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We should have a reward here for the most misleading topic.

The very linked article itself, and further research about "Great Unconformity" clearly state that this particular unconformity is limited to the Great Canyon GRAND CANYON - THE GREAT UNCONFORMITY and from wikipedia Great Unconformity one can further learn about this "annomaly" together with it's explanation:

Unconformities in general tend to reflect long-term changes in the pattern of the accumulation of sedimentary or igneous strata in low-lying areas (often ocean basins, such as the Gulf of Mexico or the North Sea, but also Bangladesh and much of Brazil), then being uplifted and eroded (such as the ongoing Himalayan orogeny, the older Laramide orogeny of the Rocky Mountains, or much older Appalachian (Alleghanian) and Ouachita orogenies), then subsequently subsiding, eventually to be buried under younger sediments.

We could've avoid all the wide speculations if only the topic was reflecting the content, as "Hi, look what interesting about geology I found - it's old but a great read".

Mars Want to Launch a Giant Magnetic Shield to make Mars Habitable The Paper

With the atmosphere of Venus being as thick as it is, how you would see the surface when standing on it is considerably affected by the air. It would not look dark gray -- it did not look dark gray to Venera 3 when the probe landed. Comparison: https://www.lpi.usra.edu/publi...

And in order to fix this ridiculously modded up comment...

The fiction:

and the atmosphere too thin for aerodynamic braking. Which means mixed mode braking, and freakin' enormous parachutes. Not long ago it was estimated that a LEM sized lander would need total parachute area larger than a baseball infield

The reality:

The Dragon-variant spacecraft would perform a direct entry into the atmosphere at 6.0 km/s and utilize entry guidance during both hypersonic and supersonic phases of flight. Unlike MSL, the spacecraft would not deploy a parachute decelerator but rather would transition directly from atmospheric flight to powered descent at Mach 2.24.

Because the most useful concepts describe what you're looking at in such a way as you get an accurate perception of what they are. The current non-planet trend for Pluto doesn't do that for me.

If you follow the latest "trends", Pluto is trending back...
Unfortunately, as part of this trend, "that's no moon orbiting around the earth, that's a planet..." And we get 110 "planets"...

All in the spirit that everyone gets a participation medal ;^)

I think you are being too pessimistic, Barbara.

Space industry as of 2015 was $335 billion in economic activity ( see page 7 of http://www.sia.org/wp-content/... ), with about 1400 operational satellites in total. We don't have a way to effectively repair or refuel these satellites. When they stop working, we have to replace them at great expense. Saving money or increasing profits provides plenty of "will and commitment" to build the first generation of space mining and production. This would start with propellants, since just about every satellite uses them, and they are a simple product to make.

> we don't know where (or even if) the needed resources exist in viable quantities or concentrations

On the contrary, nearly all satellites operate on solar energy, so we know that is feasible. The total solar flux passing closer than the Moon is equal to the whole world's fossil fuel reserves *every minute*. That's more energy than we know what to do with, provided we can tap it economically.

Meteorites are pieces of asteroids that hit the Earth and survived re-entry. So we are able to examine those in detail, and then infer the composition of asteroids still in space by comparing spectra. For a handful of asteroids, and the Moon, we have visited by scientific missions, or in person, and gotten more direct information. So, for example, we have detailed geologic maps for the Moon ( http://www.lpi.usra.edu/resour... ) and are building up our knowledge of other bodies.

> human colonies are a death sentence to anyone living there permanently

I will set aside the fact that the human condition has a 100% mortality rate so far, and that a minor oops driving to work will kill you on Earth. But I helped design and build the Space Station, and it's been occupied for 15 years now. Think of it as a proof of concept. A space colony in orbit or on the surface can deal with gravity by rotation. On the ground that means a merry-go-round or racetrack setup that people use for as many hours as required to maintain health. Bulk rock is easy for surface locations, and not so hard for orbital ones. Enough thickness will provide good shielding. Most illustrations of space colonies are "artist's concepts" and don't address safety in the way engineers building bridges and skyscrapers have to. A real colony would have multiple layers of pressure shell, compartmentalization, emergency shelters, and other safety provisions. Yes, accidents and failures will happen, but we live with fires and natural disasters on Earth. The question is can you bring the risks down to a comparable level as on Earth. I think the answer is yes.

> at the rate we're avoiding meeting even our moderate climate change goals, we'll have a massive depopulation or extinction event long before that.

We are installing over a hundred billion watts of solar and wind capacity worldwide this year. Coal use has dropped by a third in the US in the last 10 years. Things could move faster, but when oil states like Saudi Arabia and Dubai are installing renewables, it should be obvious change is happening ( http://www.pv-tech.org/news/sa... )

The soils contained heavy metals such as lead, arsenic and mercury, and there were concerns that these could be taken up by the plants.

"concerns" doesn't mean that the toxins were taken up, just that there were "concerns". That's a bit odd, because such analyses are pretty trivial, and absolutely routine. Odd that.

