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Old 2021-07-01, 00:26   #45
diep
 
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Quote:
Originally Posted by chalsall View Post
Or... Perhaps...

You are Dead On Arrival (DOA) with your arguments.

Please know we are just fscking with you now. You have no standing. And you fail every time you try to advance your cause.
Dumb people are not capable of grasping concepts outside their confort zone. Science is overloaded with such persons who qualify on paper but in reality do not grasp the whole picture when it doesn't fit in that corner where they work.
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Old 2021-07-01, 00:31   #46
chalsall
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Quote:
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Dumb people are not capable of grasping concepts outside their confort zone.
OK. Let's do this.

Please argue for the use of Humans deployed to Mars.
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Old 2021-07-01, 00:35   #47
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kriesel: on those self builders. I design 3d printers here. I notice in construction at all kind of sectors big mistakes made by engineers, yes fulltime engineers, with temperatures. Expanding and shrinking constructions built at both small as well as huge scale (think of 20 meters of baking oven for bread to daily eat for a bread factory).

From stadium level to as small as 3d printers can be. They all make huge mistakes there despite having a calculator at hand and paper to calculate shrinkage/expansion.

At night -70C or so. You really want to live in say 19C roughly. That's nearly 90C difference.

I see them all make huge mistakes there. Just some 'build something ad hoc here' is never possible. Everything needs careful calculation back on Earth by engineers who really know about this problem. Big experts on temperature differences of materials. That's not something you learn overnight by some googling.
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Old 2021-07-01, 00:51   #48
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Originally Posted by kriesel View Post
I should introduce you to some of my former coworkers.
I have never met them. But I trust they would know their shit based on your recommendation.

People can talk themselves up all they want.

It would be cool if people would do what they promised.
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Old 2021-07-01, 01:03   #49
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Ooh, scary word to some, radiation. Sunlight at the earth's surface is radiation. Manage exposure to limit sunburn. I've designed modular radiation shielding for attenuation of hard xrays up to about 107:1 (My attenuation design calculations were checked by physicist Don and again by Geiger counter on the hardware.) We aimed for no more than 50mrem/year attributable dose for the 40 hours/week machine operator, and achieved adequate margin below that.

The minor attenuation needed for long term Mars stay is a solvable problem with locally sourced material.

It's routine at particle accelerator facilities to use concrete and mounds of dirt as part of the shielding solution.
An average Terran is exposed to about 0.6 rem/year. Standard for a radiation worker as I recall is 5 rem/year limit. Unprotected Mars surface is up to 20. rem/year. https://phys.org/news/2016-11-bad-mars.html So, need shelter with of order 100:1 attenuation to allow nonradiation worker type average levels including occasional limited emergence from shielded shelter to surface.
Per https://www.mars-one.com/faq/health-...-be-exposed-to several meters of Martian soil provides adequate shielding for 60 years residency. Shallow enough we could walk the ramp or stairs. Old lava tubes or caves will be in demand to reduce excavation work. Miners install rock bolts, mesh, shotcrete, as needed to stabilize, then smoothing foam and a gas-tight membrane, airlocks. (Learned about that mine tech re the Homestake Mine conversion to a 4850 foot deep physics laboratory. In other mines there are clean rooms inside of clean rooms.)
Caverns will be pre-located and prospected by orbiting ground-penetrating radar before the manned missions.
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Old 2021-07-01, 01:34   #50
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Quote:
Originally Posted by diep View Post
Sardonicus - i do not know what world you live in - but in 1969 we didn't have autonomeous robotic systems.
In fact factories weren't even using CNC milling machines back then.
<snip>
My mom would have said, "What's that got to do with the price of fish?" It's something she would say in response to irrelevant or non-responsive comments.

In the present instance, I never said anything about "autonomeous" robotic systems, and they do not pertain to your statements that I addressed. I pointed out that you acknowledged that the Apollo missions took place, but also said that "our technology is too primitive right now to get humans farther than the ISS." As I indicated before, these two things are logically inconsistent, unless you are claiming that the Moon is closer to Earth than the ISS (it isn't) or that our technology is more primitive now than it was when the Apollo missions took place (it isn't).

Last fiddled with by Dr Sardonicus on 2021-07-01 at 01:38 Reason: Omit unnecessary words!
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Old 2021-07-01, 01:50   #51
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Quote:
Originally Posted by diep View Post
I design 3d printers here. I notice in construction ...

At night -70C or so. You really want to live in say 19C roughly. That's nearly 90C difference.
Let me get this straight. You design 3d printers. You build them. You notice big issues with temperatures and expansion. But it's OTHER designers' fault.

There's a solution to that. Only use competent staff on planning, design, construction, assembly, inspection, and prove-out for such missions. highly competent reviewers at organized design reviews. Also same schedule as internet access, mission control and engineering support team is reachable.

