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#1 Re: Life support systems » Livestock » 2012-07-19 16:43:01

I stand corrected. My chicken expert informs me that you can freeze whole eggs. She will be trying this for me soon with a few fertilized eggs. I will update you shortly.

#2 Re: Life support systems » Livestock » 2012-07-19 09:05:26

I think the problem is the ovalbumin. That's why frozen, say, egg beaters, don't taste so hot... weird mouthfeel? It's the LONG complexes of albumin that got denatured by the freezing temperatures. Never quite comes back. As far as transplantation... or testing of freezing... I can check with my graduate advisor since he's done cell culture related stuff.

Wow. That sounds terribly technical. "cell culture stuff"... *facepalm*

But anyhow, timeline wise it should be possible to freeze the embryo... I'm just not sure how you'd implant it into another egg unless you genetically modified a hen to lay eggs with zippers on them.

o.O

The embryo will be about a quarter to half the size of a grain of normal white rice by the time the egg is laid. I don't think that in itself poses problems. Just access through a rigid shell, which Mother Nature failed to provide with an emergency induction port.

As soon as these chickens are laying, I will attempt a test... I do not have a rooster, so I may see about testing it with a friend's eggs... might be crossing his rooster with my hens next spring, since Americauna/Barred-Rock crosses lay OLIVE GREEN eggs. I mean seriously, how can I resist? CAMO! lol...


Louis: the proto-chicken is ~24-30 hours old, since chickens tend to lay eggs about the same time every day. They don't, however, always lay one egg per day. It's essentially a daily menstrual cycle.

#3 Re: Human missions » Landing on Mars » 2012-07-18 18:59:02

Also, regarding the Bigelow units... I've got some kevlar-based armor that's performing quite well against handgun rounds with only 4-6 layers of fabric, so we well might be able to shrink the foam-and-foil down by a solid factor of 2 or 3. I do, however, realize that meteorites have kinetic energies about 2 orders of magnitude higher than even a rifle round, but our technology is something that can be integrated into the structural/pressure shell material of the inflatable hab itself, resulting in a much more resilient hull, and that translates to lower weight, which in this case, is everything.

Another thought - if the first mission is unmanned, perhaps it could go nearly-fully-loaded, and provide something for the second mission to dock with, doubling Mars-orbit  accomodations in the short term, prior to EDL of the components? Seems like over the course of two launches, you could have a space station in orbit around Mars that's larger, in terms of habitable volume, than the ISS, providing a long-term safe haven for astronauts, should things go wonky with surface systems - they can get up to the station, dock, and sit tight, and still do at least some science from orbit, while they wait for the third mission to provide a way back home (assuming ISPP can't cook up enough juice for the whole trip before they had to bail from the surface habs?)

#4 Re: Interplanetary transportation » Reaction Engines » 2012-07-18 17:29:43

Der Germans can supply the CNC machines to cut all the parts that the other guys design. :-D

#5 Re: Human missions » Landing on Mars » 2012-07-18 17:28:13

That test is going off about 80 miles west of where i live. I'm driving ~30 mins down to Virginia Beach (Chicks Beach to be more accurate) and I'll try and get some photos. If they turn out, i'll post here. Its ground track should take it almost directly overhead, beginning its reentry phase just out to sea.

This test goes to nearly twice the altitude and speed of the last test. Slowing 600kg down from mach 6 with a 10 foot diameter inflatable that packs into a 22 inch diameter canister... ain't too shabby.

#6 Re: Science, Technology, and Astronomy » The use of filler mass in propulsion. Could it help? » 2012-07-18 09:33:03

Adding a noncombustible means you're sapping thermal energy from the exhaust stream. Injected after the nozzle throat, it may help to cool the nozzle and add to total mass flow, as water injection was used to increase mass flow rates on jet engines back in the 60's and 70's before high-bypass turbofans were developed.

Carbon black is added to solid rocket fuel to alter the burn rate and enhance combustion stability, as are a few other inert compounds, but you'll find these in concentrations well under the 1-2% mark by mass. Carbon black can make an otherwise infrared-transparent fuel grain opaque, so the whole thing doesn't soften, melt, and splort out the nozzle before it's supposed to be burned. Other modifiers keep the fuel grain from simply detonating as surface area increases and pressures go up in a core-burning grain, and there are other plasticisers that aren't the best for "fuel" that can keep the grain from cracking or aid in thermal gradient management. Keep in mind the color of the exhaust plume on the SRB's, too - damn near white.

#7 Re: Human missions » Landing on Mars » 2012-07-18 08:44:17

I was simply thinking the aerospike's spike/plug could be utilized to set up a bow shock, thus stabilizing the plume, or at least reducing the velocity of the incoming air to subsonic, at which point the exhaust plume would dominate the interaction, instead of the other way around.

#8 Re: Life support systems » Lets brainstorm on suit design - We will need suits after all » 2012-07-18 08:34:51

IIRC, though, your sweat would freeze solid at some point, sealing your pores, or the suit... basically boiling until it froze... the fabric suit keeps your skin from exploding and rupturing blood vessels, but as the liquid sweat is able to wick through the fabric, it would evaporate until it froze solid... and then slowly sublimate... would this be quick enough to carry heat away? I'm thinking a couple of peltiers and a wee bit of insulation would be a halfway decent idea. a pound or two of peltier junctions and battery should be able to tweak a heat balance issue on the hottest/coolest excursions - maybe just two, plastered right to your lower back over the kidneys, or right under the arms for maximum heat transfer to/from the bloodstream.

I would agree, though, that given the non-michelin-man form factor, you wouldn't need the liquid cooled undergarment currently used on EVA suits.

