Wikipedia:Reference desk/Archives/Science/2016 April 26

= April 26 =

Incremental cost of ice drilling
Years ago I used to work on ice cores. An early deep core, e.g. GISP2 (3000 m), had a full cost of retrieval of about $60M, making each meter of ice nominally worth about $20k. Of course, deep cores are much more expensive than shallow cores. In addition, there has been much improvement in ice core technology and infrastructure. I've heard that projects like the Rapid Access Ice Drill (RAID) for ice cores, and the fast hot water drill projects (e.g  for subglacial access, but not coring) have made the cost of ice coring and ice drilling much lower. However, I have had trouble finding specific information on current costs. What is the incremental cost of collecting a 100 to 200 m ice core these days? Alternatively, what is the cost of drilling through 100 to 200 m of ice to reach the subglacial bed if one is willing to discard / destroy the overlying ice? Dragons flight (talk) 09:44, 26 April 2016 (UTC)
 * If you really want the marginal cost, I think you'll have to do some deep-diving into research program budgets. The way to approach this is to look at the cost structure of the project: how much money is overhead, how much is capital outlay for specialized equipment, how much is variable cost for labor, fuel, travel and transportation expense, equipment operation?  I'm tempted to say that the cost is dominated by overhead, which implies a very small incremental cost for each additional unit of sample retrieved.  Many of the programs listed, e.g., in the NOAA data set archive were part of publically funded research projects, so if you look for their budgets (e.g. by chasing down the individual grants cited in each author's research-publications), you'll probably find their accounting summaries.  It seems that it would be a research project just to track that information down, let alone to distill it into a meaningful average across a large number of recent sample-retrieval missions.
 * More to the point: do funding agencies or researchers really think in terms of unit-cost per meter of core sample, or are they more concerned with other more abstract metrics like "scientific merit per Government-dollar"?
 * Nimur (talk) 11:49, 26 April 2016 (UTC)


 * I recently had an idea for some interesting glacial work. (Or at least I think it is interesting.)  However, it would require drilling a substantial number of holes 100-200 m through ice.  I'm trying to get an idea of the feasibility of the idea.  If it is a $10M+ project, then I would probably just abandon the idea as being too costly to be worth pursuing.  If it is ~$1M project, then maybe it is worth trying to advocate the idea to other people.  (As I don't personally do ice core collection, I'd obviously have to get others interested in not only funding the work but also doing the study.)  I'm trying to get a rough idea of the costs involved before I waste too much time on something that might be a total non-starter.  Dragons flight (talk) 12:42, 26 April 2016 (UTC)
 * Again, I suspect the cost can scale dramatically. It's much easier and cheaper to drill through 800 feet of rock in Oklahoma than through 200 feet of ice in the middle of a glacier in Greenland.  I suspect you could get a lot of good science on a very tiny budget; and if you could make the case for getting better science on a bigger budget, you could probably find the money - money is surprisingly cheap.
 * Clearly, there do exist organizations who will fund field research of this nature; if you are not already building experience towards the kind of project management to initiate and lead such a project, your best bet may be to attend a conference and find some research collaborators. I'd start at a big conference - like AGU, where you can survey the entirety of the field from multiple different angles - and then gradually migrate to a more specific subject-area meeting.  If my memory serves correctly, you are already PI on some other private-sector projects, so you're probably in as good a position as anybody to initiate a field-data-collection program; but funding agencies like specific experience as part of their risk reduction strategy.  Find somebody who has the right resume, work with them, and co-list them as a cooperative researcher.
 * Large projects of this nature are usually preceded by much smaller exploratory programs to establish proof-of-merit; you could try putting out a paper just to develop the idea, and test the reception for the basic premise before burning any large quantity of money on field work.
 * Nimur (talk) 13:15, 26 April 2016 (UTC)


 * I know you are trying to be helpful, but you aren't really saying anything I don't know already. I'm trying to put together a sketch of project, before taking it to other more knowledgable people that I hope might be interested.  Part of that though is having some idea of the scale and cost of the program.  Admittedly it isn't easy to find cost information for something like this, so I was hoping someone might have better luck at tracking it down than I have so far.  If not, I can keep looking and thinking of who else to ask.  Dragons flight (talk) 14:25, 26 April 2016 (UTC)


 * To be fair we are more like librarians, not subject matter experts. This is a difficult, deeply technical, question.  You seem to have a ton of knowledge about it already -  and it's astronomically unlikely that any of the few dozen reference desk regulars will have more knowledge on the subject than you do.  So we're definitely not going to be of direct help.


