The scientific tourist #308 — salt layers

A look at layers in the walls at the Kansas Underground Salt Museum (recently renamed Strataca) in Hutchinson, Kansas:

Salt layers

The salt deposit that is being mined in Kansas forms a bed about 400 feet thick, 150 miles wide, and 200 miles long, and contains approximately 30 trillion tons of salt.  This was all laid down in the Permian period, some 275 million years ago.

At the time, Kansas was in the northern tropics and was partially covered by a shallow sea.  Some branches of this sea were apparently cut off from the general circulation — at least from time to time.  So when this branch saw little inflow from streams, it could evaporate, leaving a deposit of relatively clean and clear salt behind.  When sediment was washed into it from streams, a thin dark coating of mud settled over the last salt layer.

A variety of processes can be used to clean rock salt for use in food for people, but this deposit is mostly used as-is for road salt and in livestock feed.

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Carnivalia — 2/26 – 3/11

I missed last week, so this week you get a double-dose of (mostly) science-related blog carnivals:

Carnivalesque #101

69th Carnival of Evolution: Darwin’s Day Edition

Carnival of Space #343

Friday Ark #466

Health Wonk Review: In Like a Lion

Morsels For The Mind – 07/03/2014

Morsels For The Mind – 28/02/2014

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The scientific tourist #307 — Snark cruise missile

On display at the National Museum of Nuclear Science and History, here you see a Northrop SM-62 Snark cruise missile.  Essentially an unmanned jet-propelled aircraft, and the only intercontinental cruise missile to be fielded by the U.S., it serves up another interesting (if not terribly successful) chapter in Cold War aviation history:

Snark cruise missile

Development of the Snark began in 1945, but it was not to be fielded for more than another decade (and only briefly, then).  Work began with an Air Force requirement for a 600 mph, 5,000-mile-range missile that could cary a 2,000 pound warhead.  But the program was bedeviled by challenging and ever-changing requirements, limited funding, and here-today-gone-tomorrow political support.

In 1950, the Air Force increased the Snark’s requirements yet again — the range was now to be 5,500 nautical miles (6,350 statute miles / 10,200 km), the payload increased to 7,000 pounds (3175 kg), and the required accuracy tightened to 1,500 feet (460 meters).  These were audacious for the technology of the time, and required a complete redesign.

Yet even subsequent relaxations of some of these requirements were not enough to salvage the program.  So many of the test Snark missiles crashed offshore of their Florida launch site that local wags dubbed the area “Snark infested waters.”  Meanwhile, the missile was only capable of straight and level  flight, making it highly vulnerable to interception.  Even the Strategic Air Command had lost its ardor for the missile by the time it was finally fielded at a single operational site in Maine in February of 1961.

As a result, the same site was deactivated (and the Snarks scrapped) in June of 1961 — less than four months after the site had been declared operational. 

From the placard:

Length: 69’ (21 meters)
Wing span: 42’ (13 meters)
Diameter: 5’5” (1.65 meters)
Weight: 51,000 lbs (23,133 kg)

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The scientific tourist #306 — everyday (Roman) currency

Courtesy of the “A Day in Pompeii” traveling exhibition, here’s a nice array of imperial Roman currency:

The coinage of Pompeii’s time was based on the bronze as.  The lowest value coin was the uncia, worth 1/12 an as, while the highest value coin was the aureus, with a value about 400 times that of an as.  Over time this changed, of course, as emperors tinkered with the coinage here and there.

Originally, the value of Roman coinage was primarily based on the intrinsic value of the metal it was made from.  But over time, the coinage gradually became more of a fiat currency, as the empire ran low on precious metals, and in response the coinage was increasingly debased.  Since the imperial government issued currency made of base metals, while only accepting taxes in gold and silver, the debasement of the currency led directly to bouts of runaway inflation in the later years of the Western Roman Empire.

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Carnivalia — 2/19 – 2/25

The past week’s science-related blog carnivals (a bit thinner than usual):

Carnival of Space #342

Morsels For The Mind – 21/02/2014

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The scientific tourist #305 — Legal Eagle II

Here’s Legal Eagle II, a B-29 “Superfortress” bomber on display at the South Dakota Air and Space Museum in Box Elder, South Dakota:

Boeing B-29 "Superfortress"

The B-29 was one of the largest aircraft of the second world war — with a wingspan of more than 141 feet, and gross weight of 105,000 pounds (the heaviest production aircraft in the world at the time).  It’s tail was (as the manufacturer liked to remind people) as tall as a three-story house.