#9 Re: Human missions » Landing on Mars » 2012-07-18 01:58:26

Would an aerospike engine configuration get around the into-the-wind issue?

#10 Re: Life support systems » Lets brainstorm on suit design - We will need suits after all » 2012-07-18 00:33:13

So a mechanical counterpressure suit, and body armor that you strap on over top?

Seems like you could make a relatively flimsy pressure suit, and just wear overgarments to prevent damage to the suit. Perhaps slip a wetsuit on directly over the mechanical pressure suit, which may add nominally to the effective pressure of the suit, and have velcro all over the wetsuit bit, to which kevlar gloves and sleeves and torso protection garments could be attached. Or you just put on a pair of slightly oversized normal work boots (oversized to accommodate the wetsuit and pressure suit thickness), and wear a long sleeved shirt, jeans, gloves, and a parka, with an oversized hood to fit your helmet?

#11 Re: Life support systems » Livestock » 2012-07-17 22:37:59

Oh, and there's always tilapia (bland, not great on nutrients) and arctic char... kind of like a cross between salmon and trout... freshwater fish... great for aquaponics, grows relatively fast, and has a pretty decent lipid profile (ALA's and Omega 3's, etc.). I'm pretty sure the eggs can be frozen... and in any case, they don't need much space for weeks and weeks and weeks until they get past fingerling size... THAT might give us enough flight time to bring the thrust requirements down to a reasonable level for a small, low-cost, continuous-thrust "quick trip"...

#12 Re: Life support systems » Livestock » 2012-07-17 22:34:05

I raise chickens, currently. Woot.

Here's a thought... Chicken eggs are full of water, essentially. If that's all you're transporting, then why not do a relatively small rocket with a few dozen eggs (the chickens will be laying six months after hatching, so as long as you have six months, you're OK...) and go for a continuous-thrust, high-power ion thruster... the payload would be measurable in kilograms, and with a 1g acceleration, and turning around halfway to Mars, you could have the whole package in Mars orbit in 72 hours... but i don't know of any thrusters that could do that... without ridiculous levels of power... i think the best ion thrusters now are about .02 lbs of thrust on 2000+ watts...


Has anyone run the numbers?

We have only three weeks... 60 million  kilometers... but WAIT! we have a slight time advantage... it takes 21 days for an egg to hatch, once it's brought up to incubation temperature... so we can kill the freezer at just shy of 3 weeks, and we have another 3 weeks before the little buggers start popping out... and the chill time will give us an extra buffer, since chilled eggs tend to hatch slightly later than under-chicken-butt eggs... and all we have to do is spin the module with the eggs in it and we've got something close to Mars gravity with little or no effort... so let's run the math and see what kind of acceleration we need to get there in 6 weeks with a negligible payload... and have chickens hatching (hopefully) soon after touchdown... unless we had a little space station in orbit around mars that could capture them and feed them, and then drop them to the surface along with the next crew... hmm... but that's later... let's see what kind of acceleration we'd need.


Let's just go with Newton on this one, and linear kinematics (just assume a straight line shot to Mars near closest approach) even though we'll be doing a rather more curved path in reality, we'll get an order-of-magnitude number:

3,628,800 seconds in 6 weeks...

if we're doing a turn-around-halfway-there approach, that's 1,814,400 seconds...

Overestimate to 7e7 km... half would be 3.5e7 km

If we assume we're in LEO, then launching our eggs from about 200km, that's roughly 7km/s initial velocity...

and we're solving for acceleration, so for the first half of the trip,

s=Vt+.5at^2 becomes...

(s-Vt)/.5t^2=a

[(3.5e10m)-(7e3m/s)(1.8e6)]/[.5((1.8e6)^2)]= .0076

.0076m/s^2

someone please check my math?

Assuming a 500kg of non-payload junk, and a 20kg payload of two dozen chicken eggs and the rack to hold/rock them, and we only use vehicle spin for a modicum of "gravity"... this would be a whopping 4 newtons of thrust for three weeks, followed by another 4 newtons of thrust for three weeks, then aerocapture from our original ~7km/s that we didn't bleed off in the second three week thrust phase...

Maybe we'd need more spacecraft mass just to make 4 newtons worth of ion thrust for the payload, but this is a startlingly low acceleration... seems like it might be slightly feasible. Or just barely not.

thoughts?

#13 Re: Interplanetary transportation » Paraffin, propulsion and other uses, crash-landing it. » 2012-07-17 13:13:13

Ok, so luck of the draw, I get an email from a friend of mine. I copy it below, as the NASA press release. Neat stuff. Anyone want to tag along?

RELEASE: 12-236

NASA HYPERSONIC INFLATABLE TECH TEST SET FOR VIRGINIA LAUNCH JULY 21

WALLOPS ISLAND, Va. -- NASA Space Technology Program researchers will
launch and deploy a large inflatable heat shield aboard a rocket
travelling at hypersonic speeds this weekend during a technology
demonstration test from the agency's Wallops Flight Facility on
Wallops Island, Va.

NASA has four consecutive days of launch opportunities for the
agency's Inflatable Re-entry Vehicle Experiment (IRVE-3), starting
July 21, with the liftoff window from 6 a.m. to 8 a.m. EDT each day.

The test is designed to demonstrate lightweight, yet strong,
inflatable structures that could become practical tools for
exploration of other worlds or as a way to return items safely to
Earth from the International Space Station. During this technology
demonstration test flight, NASA's IRVE-3 payload will try to re-enter
Earth's atmosphere at hypersonic speeds -- Mach 5, or 3,800 mph to
7,600 mph.