 * So, perhaps the best way we might be of assistance is if you give us the names of organizations or individual people who are likely to be more up to date than you are - give us any jargon terms that are unique to this line of work. Then let the (impressive) search skills and legendary tenacity of our reference desk "librarians" do the work.  An alternative might be that we could find an online forum where ice core drillers hang out and we could perhaps get an answer there?  SteveBaker (talk) 15:05, 26 April 2016 (UTC)


 * (EC)Right, so if you're a real scientist who has done real science on ice cores, then probably none of us know more off the top of our heads than you do, and as Nimur said, this is no small research project in and of itself. Anyway, it's not clear what you have and haven't looked at. You say you know what Nimur told you. Have you looked at this NSF grant? That project is ongoing, and over the last few years "1,511 m of the total 3,470 m of ice at the site has been collected", with about $1million paid out so far. Of course not all the money went to drilling. Have you looked for budgets for other projects NSF PLR has funded? Have you used the NSF award search to search for everything related to drilling and ice cores? I think this  is saying that you can get budget info on funded grants via FOIA requests, but I have not tried that and I'm not sure. One of the simplest ways to get budget info would be to contact some of the PIs directly. SemanticMantis (talk) 15:08, 26 April 2016 (UTC)


 * After browsing around on NSF's Polar Science program and Ice Cores website, I found the U.S. Ice Drilling Program resources for scientists. This is a non-governmental organization whose primary purpose is to support specifically-NSF-funded scientists, and to assist them in budgeting and managing field research.
 * If you aren't already familiar with their publications, it might help to read through the Long Range Science plan, the Drilling Technology plan, and the listing of expeditions, to get an idea for the typical budgets and scope of support. You can also download their paperwork for research proposals, or contact their representatives.  "Your email will be received by the IDPO-IDDO and personnel from IDDO will contact you to discuss your needs and provide a Letter of Support and Scope of Work/Cost Estimate for your project."
 * NSF's website links to this service, but they remind you that U.S. Ice Drilling Program is not a Government website, and NSF doesn't officially vouch for its accuracy or merit.
 * In particular - their science program matrix includes an entry for a "Borehole Array" project (multiple borings), and they are planning for that program to require about a "week" of field time, plus a Twin Otter support aircraft. That may help set a lower-bound for the kind of budget - you're talking about funding an aircraft that probably costs around $1500 per Hobbs-hour, plus a crew, for a week, just to get set up at a place that's worth allocating the scientific equipment.  In other words, this kind of work is planned to be conducted under the auspices of a major NSF grant with a daily budget in the neighborhood of tens-of-thousands-of-dollars-per-day.
 * But again - the issue isn't the money - they'll let you use the drills - but the issue is that these kind of ice drills are owned by the United States Government; they are scheduled to be used in specific locations; and if you want to use this unique equipment and the specialized crew who are trained to operate them, you have to go through the effort to get into the "system," so to speak. Your project has to line up with their projects and their objectives.
 * Nimur (talk) 16:58, 26 April 2016 (UTC)

mastoids
My mother (now 91) & her sister both had "mastoids" when they were young. Her sister almost died from this, & Mom says her "mastoids were removed". According to Mom, her "mastoids" drained externally out of her ear---while her sister's drained internally & almost killed her. Neither of us knew what mastoids are, so we looked it up in Wikipedia. You say they are a bone protrusion on the skull for the attachment of muscles. This is not making sense, & I sure would appreciate a better understanding.

Thanks--aj seaman  email address redacted by LongHairedFop, to stop spam  — Preceding unsigned comment added by 201.191.91.18 (talk) 14:51, 26 April 2016 (UTC)
 * See Mastoiditis. The Mastoid part of the temporal bone behind the ear contains air-filled spaces.  Mastoiditis is when those spaces become filled with fluid, and must be drained.  As noted in the article, infections associated with mastoiditis used to be a major cause of childhood mortality, so the accounts of your mother and aunt are fully in line with that.  I hope that helps!  -- Jayron 32 15:04, 26 April 2016 (UTC)
 * Another weird thing that can happen with mastoids is Cholesteatoma, where skin starts growing in places it shouldn't. That can require a mastoidectomy. SemanticMantis (talk) 15:12, 26 April 2016 (UTC)
 * What a difference antibiotics have made. Klbrain (talk) 00:12, 27 April 2016 (UTC)
 * Though alarmingly Antimicrobial resistance is spreading so fast that most if not all of the existing ones may soon be useless. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:29, 27 April 2016 (UTC)