My guess would be that they didn't analyse the "soils" either, and just took the composition, including the toxin content from the wrapper. [Googles] And here's the MSDS : http://www.orbitec.com/store/J... ; I don't see any grounds for concern there. Another source http://www.orbitec.com/store/J... also has no grounds for concern. A study on mouse response to the dusts : http://sci-hub.io/http://www.t... - no concerns. Ah, some composition for the lunar stimulant from http://www.lpi.usra.edu/lunar/... - and that quantifies the arsenic at 19+/-9 ppm, about twice what is typical for soils. Which would b a problem if this were a level in drinking water, but it's not. How much of that mobilises, and how much concentrates into the plants simply needs analysis.

Even so, those levels are probably manageable. You might need to make sure the soil is well oxygenated (not difficult, particularly with the perchlorate in the soils) and at a near neutral pH (again, you need that anyway for your plants to grow). You might need to grow some crops of "scavanger" plants with newly made batches of soil, then discard them along with the mobilised toxins. Or it might simply not be a high enough level to worry about.

Looking from the other end of the telescope, Cornwall is well known for arsenic minerals (well, I'm a geologist ; "well known" amongst geologists), and there's a lot of agriculture there. How much arsenic do they have to deal with?

http://www.ncbi.nlm.nih.gov/pubmed/24213800 " garden soils in the historical mining area of Hayle-Camborne-Godolphin, Cornwall, England are large and range widely (144-892 μg/g [=ppm]). [...] Examination of 6 salad and vegetable crops grown in 32 gardens has shown arsenic concentrations in the edible tissues to be only slightly elevated. [...] Arsenic in all the vegetables sampled was below the statutory limit in the U.K. of 1 mg/kg [1ppm] fresh weight."

On the basis of that, I doubt there would be a real problem. It'd be worth including a portable XRF in the load out, but that's probably in the mining and surveying gear anyway.

Volume is then 1.4*10^34 m^3.

Let's pick a number from http://www.lpi.usra.edu/books/... for the density. 2g/cc sounds a very convenient number (2000 kg/m^3). That makes the mass 2.8*10^37kg.

About 15,000 solar masses. I rather think we'd have noticed it.

I think this guy was talking through his hat. Average Martian soil is about 18% iron oxides which makes it lower in iron content than many Hawaiian volcanic soils, in fact the composition of Martian and minimally weathered Hawaiian soils are often compared. And we know what a barren wasteland devoid of life the Hawaiian islands are...

In an HX thruster, liquid propellant is pressure- or pump-fed to a lightweight planar heat exchanger. For orbital launch, the propellant of choice is liquid hydrogen. H2 provides a vacuum Isp of 600 seconds, sufficient for a robust single-stage-to-orbit capability, at a heat exchanger temperature of only 1000 C (less than 2000 F). The heat exchanger can therefore be made of ordinary materials, rather than exotic high-temperature alloys, which allows building cheap expendable vehicles.

Kare, Jordin T. "Modular Laser Launch Architecture: Analysis and Beam Module Design." Final Report USRA (2004).

This report is about laser heat exchanger launch system but should be valid. Dr. Kare has studied both laser and microwave launch systems. A single-stage-to-orbit vehicle does not shed tanks or stages. When it reenters the atmosphere is it a big empty tub with a very low cross-sectional mass density. The temperatures it encounters are dramatically lower than a capsule or the shuttle.

In other words, this is far from being the most difficult part of the system.

As to it taking less fuel to get to mars then the moon... How? Just explain how that is possible.

Aerobraking. The vast majority of your spacecraft's fuel and cost is spent getting out of Earth's gravity well. If you've burnt enough fuel to get into a lunar transfer orbit, it takes just a little bit more to escape Earth entirely and go to Mars. But to *land* on the Moon, you need to spend more fuel to slow down and stop on the surface. To land on Mars, you just need a heat shield, because Mars has an atmosphere you can use to slow down.

http://en.wikipedia.org/wiki/D...

So that's reason #1 why Mars's atmosphere isn't a joke.

I'm quite certain you could "throw" things from the moon to the earth. So the return trip wouldn't even take fuel. You could literally just give it a push.

Unless you can throw things at 2.4 kilometers per second, no. The Moon's gravity is less than the Earth's, but it's still serious business. You need quite a bit of fuel to take off from the Moon. You need fuel to take off from Mars too, but Mars's atmosphere has carbon dioxide: bring a little hydrogen with you (or use the local water) and a source of energy (solar panels or a reactor) and you can synthesize methane and oxygen fuel while you're there. No need to carry fuel for the trip home!

http://www.geoffreylandis.com/...

Reason #2 why Mars's atmosphere isn't a joke.

[Mars's atmosphere] is not enough to appreciably reduce radiation to the surface.

Oh, but it is. Mars's atmosphere is thick enough to shield radiation about as well as several inches of concrete, reducing radiation exposure by a factor of 2-3. It's also further from the Sun than the Moon, which reduces solar radiation by a factor of 2. Neither of these effects are enough on their own: you're right that Mars habitats will have to be underground too. But going outside is noticeably safer.

http://www.lpi.usra.edu/lunar/...