"As we investigate new ways to bring cargo back to Earth from the
International Space Station and innovative ways to land larger
payloads safely on Mars, it's clear we need to invest in new
technologies that will enable these goals," said Michael Gazarik,
director of NASA's Space Technology Program. "IRVE-3 is precisely the
sort of cross-cutting technology NASA's Space Technology Program
should mature to make these future NASA and commercial space
endeavors possible."

The IRVE-3 experiment will fly aboard a three-stage Black Brant XI
launch vehicle for its suborbital flight. The payload and the heat
shield, which looks like a large, uninflated cone of inner tubes,
will be packed inside the rocket's 22-inch-diameter nose cone. About
six minutes after launch, the rocket will climb to an altitude of
about 280 miles over the Atlantic Ocean.

At that point, the 680-pound IRVE-3 will separate from the rocket. An
inflation system similar to air tanks used by scuba divers will pump
nitrogen gas into the IRVE-3 aeroshell until it becomes almost 10
feet in diameter. Instruments on board, including pressure sensors
and heat flux gauges, as well as cameras, will provide data to
engineers on the ground of how well the inflated heat shield performs
during the force and heat of entry into Earth's atmosphere.

After its flight, IRVE-3 will fall into the Atlantic Ocean about 350
miles down range from Wallops. From launch to splash down, the flight
is expected to take approximately 20 minutes.

"We originally came up with this concept because we'd like to be able
to land more mass and access higher altitudes on Mars," said Neil
Cheatwood, IRVE-3 principal investigator at NASA's Langley Research
Center in Hampton, Va. "To do so you need more drag. We're seeking to
maximize the drag area of the entry system. We want to make it as big
as we can. The limitation with current technology has been the launch
vehicle diameter."

Cheatwood and a team of NASA engineers and technicians have spent the
last three years addressing the technical challenges of materials
withstanding the heat created by atmospheric entry and preparing for
the IRVE-3 flight. The team has studied designs, assessed materials
in laboratories and wind tunnels, and subjected hardware to thermal
and pressure loads beyond what the inflatable spacecraft technology
should face during flight.

This test is a follow on to the successful IRVE-2, which showed an
inflatable heat shield could survive intact after coming through
Earth's atmosphere. IRVE-3 is the same size as IRVE-2, but has a
heavier payload and will be subjected to a much higher reentry heat.

IRVE-3 is part of the Hypersonic Inflatable Aerodynamic Decelerator
(HIAD) Project within the Game Changing Development Program, part of
NASA's Space Technology Program. Langley developed and manages the
IRVE-3 and HIAD projects.

Journalists interested in attending the IRVE-3 launch at NASA's
Wallops Flight Facility should contact Wallops Public Affairs Officer
Keith Koehler at 757-824-1579 or keith.a.koehler@nasa.gov to arrange
for media accreditation.

NASA TV will air the IRVE-3 launch live and stream it on the Web at:

http://www.nasa.gov/ntv

For more information about IRVE-3 and the HIAD Project, visit:


http://www.nasa.gov/hiad

For more information about NASA and agency programs, visit:

http://www.nasa.gov

#14 Re: Terraformation » Artificial Magnetosphere - Electromagnetic Induction » 2012-07-16 23:15:19

This thread:

http://newmars.com/forums/viewtopic.php?id=6052

made me think...

Why not try for an artificial magnetosphere on the Moon, to limit charged particle interactions with the surface/habs/inhabitants? With a significantly smaller radius, and with the benefit of Earth nearby, it may be possible to generate a pretty decent magnetic field with orders-of-magnitude less cable, and WAY cheaper launch costs... and then we'd have a working model to tool around with. The LHC seems like a pretty decent equivalent budget target...

Thoughts?

#15 Re: Interplanetary transportation » Paraffin, propulsion and other uses, crash-landing it. » 2012-07-16 15:31:52

I like the idea, personally. I had thought of something similar, for harder resources like already-alloyed metals (making iron/steel on site wouldn't be difficult, given enough of an oxygen sink... I do it all the time in my forge at home, reducing iron oxide into iron at high temperatures in a charcoal fire... on Mars you'd use an oxygen grabber like carbon, and an induction furnace, though) but hadn't thought about dropping softer items.

What if the ParaffinPak(tm) (just for fun) was a big sheet wrapped around the spacecraft, or a long ribbon? Seems to me it could aerobrake from a relatively stable orbit without gaining too many BTU's to maintain containment. Say, an aluminum foil pack around a paraffin sheet. Kind of like a CapriSun drink, or any number of freeze-dried or vacuum-sealed foods in foil packs.

There's also stainless steel foils that would do quite well at elevated temperatures, but you'd have to worry about boiling the paraffin and rupturing the container.

Anyhow, it would seem like the whole thing could be made to have a ridiculously low terminal velocity. Slow down to low supersonic speeds, shed the paraffin blanket like a sabot on an artillery shell, and let the whole thing drift down rather gently over the course of 3/4 of an orbit or so. Or as above, drop it off prior to significant aerobraking, and let it skim the atmosphere for 2-3 orbits before it starts plunging to its doom.

Lots of numbers to be run to see exactly how hot it would get - I'm not sure if it's possible to aerobrake with something like an airfoil shape that would be effective at such high altitudes, but to repeatedly skip along the atmosphere and bleed kinetic energy a little at a time, never quite heating the material beyond its boiling point, and then descend when it's slow enough that the stagnation temperature is well below the boiling point to begin with.

Then there's always semi-active cooling - set up the foil bag so it's rigid under the pressure of expanded, molten paraffin, and design it so that it self-circulates the paraffin through the structure and dumps heat on the top side, and picks it up on the leading edge and bottom where it's hottest, and just build in expansion areas to keep the whole thing from rupturing and turning into a streak of fire across the sky.