Volume expansion or contraction for mixing two solutions
What is the volume expansion or contraction when mixing two aqueous solutions of salts or a solution of salt and another of sugar as function of their mixing mass or molar ratio? Are there any data pages on this issue?--5.2.200.163 (talk) 15:33, 26 April 2016 (UTC)
 * It's a whole lot of messy calculus to do such calculations, but if you want an overview, here's an old ACS article that covers the concept using ethanol-water mixtures as a model. Here is an even older article on volume changes when dissolving various halogen salts.  In Wikipedia, you can read about concepts like Ideal solution (for when volumes are additive) and Margules function, and more generally about Chemical potential which is the root concept which affects a whole lot of deviations from ideal behavior in a lot of situations (Ideal gas, ideal equilibrium constant, etc.)  -- Jayron 32 18:29, 26 April 2016 (UTC)
 * I see that the first article says something about a shrinkage factor whose definition would be very interesting to see. In other sources encountered there was just some mention of a percent expression of this factor, without formula.--5.2.200.163 (talk) 16:34, 27 April 2016 (UTC)
 * I see also that the article introduction says something about the relation of the concept (shrinkage factor) to established ones like apparent and partial volume. That would be extremely interesting.--5.2.200.163 (talk) 16:39, 27 April 2016 (UTC)
 * Volume of mixing is a redirect to the Partial molar property article. DMacks (talk) 20:20, 29 April 2016 (UTC)

Phase-transition of water: Supercritical --> solid?
Hey there,

I stumbled about a question today and I can't get my head around it. My Physical Chemistry textbook shows a phase diagram of that indicates, that there is a phase-transition of super-critical water at around 600 k and 10 GPa. Does anyone now, if it is possible to form ice directy from supercritical water?

Thank's --134.61.98.4 (talk) 18:10, 26 April 2016 (UTC)
 * No, because at no point does the solid-liquid or solid-gas transition happen at or above that temperature and pressure combination. The supercritical transition occurs when there is no distinction between gas-like behavior and liquid-like behavior in a fluid (basically, increasing temperature makes a liquid more gas-like.  Increasing pressure makes a gas more liquid-like.  Raise both above a certain threshold, and the difference between a gas and a liquid becomes inconsequential, that's a supercritical fluid).  The solid phase of water should not be anywhere near these conditions.  -- Jayron 32 18:32, 26 April 2016 (UTC)


 * As shown at water and carbon dioxide it is entirely possible to have a supercritical fluid to solid phase transition. Generally, the transition occurs by taking a supercritical fluid and subjecting it to enormous pressures until it converts back to a solid.  Dragons flight (talk) 19:12, 26 April 2016 (UTC)


 * So stricken. Thanks for providing a link to the more accurate phase diagram showing the solid-supercritical phase transition.  I should probably actually have looked than speaking extemporaneously.  I've been correctly chastised.  Thank you.  -- Jayron 32 20:15, 26 April 2016 (UTC)


 * Lighting the grail-shaped beacon, eh? Bad, bad, naughty Zoot! μηδείς (talk) 20:38, 26 April 2016 (UTC)


 * Next time I try to state my question clearer and provide a diagram myself. But I could find one through my quick search.--134.61.98.4 (talk) 13:32, 27 April 2016 (UTC)


 * Thank you both. This is exatly what I meant Dragons flight. You don't happen to know where I can get more information about the nature of this transistion or if there are any applications that use it? Can I imagine it to be some sort of sublimation/ re-sublimation? I was under the impression, that supercritical fluids cannot be in equilibrium with other phases, so this somehow makes me curious ;) Thanks again --134.61.98.4 (talk) 19:40, 26 April 2016 (UTC)


 * Supercritical fluid phase can perfectly well be in a thermodynamical equilibrium with the solid phase. Imagine a cylinder filled with a supercritical fluid, where the piston can be moved in (or out) so that the cylinder volume is reduced (or increased) but none of its contents escape, and the temperature of the contents is kept constant.  This process - provided the contents of the cylinder have time to reach equilibrium - is called isothermal compression (or expansion). Let's assume the temperature is above the critical-point temperature. Isothermal compression of the supercritical fluid will cause the pressure to rise until you reach the phase-transition pressure - the pressure at which solid phase and supercritical fluid phase coexist. As you keep compressing, more of the supercritical fluid will condense into solid, but the pressure will remain constant as long as any supercritical fluid is left. If you stop compressing at tha point, you will have an equilibrium mixture of solid and supercritical fluid phases. Further compression beyound the volume point at which there's no supercritical fluid left will cause the pressure to start rising again, as you are now in a solid phase and not in coexistence of solid and supercritical fluid phases. Does this help? --Dr Dima (talk) 20:57, 26 April 2016 (UTC)
 * Regarding your question where to get more information: at an undergrad/grad level, I strongly recommend Landau & Lifschits textbook, and Zel'dovich & Raiser textbook (this one), but those are not an easy read. At a high-school level, I need to think what would be the best place to start from. --Dr Dima (talk) 21:03, 26 April 2016 (UTC)