My quarters range from ~16C- ~30C with the seasons. The outdoors swing much more widely.

My lifetime range has been -37 to +~104F weather so far (-38 to +40C) and both extremes in this county. At +40C outdoors, I was working on a ladder in a high ceiling room with no air conditioning, fixing ancient ceiling fixture electrical wiring, so probably +45C or higher. Some of my former coworkers went to South Pole Station and worked there in "summer" (similar to US upper Midwest winter, except at higher altitude). Some people overwinter at SPS. It's currently -70F/ -57C and snow flurries. A week ago it was -89F (-67C) https://www.timeanddate.com/weather/...h-pole/climate. But SPS staff don't sleep outside, neither do we usually, nor would Mars colonists. Several meters of radiation shielding should also provide considerable thermal buffering.

I've designed hardware for occasionally cycling 20.-150.C while maintaining UHV leak tightness for a 20. year design life. Withstanding focused electron beams. Or room temp to LN2. Other hardware to operate up to 1000.C (in-vacuum sample holder/manipulator). Other down to 0.007K (CUORE calibration system). ~180,000:1 absolute temperature range overall. Unless you add in my college days, furnace design including uncooled flameholders. Or peak spot temperature in a tungsten xray target, probably above 2000.C at times.

In an earlier diep post there was something about all of Mars being jagged rocks. The photos including tracks and other data say otherwise. https://en.wikipedia.org/wiki/Martian_soil


Quote:
Originally Posted by chalsall View Post
I have never met them. But I trust they would know their shit based on your recommendation.
Working with someone for decades gives plenty of time to notice who underpromises and overdelivers and has broad knowledge and skills. Those are the ones I hated to lose to retirement.

Last fiddled with by kriesel on 2021-07-01 at 02:06
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Old 2021-07-01, 02:16   #52
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Quote:
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The settlement on Mars would need to survive probably 10 million years before they can 'go back to earth'. You believe a few dudes on Mars will manage to keep alive when the rockets full of supplies stop?
Fundamental mission plan failure there. You'd need a largish complement of fertile dudes and perhaps mostly dudettes in the population, for long-term-tenable genetics. Also launch weight of dudettes tends to be lower than for dudes.
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Old 2021-07-01, 03:15   #53
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A human on Mars would be a precious person. Not someone you would like to get killed today. So basically a human on Mars simply put you cannot have walk on the surface in a pressure suit. That's way too dangerous.
That's why there's cross training, more than one doctor, EMT, etc. But zero-risk policy is not an option. That leads potentially to terran-only, population crash, new stone age.

Quote:
Mars is a very hostile environment. Far more hostile than any sort of environment here.

If you drive on Earth at some spot, you typically use rubber wheels.
On Mars you cannot use Rubber wheels. There is no 'sand' as we know it in the 'desert' there.

It's all razorsharp what is there. A rubber wheel would directly get penetrated and no longer function. Also the temperature might not be very ideal for rubber.
I call hogwash about no sand there, razorsharp, etc. https://en.wikipedia.org/wiki/Martian_soil

It is probably below the glass transition temperature of most rubbers and plastics though. But silicone rubber and grease have tremendous temperature range. https://www.hitachi-hightech.com/fil...on_TA_018e.pdf
I've sent Dow Corning 33 to SPS for outdoor unheated use, after some Purdue prof used ordinary grease, which froze solid into a babbitt on a plain main bearing on a large rotating platform, as if he'd glued it in place. The prof I worked with went there with instructions to pump the 33 into the zerk on top until it broke the frozen bearing free. Worked great!

Quote:
And still the dudes might die over there. Lack of gravity long term - what will THAT do to a body?
Or a few small holes in the bunker deep underground there. Losing pressure means direct death.

Designing a bunker would be complicated as well. You would need to design kind of a cube inside a cube.

So outside cube having 'earth pressure' and inside cube as well. Humans only living at inside cube. If outside cube loses pressure you still might survive at the inside cube.
CUBES? One of the worst ways to design a pressure vessel, if material efficiency, stresses, etc. matter. Spheres, conical transitions, and domed cylinders are used for good reason. Don't see many brick shaped tanker trailers on the highway.
Tunnels in rock are often created flat bottom and wall and arched ceiling. Pressurizing them would actually help the rock bear the stresses from gravity. Over time (centuries) at considerable depth they will warp and flow.

Gravity, well, 38% is a long way from weightless. Exercise is needed from 0 to 1+ G.

