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January 26

Atmosphere of Venus / compressing C5O10N2

I was musing over a Venus terraform in a very crude way, considering what the prevalences in a 92 bar atmosphere are relative to Earth:

CO2: 8878% vs 0.040%

CO: 0.16% vs ~0

N2: 322% vs 78.084%

Ar: 0.64% vs 0.93%

H20: 0.18% vs 0.001%-5%

He: 0.011% vs 0.0005% (waaaat?)

Ne: 0.064% vs 0.0018%

SO2: 1.38% vs ~0

I get that in order to make Venus atmosphere Earthlike, you basically have to dump 364 pounds of C, 970 pounds of O, 36 pounds of N and a mere 0.1 pounds of S onto every square inch of the planet's surface - or beneath it. Ignoring the S, which can clearly be made a solid but seems too small a component to figure into a bulk formula, that's an empirical formula of C5O10N2. Now we saw in a thread above that even bulk CO2 can be pressurized into an extended solid, but is there any way to predict what this composition would turn into, at what pressure? For example, I'm thinking you might get two NO2 groups on a C5O6 extended structure (almost a polyketone, though adjacent ketones are high-energy and disfavored) ... but I certainly don't know that. It seems empirically like a doable experiment, but has anyone done it? (yes, I realize that this is nearly 1 million times harder than fixing global warming, possibly using similar carbon sequestration technology, without a local infrastructure, and so it is not going to be done by any normal means we know of today... and the planet is still extremely dry)

Another question: why so much helium? I thought the conventional wisdom was that light gasses are lost, but if you sequester away the other stuff there's like 200 times more helium on Venus than here - even though the argon level is lower. and there's also 60 times more neon. I thought a noble gas was a noble gas... There might be an answer at [1] but I didn't have access, and can't riddle it out by the abstract. Wnt (talk) 17:27, 26 January 2016 (UTC)[reply]

The thermosphere of Venus is much colder than that of Earth. Therefore the losses of light gases are smaller. Ruslik_Zero 20:37, 26 January 2016 (UTC)[reply]

Well! I went back, looked at that article and atmosphere of Venus - sure enough, Earth's thermosphere can get up to 2500 C, and Venus can get up to ... 120 C or so. I have no idea why. But I thought the popular wisdom was that all Venus' hydrogen was lost to space. How can that be so if helium doesn't escape nearly as much as on Earth due to the colder thermosphere? I clearly have more shocks in store for me here. Wnt (talk) 14:26, 27 January 2016 (UTC)[reply]

I assume it's cooler because of Venus's albedo. Venus's thick atmosphere reflects most of the incoming sunlight (as demonstrated by the fact you can't see the planet's surface from space). Hydrogen is of course even lighter that helium—only a fourth the atomic weight—so that still might not be enough to retain hydrogen. These are just educated guesses; I'm not a planetary scientist. --71.119.131.184 (talk) 11:11, 28 January 2016 (UTC)[reply]

Research article query

According to the article found at [2], figure 2 implies that as the hydrogen content in chromium approaches nothing, the FCC and HCP crystal structures of chromium become stable at ambient pressure. This is a problem, because it is know for a fact that the BCC is the solely stable structure at ambient pressure and temperature. How does one reconcile this implied inconsistency? Plasmic Physics (talk) 20:42, 26 January 2016 (UTC)[reply]

I don't know about "known as a fact" (or crystal phases of chromium hydride, at that). In general, science is always preliminary. But in this case, the system is at 150°C, which certainly is not "ambient temperature". --Stephan Schulz (talk) 22:12, 26 January 2016 (UTC)[reply]

Chromium with zero percent hydrogen can hardly be considered as chromium hydride, can it? Looking at the pressure-temperature phase diagram of chromium, it should remain as BCC up to its melting point. So, the system being at 150 degrees should not matter. Plasmic Physics (talk) 22:54, 26 January 2016 (UTC)[reply]

Earliest predictions of man on moon in 60s?

May 25, 1961 President Kennedy announced the US goal to send men to the moon and return, 'by the end of the decade'. Are there records of earlier predictions by scientists, policy makers or governments (not looking for the 'Jules Verne' long literary history), that men could land on the moon in the 1960s or by when? I'm interested in finding the first informed, professional prediction that proved correct - men walking on the moon before the end of the 1960s. Thanks if you can point to a link or citation.