 * This is very helpful, thank you. If I understand you correctly, the transition supercritical fluid --> solid is thermodynamicaly not different from the transition gas --> fluid where the pressure also remains constant until all gas/fluid is gone?
 * The literature looks good. I'm at graduate level but my area of expertise is actually inorganic chemistry. The second book looks promising, I will definitively check it out when I get the time.--134.61.98.4 (talk) 12:59, 27 April 2016 (UTC)


 * Here's some interesting video of supercritical water in a "hydrothermal diamond anvil cell". SemanticMantis (talk) 21:40, 26 April 2016 (UTC)
 * Nice video, thanks --134.61.98.4 (talk) 13:14, 27 April 2016 (UTC)

Reusing lunar rovers
1) Is it true that there are 6 rovers on the Moon now ?

2) How many were in good working order when last used ?

3) Would it be possible to land near one, replace the batteries, and get it to run again ? If so, this would seem to allow us to dramatically decrease the weight versus bringing a new rover, although at the cost of only being able to land where a working rover is present. StuRat (talk) 19:19, 26 April 2016 (UTC)


 * Well, there were three Apollo moon buggies - a couple of Russian Lunokhod rovers from the same era - and the Chinese Yutu rover that failed after the first day or so...so, yeah - six in total.
 * The three Apollo buggies were still in working order when they were abandoned. The first Lunokhod worked for nearly a year - I'm not sure about the second one.
 * Maybe...but electronics don't like to be frozen and most spacecraft die when the heaters fail to keep the electronics warm enough. But getting an existing rover to run again doesn't help if it still has the same set of sensors and cameras aboard.  The Apollo buggies only really had a camera aboard - and after 11 months of driving around, the Lunohkod probably gathered as much data as would be useful.  What makes most new missions interesting is that they have new instruments aboard that can measure things we couldn't manage previously.
 * SteveBaker (talk) 19:34, 26 April 2016 (UTC)


 * 3) Then couldn't they swap in new instruments, too ? Still cheaper than replacing the entire platform, I imagine. StuRat (talk) 19:38, 26 April 2016 (UTC)


 * Lunokhods are still being used, in a sense; see Lunar Laser Ranging experiment. The electronics is probably dead due to radiation exposure, but it's possible that the chassis and motors may be salvaged and reused if needed. --Dr Dima (talk) 21:27, 26 April 2016 (UTC)


 * This article might be useful. Regarding replacing the instruments of an existing rover, I doubt there would be any benefit. There's a finite amount of time in a mission. You don't want your crew playing mechanic on the Moon when they could be doing more useful work. And there's the risk that they might not succeed in retrofitting the rover, or that it's unusable. Space is a hostile environment. --71.110.8.102 (talk) 22:15, 26 April 2016 (UTC)


 * Ship of Theseus proves that you can get the rover to work again on the Moon. The rover consists of a finite number of components. Let's name them as component#1 to component#18345. Step one: replace component#1 Step two: test if rover is working again Step three: if rover works then your job is done, otherwise return to Step one and replace the next component. 175.45.116.66 (talk) 00:00, 27 April 2016 (UTC)


 * On Earth, the NASA Apollo lunar rovers weighed 460lbs and the lander weighed 35,000lbs (For comparison, the Spirit and Opportunity Mars rovers are each about 400lbs Earth-weight). If this is a manned mission (which it's gonna need to be if you're going to start repairing a rover) - then adding a rover to the launch weight isn't that big of a deal...especially since you're going to need to take replacement batteries and whatever other spares seem likely to be needed plus the tools to replace them.


 * The two Lunakhods each weighed in at 1,667lb - they did have solar panels - which is why Lunakhod 1 lasted 11 months - but what finally killed it was the radioactive Polonium 210 used to keep the electronics warm ran out. Lunakhod 2 lasted 4 months, failing with a cooling problem.


