sndrtj
-
Posts
106 -
Joined
-
Last visited
Content Type
Profiles
Forums
Developer Articles
KSP2 Release Notes
Posts posted by sndrtj
-
-
Busting proteins with heat isn't always a big deal. I actually have a bio degree and know how they deal with spaceship sterilizations and I've had to work in sterile environments for cell culture and such... left that out of the op. I've denatured plenty of proteins with heat for certain kidns of assays. Plus bacterial endospores can be fine with boiling water, as can other kinds of 'living' things. And I'm sure you all know about tardigrades or Deinococcus radiodurans. I know you can't be 100% sure of sterile anything. I'm just thinking, if there's potentially a bunch of liquid water there, you're going to have to think pretty hard to make sure you don't accidentally dump something that can live in there. I mean, it might not actually be able to live in there, but that's not really something you can chance.
Maybe we just gamma radiate the probe for a long time and hope the instruments are cool with it.
Dude, go back to biology class please. Just the fact that you whiff some ethanol in your fume hood before and after you work in the cell culture lab, does not mean anything is truly sterile there! Your lab coat, hair, gloves, basically _ANYTHING_ has bacteria adhere to it. Just one tiny flake of skin, a broken hair, a tiny thread of cloth, and it all contains several hundred of thousands of microorganisms. Everyone who's worked on a daily basis in a regular cell culture lab has at one point experienced a yeast infection in their cultured cells; that's not a shame, that's just part of the deal And just heating things... good enough to denature proteins if you're working with the raw material, but real living things have such things as heat shock proteins, chaperones, sugar-coated surfaces etc eetc. That's why your biological waste (probably the blue bins in your lab) are not just heated, they are autoclaved. Even then you still have the extremophiles; I've worked with archaea whose optimal growth temperature is actually 80 degrees C.
I once had a pet project where the goal was to kill a culture of simple E. coli without using chlorine. It's much harder than you'd think. It involved several cycles of water bathing at near boiling temperature, followed by flash freezing (liquid alcohol: approx -80C), repeat a few times, try incubating with lysozyme and more. Even with all these, there were still some nasty cells that just wouldn't want to die. Conclusion: killing bacteria is harder than you think.
-
From the slug's reference frame, their encounters with the air molecules take the same amount of time as always to resolve, converting the slugs to gas and then probably subatomic particles.
But from the earth's reference frame, the slugs take longer to break up.
That also means the ball, from Earth's reference frame, can interact (because interaction takes time from the ball's reference frame!) with air molecules only at a slower rate.
-
I assume that plants have a greater radiation tolerance than large animals like us. Trees don't get skin cancer after decades, centuries, in the sun. Also, a seed vault in the protected area could mitigate against the risk of total loss. But I also assume that any radiation, ionizing radiation, sufficient to kill off plants in a greenhouse may also render that greenhouse so contaminated that people might not be able to return to it for a while.
Mwa, that's unfortunately not really true. Plants can get tumors, and for any given moment just a tiny fraction of a tree is actually alive.
-
And It thought ariane 5 reminded me of something. On Google, aaaaandddd...Energia
"Copy-Paste" much?Specifically Energia-M:
Ah, that explains the slantedness! It's one big normal cone when viewed as whole.
-
That suggests the iron slugs wouldn't get much further than the upper atmosphere. Interesting thought.
-
One could, say, limit the radiation shielding to some sort of 'storm cellar' for the astronauts to hunker in whenever the Sun spits out a nasty flare. The rest of the living space can be inflatables, or otherwise built out of lighter materials, shielded just enough to block background cosmic radiation, with additional rad-shielding in the form of water bags. A lot of them would be needed on such a long trip anyway, might as well use them as shields.
Not sufficient if you rely on a greenhouse. Just like you, the plants and animals in your greenhouse are sensitive to radiation. You might save yourself by temporarily hiding in a bunker, but if that means you're going to starve later on, it's not much use.
-
Why is its nosecone slanted?
-
how the heck would that help here??? Im not a billionare!
You don't need to a be a billionaire for this, although probably a millionaire, so the following is just a thought experiment. DNA can last of tens of thousands of years if stored properly, so if you want good data retention, well.., i think you get my point
Anyway , it sounds more complex than it is. Just read https://en.wikipedia.org/wiki/DNA_digital_data_storage. Storage isn't the cost here (you only need a prinprick of DNA), but data encoding (= creating artificial DNA without template) is difficult and very expensive. -
No it doesn't. The magnetic charge tends to get wiped out after a while. Tapes have to be duplicated on a regular basis. There are departments in NASA whose job is to continuously rewrite data tapes from the old science missions to new tapes before they get corrupted, which is a neverending job as the amount of data continuously grows.
Is there any digital medium that DOES work?