(That in itself is an interesting thought... would the paraffin have anything to react with in a nearly pure CO2 atmosphere? would there be enough reactive species from the shock wave to "ignite" the leaking liquid, or would you be spilling a hundred-mile-long strand of paraffin droplets across the surface?

*ponders*

#16 Re: Terraformation » Artificial Magnetosphere - Electromagnetic Induction » 2012-07-16 11:55:19

Hmm.

Ok, first, Nitrogen. We BATHE in it here. I think we'll need a bit more than trace amounts for a successful nitrogen cycle on Mars. Just my thoughts. Or, as mentioned, acclimatization or genetic engineering to handle the different gas ratios. Who knows, maybe some latent adaptation from early Earth will come to bear in the otherwise silent genetic code of terrestrial plants when transported to the new environment.

I'll poke around the other thread on buffer gases before I prattle on about Nitrogen again, thanks for the link.

As far as the core temperature, I have two chief points to address. I'm making this quick, as I've been outside mending a fence for my chickens, and I'm terribly hot and uncomfortable, so please don't take a short/terse post as any sort of argumentative tone, I'm simply sticking to my chair at the moment, and that may color my responses. Ick.

So, the first point is the cooling time of a planet from formation. I am on a slow connection, but IIRC, Lord Kelvin calculated the age of the earth to be somewhere in the 5-10,000 year range, based on the surface area to volume ratio of Earth (at that time known fairly well) and he was, from what I recall, within an order of magnitude on all his calculations. So let's be terribly generous and call it 100,000 years. Earth's core should have cooled and solidified a billion years ago, then, if there is no process heating things up inside.

Nonradioisotopic mechanisms available are tidal heating, magnetospheric interaction with the Sun, and impactors. either way, it's been more than 100,000 years since the last impact large enough to liquefy any significant fraction of the planet, and all three of these processes would affect Earth's orbit. The Moon seems a possible candidate for the tidal option, which would not alter Earth's orbit appreciably, but would have circularized and tidally-locked the Moon. Oh wait. The moon is tidally-locked.

Did that happen more than 100,000 years ago? I think, quite likely, it did.

So we are left with, as far as I know, either a magically self-sustaining magnetic dynamo, which would violate conservation of energy (since Earth's orbit isn't perpetually decaying toward the Sun at an appreciable rate) or, radioisotopes in the core/mantle.

I'm not sure why one would assume that the core had no radioisotopes in it. These isotopes are all heavier than, and generally soluble in, liquid iron. We need not have a significant loading of radioisotopes to add heat to the system and keep it molten, but it must be present. I tend to think even if they were all segregated somehow to the mantle, then you might just have enough to melt the outer core and keep it fluid. Just barely.

Now, this brings us to the thermal gradient. As we drill down in the earth, past the first few feet of soil, the temperature of the Earth increases at a few tens of degrees per thousand or so feet, as I believe was posted earlier.

Think of it this way, we have what amounts to a light bulb, providing relatively constant illumination to a sphere of material of known transparency. As the thickness of the sphere is increased, the illumination at the surface of the sphere falls off with the inverse square of the radius of the sphere. By the time you reach the surface, the temperature differential between, say, 100 feet down, and 1000 feet down, isn't terribly high. Tens of degrees. The heat flowing out of the body is spread out over a rapidly increasing surface area as you get away from the core, or even the mantle. This temperature gradient is exactly what you'd expect to see if there were something hot in the center of a body, radiating outward, just as the light bulb. The heat gets "dimmer" as you move outward, since the total heat input is the same, give or take, for each increment we examine, but the surface area explodes as the square of the radius. We're a couple of thousand miles from the core, standing here on the surface. Think of a bonfire. Stand next to it and you're likely to singe your eyebrows. Stand 100 feet away, and you're likely to barely feel its warmth. Wrap it in concrete, and the difference is even more substantial.

Think then, as well, of a furnace in a home. My oil furnace burns at a couple of thousand degrees, yet the outer shell rarely gets over 80 degrees farenheit. Admittedly there's a bit of a cooling system involved, carrying hot water to the rest of my house, but the thermal mass concept is the same - even with the circulation pump shut off, the inside surface of the furnace may be upwards of 600 degrees farenheit, but the outer surface will never exceed 80 or 90 degrees. Why? Because the fire box is only about a foot by a foot square by a foot and a half deep. The outside of the furnace is a full 5 feet long, three feet wide, and four feet tall. (Yes, this is ridiculously large, my house was built in 1957, but that's beside the point)

So all the heat of the core has to leave through the surface. If a planet is light, and not terribly dense, as Mars is, and we can assume it had some sort of geological activity in the past, then one must ask, where did it go? I posit that simply it was on a knife-edge, in terms of equilibrium. It got just enough radioactive elements to keep it hot for just long enough, and either we've witnessed the end of its geologic age due to radioactive depletion, or it's got round about as much hot rock as it had prior to a cataclysm, but it has lost just enough insulation to let it freeze up, its heat rejection outstripping its heat generation by some factor sufficient to cool it in the time since the cataclysm until now, or at least a few hundred thousand to a few million years ago, based on crater evidence @ Olympus Mons, etc.

So the atmosphere can in fact provide a substantial insulation for a molten core tucked away thousands of miles deep. The sun, or any surface activity really, won't have much effect on the core temperature - you're not going to shine a flashlight on an aluminum can and melt it any time soon - but a small heat source, properly insulated, can last a very, very, very long time.

