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Old 2009-07-19, 05:24   #12
cheesehead
 
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Originally Posted by Mr. P-1 View Post
A return trip, by contrast, would require a craft or crafts capable of delivering into Mars orbit a craft capable of returning the crew to earth, additional supplies for the return journey, and a lander capable of landing the crew + supplises, and returning the crew to orbit.
Yes, but it doesn't have to be done in the same straightforward way as the Apollo moon missions -- taking everything needed for the round trip in one big package at the same time.

One can use the Interplanetary Transport Network (ITN), AKA Interplanetary Superhighway, to preposition return-trip supplies in Mars orbit in advance. See http://en.wikipedia.org/wiki/Interplanetary_Transport_Network. Then the outbound manned trip need not haul along fuel and other stuff for the return trip -- those will already be in Mars orbit when they get there. The unmanned advance cargo trips can use low-energy transfer orbits that take longer than a Hohmann transfer but for much less fuel.

Result: lower total expense (more payload per fuel and rocket structure), in exchange for more complicated planning in advance. But computers take care of the complicated orbits that were infeasible (indeed, not yet fully discovered) back in the 1960s-70s.

We've already been doing some versions of these low-energy transfer orbits with unmanned probes (ISEE-3/ICE, Hiten, Smart-1).

The gravity assists used for many recent interplanetary missions to Mercury, Venus, Jupiter and Saturn are somewhat related, in that they also trade a longer travel time for smaller total fuel requirement, but that isn't the same as ITN. It might be said that ITN uses gravity assists around Lagrange points instead of gravity assists around planets, but don't quote me on that.

Last fiddled with by cheesehead on 2009-07-19 at 05:39
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Old 2009-07-19, 05:56   #13
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The latter option would undoubtedly require many additional millions of full-time worker-years to engineer, with consequent loss of many more lives.
I'm looking at the PDF, but don't see a line for spacecraft engineers.

"Architecture and engineering occupations" has a very low fatality rate, 1.7, compared to the 4.0 figure for all occupations in total. Even "Arts, design, entertainment, sports, and media occupations" has a higher rate (2.0).

Wait -- there's "Aircraft pilots and flight engineers". (70.6) Wow. Is that what you meant?

Not "Government" (2.3)?
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Old 2009-07-19, 06:54   #14
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One can use the Interplanetary Transport Network (ITN), AKA Interplanetary Superhighway, to preposition return-trip supplies in Mars orbit in advance.
Also see Buzz Aldrin's Cycler:
http://en.wikipedia.org/wiki/Mars_cycler
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Old 2009-07-19, 07:28   #15
cheesehead
 
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Also see Buzz Aldrin's Cycler:
http://en.wikipedia.org/wiki/Mars_cycler
That's the one I was trying to think of.

Someone should crosslink the Wikipedia articles on ITN and Mars cycler / Lunar cycler.
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Old 2021-05-12, 08:25   #16
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By 2050, the world's population will increase to 9.9 billion people. The planet's resources are dwindling, and humanity hopes to find them in space. But on the other hand, lots of Earth's resources will be sent to keep the people on Mars healthy so probably the resources could end faster..
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Old 2021-06-30, 18:27   #17
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By 2050, the world's population will increase to 9.9 billion people. The planet's resources are dwindling, and humanity hopes to find them in space. But on the other hand, lots of Earth's resources will be sent to keep the people on Mars healthy so probably the resources could end faster..
We see a number of total BS arguments getting used to support manned missions.

Let's start debunking a few problems.

Now i'm not a specialist in rocket technology nor propulsion but from what i understand is that past decades AI experts had problems getting contract jobs - myself included - at any sort of company other than espionaging the telephone system (and others). A job most AI guys do not want to do - myself included - besides it pays bad such government job.

So instead of spending a few million on better autonomeous software - something which would benefit all of humankind - they want to ship a few gorilla's on a mission into space.

Let's start debunking problem 1. Getting resources from far away with a rocket stumbles upon a few small problems.
Problem 1 is the rocket formula. The only way that works to navigate in space is by outputting mass. The amount of mass you need to take from planet earth in order to get anywhere is huge. So you just lose mass if you undertake such missions.

Now if the amount of missions is small enough, earth won't really notice losing mass at all.

I'm unaware whether earth gains mass or loses mass netto (as each second fragments from space hit earth and keep there meanwhile other stuff like Helium escapes from planet earth).

Yet if we do a small amount of missions no raw material on earth is worth the price of the mission. We can easily prove that coming millions of years using this same type of propulsion getting raw materials from meteors or asteroids is not worth it when the missions are at a small scale.

When the missions are at a huge scale then we lose lots of raw material. More than such mission will take back.

Besides that most missions will take hundreds of years if not more - no investor will ever fund that.