Extensive predictions, varying in accuracy and credibility from fringe lunatics to public statements by esteemed scientists, major movers and decision-makers! I have a stack of moon books at home written in the 1940s and 1950s; they make for great historical reading. If you'd like a complete listing, I can provide titles and authors.

Perhaps the first place to start is our article on Wernher von Braun:

"In 1930, von Braun attended a presentation given by Auguste Piccard. After the talk the young student approached the famous pioneer of high-altitude balloon flight, and stated to him: "You know, I plan on traveling to the Moon at some time." Piccard is said to have responded with encouraging words."

By the mid-1950s, the accuracy of the mission-statement was becoming very concrete and there are hundreds of scientific publications that aptly describe how a manned moon mission would probably look.

The reason that Mr. Kennedy's statement was so important was that he had the power to finance the program.

This 1979 documentary by James Burke, The Other Side of the Moon, is spectacular. He overviews the political clime, including interviews with several scientists and program managers. Among the key statements (somewhere probably around half an hour into the documentary) is a description of how they managed to get Mr. Kennedy to make a statement: it had been decided that it would be politically expedient for Vice President Johnson to formally advise the president in writing that a moon mission would be possible, and that it would be politically expedient for the President to proceed to order a study, and eventually make a formal public statement. The discussions that led to that point were quite extensive.

Nimur (talk) 23:34, 26 January 2016 (UTC)[reply]

See Moon in fiction, which lists many previous stories of human landings on the moon. Use your own judgment as to how realistic any of the twentieth-century stories were. Robert McClenon (talk) 23:37, 26 January 2016 (UTC)[reply]

But the question was about "informed, professional predictions", not fiction. --76.69.45.64 (talk) 05:59, 27 January 2016 (UTC)[reply]

I'm the OP: After further research myself, I came on this, which I think is the type of information I was looking for. Can anyone get closer, more specific, earlier in terms of the type of prediction this demonstrates: "Copenhagen, Denmark, Jan 8 (1960) (AP) - A Soviet rocket expert said today that man may set his foot on the moon some time in the 1960s. Stopping over at Kastrup airport en route to an international conference in Nice, France, Lt. Gen. Anatoloy A. Blagonravov told newsmen it is still too early to set a date for the firing of a manned moon rocket, 'but I would consider it probable that it may be sent to the moon within a brief period of years, possibly in 10 years." - ...I find it interesting that it was a Soviet expert that made this prediction, and that he predates Kennedy's declaration. This guy turns out to be pretty interesting as he was key in representing the Soviets in all talks on cooperation and joint space activities. Wikipedia has a brief article about him, but amending it to include the information about his prediction is above my skill set, I think. I also wonder if this info was hard to find or not obvious to Wikipedia researchers as the guy was a Soviet instead of an American? Research bias? I'm not accusing just wondering... — Preceding unsigned comment added by 94.210.130.103 (talk) 10:17, 27 January 2016 (UTC)[reply]

I would note that moon shots weren't really an independent new technology to predict. To this day, moon shots and other orbital activities serve as a sort of respectable face for ICBM development, and I believe on examination many components can be found in common. Since the latter was seen as a very high priority and subject to great planning and anticipation, the former should have been more predictable than if it were done solely by ivory-tower researchers looking to have a space jaunt. Wnt (talk) 15:34, 27 January 2016 (UTC)[reply]

Here's a good starting book: Realities of Space Travel, (1957), by edited by Leonard Carter. This book details the mechanisms of moon- and interplanetary flight, endorsed by several scientists from the American Institute of Physics, the British Interplanetary Society, and so on. Understand that this book, published in 1957, predates the formal existence of NASA...

The book is full of citations, science, math, technology reviews, and so on.

The introduction to this book walks the reader through an orbital dynamics equation to calculate the necessary energy budget for a manned rocket flight to the moon.

Later chapters detail the state of the art in technology, including rocket design, electronics, biomedical factors, and so on.

Nimur (talk) 17:15, 27 January 2016 (UTC)[reply]