Perhaps we should use DNA (as plasmids) in stead. You can freeze it adequately well for decades, and recreating it is dead easy (just let some bacterium copy your plasmids for a good few hours, and then refreeze). The expensive part is reading it out; you need a sequencer for that.
-
Well I'd put it on a USB or something like that- but I don't trust that... So got any better ideas? :/
Tape. Old technology, but lasts long.
-
Actually, in Kim Stanley Robinson's Mars Trilogy, Phobos is artificially deorbited to prevent it being used as a weapons platform. In any case, Phobos won't come crashing down as hard as an asteroid from interplanetary space would. If we could artificially deorbit it, I'd opt for crashing it on the southern pole (yes, that requires massive change in inclination), as that would release large quantities of frozen CO2, which would heat up the planet on the long term.
-
I imagine Mars having flowing water somewhere in the next 50 million years, but not because of Phobos; probably we humans will do the magic trick. Phobos will just pass its Roche limit in 50 million years; that doesn't mean it will crash into Mars in one single piece. Passing the Roche limit means that it will loose its own cohesion, and be pulled apart in several fragments, or possibly a ring structure. These fragments might or might not eventually hit the surface, but it's unlikely Phobos will come crashing down on Mars in one single piece.
-
Celestia would be the go-to place.
-
I endeavored on my first asteroid capture mission. I decided to pick the class E asteroid which was heading for a crash on Kerbin. It was a very informative mission, as Mechjeb was totally useless here and had to maneuver mostly by hand with just a few ion engines (i.e. many real-time hours of thrust). Obviously my dV wasn't enough to put the asteroid in orbit around kerbin, but i did manage to make the atmospheric entry slightly less steep. I was surprised that it did not just blow up when crashing into Kerbin's mountains. It's still there, frankly.
Final approach
Entering the atmosphere
opening parachutes
Returning to the ground
In the meantime (this mission lasted 175 days), the first of my Electric Castle fleet of ion probes made its flyby of Moho.
-
It's already late, but I guess I might have found my problem: I think I forgot that because Cooper's clock seems to go slower from the far-away observer's point of view, the amount of (visible) work on Cooper/Endurance can also only be (very) small per time unit for the far-away observer's point of view. As he goes faster and faster, the amount of observed work dwindles to nothing, which means the observer sees Cooper approaching but never quite reaching the black hole. But for himself, even if takes a billion years from the observer's point of view, he will eventually cross it in a relatively short finite time from his point of view. I think I get it now :-).
Reference frames, reference frames. Blah
. -
1) You have it backwards. Cooper falls into the black hole in roughly the time you would expect. I think. Certainly, he falls in in a finite time. For an outside observer, he seems to slow and you'll never see him cross the event horizon. This does mean that the scene in the tesseract must take place in the very distant future, but the aliens can manipulate wormholes so there's still no difficulty in returning Cooper home to the right time.
2) Again, duration for the Endurance is a few minutes, duration for an outside observer is 51 years. If you watched Endurance from a distance, it would do the slingshot maneuver but very slowly.
How does that work? Time dilation slows down the subjective clock of Cooper/Endurance, not the clock of a far-away observer. If they're close to the black hole, musn't they actually go extremely fast (whole fractions of c)? The closer you get to a black hole, the greater your speed, the slower your clock goes, isn't that true? So how can you then pass the horizon? I get that your acceleration as measured by a far observer must be extremely tiny - and decreasing - since you would be asymptotically approaching c. Would that means that the acceleration is so tiny it would take them a burn of (as seen by a far observer) 51 years? But would said observer not see them orbiting Gargantua for the same amount of time?
There is something here I don't quite understand. Wikipedia seems to tell me you can't see an object passing the horizon, because you can't actually see that event happening (hence the name event horizon). In stead, the object would red-shift forever (which, eventually means that for all practical purposes you're going to loose sight of the object, since your instruments won't be able to detect nearly infinitely red-shifted light).
-
So I went to Interstellar last night. I have some questions regarding the end of the movie, both related to the black hole.
1) At the end of the movie Cooper falls in the black hole and has his epiphany. However, how could one subjectively actually fall in a black hole? From a reference point far from the black hole, one of course can see things falling into a black hole, but how is this possible from the reference point of the falling object itself? As I understand relativity and orbital mechanics, one likely approaches light speed when very near the event horizon, which means time dilation basically becomes infinite, and the object will never actually experience passing the event horizon. Or is this some kind of paradox here? The only way I can figure out Cooper being aware of himself falling would be if he would have killed most of his velocity (good luck with that with relativistic speeds), and falling sort of straight into the black hole.
2) Just before Cooper enters the black hole, the Endurance is slingshotting past the black hole, upon which Amelia remarks "This little trick costs us 51 years". Wouldn't this have to mean they would be orbiting Gargantua for 51 years as seen from a reference point far from the black hole? That no longer seems like a slingshot - unless Gargantua is truly insanely huge - but rather like a stable orbit around it. Wouldn't a real gravitational slingshot just last several seconds from a time-dilated reference frame?