Manned missions to anywhere outside low orbit of Earth are IMHO a show of low IQ and total waste of resources.
Much better to write better autonomeous software. First of all it's of generic use such software. Secondly it's much cheaper.

Another few good reasons to not ship humans to a manned mission to Mars using the current propulsion technology we have is very simply put the risk of failure and the short term exploration and the fooling of yourself.

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.

Such human would sit in short in a bunker deep below the surface of Mars and basically operate any sort of robot there which wouldn't be autonomeous, with a remote control.

Do you want to pay a few trillion dollar for a human on Mars just to have a couple of minutes advantage of remote controlling a robot on the surface?

That's pretty much fooling yourself isn't it - with a few trillion dollar pricetag.

Now on the actual staying on Mars. A mission to Mars - how long is the human gonna sit there and stay there?
Just doing what happened in the 1969 and start 70s with missions to the Moon - that was very short visits there.

Autonomeous robots can work way longer and therefore collect way more data than a manned short term mission.

Now on a long term 'colony' type mission to Mars. Besides a good Hollywood show there is really zero advantages.
The whole mission is no longer gaining knowledge for humankind - yet the mission would then be just a hollywood show how long the Marsonauts manage to stay alive. The mission in short has failed and you lost trillions of dollars, if the marsonaut(s) die.

It's just a gorillashow in short without any sort of scientific advantages yet a very high risk of failure of the mission.

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.

So everything you ship to mars wears out very quickly. A human mission to Mars would need thousands of tons of equipment shipped from planet earth just because of the quick wear out of all components - and you cannot produce those on Mars.

A big issue is also power.

The theoretic models regarding planet earth date back from the 1950s invented by some civil servant who had no clue back then how things would be today in the 2020s. They just look how much food the planet can produce and calculate based upon that how many inhabitants can live then on planet earth. This is wrong way of calculation.

What matters is how much energy you can produce - as that determines how many people Earth can support.

My guesstimate there is that this would be 500 million inhabitants. Currently we got 7.x billion inhabitants. Way too many humans living on planet earth.

The yanks might raise their eyebrose here - but realize that in USA you got roughly 25 inhabitants on each square kilometer in USA - yet in this nation, Netherlands, if we remove some waterways and lakes, we're closer to 1000+ inhabitants each square kilometer and that's farmers and farmground included.

The most epxensive thing here is owning a few square meters of ground. I would like a barn for example where i can put my lathe and CNC milling machines. Would cost me right now 3000 euro a month for rent.

On planet Mars the same problem is there. It's all about energy. How do you generate energy there?

We simply see how the latest mission shipped to mars isn't using a solar panel yet is using a nuclear battery.
In short it seems NASA concluded solar panels do not work on Mars - or do i conclude this wrong?

If i do math on that latest Rover mission from NASA to Mars there it doesn't make sense to me anyway. They needed dozen of kilo's extra for a couple of watts of power. Say a 100 watt. And then they waste 10 watt nonstop to some sort of CPU in special package from the 1990s which eats a whopping 10 watt. Instead of pay a few million to design a new cpu package which would eat under 2 watt under full load and probably be factor 100 faster than that CPU they got now.

How to generate power for a manned stay on Mars?

What's the weight of a nuclear central on Mars and how many hundreds of tons (in weight) of spare parts do you need to maintain it in case of problems?

To fix the nuclear central you would need a backup. In short a 2nd central at a different spot.

We speak about thousands of tons of equipment. Especially bulldozers and digging machines the parts wear out quickly and on Mars they would wear out quadratic quickly because there is no sand. It's all razor sharp small gravel there on the surface that will kill any sort of equipment quickly when you start digging and constructing.

If we guesstimate a few thousands of tons - say 2000 tons of equipment. Say 10 million dollar a kilo. Now maybe you can reduce that price a tad to 5 million dollar each kilo to be shipped to mars. That's a mission price of 10 trillion dollar for a manned settlement on Mars.

That's a pretty careful estimate. It'll be way worse in reality.

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.

Right now zero huge bunkers on planet earth are waterproof. In case of a nuclear attack - in the long term everyone dies from radiation pollution anyway as it always will leak into the bunker within a few weeks/months.

How would you construct such bunker on Mars which besides being waterproof also needs to be pressurized.

You need so much energy for keeping such bunker working.

How to maintain all that equipment needed to keep such bunker afloat?

It means in short more spare parts and machinery you need to ship. Bearings huh?

Your own furnace to melt metals and construct any sort of shape out of it.

Basically what i design here CNC machines (3d printers especially, but also have done some cnc milling machine designs) is the most important thing to have there.

Know a couple of problems of them?

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. bullets in 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.

You need special rooms to wash off poisenous stuff that is on the surface of Mars, from any vehicle you want to maintain. How to maintain vehicles as a human?

If you always need to wear a suit while maintaining robots or whatever.