But while the B-29 saw most of its action late in the war, it’s history traces back to 1938.  As WWII was just starting to flare up in Europe, the U.S. Army Air Forces grew concerned about the potential need for a heavy bomber with much greater capabilities than the B-17 Flying Fortress could provide.  Starting as a derivative of the B-17, the B-29 soon became a very different beast entirely, and a major departure from typical bomber designs of the time.  

To help give it extra range, the B-29 would fly high — high enough to require pressurized crew compartments (at the front and rear of the craft, connected by a long tunnel).  Since the gun turrets could not be pressurized, they were remotely controlled from periscope-equipped crew stations.  Analog computers were used to increase the guns’ accuracy, accounting for airspeed, gravity, temperature, and humidity.  The B-29’s fuel tanks were self-sealing to increase the craft’s durability in the event of damage.

Given the aircraft’s advanced systems, and the pressure put on production of the type, it’s no surprise that the aircraft had “teething” problems in its early days.  Changes to the design came so frequently that special modification depots were set up to update B-29s as soon as they came off the production lines.  Some problems (namely, engine durability and safety) were not solved until after the end of WWII.

Although originally desired for combat in Europe, the B-29 was primarily used in the Pacific theater during World War II.  Nearly 4,000 were built between 1943 and 1946 — and some bombing raids on Tokyo used as many as 1,000 B-29s at a time.  Two B-29s in particular — Enola Gay and Bockscar — were adapted to carry early atomic bombs and dropped the only two such devices yet used in war.  After World War II, the B-29 saw military service again in Korea between 1950 and 1953, but it was no match for even the early jet fighters, and so was soon retired from front line service.  The last B-29 in active duty was retired in 1960.

The Legal Eagle II, above, is a late variant B-29.  It was rescued from use as a bombing target in the 1980s and restored in the 1990s.

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Carnivalia — 2/12 – 2/18

The past week’s crop of (mostly) science-related blog carnivals for you:

Carnivalesque 100: the World We Have Lost/Gained edition

Carnival of Space Number 341

Friday Ark #463

Giants’ Shoulders Vol. 68: A Leaf On The Wind

Health Wonk Review for February 13, 2014

Morsels for the Mind — 14/02/2014

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The scientific tourist #304 — hard at work in Balcony House

Should you ever find yourself in Denver, Colorado, the History Colorado Center gives you a great view of local history.  One of the treasures on display is a beautifully produced miniature diorama of life in the Balcony House cliff dwelling in Mesa Verde.  That being said, the diorama was built in the late 1930s (funded by Depression-era public works projects) — so we’ve learned a thing or two about Mesa Verde life since then.

Hard at work in Balcony House

Here you see scantily clad men and women hard at work — the men working on pottery while the women are upstairs weaving.  It’s a beautifully rendered miniature, but we now know that the scene depicted has 3 things wrong with it:

  1. The residents of Mesa Verde wore much more clothing than this, given the worn-out pieces of attire found in the site’s rubbish dumps
  2. Based on modern-day pueblo life and archaeological discoveries, pottery work was primarily done by the women of Mesa Verde
  3. Similarly, weaving was a man’s job back in the day
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Carnivalia — 2/05 – 2/11

The past week’s science-related blog carnivals for your reading enjoyment:

Carnival of Space #340

Friday Ark #463

Morsels For The Mind – 07/02/2014

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The scientific tourist #303 — the M454 Artillery-Fired Atomic Projectile

Here’s another interesting little bit of Cold War history — the M454 AFAP, an atomic artillery shell:

M454 Artillery-Fired Atomic Projectile (AFAP)

To be precise, what you’re looking at is an M455 — the training version of the M454 projectile — on display at the National Museum of Nuclear Science & History in Albuquerque, New Mexico.

The M454 was the smallest nuclear artillery round that the U.S. Army ever deployed, primarily assigned to M-109 155mm Self-Propelled Howitzers (a fairly standard artillery piece).  Its measurements, from the placard:

Length — 2’10” (86.4 cm)

Diameter — 6.1” (15.5 cm)

Weight — 119.5 lbs (54.2 kg)

In service — 1963-1992

The M454 round carried the W48 warhead, a Pu-239 implosion device with a yield equivalent to that of between 72 and 100 tons of TNT (depending on which source you choose to believe).  Some 3,000 of them were produced, the last one being decommissioned in 1996.

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