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Comment Remember Chelyabinsk! (Score 1) 182

Even relatively small impactors can do a tremendous amount of damage. something the size of a bus injured hundreds of people a little over a year ago in Chelyabinsk. Something the size of the Meteor Crater impactor would cause millions of casualties today. Say, most of the military casualties of World War 2 happening in a matter of minutes in a couple of adjoining countries.

Meteor impacts are as much a hazard today as yesterday.

Comment The Chixulub impact didn't DEFINITELY kill dinos. (Score 1) 182

Leaving aside the point I've used as a signature below for some years, it is not an entirely settled point amongst geolgists that the Chixulub impact was what did the dinosaurs (well, some of them) in.

Within the geological profession, there is no dispute that the Chixulub impact happened, or that it was a pretty bad day, and started a pretty bed few millennia.

Whether it was what actually "did" for the dinosaurs is a more challenged question. There was a serious environment-degrading long term terrestrial event happening over the same time period - the Deccan "Large Igneous Province", a.k.a. the "Deccan traps" (which also outcrop in South Africa), which also had serious, long-lasting environmental effects. With the limitations of the geological record, it isn't clear if the dinosaurs died out at the time of the Chixulub impact, or at a later (or even earlier) time. field work continues to try to relate the two events, but currently the best dating is that the Deccan had been going for half a million years before Chixulub, and continued for another half-million or so after ; exactly when in this time period the dinosaurs died out isn't at all clear. (Incidentally, this kills, stone dead, the trope that the Chixulub impact triggered the Deccan. Interesting idea, but the energetics never worked, despite the hours of puff that it has been given on TV.)

It remains possible that the Deccan was well on the way to killing off the dinosaurs when along came the Chixulub impactor and did the remaining few percent of stragglers. Or, that the more evolutionarily flexible dinosaurs were surviving OK while the giants were dieing out, but Chixulub's effects just increased the rate of change beyond what the (non-avian) dinosaurs could handle.

It is worth remembering that there have been many major impactors that have not been associated with mass extinctions, whereas the only LIP larger than the Deccan was coincident with the biggest mass extinction of them all - the Permo-Triassic extinction. That is suggestive.

Comment Re:Real World? (Score 1) 122

Niven, of Ringworld, once wrote that he likes to keep his SF to no more than 6 impossible things per story, because much more than that allows you to get the protagonists out of any scrape. The "with one mighty leap, he was free" syndrome. So, faster-than-light travel at 3 LY/day (subjective), plus ageing-retarding "boosterspice" makes for a more interesting "universe" than infinite velocity and infinte lifetimes. An unbreachable protective shield ruins wars, unless it needs someone on the outside to turn the field off.

The Mars rover guy - now writes code for Google - tweets as @Marsroverdriver.

Comment Re:Real World? (Score 1) 122

It's a way of leaving Watney behind that seems maybe plausible if you don't think about it. That's the best I can say about it.

That's not a lot to say, really. I prefer my sf to engage my braincell a bit more than that. Well, I'll probably see it at some point, but I can't say that I'm motivated to actually go out of my way (e.g., to a city with a cinema, or to log onto the wife's DVD library website to book it) for it. I'll see if the copy of the book turns up on the recreation room's library. Frequently the book is considerably better thought out than the screen play. Different audiences.

In Earth's atmosphere, it is possible for wind to drive solid objects through others, but it typically takes a tornado.

A rather different situation. In one case, one object is stationary and the other is acquiring kinetic energy by being blown around in the wind for an indeterminate period of time. (Actually, there was another SF film a few years ago where the MacGuffin was a device for measuring some aspects of that movement.) In the other case, both objects start at zero velocity (with respect to the ground and each other) in the significantly slower wind at ground level.

I have no idea what sort of wind would be required for the Martian air to do that.

I don't have numbers to hand, but work has been done on this looking at dust devils (mini-tornados) on Mars, imaged by the very mapping satellites I mentioned earlier. There are also weather stations on all of the landers, of varying degrees of complexity. We may not have as good an understanding on Mars as we do on Earth, but our scientists and their robots are finding out this sort of thing.

I swap tweets from time with a guy whose signature line was "There is a robot on Mars. I give it instructions, and it does what I tell it to do." I like keeping up to speed on interplanetary exploration activity.