Reason #3 why Mars's atmosphere isn't a joke.

Mars's atmosphere doesn't provide complete radiation shielding, but it does provide complete protection from meteorites up to about 1-2 meters in diameter.

https://janus.astro.umd.edu/as...

Reason #4 why Mars's atmosphere isn't a joke.

And finally, the Moon has craters and lava flows and that's all. Mars has those, plus volcanoes and canyons and ice caps and wind and clouds and storms and snow and glaciers and sand dunes and landslides and groundwater and river valleys and maybe an ancient ocean and maybe, once upon a time, life. Why? Because Mars has an atmosphere.

Reason #5 -- the most important one -- why Mars's atmosphere isn't a joke.

As to why not do it on earth? That question doesn't even make sense.

It was a rhetorical point, not a serious proposal. I'm saying that if you're going to spend your whole life hiding in a sterile burrow, does it really matter that you're on another planet?

For the record, none of these ideas are my own. I'm quoting chapter and verse from "The Case for Mars" by Robert Zubrin. Zubrin's got his problems -- he's a little too casual about the radiation dangers, for instance -- but IMO it's a good starting point for any serious discussion of colonizing the solar system.

http://www.amazon.com/Case-Mar...

You know. I tried to write a calm, and sensible reply to this poisoned barb you have thrown at me, and I just couldn't do it.

Let's just say that you are simply wrong on a good many of your points.

Here are just a few of them:

1) You make the mistake in asserting that people leaving earth as political asylum seekers would be doing so without something already being there. Even the puritans didnt leave england en-mass until AFTER the colonies in north america were fully settled and productive. --What you are are failing to grasp, is that there would not be such a place to go, if nobody makes the damned colony; The puritans would never have left england, because the colonists never would have preceded them. Did all the irish people fleeing ireland after the potato fammine come with metric fucktons of food and other things? No-- they sold themselves into indentured servitude to come here, with just the clothes on their backs. Why? because there was a means of producing food over here already.

There is nothing inconsistent with wishing to create a colony, with the intention of permitting political asylum once it is able to accept such persons. Granting asylum is a great way to get desperately needed genetic variability and skill diversity for such a project once it is ready to accept such people. The notion that the colony would be built by political refugees when they have no money or resources with which to do it is a strawman of your own construction-- Good thing it isnt what I advocated! Beat that strawman all you want, his stuffing coming out does not impact my position in the slightest.

2) You make the implicit assumption that no industrial capacity or food production would ever be possible on-site at mars. This is a very laughable position to take, so laughable in fact, I wonder from what body of information you produced it from. Data from multiple rovers at very diverse areas on the martian surface has revealed very useful and valuable minerals. Not terribly useful here on earth mind-- we have water, nitrogen and oxygen in copious abundance-- But for martian colonists, those minerals would be more valuable than gold. Do you have any idea how much water is chemically stored in gypsum? Here's a hint-- Gypsum has the chemical formula CaSO4(2 H2O) It's a hydrated sulfate mineral. For every mole of gypsum, 2 moles of water can be produced. The process to do so? Heat it up to about 500 degrees F, and catch the vapor that comes out. Is gypsum a common soil mineral on mars? Apparently so-- Nasa's rovers have found very large veins of the shit.

In fact, There are entire expanses of sand dunes made of gypsum sand in the northern hemisphere of mars.

To quote the linked page:

Observations from orbit had detected gypsum on Mars previously. A dune field of windblown gypsum on far northern Mars resembles the glistening gypsum dunes in White Sands National Monument in New Mexico. The origin of that windblown gypsum is, however, uncertain.

"It is a mystery where gypsum sand on northern Mars comes from," said Opportunity science-team member Benton Clark of the Space Science Institute in Boulder, Colo. "At Homestake, however, we see the mineral right where it formed. It will be important to see if there are deposits like this in other areas of Mars."

Somehow I don't think getting sufficient water will be a problem for a martian colony. Harvesting that dune field alone would produce enough water to supply a massive colony site.

Know what else the rovers found? Ammonium salts at rock nest. The linked paper does give the caveat that the sample could be evolved methane and not reduced nitrogen, and suggests further study with the laser spectrometer. However, the gas form of nitrogen i

He has been saying this for a while, most recently (to my knowledge) at the recent Small Bodies Assessment Group (SBAG) meeting in DC. I was there and have to say that the community (at least, the sample of the community in that room) did not come to even rough consensus on his proposal, and was in fact split roughly 50-50. There is, however, a pretty strong consensus on the funding of a asteroid survey mission, an infrared telescope on an interior orbit to the Earth to find most of the possible "city-buster" NEA. This is pretty much what the B612 foundation is proposing, but they haven't raised the money yet, nor is on any NASA funding plans.

My own personal opinion, FWIW, is that Binzel is wrong and that the ARM mission is a first good step to Mars.

The real goal of the habitat is the Martian moon, Phobos, which is reachable for nearly the same expenditure of energy as the high retrograde lunar orbit planned for ARM. It would take a good deal longer, though, thus the need for a habitat.