Also, keep in mind that the subsurface temperature within 10-12 feet of the surface of Earth stays at a relatively constant 55-60 degrees in most places. Our average air temperature is slightly higher.

I am a blacksmith in my spare time, and I should also mention that, a properly insulated knife blade, or really any piece of metal I'm annealing, can go into my bucket of perlite or dry kitty litter glowing orange-hot, and many many hours later, still be hot enough to burn you, while the outside of the container isn't even warm to the touch. Direct physical contact, but decent insulation results in a very slow cooling time. I've thought for a long time about mounting a hot metal rod in a thermos bottle and seeing how long it takes to cool down from ~2000 degrees, what with the vacuum insulation and vapor-deposited aluminum mirror surface keeping things toasty.

The question is, what's the cool down time, and what's the actual rate at which heat from the core leaves the surface, and what energy input is needed. Then we can see if the possible radioisotopes dropped on Mars are sufficient to sustain this requisite energy output without undergoing an actual chain reaction, and then see how close we are when we factor in the insulating blanket of a nice, warm atmosphere. I dare say that if the numbers come up close, then we must assume that Mars had a dense atmosphere in the past, and its loss is what drove the core freezing event.

If it is not even close, on the short side, then we can assume that Olympus Mons and its siblings were catastrophic volcanic events resulting from a somewhat molten core and a large impact event, leading to a short-term melt/volcanism event.

But, that's just what I've come up with after some back-of-the-envelope calculations. Anyone wishing to chip in and do some of these calculations and beat me to it, feel free. I'm curious to know how far off my own estimates are.

#17 Re: Terraformation » Artificial Magnetosphere - Electromagnetic Induction » 2012-07-16 02:11:41

Oh, and another point...

The magnetosphere may only be needed for a while... the artificial one at least.

Think of the planet as your body, for a moment.

The core is powered by nuclear reactions which occur at a relatively constant rate, at least measured over short time spans less than the half-life of the material in question.

If Mars and the Earth are roughly equal in age, and we don't expect the Earth's core to freeze out to nonproductive (magnetically, at least) levels for a billion years or so, then given Mars's 70-ish % surface area compared to Earth, we should expect about 70% of the core life span, given the same radiative cooling apparatus, and roughly equivalent deposition of radioactive elements. Just give-or-take, so Mars should have a geologically active core/mantle. The problem is, it doesn't seem to.

Now, think again of Mars as your naked body. Your core is fueled largely by glucose, but we can neglect that for the moment, and on a small timescale, give you a meal's worth of energy, just as Mars has a formation's worth of radioisotope/thermal energy.

We put you naked into the desert. You are rather warm. You burn very few calories and your core temperature begins, very gradually, to rise. Your energy is largely coming from solar radiation, so your body does not need to burn its calories to maintain heat, but only for motion and brain function. Nontheless, it burns more than it needs for heat, and thus you must sweat to cool off... Mars can't do this, so it would just heat up if we moved it in, to say Venus' orbit. Venus is rather warm, as well.

If we instead, put you out in the middle of the arctic, you would freeze to death in a matter of minutes to perhaps an hour. You are naked. There is no insulation between you and the cold of your effective outer-space, and thus the dominating factors of your body temperature are your metabolism (equivalent to the decay rate/loading of radioisotopes in Mars' core/mantle) and your surface area (likewise on Mars, though spherical).

If I then give you a parka, and boots, and nice thinsulate undergarments, and shove you out onto the tundra, you will be fine for HOURS. Keep your face covered, please, so your nose will remain intact.

You have the same surface area, the same calories to burn at roughly the same rate, but you have insulation which slows the escape of heat from your core to the space beyond your body.

Likewise with Earth. We have an atmosphere. It traps sunlight/infrared radiation, keeping the surface warm, which slows the rate of heat flow between the core and the surface. Temperature differential is where it's at. If you've got two articles that are close in temperature, in physical contact, then heat flows slowly. If one is ice cold and the other is near molten, then the heat flow is rapid. The Sun may not have enough energy to actually melt the core, but it does have enough energy to warm the surface of our planet to an average of 72 degrees. This may be just enough, or plenty enough for the Earth to maintain an active core. If the Sun were flicked off, however, then in a matter of hours, our atmosphere would fall as a layer of oxygen and nitrogen snow, no matter if the core kept molten or not.

I think Mars lost its atmosphere and froze to death.

The large impact basin directly opposite the elevated plateau where Olympus Mons and her sisters reside, the semi-equatorial cliff, the vast lava plains... i think a large impactor disturbed the atmosphere, jacked up convection currents, and before everything got established again, the core cooled too quickly, since Mars' surface area to volume ratio is higher than Earth's. (Smaller diameter spheres have more surface area for their volume, it's the whole pi*r^2 vs pi*r^3 thing, with all those constants thrown in, the volume grows way faster than the surface area, so the ratio of the two also grows with increasing r...) So, it lost its heat very quickly when the atmosphere was disturbed, and then stripped by the solar wind. This would explain why there is little or no nitrogen. Carbon and Oxygen exist in solid form all over the place. just about every rock is an oxide of something, and there are plenty of carbonates and carbonaceous meteorites. Nitrogen, however, only exists as ridiculously unstable solids, as nitrates, which are explosive or ridiculously combustible. You would not expect primordial nitrates to stick around on a hot protoplanetary surface, or even subsurface. They would decompose into oxygen and nitrogen, and if there were no magnetic field, the nitrogen would be stripped off as a gas. Later, when a magnetic field re-established itself, you would be able to build an oxygen/carbon dioxide atmosphere, but you would have no nitrogen reservoir from which to pull.

