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eppur_se_muova

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Hometown: Alabama
Member since: Fri Sep 9, 2005, 06:39 PM
Number of posts: 27,213

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Use a two-part sail, which splits in two for the deceleration phase.



http://www.transorbital.net/Library/D001_AxA.html
http://www.lunarsail.com/LightSail/rit-1.pdf

scroll to Fig. 5 on p. 8. This paper describes laser-pushed sails, but microwave-pushed sails would use similar principles. Interestingly, both electric and magnetic sails can be used for propulsion.
Posted by eppur_se_muova | Sat Mar 11, 2017, 10:10 PM (1 replies)

Quick answer to the question: Where does the radioactivity come from ? Basically, "radiobarite" ...

I.e., barite (BaSO4, the major barium mineral) containing small amounts of radium as RaSO4. Both have extremely low solubility in water (under normal conditions), so any radium salt that gets dissolved quickly precipitates back out, together with the more abundant barium, as soon as it encounters sufficient sulfate ions in solution. Here's a 2010 post on that:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x249200

Scaly precipitates on oil industry equipment may show the radioactivity as high as 103 Bq/g.

http://www.mindat.org/min-7267.html


Note that's per gram, not per kilogram.
Posted by eppur_se_muova | Mon Jun 27, 2016, 04:03 PM (0 replies)

Stewart's response to this was absolutely epic -- watch the video !

http://thedailyshow.cc.com/videos/vc61pl/when-barry-met-silly---
Posted by eppur_se_muova | Fri Jul 31, 2015, 10:00 AM (0 replies)

*Simple* carbon compounds are widespread, but have nothing to do with life.

This is rather like finding sand and calling it "the rudiments of semiconductor manufacture". It might be, but chances are overwhelmingly against it.

Carbon is not a particularly rare element. It is a reactive element, so it's usually found in combination with other elements, and **ALMOST ANY COMPOUND CONTAINING CARBON IS LABELED AN 'ORGANIC COMPOUND'*** by convention. "Organic" in colloquial usage means "associated with a living organism"; in scientific usage it means "contains carbon", with only very simple compounds like CO2, CO, and metal carbides being excluded. Simple organic compounds like methane, formaldehyde, hydrogen cyanide, even methanol, are not evidence of life or even the probability of life. It just means that carbon reacted with whatever was present, and that usually includes hydrogen (the most abundant element in the universe) and oxygen (which forms particularly strong bonds with carbon).

I've never understood the attraction of the hypothesis that life originated elsewhere. If such a thing had occurred, it would be fundamentally impossible to prove. And it only "begs the question" -- if you ask "where did life come from ?" and the answer is "somewhere else", then you have to ask, "well, how did it originate *there*?" and you can't answer that, because you can't investigate "there". Frankly, it seems like more of a hopelessly romantic -- even magical -- notion than a testable scientific hypothesis, but for some reason, it's become en vogue (again -- *sigh*) among so-called science journalists and won't go away, despite a paucity of evidence and a complete absence of even remotely unambiguous evidence. Frankly, it just seems to pander to a public appetite for romance over reason.
Posted by eppur_se_muova | Tue Nov 18, 2014, 09:38 AM (1 replies)

The car that runs on sunshine and sweat (BBC)

Ken Wysocky

In a perfect world, someone would invent a small personal vehicle that runs on nothing but sunshine and calories – and carries a week's worth of groceries, for good measure.

Don’t look now, but it’s already here. The Elf, manufactured by Organic Transit, based in the US state of North Carolina, is the brainchild of inventor Rob Cotter, Organic Transit’s founder and chief executive officer. And it evokes nothing less than the love child of a recumbent tricycle and a Messerschmitt bubble car.

The Elf’s car DNA is visible in features such as its tadpole-like polycarbonate shell, which shields riders from the elements and – abetted by LED headlamps, taillamps and turn indicators – makes the impish vehicle more visible on roads than a traditional two-wheeler. Its bike pedigree shows up in its control scheme; its narrow front wheels, equipped with disc brakes, are steered and stopped by hand grips rather than a car-style steering wheel and brake pedal.

Equipped with a standard three-speed internal-hub transmission or an optional NuVinci continuously variable planetary transmission, the Elf moves by pedal and/or electric power; its one-horsepower electric motor is powered by a lithium iron phosphate battery pack, which is fed by a 100-watt rooftop solar panel. The pack takes seven hours to charge by sunlight or 1˝ hours when plugged into a standard household outlet.

Speeding tickets likely won’t be an issue. The Elf tops out at 20mph on electric power alone, 30mph with pedals pumping. Ideally suited to quick urban jaunts, the Elf is less useful for long-range travel, unless you happen to be an ultra-marathoner. Its motor-only cruising range is a modest 18 miles, although pedalling can bump range to as much as 40 miles.
***
more: http://www.bbc.com/autos/story/20140609-bike-to-the-future




An enclosed electric moped, more or less ...
Posted by eppur_se_muova | Tue Jun 10, 2014, 12:28 PM (2 replies)
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