If you think of ARM as a training wheels dry run for Phobos, you would not be far off.

Stone Aerospace has some elaborate plans:

"When we speak of the Europa mission at our shop we are talking about going for the gold ring: landing on the surface of Europa; sending a nuclear-powered cryobot carrier vehicle through the ice crust; discharging a nuclear-powered 'fast mover' autonomous underwater carrier vehicle that has planet-scale range, and selectively launching a series of miniaturized, highly intelligent AUVs [Autonomous Underwater Vehicles] to go into the more dangerous areas (e.g. around black smokers, up into ice cracks, into corrosive chemical plumes) to search for and collect biological samples and bring them back to the mother ship,"

but I don't know anything about their comms plans. A german group plans to have a submersible return to the surface and then broadcast everything back.

I would strongly prefer to have a transmitter on the surface (sending either back to Earth, or to an orbiter somewhere), and use acoustic signaling, just as you would do with a deep submersible here on Earth. Problems with the "go back to the hole" plan include

- a failure on the return trip means no data comes back at all
- a good fraction of the under-ice mission time would be spent going back to the hole, or making a new one, rather than further exploration.
- if the submersible gets into trouble, or has to make a decision as to what would be best to sample/explore/go to next, Earth cannot help.

Of course, we know nothing of the acoustic noise level in Europa, so this might require a precursor seismology mission just make sure it would work.

Exactly. Why has NASA been dragging their feet? They have been studying this mission for 10 years at least without funding it.

It gets proposed, but every time a proposal takes a serious look at how expensive it would be, the funding isn't there, and they are asked to scale back.

Jupiter is hard. Jupiter is nearly a billion kilometers away-- Mars is hard, but even at its furthest, it's only a quarter billion kilometers distant. Compared to Jupiter, Mars is easy. Jupiter also has a huge gravitational potential (which makes it hard to stop when you get there), and that doesn't even get to the issue of landing on Europa once you get there (no aerobraking nor parachutes for Europa!) and the difficulty of penetrating the ice.

Clearly the first thing needed is just a probe that can take a deep penetrating radar to the system and find out just how thick the ice over the interior ocean of Europa is, and whether there are places that are thinner than others, and whether cracks go down all the way to make an easier route to the interior. That would be a lot easier than actually trying to land, much less access the ocean... but even that is not at all easy. When you're in Jupiter orbit you're having to operate in a ferocious radiation environment.

This is not the only attempt to say that NASA can't afford to continue to use resources they've already developed and launched.

If you look at the SOFIA Project, you will find that the aircraft recently reached a fully operational status. This is a platform that should run for about 20 years collecting data and expanding our scientific understanding. They were scheduling and assigning people time slots for years on out before this budget release.

The budget proposal shows other priorities. NASA has been asked to mothball this platform to save the money that would be required to operate the airplane.

In the spirit of full disclosure, I am not an uninterested party. My spouse is a civil servant working on that program. We are close enough to retirement to handle these types of priority changes. But I do feel sorry for the younger people who moved from AMES and bought a house here expecting to collect scientific data for years to come.

No. Glycine -- the simplest amino acid -- and other straight chain amino acids have been detected outside our planet in comets, interstellar dust and martian meteorites. Life on Europa, or anywhere else, that had decomposed into amino acids would leave a mix of complex amino acids. We could even separate a non-life natural source of complex amino acids (even though there hasn't been any found) from a life source. The proportion of left vs right chirality would indicate life vs naturally occurring amino acids. We're planning to have that kind of detection capabilty on the ExoMars Rover. Now, quit being a dumbass.

The lander did not land in Sinus Iridum, but in Mare Imbrium proper.

I do not think this was a mistake, as they could have waited a few more orbits and made the original landing point in Sinus Iridum. For some reason, a site in Mare Imbrium was chosen. As the actual landing site is on the border between the Titanium rich and Titanium poor parts of Sinus Iridum, I suspect this was not an arbitrary choice, but driven by a desire to understand better the mineral resources of the Moon.

If we are really lucky, the rover will drive the 120 km North to Montes Recti, a mountain range to the North. (These mountains are really islands of old terrain high enough to avoid being submerged in the Mare Imbrium lava flows.) At 100 m/day, it would only take 3 years...

It's not as though the dust is going to float for days (or even minutes) in the (virtually non-existent) lunar atmosphere. (Sure sign of badly written SF or shot-in-a-studio movie footage: dust on the real Moon doesn't cloud, it sprays then drops.)

Unless, of course, the scientists in the charge of the LADEE project were right again. (I have no idea what you thought this mission was supposed to verify if you thought that the dust drops immediately.)

We've known about the plumes for a long time:
http://www.lpi.usra.edu/meetings/LPSC99/pdf/1603.pdf

This is just direct confirmation of what we already knew about.

That paper talks about the possility that one might observe plumes, as one of several possible explanations for the terrain features seen on Europa. Actually observing such plumes is something else entirely.