Someone stole Mars' parka, and all its nitrogen was in the pockets.

So, we can walk around on a terraformed mars (using only the artificial magnetosphere), but we will not be able to grow plants (no nitrogen) and we won't be able to light a campfire (no woody plants to burn) without spontaneously combusting everything around us (no buffer gas... 100% oxygen + 2-300ppm CO2... *POOF*). So we must find an appropriate buffer gas. As far as I can see, given Mars' low gravity, our only options are Nitrogen, Argon, or CO2 itself, which would be rough since we can't breathe high concentrations of CO2... and you'd need at least 20-30% non-oxygen gas to keep the whole place from being positively explosive. I mean, forget trying to repair your spacecraft with any kind of welding equipment - as soon as you got hot enough to weld, the atmospheric oxygen above 90-ish% concentration would start a self-sustaining burn on virtually any kind of steel or aluminum you were working on... kerpoof, there goes the neighborhood.

Just something else to ponder... if we warm the atmosphere, is there enough radioactive material in the core to re-heat and re-melt it, and get the dynamo going again... it should self-start, if molten, just due to momentum and convection... then god forbid, we'd have plate tectonics again, and future Martians wouldn't be relegated to living on a nearly spherical dune-swept marble, but a dynamic, mountain-range-building, living planet. Can you imagine what Himalayan mountains would be on Mars? Equal thermodynamic forces acting opposed to 1/3 the gravity... Mountains that reach to the sky!

*breathes*.

I shall sleep now.

#18 Re: Terraformation » Artificial Magnetosphere - Electromagnetic Induction » 2012-07-16 01:24:08

I have done some back of the envelope calculations on this very topic recently, and I will post merely the results - if anyone's interested in seeing the actual calculations, I don't mind scanning and posting an image of my notes at some point.

In any case, I assumed the worst - a single loop of "wire" - the most malleable/ductile superconductor we have currently is niobium-tin, or in some cases niobium-tin-copper compositions. Assuming this is a single large cable to be unspooled in orbit around Mars, "spun up" as an MRI machine's magnet is powered up, and the whole thing encased in a fairly thin, thermally insulating conduit, and provided with a solar shield around its periphery, this should be able to maintain a low orbit at roughly 200-250Km.

I chose this altitude, versus geostationary, since we want to use the lowest current possible to generate a magnetic field, and the least amount of material possible. Further, the rotational motion of the coil relative to the spin of the planet may add a bit to the effective current, if only a negligible fraction.

My calculations left me somewhat disappointed: For an Earth-equivalent field of roughly 70 gauss, a one-meter diameter niobium-tin alloy superconducting cable, assumed to be solid for purposes of calculation, cooled with liquid helium, would be sufficient, but would require roughly 100% of our annual worldwide niobium mine output for a period of roughly a century, and nearly 10 years worth of Tin production. Taking into account mines that are planned or currently under construction, this could be reduced to roughly 65-70 years. The cost is astronomical, just for materials.

On the bright side, this technique is aided by the damn-near absolute-zero of outer space, so the portion of the cable eclipsed by the planet's shadow should provide enough cooling to allow something as simple as peltier junctions mounted every few meters to counteract any solar irradiation incurred beyond what a properly-spaced reflector could not handle on the day side. Since the whole cable would ride through the shadow every 90 minutes or so, and the solar shield/reflector could be composed of solar panels, the feasibility, if not the initial cost, becomes evident.

Further, the calculations assume that there is absolutely no planet in the middle of the coil. Since Mars has quite a bit of iron through its surface, mantle, and core, presumably, this would become a ferromagnetic core, increasing the field strength. Also, I neglected any plasmadynamic effects. If the field were caused to oscillate, or even held steady, but allowed to gather energy as an electric guitar pickup does, from the moving, time-varying plasma current, one could assume that the power for the coil could be had on-site, and only a minimal current required for start-up, with the current building in opposition to the solar wind, so long as seasonal variations were somewhat sizeable. Depending on the effective permeability of the planet as a magnetic core, the entire thing might well be scaled down by an order of magnitude or two. Further, with vastly superior deflection of electrons than protons, an electron-rich solar wind would allow the induced electric field to do most of the work. Another concept I failed to explore further, mathematically, would call for a non-single-loop coil geometry. Multiple turns wouldn't get you very far, but a helical or interlaced loop geometry could enhance local field strengths such that the aforementioned plasmadynamic effects could yeild a higher electric field strength, and thus better shielding. In any case, any shielding effected would be better than nothing, and the atmosphere should build.


Please consider this one key fact that is often overlooked: Mars' atmosphere is in a state of dynamic stability - it is continually losing atmospheric gas to nonthermal loss mechanisms, yet its atmosphere continues to remain at a stable, if low, pressure and density. If we inhibit even a small fraction of the loss, the atmosphere would build. If on the other hand, we build the atmosphere, we will be losing, perhaps the same percentage, but much more of the atmosphere. We'll be driving the reaction towards loss by adding gas to a lossy system. If we instead reduce loss mechanisms, the gases will add themselves, from whatever surface or subsurface sources are already in operation (anyone notice the detection of subsurface Methane sources not too long ago?). I'll have to look up the effective velocities, and calculate turning angles required for various orbits, perhaps writing up a system of equations and optimizing them for minimum material required (low loop current vs. shorter cable). It may very well be that a geostationary ring would require vastly lower current to achieve an adequate turning angle of maximum solar wind velocity, since it is further from the planet, or it could be that we would be better off with a larger diameter cable much lower in orbit, permitting a larger field but with considerably less cable length to encircle the planet at a lower altitude.