 * The Chinese Yuto weighed 310lbs - so it would be even easier to ship an entire new one rather than locate and repair it. It's motors (probably) didn't survive the first lunar night - although the rest of the rover carried on working for a few months after that.  It also used solar panels for battery charging and a radio isotope source for keeping things warm through the 14 day solar nights.


 * Sending a spirit/opportunity look-alike - with a likely 2000 day mission life - would make a whole lot more sense than repairing a golf-cart that doesn't have useful sensors - and doesn't even have solar panels to rechargeable its' batteries. However, they'd require some redesign for surviving the long lunar nights without freezing up.


 * Given the ungodly cost of sending humans to the moon, the cost per hour to have them there is enormous. Having them spend time repairing a rover that could easily be replaced (and with vastly higher utility - newer sensors, fancier electronics, etc) - with not much confidence that it can indeed be repaired at all - it just doesn't make sense. SteveBaker (talk) 03:43, 27 April 2016 (UTC)


 * There can always be some combination of circumstances that motivates people to do something. For example, there you are making a routine crew exchange run to the Chinese base at the Lunar pole, when a minor course correction turns into an explosion.  Your orbiter is heading directly at the Moon, and you can't get the rockets working.  So you herd everybody into the lander (minus whoever you arranged to draw the short straw) and just manage to clear the Moon, but you're in an equatorial orbit.  You land at whatever site you can reach with usable materials.  Just so, you're looking at a moon rover and you have a trunk full of tools and solar panels.  And, oh, seventy-two, nay, make it ninety-six hours worth of air.  Having 5,000 miles to the base and going about 5 mph, this is a problem, but hey, you might rig some CO2 scrubbers out of your cargo.  Or stop at some abandoned lander on the way.  And NASA can hear your suit radios, even if you can't hear them, and might be negotiating for a rescue from the Chinese.  Or have a plan to drop a care package.  In any case ... better get working on that moon rover, time is ticking. :) Wnt (talk) 10:16, 27 April 2016 (UTC)
 * So when is this novel coming out, Wnt? (Hey, it worked for Andy Weir). {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:32, 27 April 2016 (UTC)
 * Ha, I'd give that book a shot too :) SemanticMantis (talk) 16:15, 27 April 2016 (UTC)
 * This isn't really my field, so getting all the lingo right would be tough. Doing research to see which rover parts endure and which don't, whether a plausible portable 3D printing technology can replace them etc. is tough.  Getting characters right is really tough.  But if enough people were interested enough, we could try setting it up at WikiBooks as a collaborative writing experiment.  We might even work in that super-durable glass disc holding all of Wikipedia somehow.  (probably crack it in half and use it as mirrors to signal to each other. :) ) Wnt (talk) 18:31, 27 April 2016 (UTC)
 * No...they're hoping that the information they need is encoded in one of the roughly 6000 articles that we have on Japanese railway stations.
 * Well, the surface area of the moon is about equal to that of North America and Europe combined - even if you are on the earth-facing side - you're looking for things the size of a small car in an area the size of Europe. I kinda suspect you'd need to be either extremely lucky - or to endure a LONG diversion to find a handy rover...and I still maintain that their electronics would be frozen to the point of destruction.  On the moon, an unheated rover would be chilled down to -150 degC for a long time - even the most rugged military-grade electronics are junk if you let them get below -55 degC.


 * Still, it evidently worked for Mark Watney as he took a little sojourn on Mars. But then Martian nights aren't two weeks long and there is at least some atmosphere to help retain the heat. SteveBaker (talk) 22:33, 27 April 2016 (UTC)


 * One nice thing about sci-fi is you can steer around these problems in the fourth dimension, i.e. postulate, as I hinted above, that routine equipment for a moon base includes a small 3D printer capable of producing electronic circuit boards (or some functional equivalent). Wnt (talk) 11:04, 28 April 2016 (UTC)

Why exactly can't lunar rovers handle cold ?
Considering the expense of getting them there, I'd think they could be made out of a platinum-iridium alloy with zero coefficient of thermal expansion, at minimal additional expense. So, then, what about cold destroys them ? StuRat (talk) 01:19, 28 April 2016 (UTC)


 * Hehe, NASA would love platinum and iridium, if only they would go on a diet before launch. There are other materials with negative thermal expansion - I don't see a list here for zero, but I suppose it can be arranged.  But I don't know if you can make electronics out of them. Wnt (talk) 10:56, 28 April 2016 (UTC)