It's pretty clear Europa probably has some form of life under the ice. The odds are definitely in it's favor. It's just a matter of confirming it, just like these plumes. The really exciting bit will be if it's multicellular or even fish like animals. I really hope I live long enough to see it.

How is that clear? On what do you base the claim that the odds are so good that "it's just a matter of confirming it"? I don't think you would find anybody working in that field willing to make that bold claims.

We've known about the plumes for a long time:
http://www.lpi.usra.edu/meetings/LPSC99/pdf/1603.pdf

This is just direct confirmation of what we already knew about.
It's pretty clear Europa probably has some form of life under the ice. The odds are definitely in it's favor. It's just a matter of confirming it, just like these plumes. The really exciting bit will be if it's multicellular or even fish like animals. I really hope I live long enough to see it.

You could use a magsail to push items away, at least, any item you can induce a current in. And I do believe there were a few prototypes tested. Anyway, here's a NASA paper [PDF] on it, so yes, NASA thinks it may work.

Fetuses don't work against gravity to move their bodies.

Irrelevant.

There's a pressure gradient to be felt across their bodies, but it's small as a consequence of their bodies being small.

Irrelevant.

Do you think the whales will magically be unaffected by a micro gravity environment even though land based mammals clearly are? That the effect of microgravity is confined to needing to find new means of propulsion and pressure differientials in the surrounding media? It has nothing to do with those things .

You have absolutely no data showing that in-utero animal development is affected by gravity.

Absolutely no data?. Feel free to continue to deny science. What's next, will you allude to a conspiracy of science trying to keep down the plucky efforts of the cultists who are trying to establish themselves on Mars - on somone else's dime?

Yet you feel qualified to extrapolate from that zero data to a conclusion that humans can't (or probably can't) reproduce on Mars.

On the basis of available data, yes. Rather than getting all huffy and self righteous, maybe you should provide data to indicate why, against the flow of evidence, we would expect either adults or developing humans to be unaffected by the low gravity on Mars as opposed to the microgravity in LEO. See here, here and here. Don't just quote your religious texts, don't just get angry because there are people who don't believe. We are not condemned due to not being members of the Mars cult.

You say I'm in denial, but you're obviously presenting baseless speculations as if they were established facts.

I say you're in denial, because your tactics so far resemble those of climate denialists:

(a) Shout loudly about how there is no evidence or research, when there is

(b) Bring up irrelevant samples of information (in your case, factoids about buoyancy) and act as if they cancel out fundamental forces

(c) Claim the supposed lack of data supports your side that there a zero long term effects from micro/partial gravity on humans when the lack of data (if there were a lack of data) would allow us to draw no conclusions.

Here's a fact for you: no large animal species has ever been observed during pregnancy in any gravity environment except Earth's.

Once again: http://www.ncbi.nlm.nih.gov/pubmed/15607544. The reason no large mammals have been transported into LEO or similiar is that we have technology that allows that to happen. Let alone beyond LEO. Yet Mars One justs collected $3.8 MILLION dollars, they do not have a spacecraft, any roadmap to build a spacecraft, or a habitat.

In fact, they do not intend to go to Mars.

What they intend to do, and have in fact done already, is to make money from the gullible.

It's a scam.

There's a fact for you.

Fortunately, NASA already did that...

http://www.lpi.usra.edu/lunar/missions/apollo/apollo_15/experiments/ps/

Definitely too small to be noticed or tracked, but it was bigger than a loaf of bread. The 2003 Chicago meteorite was about that size, and while it lit up the night sky like nobody's business, there was no significant shock wave. I'm going to guess this one was about 1-10 meters across based on its effects.

http://www.lpi.usra.edu/meteor/metbull.php?sea=Park+Forest&sfor=names&ants=&falls=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&phot=&snew=0&pnt=no&code=18106

http://www.purdue.edu/impactearth/

They made some assumptions out of necessity, but some of them are questionable. Since one of the shuttles lands on a field of "iron ferrite", they assume the entire asteroid is iron, with a density 7000 kg/m^3. However, it is implied in the movie that landing at that spot was particularly bad luck since there were other landing spots that weren't iron plates. The actual bulk density of most asteroids is between 1000 and 3000 kg/m^3. http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3022.pdf Furthermore, "the size of Texas" was assumed to mean a sphere 1000km across. Saying a sphere is the same size as a two-dimensional object is meaningless, so it's tough to say how big the asteroid was meant to be. If we were trying to make the plotline work, we might say that the asteroid had the same surface area as Texas. That means a sphere with diameter ~300km, or a misshapen object (like most asteroids are) of significantly less mass than a 300km sphere. Not to diminish the value of this project for teaching physics, but in about 15 minutes of Googling I reduced their "9 orders of magnitude" claim to 7 orders of magnitude, even less if you take the low estimates on both density and diameter. Next step in making the plotline work (but it would require actual thought, so I'll leave it as an exercise for the reader) is to see if the movie indicates the asteroid is headed right at the center of Earth. If not, perhaps it would be necessary to split the asteroid into two equal hemispheres, but instead to push most of the asteroid off in the short direction, and a smaller piece of asteroid at a higher velocity in the opposite direction. Not sure how much that reduces the required kinetic energy (if at all), though.