Comment Re:Real World? (Score 1) 122

Wait - hang on. The wind was sufficiently powerful to pick up an item of mean density 3 or 4 tonnes/ cubic metre. and "slam it into" something of mean density about 1+a-bit tonnes per cubic metre which wasn't moving. I don't know about you, but when I last got picked up by the wind, my ice axes (metal and GFRP ; they sink, I float) stayed laying on the ground because they were denser than me. (My rope also held, which is why I was using a rope.)

Oh, sorry, I'm forgetting that the "left behind on Mars" is a MacGuffin. Given that it's over a decade since we put the first (semi-)permanent mapping satellites into Martian orbit, such a storm sneaking up on a landed mission simply is not credible.

I only had four of my six impossible things before breakfast today. But I feel full, and don't think I can swallow that one.

Comment Re:Real World? (Score 1) 122

Yes, they knew where he was and couldn't (or wouldn't) do anything to help him. But they knew where he was. The big difficulty, particularly for people who are intending to help, is if you can't find someone who you think is missing, or if you think someone is missing, but don't know they are missing. Or in the cave rescue scenario, you know someone is in a cave somewhere within walking distance of here, but you have to thoroughly search every one (including the unexplored or un-published ones), when there is no way of knowing if you're within 2 feet of the missing person or party unless you're actually within the same cave system as them.

Everest isn't a good example of normal mountaineering because there are a lot of people who take their egos and business plans there, leading to some extremely distorted and aberrant behaviour. That it also makes headlines is unfortunate. It'd probably do a lot of good if the Nepalese government shut it down for a decade or two, or required people to have climbed all the other 8 thousanders before being allowed on Everest. That should weed out the money bags and incompetents.

Comment Re:It is "hctaw s'yelaP" argument. (Score 1) 41

Darwin was certainly aware of Paley and his interpretation of biological design, but it's also pretty clear that he didn't share Paley's interpretation. Darwin's own description of "Origin" as "one extended argument" is precisely challenging Paley's interpretation of the appearance of design as being the result (per Darwin) of descent-with-inheritance interacting with his mechanism of natural selection, while Paley looked at the same evidence (the appearance of design in biology) and interpreted as supporting the inference of a designer. (The more modern "neo-Darwinian synthesis" approach to evolution puts more weigh on differential reproductive success rather than out and out inter- and intra-specific conflict, but that's a minor change of emphasis.)

That fundamentally remains the case in the non-debate over the reality of evolution - is it the result of natural forces, or of a supernatural "designer", a.k.a. a god.

Comment Re:Okay. (Score 1) 41

So the mammoth was killed by humans.

Even TFS doesn't say (or claim) that.

analysis of cut marks - if any - could confirm that the animal was butchered by humans. Whether it was killed by humans is a distinct question. Not unrelated, but there never has been anything to prevent opportunistic gatherers from taking advantage of a kill made by other means - including old age, falls, enmirement. (IS that a word - coffee not takeneffect yet? Stuck in mud.)

Such coincidental finds, traps or kills may have suggested hunting and trapping methods to early hunters.

To demonstrate human killing of the beast, you need to find something like a spear point (or several) in important parts of the body. But that still leaves open the possibility of an animal downed by some other reason, then killed by pin-cushioning by humans. So what you really want is an animal with a (partly-)healed spear wound penetrating the hard anatomy.

I'm not someone who follows this line of research myself, but I know that there are multiple examples of healed tooth scars in the dinosaur corpus of fossils, and in other areas of palaeontology, so I'd be fairly surprised if the type of specimen wasn't known at all. Whether this specimen shows such evidence is another question.

Comment Re:Yeah, I thought this problem was solved (Score 1) 118

Hmmm, they're all (in high enough concentrations) pretty effective biocides, and given their propensity to oxidise the living daylights out of anything, they'd probably be biocides against silicon-based life forms, if such a thing existed.

But whether H2O2 is more expensive ... a bit thornier a question. Yes, it's a continuing cost for chemicals. But there is a continuing cost with UV for both the electricity to run the lamps, the plumbing and pumps to force the water past the lamps ; the lamps themselves have a finite lifetime and need monitoring (another on-going cost). Similarly ozone made using a silent electrical discharge draws the juice too, needs plumbing, there is likely to be wear/ corrosion eventually on the electrodes, you still need pumps to mix ozone and the water. And monitoring, including of ozone discharges in many jurisdictions, because it is a VERY potent gaseous poison.