Either way, i would point out that any solution with a multitude of orbital components that are not physically connected, will be subject to magnetic attraction, or at least torques, which would require continual energy input to overcome. I think a single loop, or some variation on this Dyson-like ring is a better bet, since the loop would auto-inflate to a nearly perfect circle under the influence of its own magnetic field, much like a loop of string floating on a soap bubble. Individual magnets would pull together, and multitudes of loops would at the very least rotate to become a toroidal magnetic field, and the gaps between the loops would actually cause a degree of focusing.

It has also occurred to me that a slightly weak magnetic field might result in protection near the tropics, but deposition of solar wind components near the poles - thus heating the poles somewhat, but also adding hydrogen and helium to the atmosphere. Admtitedly, these would boil off rather quickly, but there should be enough radical production that water vapor would be created, and gravitationally retained within the atmosphere... I am uncertain as to the equilibrium state with high incidence angles for stellar wind particles on the atmosphere, if they would eject atmospheric particles more, or if they would be captured at a greater rate than the loss mechanisms... it's an interesting mathematical problem.

#19 Re: Science, Technology, and Astronomy » Any ideas on experiments to prove what causes a planet's ... » 2007-08-06 16:23:18

Not sure about venus, but mars, pluto, and most every other rocky body in the solar system are all pretty inert in terms of magnetic activity.

Mostly it's convection currents driven through the core by radioactive decay. Starts out hot, and stays hot due to its mass and the excess heat of decay.

Beyond that, once a current is set up, it's sort of self-sustaining.

There was some research a while back using about a ton of molten sodium in an insulated spherical vessel. They tried to mimic conditions in the core of the earth, and got some promising results that roughly agreed with theory.

it would seem that once a magnetic feild is set up in the core, the current path is restricted by the same feild that it created, so instead of random bubbles of hot gunk moving around, it's a pretty steady-state flow. Feild disturbances occur, however, and that is what leads to current instabiltiy and new feild evolution/polar shift.

This is all just info that i've collected over the years, so there may be some innacuracies and some incomplete information, but this should give you a good start to look for things on document services (NASA/JPL for one...) and google.

Hope it helps,
Rion

#20 Re: Unmanned probes » MOLTOV - Mars Orbital Laboratory... launch in '05 » 2007-08-06 11:57:34

Ok, looks like I overshot the website debut by about 3 years...


I will be posting back soon, but Just wanted to touch base. Have had some major health setbacks in the family, almost losing my mother three times since my last posts on this forum. (by way of cancer and thromboembolism)

Will catch up soon
Rion

#21 Re: Life support systems » Optimal air pressures.. - Which is best? More O2 or more pressure? » 2006-10-24 12:07:04

believe it or not, it's not nerve stimulation that causes bone building... it's the piezo-electric effect. Same thing works on dental braces: pull back on the tooth and it leverages against the enclosing jaw bone tissue, inducing a tiny voltage differential across the faces of the bone - the osteoclasts and osteoblasts detect this voltage and alter their activity in the regions of altered potential - the bone gets chewed away on the compressed side of things, and redeposited elsewhere. Take the pressure away and apply a voltage, the same thing happens.

Yay for bioelectrics and finally taking grad classes.

It's been over 2 years since I posted here...

I'm now finishing up my BS in Biology with a minor in Chem. Only problem is I forgot to take a few classes like Dance and it's Audience, and Sociology.

Like gee whiz. I did, however, take ballroom... man that was fun!

Hopefully this topic isn't woefully dead and unread.

Rion

#22 Re: Planetary transportation » Air Transportation on Mars - Gravity's affect on Air travel on Mars » 2003-04-04 10:45:52

ah yes, i forgot that a sailboat can tack because the otherwise reverse thrust from the oncoming wind is able to be turned into propulsion because of the force exerted on the keel. I'm sure, however, that there is a way to achieve something similar so that a dirigible can at least go cross-wind, or at a slight upwind angle. On earth of course, there is so much air through which the craft must navigate, that the drag would easily overcome the thrust of any engine the craft could carry, to the point where it might as well be an airplane or helicopter. On mars however, i am not sure this is the case, though the cross sectional area of the craft would be immense compared to one on earth, since to achieve equal buoyancy one needs greater volume. This might wind up giving you roughly the same drag force with the higher wind speeds and lower density of the martian atmosphere. It's still worth checking out, since a dirigible could be anchored during high wind and simply released once the wind died down. It is a highly valuable option if properly executed, since an aircraft may well be heavier if not larger than a semirigid blimp/diridgible type craft. Deflated, it should be able to fit into a container not much bigger than two 55 gallon drums, not counting any crew compartment or engine, yet it should be able to 1-2 tons. An aircraft would more likely weigh upwards of 75% the weight of its cargo.

well i'm utterly exhausted and it's only noon... not exactly up for an hour and a half drive to Richmond this afternoon, but what are friends for... UGH!

take it easy guys, and keep the ideas coming

#23 Re: Life support systems » Optimal air pressures.. - Which is best? More O2 or more pressure? » 2003-02-14 13:28:54

The biggest thing that nitrogen does for you is keep you from burning up. I don't like nitrogen in breathing air, since it is what causes the bends, with pressure changes causing nitrogen to either become dissolved in, or to precipitate out of your blood. Nitrogen Embolus is quite fatal, and is why subs use helium (not U.S. Navy subs, but rather research subs and the like). You sound funny, but it's doable. I think there should be another gas you could use other than helium since it is rather hard to come by on mars, perhaps argon or something, but you really need a noble gas since anything else by definition would be reactive and have a biological function. (definitely don't want chlorine as a buffer gas...). Nitrogen could work but I guess you could "cut" it with some helium so that you minimize the effects of fast pressure changes. If you get a breach in the hab, it could be slow enough to not flash boil you, but if unnoticed you could experience a rather quick pressure change that would give you the bends. Surviving a hull breach only to die of the bends is definitely NOT something to put on a brochure.