Arslan BK and Gaucher EA Replaying the Tape of Life Through Experimental Evolution of Ancient EF-Tu proteins Astrobiology Science Conference 2010: Evolution and Life: Surviving Catastrophes and Extremes on Earth and Beyond, held April 26-20, 2010 in League City, Texas. LPI Contribution No. 1538

Which I think was just a presentation that provides very little information given all I can find is this PDF:

Whether evolution would ‘replay the tape of life’ if given the opportunity has long fascinated biologists. Paleogenetics via laboratory resurrected ancient genes not only reveals information regarding ancestral phenotypes and environments but also provides an opportunity to ‘replay’ the molecular tape of life. Recent work has demonstrated that ancestral sequences can be computationally determined and experimentally resurrected. The ideal paleoexperimental evolution system requires an organism with a short generation time and a protein whose ancestral genotype and phenotype used to replace the modern gene and causes the modern host to be less fit. The research described here focuses on Elongation Factor Tu (EF-Tu) involved in the protein synthesis machinery of both eukaryotic and prokaryotic organisms. The optimal thermostability of EF-Tus correlates with the optimal thermostability of their host organisms and are ideal for these types of experiments. Previously we have resurrected ancient EF-Tus and showed that these ancient proteins display a range of thermostability profiles. We will replace the modern EF-Tu sequences with ancient EF-Tus and observe their adaptation through experimental evolution. Results from this work will help us identify whether evolution is repetitive for this experimental system.

I don't think that really answers your question and I think this research has only been presented at conferences, published in conference proceedings and not yet peer reviewed in a journal (if it has there is no mention of it on Kacar's CV). I also find it odd that on her site she's using the phrase "tree of life" and not "web of life" which I thought was a more modern way of looking at evolution -- especially in prokaryotes.

I will say that it is probably within line to chide the researcher for putting this little blurb on her research page:

Experimental Evolution of Ancient Proteins

To assess the role of contingency in evolution, I construct an experimental time machine in the lab by inserting previously resurrected genes into a modern bacterial genomes, then subjecting them to experimental evolution. Observing the real-time evolution of ancient genes as they adapt to the conditions of modern bacteria allows us to analyze evolution in action.

"Experimental time machine?" Please, leave the hype and sensationalism to the "science" reporters.

Are you exploring any possibilities for creating fuel for a return trip while on Mars? There is at least one study for the possibility, most likely more. If you're planning on the trip being a one-way mission, why not at least experiment with the idea for future Mars missions? And if it works, you get a ride home, and you've made some pretty hefty contributions to space travel.

SpaceX will be first on both the moon and Mars. Musk has repeatedly said he intends the manned version of the Dragon capsule to be capable of propulsive landing on both bodies, and he expects it to be flying by sometime around 2015. By that time he may very well also have his "Grasshopper" reusable Falcon launchers working, which would cut the cost by a couple orders of magnitude, but leave that aside for now. Even with a disposable Falcon, the availability of a human-rated Dragon will bring the cost of a lunar landing mission well below half a billion. Given that Space Adventures has already sold one of two $100M tickets for a free-return "slingshot" ride around the moon, how many would line up for a cheaper ride to the lunar surface?

I fully expect to see a privately funded human mission to the moon, using SpaceX hardware, within the next 10 years, probably by the end of the decade. I can't think of a single entity on the planet, public or private, in a better position to reach the moon faster than SpaceX.

As for Mars, that's a lot harder to predict. But again, at this point in time, who is in a better position than SpaceX? China's the only one even claiming to try at the moment. There are plenty of others in the US and elsewhere who are "working on" various aspects of Mars exploration and settlement, but to my knowledge, Elon Musk and China are the only two contenders for actually getting there first.

Eat it ? You would die if you even tried to touch it (unprotected).

Of course, the metallic snow is a hypothesis, to explain the high radar reflectivity observed in the Venusian highlands. There are other explanations. To find out, someone needs to send a lander (but don't hold your breath on that one).

I support nuclear propulsion for submarines as a military necessity. Solar tends to do better in the inner solar system (including Mars) than nuclear as a power source. Lower weight to power ratio. People have been looking at it as far out as Uranus as well. http://www.lpi.usra.edu/opag/nov_2007_meeting/presentations/solar_power.pdf

The full abstract for the talk is available at the LPI's website (along with pretty much every other abstract for every conference they've ever hosted):

http://www.lpi.usra.edu/meetings/lpsc2012/pdf/1578.pdf

Mare Acidalium is loaded with uranium and thorium. Why not set up atmospheric fuel production there using breeder reactors?

Here;

http://www.lpi.usra.edu/pss/

you can read the report from the Plantary Science Subcommittee of the NASA Advisory Council, to the Science Committee.

It'd be awesome if /. posters read any of this before posting snide/uninformed/trolly comments about NASA, Obama, Space-X, budgets, etc.