-
Titan itself might not be the critter in question. Suppose a fungal-like creature colonized the moon at some point in the distant past and now covers the entire surface, as well as penetrating into the interior?
Read the first paragraph of my earlier post, and you'll an equivalent answer.
In this scenario Titan is not alive as an individual organism; it functions as a substrate for living organisms giving Titan features of life on a meta-scale.
-
Mwa, that's overly pessimistic. A human lifetime at current life span might not make it. Assuming generation ships, and increase in human life span (perhaps combined with cryogenic sleep periods) will mean that human interstellar flight might be in reach after all. Just the time spans on which this flight occurs will be on the order of several hundred years, if not more.
-
Stop talking about things you know nothing about, it's pretty clear you don't even know the difference between acetylcholine and acetylcholinisterase-this is high-school level stuff. Given the major differences in biological pathways we already have between organisms, and how easy you're suggesting producing lethal toxins by chance is, why isn't the world already completely full of poisons? There's just as much reason for an alien organism to produce Sarin as there is for most plants to, given they don't utilise acetylcholinisterase; why hasn't your scenario already come to pass?
I guess you're taking his point a wee bit too literal. What Greg is pointing is a true and existing risk. Remember that paper from Science a few years ago that caused a slight fuzz with its supposedly arsenic-utilizing prokaryotes? Well.. turned out they were in stead merely resistant to arsenic, and used plain phosphate instead, but the idea itself is quite relevant for astrobiology: on an alien world where there is very little phosphate but ample arsenic (and assuming it has life), evolution would probably have used arsenic, which is very toxic to almost any Earth life. And there you'd have it: toxic lifeforms to us. The soup of alien metabolites is sure to contain some molecules known to man, and not all of those will be harmless (they will probably have completely different functions in alien life forms than on Earth, and that's exactly what makes it dangerous).
-
I decommissioned my Munar station, and hauled its power unit down to Kerbinstationary orbit. Then build a skeleton around it, and attached two of my Generic Habitation Modules. It's not wobbly, but it seems my computer is kinda hitting a limit here on the part count :/ (I should really buy a new one)
The power beam down to kerbinstationary orbit
Building the skeleton
First habitation module approaching (no mechjeb!)
The complete thing (and some space junk in the background which was later deorbited) -
ah, but Mars takes less Dv to get into orbit.
And the Moon takes less as well, but Deimos has practically no gravity, so mining it and Phibos is preferable.
How exactly do you intend to mine something with an escape velocity on the order of just a few meters per second? Any drill would fling off bits and pieces of your favorite moonlet into an escape trajectory. Not only is it difficult to capture, you're also creating some dangerous Kessler bomb around your primary (i.e. Mars in this case).
-
You're assuming alien organisms would be more similar to us than we are to the vast majority of the organisms on our own planet-unless you've met someone who's ever come down with T4 bacteriophage or tobacco mosaic virus. That's not exactly a very tenable assumption.
Actually, since you have no clue what the normal biochemistry of alien species is, you must take extra care. I'm not postulating anything would have evolved to be pathogenic to any Earth life form - that'd indeed be ridiculous - but alien by- and waste products could potentially be very toxic. What if some alien metabolic byproduct happens to be a small molecule inhibitor of GAPDH, Actin or some kind of basic neurotransmitter, just to name a few ideas. Such a thing would have difficulty evolving on Earth (as any pathogen like that would kill its host quite rapidly), but if the biochemistry on alien world X is strikingly different, there is no reason why it couldn't evolve there. The complex cocktail of small molecules that makes up the metabolism of some alien life form is sure to be toxic to at least some of our one billion protein species.
-
I did come up with one myself once, but lately I've started to think it wouldn't actually work.
Could it be possible to have a hollow, bubble-like planet that has a solid outer crust and an essentially empty interior (filled with gas maybe)? The idea was to make a planet with a huge surface area but not too much gravity. The concern is that there'd be nothing holding the higher latitudes in place.
You could strut it?
Or use unobtanium ;-)
"Copy-Paste" much?
Anyway , it sounds more complex than it is. Just read
Ubuntu
in The Lounge
Posted
The windows boot manager is of absolutely no use when you want dual boot systems with Linux. It will only recognize itself. Did you install windows after you installed Ubuntu? Generally, you should do the opposite - installing Ubuntu after Windows - and the Ubuntu boot manager - GRUB - can detect any system, not just Linuxes.
So, to fix the problem: Boot Ubuntu (or any variety of distros) from a usb drive of liveCD. Then follow these instructions: http://howtoubuntu.org/how-to-repair-restore-reinstall-grub-2-with-a-ubuntu-live-cd
- - - Updated - - -
You DONT have to reinstall windows. That's quite a drastic measure for something quite simply. Just fix GRUB per last post.