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My day job requires that I can practice the art of calorimetry with some reasonable extent of expertise, so in that vein I have been cracking open some of my dusty p-chem texts and revisiting basic thermo.

The other day while on an excursion to a bricks and mortar bookstore to pick up some of my favorite periodicals (Kitplanes and Vanity Fair), I happened upon a copy Elements of Chemical Thermodynamics by Leonard K. Nash (1970, Dover, $12.95). Feeling bad for Borders and their current run of poor luck, I bought the book as though it would make some difference.

Figure 2 on p 5 (below) shows a schematic of a ice calorimeter.  An ice calorimeter uses a thermally isolated enclosed space M completely filled with liquid and solid water immersed in an insulated tank of ice and water B. The internal, thermally isolated, working volume of water has two important features- it has a small volume sample container R protruding into it and it has a calibrated small inside-diameter expansion capillary C. 

A sample in container R is in thermal contact with reservoir M.  Heat absorbed in M melts some ice and results in the loss of low density ice and the formation of higher density liquid water. The net volume of the contents then decreases and is registered as a column height change in capillary C.

Given the volume change and knowing the density and heat of fusion of water at 0 C, one can calculate the heat absorbed by the reservoir.

So, what about Saturn’s moon Enceladus? The moon is thought to be covered by water ice with liquid water underneath. It’s reasonable to assume that if some volume of water below the ice transitions to the solid phase then the collective volume for liquid water is decreased resulting in an uptick in pressure.

If this happens, it could provide a mechanism for the geyser phenomenon witnessed by the Cassini probe. The geyers could simply be a result of PV work energized by gravity and radiative cooling of the surface and subsequent thickening of the surface ice into the underlying liquid phase.

I’m sure the boys and girls at Cassini have thought of this, but since I’m not tied into the literature I have not heard anybody express it.

The program called Gold Rush Alaska which is being aired on the Discovery Channel is well worth watching if you are curious about what it takes to do placer mining.   In addition to the strenuous task of digging down to the gold bearing layer of sediment, the miners are challenged by the short mining season in Alaska (~100 days or 2400 hours) and the remoteness of the location. 

There are several unit operations in play. The first operation using the trommel classifies or sorts the sediment by size.  This results in cobbles and pebbles being excluded from the sand and silt. This is a classification process that uses gravity to roll the large rocks to a separate location. 

The next step is more of a density driven process wherein the material stream is taken through a shaker station where sedimentation of the dense fines is accelerated by mechanical agitation and the resulting material flow is transferred to a sluice where the heavy gold particles and nuggets are agitated by the riffling action of the water and settle to the bottom. The less dense solids are washed out of the sluice and discharged to a waste pile.

All of the slurry flow is gravity driven, so the process train must begin uphill and work its way down. The sluice section is where the density separation occurs in earnest and this is where the gold will accumulate.

Periodically, the sluice section must be cleaned out and the resulting gold laden silt must be further processed to isolate the gold. The fellows in the program must use panning or a shaker table to isolate the dust and larger pieces of gold.  This a definite disadvantage compared with miners in the past.

The buckets of silt isolated from the sluice would have been treated to amalgamation in times past.  This selective dissolution of gold and silver could be used to accumulate the gold until the amalgam would begin to solidify. This process requires less skilled labor than panning or using a shaker table. The amalgam would eventually be placed in a retort and heated strongly to distill out the mercury leaving the non-volatiles behind.

The gold would then be sold and sent to a smelter for further refinement (i.e., parting) of the crude gold.

Without mercury, present day miners have a rather more complicated task in isolating the gold.

Air France Flight 447 crashed in the Atlantic 400-odd miles outbound from Brazil to Paris after its evening departure from Rio de Janeiro on May 31st, 2009. While the flight data recorder has not been recovered, 24 fault messages were relayed to the AF headquarters via satellite. From these messages, and from forensic evidence found floating in the area of the crash site, a picture of the event is beginning to emerge. Spiegel Online has published an analysis of the disaster based on what is presently known.

The evidence collected so far suggests that the aircraft impacted the water on its belly with a 5 degree nose up pitch attitude. The calculated impact force based on certain kinds of material strength data is 36 g.  The aircraft departed just under max gross takeoff weight with 70 tons of kerosene fuel on board.  Abnormalities did not begin to appear until the aircraft was ostensibly at cruising altitude of ca 35,000 ft. There was a suspicious uptick in the OAT reading (outside air temperature) of a few degrees. Investigators believe that this is an indication of icing on the OAT sensor and pitot tube.

The aircraft may have been attempting to penetrate an area of thunderstorms in the inter-tropical convergence zone. This is a band of atmosphere on either side of the equator where northward and southward flows from the respective hemispheres meet and produce vertical air movement. The convergence of these flows can result in moisture laden air being lifted. Together with the natural buoyancy of warm humid air, vigorous convection cells can be kick-started into severe thunderstorms. The cloud tops in this zone can be substantially higher than those at the mid latitudes. At altitude, storm cells commonly produce icing conditions.