As far as burying the greenhouse, yeah, you get radiation protection for everything except what's pretty much directly overhead, and impact and wind damage are reduced to ONE face of the greenhouse, which could have a sacrificial, replaceable, polyethelene skin over your polycarbonate paneling. This would erode pretty quickly in a dust storm, but it would keep the underlying structural polycarb from getting toasted.

NITROGEN and OXYGEN in the greenhouse:

You don't need to put oxygen in the greenhouse to start it, since the plants are going to generate WAY more O2 during a day than they need for a night's metabolic activity. Plants actually need some of the oxygen they create all the time, since chloroplasts make sugar, and sugar is essentially burned to get ATP. I beleive it's hydrolysis of glucose that generates ATP most efficiently, and this occurs in mitochondria, which need oxygen. In any case, nitrogen would also be obviated, since you're (hopefully) using a hydroponic system for most of your plants, and you'll already have fixed nitrogen for the plants to use, since the nutrient solution has nitrates in it. Sure there's some loss, but i'd rather have it pre-mixed than have a hard to predict nitrogen sink hooked up to our life support systems. Eventually you could condition martian soil, perhaps as simply as warming it up and adding a little water to kill any peroxides that are present, and use that as your potting mix, which with some aggregate can still utilize hydroponic techniques for irrigation and fertilization. I don't like the idea of introducing microbes on mars any more than we have to, since of course humans are walking petri dishes, but you still want to keep it contained within your suits. UV radiatoin should smoke any microbes on the outside of the suit, so it'd probbably be a non issue, but when you start using nitrogen fixing bacteria, you could be extincting a local species that is yet undiscovered. Who knows? Safe bet is the containment route (damned reds...) to keep contamination to a minimum.

I think that's all the issues i wanted to address for you, but I do wanna say thanks for the quote, and maybe i'll put it up on my website...  big_smile  so anyhow, take it easy y'all, and look for a post from me about my up and coming website, we'll have a couple engine test videos for you (i'm a bit of a pyro... shhhh!)  :angry:  cool

#24 Re: Life support systems » Optimal air pressures.. - Which is best? More O2 or more pressure? » 2003-02-12 10:54:59

yes, of course it's your body temperature that matters... However, I did think about the plants. If you wore a pressure suit, and used martian atmosphere for the greenhouse atmospehere since plants eat CO2 for lunch (literally) you'd THEN have to worry about the ambient temperature. The plants would of course have to keep from freezing, but if you got them too warm, and the pressure was significantly reduced, you would wind up with exploding/freeze dried plants, since the fluids in their tissues would boil off. If you use a pressure suit then, your temperature and pressure worries are not over by a long shot. I don't really see the problem with working in a pressure suit, I've done quite a bit of work with bees and gardening using heavy gloves, since I grow blackberries, and I decided to use my beekeeper's gloves to do some harvesting and trimming of some plants, and It's quite easy to work with carrots and the like, especially in a hydroponic environment.

You can select plants with large fruiting bodies for greenhouse population on mars, such as carrots, large radishes, broadleaf lettuce and cabbage (for those with intestinal fortitude and a predisposition against gassyness...) and various other greens. Things like broccoli are easily cut with a sharp knife, and are large enough to not be a problem with bulky gloves. All sorts of choices can be made to accomodate a pressure suit in the greenhouse, but it'd be neater than sliced bread to walk around in shirtsleeves tending a garden and look down and see martian soil under your feet, and look through clear plastic at olympus mons rising in the distance.

as far as constructing the greenhouse, I think burying the whole structure except the very top is a fairly good idea, since you then reduce the strain on the entire structure to be local to the roof. The rest of the structure can translate the stress of inflation pressure to reinforced bands that line the greenhouse structure, and the roof is the only part that would bear that significant weight of 2 tons per square meter. If the rest of the greenhouse can be made of polyethylene, i don't see why you can't have a large flat or curved roof of interlocking polycarbonate panels which could be pre-prepped with a thin strip of cold set epoxy on a dovetail joint, and then when the whole thing is landed and unfolded for inflation, you simply peel off a piece of film on each tongue and groove or dovetail joint and slide them together, and the pressure of inflation forces the panels together, mixing and setting the epoxy. might be a lil complex, but i'm not sure how else to get around the vast stress that high pressure environments induce on the inside of the thin greenhouse structure.

Take care all,
Rion

#25 Re: Interplanetary transportation » Nuclear Propulsion - The best way for space travel » 2003-01-28 16:00:12

what about electric propulsion? I'm not talking Ion thrusters, i'm talking about the JLN labs concepts, and my design which uses the same principle to get a bit more thrust. There's dozens of ways to design a thruster, so I'm sure there's loads of better ways than simply a piece of copper tube and a ring electrode. Anyhow, I think this stuff has some promise, and you wouldn't need a huge nuclear thruster or fusion or anything like that. Just enough solar panel to give you some significant thrust, and you can run a thruster on about 100 watts to give you almost 100% conversion efficiency, minus resistive losses, from electric potential to kinetic energy. I'm working up a design for a cryogenic test series, since a friend of mine works at a welding shop.... free liquid nitrogen! (small rental fee for the dewar, but big deal, it's free LN2!!!) anyhow, check his site out, lemme know what you think, and take a look on www.google.com for Thomas Townsend Brown, and electrokinetic propulsion. Later y'all,
Rion

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