From first principles, I couldn't say which would be cheaper. I'd suspect that it would differ on a case to case basis.

Comment Re:The great nation ... (Score 1) 112

Ever plugged in your smartphone to your machine to maybe, synch something?

Err, not as far as I know, no. I never did understand this "sync(h)" thing, or how it differs from copying the files I want from one storage device to another.

But the laptop does make a convenient charger for the phone. It's a pity that it is such an absolute bummer finding my data on the phone and getting it off. It completely destroys the potential utility of a smart phone.

Comment Re:Ignore the "humans almost went extinct" bit (Score 1) 54

That's not from the Nature letter; apparently that's some off-the-wall addition from the submitter.

There is a coincidence of timing. However, given that previous estimates for this particular sector collapse (see my comment elsewhere for the dozens of other "recent, geologically" Atlantic sector collapses) were between 50 and 150 thousand years ago, it is little more than coincidence.

If there were a tight human population bottleneck (as opposed to a more drawn out but less severe one, with comparable cumulative genetic effects) of a few dozen generations (a thousand years, for a round number), you could fit this localised problem, the global Toba problem, and a Yellowstone super volcano all into a mere ten thousand years and still have several thousand years left over for humanity to continue expanding at 5% per generation (1 extra child per 20 families per generation), giving easily a 10-fold population increase to offset a 9-fold decimation.

Comment Re:Are and storms that fierce on Mars? (Score 1) 122

That's an effect, but unless you increase the viscosity of the (saltus, 'a leap') grains don't stay suspended for more than a couple of seconds once the turbulence drops even for a small amount.

If you look at rock pedestals, then their most severe erosion is strongly at the base. Compare the images with a more typical pyramidal hill to get the difference in erosive force between base and top.

Preventing landed craft from over-tipping with such a strongly concentrated low-level force is a job for outriggers. As the images show, the basic problem is hardly rocket science. You can make the engineering as fancy as you want to cut down weight (e.g. - two only outriggers, which can be re-positioned at ~120 degrees to the wind direction ; the weight of the re-positioning equipment being less than a third outrigger?)

I'm perfectly willing to accept the "stranded on Mars" as a MacGuffin. But that doesn't make it any the less of a hazard that would be addressed and managed. Hey, I could even take it fi there were an inconveniently situated Marsquake in the middle of a dust storm. Or a tube cave opening up under the lander because of the stresses of the lander. But it's still a MacGuffin that flies as well as the Maltese Falcon.

Comment Just for some context ... (Score 1) 54

When I was taking a volcanology holiday a couple of years ago on the Canary Islands, the count of recognised deposits from mega-landslips around the island group was 23. Many more were unrecognised, probably, due to having been overlaid by more recent landslips. The period during which these were deposited was probably only 10 million years, for an event every half million or so years, and each would probably have had significant effects between Brazil, Newfoundland, Britain and Morocco.

The Cape Verde islands are a broadly similar island group, a thousand miles to the south. So a broadly similar history can be inferred - maybe Brazil would get hit a bit more, and Newfoundland a bit less. So you're now looking at events every quarter million years.

Don't forget the Azores, on the Gibralter-to-Mid-Atlantic transform fault. There;s sector collapse risk there too. And no small risk of sector collapses in the volcanic Carribean islands too, some of which could reasonably be expected to propagate out into the Atlantic too. Say a cumulative risk in the order of once every 100,000 years.

It is not news that these risks exist, and have existed for longer than humanity has existed. And there is nothing realistic that we can do about them. Except not live too close to coastlines.

Comment Real World? (Score 1) 122

how a real world interplanetary spacecraft would pull off a rescue maneuver

Well, for starters, they wouldn't leave someone behind who wasn't dead and buried. "Dead" in the sense of "injuries incompatible with life" and/ or "failure to revive" and/ or "decomposing". This has been established by long history of mountain, cave and other remote area search and rescue incidents. If you want a ball-shrivelling account of how hard it can be to tell, read Joe Simpson's "Touching the Void" (the film wasn't too bad either; but remember that despite having been filmed by Hollywood, the events were reality. Including the crawling through the shit garden).

I suppose I'd better go and RTFA, but having just come back from a 2-million dollar/day operational planning meeting, the plan of "don't get into that situation" plays a really important role here.

I took a fish head to the movies and I didn't have to pay. -- Fish Heads, Saturday Night Live, 1977.