Out in the midocean spaces at night, airline pilots have only on-board radar and the moonlight, and perhaps a few pilot reports by others who have just been in the area, to estimate the areas of high storm intensity ahead. Flight through the intertropical convergence zone can produce bumpy rides to the point of violent turbulence. What most passengers don’t understand is that passenger jets are build to absorb considerable abuse before a structural failure occurs due to turbulence.

The upshot of the report is that the pitot tube that senses the airspeed of the aircraft failed due to icing.  This failure basically causes the computerized flight control system to shut down owing to lack of input of this key airspeed data. In flight control, airspeed is one of the very critical pieces of information necessary to sustain controlled flight.

Without airspeed information, and without computer assistance in the control of the various flight control surfaces, the modern passenger jet becomes very difficult to handle manually. The is especially true if the aircraft is under instrument conditions with low/no visibility and in high turbulence.

A complex and aerodynamically clean aircraft being jostled along all three axes at a high mach number presents a large workload for the pilots. At a mach number (o.85 or so) as typically attained in high altitude cruise, a sharp pitch down in the nose can lead to transonic flow over the control surfaces and in the engine inlet. This can lead to engine instability and loss of flight control. Sonic flows over ordinary flight surfaces can lead to flow separation and loss of control. This lesson was learned the hard way in the early days of high speed aviation. Pilots typically throttle back after penetrating turbulent air.

The investigators of AF 447 have all but concluded that the aircraft crashed owing to loss of critical airspeed information and subsequent departure from stable flight.  While the Spiegel article states that investigators are confident in this analysis, recovery of the flight data recorder will undoubtedly provide important details for refinement of the investitgation.

The YouTube video below is a reconstruction of the flight of US Airways Flight 1549, referred to as Cactus. It is interesting to note how the pilot acted to conserve his altitude by careful energy management. After the dual engine flameouts the pilots established an optimum glide to maximize flight time. They did not bank the aircraft anymore than they had to- banking without power consumes altitude. While one pilot was flying the airplane the other was consulting the manual for emergency restart of the engines. The captain evidently knew right away that the only option for maximum survivability was to set the plane in the river.

Near the end the pilots found themselves coming in a bit fast so they brought the nose of the aircraft up and porpoised ~250 ft or so before locking on 130 kts indicated for their glide to the surface. They were mindful of bringing the aircraft to the site of the accident as slowly as possible. KE = (1/2) mv^2. 

Note how he dips the tail in the water first while keeping the wings absolutely level. This brought the aircraft into the water along the longitudinal axis and thus averted a cartwheeling accident. The engines become powerful drag devices once they are in water.

So the breaking news in my neighborhood is that the Colorado Balloon Boy’s craft has landed, but the 6 year-old boy is missing. The balloon lifted off from a residence in Ft Collins and landed near Prospect reservoir, a few miles NE of Denver International Airport. He drifted at least 50 miles. Reportedly, the basket that was affixed to the balloon was not present at the landing site.

I can only say that as a former six year-old boy, I might not have been able to resist climbing into the balloon either.

There is a website by the Manhattan Airport Foundation dedicated to the proposition that Central Park in New York City be converted into a regional airport. From their press release-

NEW YORK, NY, July 15, 2009 – For the past three years The Manhattan Airport Foundation has been quietly laying the groundwork to provide New Yorkers with a most fundamental urban amenity: access to viable air transportation. And today, TMAF releases its much-anticipated Stage One call for entries to a hand-picked group of top architecture firms worldwide in what is sure to be one of the most closely-watched design competitions in recent memory.

This has to be some kind of a joke. What a horrible place for an airport. Even if the people of NYC consent to the loss of a large greenspace in the middle of their high density glass and steel jungle, there is the issue of air traffic. Do these people understand how loud jet aircraft can be? Someone should remind them that Hong Kong was so anxious to be rid of their mid-town airport that they built an artificial island to put it on. Imagine jet traffic lumbering in on final approach over the tops of the buildings in Manhattan? It might even drown out the sound of honking taxis.

Even better, imagine the noise of jets on departure, clawing for altitude at full power trying to get out of the Manhattan airspace? Imagine the the roar of jet engines reflecting off of the skyscrapers from 777’s and other heavies on their takeoff rolls. Power failure on takeoff? The skyscrapers downrange will absorb the impact energy.

Yep, this has to be a gag of some kind. Imagine someone actually trying it? Pffft!

As one begins to understand the manner in which mineralization and elemental concentration occurs as a result of terrestrial geology, it is only natural to wonder how this would occur on other worlds. On earth, the concentration of the elements in the form of mineral deposits is a partitioning phenomenon that benefits greatly from fractional crystallization, metamorphic modifications, and from a variety of transport mechanisms.

Fractional crystallization of magmas provides a condition whereby a mixture of simple and complex ions may associate to form mineral compositions that partition from the molten phase by virtue of high solidification temperature. In this way, solid, higher melting compositions precipitate from a melt sequentially, leading to the selective partition of certain combinations of elements into a new solid phase. The molten phase may be enriched in certain combinations of other elements by default- many of which may be relatively volatile.