The blog Future Planetary Exploration rounds up reporting on this subject;
http://futureplanets.blogspot.com/2012/02/ruckus.html

Current Carbon nanotube technology is still far from what's needed for a space elevator and (IMO) the field would benefit from a dramatic infusion of cash. It's not clear from this article whether they are planning to support such research, but (again, IMO) if they are not, then this is just idle day-dreaming.

There would be at least an order of magnitude increase in fiber length, and many orders of magnitude increases in fiber production rates, before a carbon nanotube space elevator would become a viable prospect. This is for a terrestrial elevator, a Lunar elevator could be built with existing fiber technology.

The peak in the center of crater Drygalski is an "uplift", which is common in craters. The Wikipedia page on impact craters describes this briefly and has other nice images. These LPI lunar maps helped me identify the crater itself.

Deep space (outside the van Allen belts, i.e., anything but low Earth orbit) has a serious amount of radioactivity. This takes two forms

- Solar flares (where the solar radiation suddenly increases by many orders of magnitude). These require shelters, with warning times in hours. The worst (biggest) flares could kill an unprotected human. These are most likely to occur at certain times of the solar cycle, and there might be a few a year to really worry about then.

and

- Galactic cosmic radiation (high energy particles - aka cosmic rays). The lifetime occupational dose for an astronaut would be reached in about 2 years. So, these can be (more or less) ignored for voyages, but cannot be ignored for habitation. In particular, a pregnant woman will need serious shielding.

Now, there is a wrinkle in shielding for high energy galactic cosmic radiation - these particles have kinetic energies > the rest mass energies of pions, protons, and the like, and, so, when they hit a nucleus in the shielding, they turn into a shower of pions, protons, and the like, each of which itself has enough energy to be dangerous. On the Earth, we avoid this as this all happens 20 + km up. In space, that means that a modest amount of shielding can make things worse if it is close to you. So, you either need room, or a lot of shielding, or both. And, if people work outside (or in lightly shielded auxiliary ships or stations) they need a solar flare warning system plus some sort of shelter within easy reach.

So, if by colony you mean "a place where children are brought to term," you need to address this. That, to me, says that the first colonies (under that definition) will be either on the Moon, in lunar caves (aka lunar skylights), where 40+ of rock will provide excellent shielding (and where lunar ice likely exists and will be much easier to access than at the Lunar poles), or in a O'Neill type cylinder or habitat, where there is enough space to shield the inhabitants properly. If I had to guess, the O'Neill cylinder / habitat would be at least 1 km long, and would be made from either Lunar material (brought up by a Lunar Space Elevator), or from an asteroid (and probably made in place, i.e., using asteroid material without moving it very much.

By the way, water (liquid or ice) would make an excellent shield, if you don't have megatons of rock handy.

The problem is not landing on the comet, the problem is that the comet's gravity is so weak that conventional sampling techniques will tend to push the spacecraft away, and it is not clear that you will be able to anchor the spacecraft firmly enough to avoid this. Similar problems exist with tether based sample return (where a long tether is used to match velocities with a target, and there are only a few seconds available to collect a sample).

There are various proposed solutions for this "touch and go" sampling problem. The recent Decadal Survey provides an overview. Hayabusa tried to fire pellets into Itokawa, to kick up some material for sampling. Other proposed solutions include cores and scoops, "sticky pads," brush wheel samplers. A reasonable approach would probably be to try several attempts, if possible.

100 feet? Current estimates are 19-25 km (12-16 miles). http://www.lpi.usra.edu/resources/europa/thickice/

And how exactly would they build that highway system across the land safely despite earthquake, landslide and river flood risks? Who will find the metals and other materials necessary to build computers, lasers, GPS systems, and microwave ovens? How would they map the moon and find the resources needed for activities there without a geological survey? (Check who made the maps of the moon: the USGS) Who would determine dam sites and the expected implications for ground and surface water resources? Yes, of course all these things could be done privately, but how exactly would you ensure that money didn't determine the results rather than actual safety or resource security, and what guarantees are there that it would be any cheaper?

The short political answer is: nobody knows that the hell the US geological survey does anyway, so it's a natural thing to cut regardless of its actual importance.

So why is NASA spending $2.5B on the next Mars Rover and planning to spend over $6B more on a Mars sample return when it can't find the money for much cheaper missions to Europa or Enceladus?"

This summary doesn't accurately describe the situation at all. The Mars missions are so more expensive largely because they are doing more. The next Mars Rover is going to be larger, heavier, and more capable than the two previous--wildly successful--rovers in pretty much every way. That $6B mission is a sample return mission, lifting off and bringing a research payload from Mars back to Earth is an enormous technical challenge. It's never been done before and that will drive most of the cost.

Also the linked missions aren't quite as cheap as the summary implies. The proposed mission to Europa has an estimated cost of $2.5 billion (and $4.7 billion is the given estimate in the last paragraph of the first link in the summary), exactly the same price as the first "overly expensive" Mars mission mentioned. The Enceladus trip is much cheaper, estimated at a little over half of a billion, so that at least is a reasonable alternative, though I still want to point out that that mission is much earlier in the planning stages, and missions that diverge a lot from previous missions are more likely to have ballooning costs as new found kinks are worked out.

