 237Np
disappeared. The USA stopped 238Pu production in 1988,
all subsequent material has come from Russia , which has almost depleted
its stockpiles.
This brings us to the definition of “we”. As the battleground over which the USA and
the USSR fought, Europe never developed its own mass nuclear warhead production
facilities; the UK and French arms supplies are only a tiny fraction of the
size of the 20th century superpowers. As a result, Europe
has never had its own large scale 238Pu production facilities.
Philae was a European mission, not a USA or Russian one, so the ESA
(European Space Agency) did not have access to 238Pu needed for RTG
production. NASA (USA) and the ESA
(Europe) are separate space exploration entities, a point that was very unclear
from this article’s frequent discussion of NASA and Philae .
Finally, RTG’s are hot, and comets are cold. The Philae lander was a very risky mission- there was a
significant chance that it would not succeed at all, and in the end the lander
ended up bounding off an unexpectedly hard surface several times before ending
up on its side in a crater.
Comets, by definition, evaporate at low temperatures- this
one is jetting out gasses despite being way out beyond the asteroid belt. So
landing a heat-producing source on it, especially on a lander that ended up
tipping over, would end up in a situation where the lander could drastically
alter the local environment of the comet through thermal contact. The whole point of the mission is to sample a
comet in as pristine condition as possible, so potentially cooking the comet due
to a landing mishap is not really a sensible design choice.
Dr. Siegel is correct that 238Pu is crucial for
missions that operate beyond the orbit of Jupiter. But the fuel used on previous missions was
subsidized by the nuclear arms race. It,
and all the wondrous outer solar system exploration it allows, was an
unintended byproduct of Mutually Assured Destruction, and the tens of thousands
of nuclear weapons that policy produced.
Since the arms race ended, production of this isotope for the sole
purpose of planetary exploration has been deemed too expensive to pursue by all
the world’s governments. Until we
collectively decide to blow ourselves up again, this barrier to outer solar
system exploration will continue.
Wednesday, November 19, 2014
Geosonnet 19
The Permian extinction was severe,
though only callous geos call it "great."
Sulfur and carbon choked the atmosphere
Siberian eruption exhalate.
A lava-coal explosion, it’s surmised
Spread fly ash all around the sickly Earth,
But if this ash is made by wildfire,
The evidence for coal fly ash is dearth.
A sulfate drought could set the world aflame,
The brimstone vapors choking off the rain.
The lava’s murder weapon’s not the same,
But "Lip" can improvise to kill again.
If carbon, sulfur
cycles stop their flow
The ecosystem has
nowhere to go.Sunday, November 16, 2014
This is how I like to eat slugs
Slugs are full of protein, but it is dangerous to eat them raw. So I process them by using a pack of domesticated dinosaurs to turn the slimy molluscs into slimy egg yolk. This has the added bonus of keeping them off of the vegetables. Everybody wins.
Wednesday, November 12, 2014
Geosonnet 18
The Vikings lived in Greenland 'till in cooled.
Ten thousand years before, as glac'ers thawed,
Melt water in the North Atlantic pooled,
The Younger Dryas cold snap shocked and awed.
In Norway, glaciers reappeared on high,
Above the fjords where stoic Norse rule lapsed.
Then Carolina icebergs floated by,
As Greenland outlet glaciers collapsed.
Why would cold make this icecap melt, not grow?
Emotionless wind froze the Baffin Bay.
Warm currents thawed the ice tongues from below;
Without a shelf, the glac'er sped away.
Today such currents threaten the Antarctic
An outburst would be deluge, not cathartic.
Geology 42 759
Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Ten thousand years before, as glac'ers thawed,
Melt water in the North Atlantic pooled,
The Younger Dryas cold snap shocked and awed.
In Norway, glaciers reappeared on high,
Above the fjords where stoic Norse rule lapsed.
Then Carolina icebergs floated by,
As Greenland outlet glaciers collapsed.
Why would cold make this icecap melt, not grow?
Emotionless wind froze the Baffin Bay.
Warm currents thawed the ice tongues from below;
Without a shelf, the glac'er sped away.
Today such currents threaten the Antarctic
An outburst would be deluge, not cathartic.
Geology 42 759
Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Wednesday, November 05, 2014
Geosonnet 17
The ozone and peroxide in the air,
enriched in isotope O seventeen,
Pass on the spike reaction products bear;
This stratospheric label’s not marine.
If limestone sulphate bears this airy mark
deceitful proxy! geosaboteur!
Thus reconstructed oceans fade to dark,
Eliminating tales that never were.
A lithologic memory withdrawn,
Built on assumptions hereby disallowed
The dreams of times hypothesized are gone
Mere fanciful illusions, disavowed.
A lab revealed the
havoc smog did wreak
Perhaps they need a
microbeam technique.