The composition and cooling rate of the magma will determine the nature of the solid rock that is formed after cooling.  Over time, rock may be lifted toward the surface and subjected to modification by hydrothermal action or by erosion and redeposition by gravity. Cooled igneous rock may be subjected to crystalline modification by exposure to heat further down the timeline.

Hydrothermal water, superheated under high pressure, is a major force in the formation of mineral deposits. The sulfides (and hydrosulfides) of transition metals (i.e., Au) are thought to be transported from source rock through cracks, faults, and porous formations to be deposited in locations where transport can no longer be sustained. The accumulation of economic quantities of uranium are thought to be the result of hydrothermal or aqueous transport as well.

So here is the point of this essay–  If preconcentration of elements to viable deposits is critical for the success of value extraction on earth, what about mining on the moon or Mars? To what extent are we dependent on these mechanisms to make viable the mining and extraction of useful materials?  If lunar geology has not been quietly concentrating minerals in the manner to which we earthlings have been accustomed, how will we come to grips with using native materials on the moon for self-sustaining habitation?

It is one thing to find x ppm of oxygen or y ppm of titanium in the lunar regolith. It is quite another to enable extraction of critical elements from low-value (dilute) material. The chemical energy inputs for processing will be severely limited owing to the scarcity of reducing materials on the moon or Mars. Reducing materials are really just reservoirs of inexpensive and useful electrons. Reducing materials would include carbon or electropositive metals for the reductive winning of other metals. 

In the absence of an inexpensive supply of electrons, all phases of extraterrestrial mining and processing will be subject to large cost multipliers. Cheap electrons are required to energize machinery, move materials, or conduct refining. All of these familiar activities are energy intensive on earth and there is no reason to think it will be different on another world. On earth, cheap electrons come in the form of diesel and coal. On the moon and Mars, it seems likely that solar and nuclear will energize most work for those who try to set up camp there.

 

Guess where this is …?

Sharpen your pencils boys and girls. DARPA is soliciting proposals for Submersible Aircraft.  Here is the synopsis-

DARPA is soliciting innovative research proposals on the topic of a Submersible Aircraft. In particular, DARPA is interested in a feasibility study and experiments to prove out the possibility of making an aircraft that can maneuver underwater. The proposal needs to outline a conceptual design along with identifying the major technological limitations that need to be overcome in order to maneuver an aircraft underwater. In addition to the conceptual design studies, performers need to outline experiments or computational models that will be used to demonstrate that the major technological limitations can be overcome.

Aircraft are constructed to withstand loads from particular directions arising from the airstream and from dynamic loads imposed on the airframe by accelerated maneuvers. A submersible aircraft must be constructed to withstand additional compressive loads all over the airframe from all directions due to conducting operations in water and at depth.

Perhaps crew chiefs will have to deal with seaweed and barnacles in addition to damage from FOD and birdstrikes. A whole new skill set will arise for naval aviators. Will these craft require anchors and bilge pumps? It is fun to speculate.

It may well be easier to devise a submersible aircraft carrier. I can see it now

Sunset in the north Atlantic. A blood red sun sets over the gray Atlantic rollers. Suddenly, the surface is broken by a large craft abruptly surfacing. The bow rises into the air then splashes to the surface as the large gray ship glides onto the surface at full speed.

Moments later, a hatch on the offset conning tower opens and sailors spill onto the broad flat deck.  Large sections of deck open skyward and elevators lift folded aircraft to the deck. These strange craft are rolled into position while scurrying crews fuel and arm them in the muted red running lights. Curling streams of steam spill to aft from vents on the carrier deck as the vessels screws push it forward.

Elsewhere on deck, sailors mount antenna arrays and open ports revealing defensive weapons. Soon, a fleet of submersible men-of-war have surfaced and set up a defensive perimeter around the submersible aircraft carrier.

After a few minutes, the aircrews run toward the aircraft and strap in. Turbine engines begin to whine as they spool up. Crews disconnect startup carts and run with their equipment to designated locations. As the aircraft power up, their wings unfold and lock into place.

Pilots engage the flapping box and the turbine powered ornithopters begin to flap their articulated wings. The pilot of the lead craft advances the throttle and rolls to the takeoff position while exercising control surfaces. The airboss clears the flight for takeoff and the pilot salutes smartly and advances the thrust to military power.

The black stealth gullwing craft diverts full power to the flapping mechanism and leaps into the air, vanishing into the dark sky.  The vacancy is quickly filled by the next craft. Moments later, another takes wing followed by the rest of the squadron.

At altitude the squadron members meet and assume formation flight. Below, the carrier has already begun to submerge to loiter in position until the appointed time where it will surface and recover the flight if any manage to return. It will be a harrowing night.

Check out this informative NASA video on tailplane icing. It is a bit early yet to make a judgement on the crash in Buffalo. But the dots do line up with much of what has been disclosed.

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