Another issue is that not only are the Mars missions promising more, but there is a much greater chance that they will be able to live up to those promises. Every single Mars mission we've done so far has added to our body of knowledge on the planet, and our ability to better plan a mission and engineer a craft that can get more and better data on the next run. From Viking and on we have answered many, many questions about Mars, and learned about even more questions (meaning that we know the sort of doodad that needs to be on the next mission to answer that new question). Starting a new series of missions to a new celestial body means that in a lot of ways you have to start back at the drawing board again. This is another reason to start small on a new body, better to have 3-4 partially successful $200 million missions leading up to that big $2.5 billion dollar rover mission rather than trying plan a $2.5 billion mission right of the bat.

I should clarify that I don't think that investigating these moons is a bad idea. I think it's a wonderful one. However I don't think that we should investigate these moons in place of Mars, when we have already accumulated so much experience on how to investigate Mars. It's also worthwhile to note that this was the viewpoint of every scientist interviewed in the article. Nobody said that they didn't want to go to Mars, they all said that they wanted this moons visited in addition to Mars, not instead of.

So as long as it doesn't hit Earth's nuts, everything should be all right. Right?

But seriously. Sure, the energy of the impact depends on mass and speed. And hence also the damage done. And if we were talking about an asteroid of 25 miles across, I'd certainly go and spend my money on some fun before it's all over.

The possible damage an object can have on impact depends on three things: Speed, mass and volume. Now, 7.5m across (that's 25ft in SI units) isn't even a pebble on the stellar scale. Still, if accelerated to speeds beyond 0.1c and having a mass of 7+ g/cm we'd be facing quite a threat (according to this it seems the average density is closer to 1-3 g/cm, though). Since the pebble is affected by Earth's gravity, enough to change its course, my guess is that the kinetic energy (which, again, depends on mass and velocity) is fairly low. An impact would certainly be noticeable, no doubt about that, and it would also most likely not be pleasant to live right where it comes down. But I guess we'll have to look elsewhere for the big killer of 2012.

...beamed back to Earth via lasers or microwaves?

I think the vast distances involved would mess that up. The lasers used to do the retroreflector experiment between Earth and the moon had a calculated divergence of about 1.04 x 10^-3 radians. Using a 1m laser at Uranus, the divergence would have to be 2.8 x 10^-4 radians just to make the beam the same diameter as the Earth. That's a factor of 4 or so. To get the beam into a circle that covers the same area as the state of Texas you'd need divergence on the order of 2 x 10^-5 radians. Suddenly you're looking at a factor of 50, and that doesn't take atmospheric effects into account. Add to that the complexities of precisely aiming such a laser, and I think you'd be hard-pressed to harvest must energy.

Huh. I've been talking about the concept of using planetary magnetic fields for antimatter production for a decade or so, but it now looks like I'm not the only one:

Extraction of Antiparticles Concentrated In Planetary Magnetic Fields

Bickford's approach is a bit different, though -- instead of including a collision target and trying to accelerate bulk solar wind up to GeV energies, they're looking to merely collect antiparticles already produced by natural collisions, via modified Bussard ram scoop. Not a good enough collection rate for a direct matter/antimatter interstellar mission (only 250 micrograms per year at Saturn, for example), but it'd certainly be a start.

Oh, and the first announcement is out on the NASA conference next year on The Importance of Solar System Sample Return Missions to the Future of Planetary Science, March 5–6, 2011. Hope the Hayabusa scientists get to go.

Aparently it's about this article: http://www.lpi.usra.edu/meetings/abscicon2010/pdf/5469.pdf

1) Producing the desired magnetic field with the proposed wire-loop can't work, you can probably get a few gigawatt from Maxwell rotating in his grave in result of that paper.

2) The electric current in the wireloop is aparently driven by a static electric field, ever hear about static electric fields being conservative?

3) Somehow electric current is generated by catching electrons, but where do they leave the System?

4) Where does the energy come from to separate electrons and protons from the plasma? To put some spatial distance between positive and negative charge you need energy.

5) A sail of 8.400 km with (square or what?) shall produce 10^27 W of energy. That means over a 4-Billionth (1/4*10^9) of the solid angle of the sun it produces 2.5 times the total energy output of the sun. Surrounding the sun completely with these contraptions should yield 10^10 times the total energy production of the sun.

This paper can't even stand up to basic highschool-physics.

Yes, they did. Go read the original if you're interested ( http://www.lpi.usra.edu/meetings/abscicon2010/pdf/5469.pdf ).

The authors original paper ( http://www.lpi.usra.edu/meetings/abscicon2010/pdf/5469.pdf ) is about building the largest practically possible chunk of a dyson sphere. This is essentially the largest piece they think we are capable of building with current technology.

The source paper ( http://www.lpi.usra.edu/meetings/abscicon2010/pdf/5469.pdf ) is about building, essentially, the largest practical sub-piece of a dyson sphere. This is essentially as large as the authors believe is possible using current technology.