Quote:
How would you construct such bunker on Mars which besides being waterproof also needs to be pressurized.
Shouldn't be a lot of water flowing outside when you're concerned about -70C. But it probably ought be captured and run through a still.
Quote:
Your own furnace to melt metals and construct any sort of shape out of it.
Given the thin atmosphere I'd be inclined to evaluate a solar furnace for up to aluminum casting.
Quote:
first of all you need good bearings. You need measuring equipment. But you also need oil. And that oil gets into the air and is not very healthy. bulletsrolling elements and separators in ordinary bearings need lithium grease. How many tons of grease do you ship to planet Mars? If you're out of grease - you cannot produce spareparts anymore in short.

Any bottle with grease you open there is going to pollute expensive air you got in the bunker.
bearing grease is just not that volatile. If the smell is an issue, a counterflow heat exchanger loop for the air with a little heat loss to the outdoors could condense most of the hydrocarbons and perhaps some human generated odors too out. Separating living quarters from shop/work areas is an obvious measure too.
They'd probably send ceramic or ceramic-hybrid bearings, perhaps solid lube coated, with seals. https://www.bocabearings.com/general...ybrid-bearings

Last fiddled with by kriesel on 2021-07-01 at 03:22
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Old 2021-07-01, 12:50   #54
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For a manned mission to Mars, IMO there should be an objective which could not be achieved by a robotic mission. Why would we be going? Offhand, I can't answer that question. "Just to see whether we can do it" is IMO insufficient. Also IMO, if missions in the near future are in prospect, the objective should be urgent enough to answer the question, "Why do we need to go now?"

With the Apollo missions, the main reason was the "space race" with the Soviet Union, AKA "the Russians." The President of the United States had set a national goal, "before this decade is out," of landing a man on the Moon and returning him safely to the Earth. It may be hard for young people to understand the "cold war." The USSR was viewed as a mortal threat to this nation, and its space achievements has us terrified. When Sputnik went into orbit, we realized that not only was their space program "ahead" of ours, but they had the ability to produce rockets to send ICBMs anywhere they chose. One response was an increased urgency in teaching science in our schools.

The Soviets ran up an impressive series of "space firsts." First artificial satellite in Earth orbit. First animal in orbit. First man in orbit. First woman in orbit. First space walk. First pictures of the far side of the Moon. And others. As I recall, the first time the USA scored a major "space first" the Soviets could not immediately match was during the Gemini missions, when we successfully docked two spacecraft in orbit. This ability was essential to the planned Apollo missions. The Soviets did achieve this capability after some failed attempts.

The "space race" came down to which nation would be first to land men on the Moon and return them safely to Earth. And when the race was won, the rationale for future manned moon missions evaporated. A Saturn V rocket built for a canceled mission was used for Skylab. The Soviets continued with robotic Moon missions. Luna 16 and Luna 20 used remote-control robotic rovers, and returned samples of lunar material to the Earth.

Missions to Mars can not rely on remote control from the Earth. It takes too long for the signals to traverse the distance. Any robotic devices have to have a lot of autonomous capability.

At present, there is IMO a lot of uncertainly in achieving the fundamental objectives of any Mars landing mission of navigating there, achieving orbit, and getting the lander to the surface intact (and, hopefully, reasonably close to its designated landing point). We do seem to be getting better at it, but even getting a robotic probe into Mars orbit is IMO pushing our engineering capabilities to the very limit. So far close to 2/3 of Mars missions have failed. China recently became the second nation ever to achieve the successful landing of a Mars probe.

I do not see any insurmountable difficulties in achieving a manned Mars mission, or even creating a Mars colony. However, I think it would be prudent to try to colonize the Moon first. For one thing, it's a lot closer. For another, I can think of a couple of mission objectives that might justify it. One, purely scientific, is a radio telescope on the far side of the Moon, where it would be shielded from artificial radio signals coming from the Earth. Another, gathering Helium-3 from the lunar surface and sending it back to earth. Assuming the need for human crews, the mission would entail devising living quarters. Possibilities include lava tubes. Challenges include dust. Lunar dust is often named as the culprit in breaching the seals in lunar "rock boxes." It is very fine, very sharp, very different than any mineral dust on Earth. It can get into practically anywhere. I does seals and machine components no good at all. Not to mention the human respiratory system.

I'm not sure how similar the dust on Mars is to lunar dust. I do know it was taken into account in designing the rovers. IMO the problem of dust storms dimming the light and accumulating on solar panels is of far lesser magnitude than keeping the stuff out of machinery, seals, lungs, and perhaps digestive tracts. But I am not smart enough to know that the problem can't be managed effectively. I know that NASA has been working on it.

But again, I don't know the mission objectives for a manned Mars mission.

Last fiddled with by Dr Sardonicus on 2021-07-01 at 15:47 Reason: Omit unnecessary words!
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Old 2021-07-01, 14:27   #55
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Quote:
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I'm not sure how similar the dust on Mars is to lunar dust. I do know it was taken into account in designing the rovers.
Lunar dust is far sharper. The wind on Mars allows the grains to hit each other and knock the edges off.
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