All the politicians and lots of people on this forum have no idea about 'make industry'. The resources you need to build something. On Earth we can touch everything. On Mars you can't.

It's a total pipe dream to have a human colony on Mars.

Yet it is like it is going always. Some sort of dude or bunch of dudes type Elon Musk can make big cash. He can earn trillions of dollars on it. So he tries convince the audience and public.

Build better autonomeous software and ship robotic missions to anywhere to increase our knowledge instead of going back the to 1960s and doing manned missions!

Our technology is too primitive right now to get humans further away than ISS. It's therefore a waste of cash.
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Old 2021-06-30, 19:32   #18
chalsall
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Our technology is too primitive right now to get humans further away than ISS. It's therefore a waste of cash.
I respectfully disagree.

Musk and China (possibly others) will have "footprints on the ground" on Mars in less than ten years.

I agree with Musk et al. There needs to be a "backup". CV19 should make this abundantly clear.

And we are about to reach the point of technological advancement where we can actually do this. This capability /might/ be constrained to a narrow "window" in the temporal domain.

Best do it as soon as we can, while we can. IMHO.

Last fiddled with by chalsall on 2021-06-30 at 19:34 Reason: s/in less/on Mars in less/; # Helps to define the objective implied.
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Old 2021-06-30, 20:07   #19
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Originally Posted by diep View Post
We see a number of total BS arguments getting used to support manned missions.
That's no excuse for your own risible arguments against. You admittedly fail to check basic facts, and use "guesstimates" and personal opinion in place of facts. But the nadir is going into the realm of logical inconsistency.
Quote:
Just doing what happened in the 1969 and start 70s with missions to the Moon - that was very short visits there.
<snip>
Our technology is too primitive right now to get humans further away than ISS. It's therefore a waste of cash.
So, you acknowledge the Apollo missions happened. But you claim our technology now, coming up on the 52nd anniversary of Apollo 11, is too primitive. These are logically inconsistent - unless you are claiming that the Moon is closer to Earth than the ISS, or that our technology is more primitive now than it was over 50 years ago.
Quote:
Autonomeous robots can work way longer and therefore collect way more data than a manned short term mission.
<snip>
So everything you ship to mars wears out very quickly.
These two statements are incompossible.
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Old 2021-06-30, 20:09   #20
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Quote:
Originally Posted by diep View Post

Let's start debunking problem 1. Getting resources from far away with a rocket stumbles upon a few small problems.
Problem 1 is the rocket formula. The only way that works to navigate in space is by outputting mass. The amount of mass you need to take from planet earth in order to get anywhere is huge. So you just lose mass if you undertake such missions.

Our technology is too primitive right now to get humans further away than ISS. It's therefore a waste of cash.
The full post above.is too large to deal with in one go, so I will restrict myself to a number of responses to individual points, quoting each in turn,

The main issue with the first is that it completely ignores in situ resource utilization, commonly known as ISRU in the trade. You do not need to take everything with you. You need take only enough to be able to build future requirements from local resources.

Incidentally, rockets are not necessary to launch from airless bodies. Linear electric motors can accelerate material to lunar escape velocity. Once in orbit, rockets are not necessary for many purposes. Solar or laser sails are not rockets, neither are aerobraking or gravitational sling-shots. The last two have been used for decades.

Technology which is now almost sixty years old was sufficient to get humans substantially further away than the ISS. Do the names Armstrong, Aldrin and Collins mean anything to you?

More later.

Last fiddled with by xilman on 2021-06-30 at 20:11
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Old 2021-06-30, 20:11   #21
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And we now know why diep's ancestors never left Europe, it is impossible to settle in a far off land.

Last fiddled with by Uncwilly on 2021-06-30 at 20:11
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Old 2021-06-30, 20:25   #22
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If we guesstimate a few thousands of tons - say 2000 tons of equipment. Say 10 million dollar a kilo. Now maybe you can reduce that price a tad to 5 million dollar each kilo to be shipped to mars. That's a mission price of 10 trillion dollar for a manned settlement on Mars.

That's a pretty careful estimate. It'll be way worse in reality..
It is already much better in reality. Perseverance weighs 1025kg. The US has budgeted $2.75 billion on the total mission which includes years of ground support. The high development cost $2.2 billion is inflated by it being a one-off design; lessons learned from Curiosity saved perhaps $100M at most. Rebuilding Curiosity would have been much cheaper ($500M for the hardware rather than $2.2G perhaps) though it would not have been able to do anywhere as much novel science. By the time Martian colonies are feasible economies of scale will kick in in a big way.

Not withstanding the above inflated prices, simple arithmetic gives $2.75 billion / 1025kg = $ 2.68 million per kilo. Already this worst case mission is four times cheaper than your estimate. Not very careful, in my opinion.
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