GRA
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Re: Mars Is a Hellhole

Tue Mar 09, 2021 5:47 pm

danrjones wrote:
Tue Mar 09, 2021 2:34 pm

<Snip>

The Physics are fine, the materials science and money is another matter.

Yup. For another example, if we had a spacecraft propulsion system with much higher Isp, we wouldn't need to rely on Hohmann transfer orbits that limit us to infrequent Earth to Mars launch windows and travel times: https://en.m.wikipedia.org/wiki/Hohmann_transfer_orbit

Never mind warp drive, just a good impulse power source would do it* :D Right now, going to Mars is like using a 24kWh LEAF for a road trip. It can be done, but it's extremely limited and a pain in the ass!


* Way back in the Atoms for Peace days, one suggested method was a spacecraft with a very strong aft shield. A-bombs would be dropped behind it at regular intervals to provide more continuous thrust:

https://en.m.wikipedia.org/wiki/Project ... opulsion)
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goldbrick
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Re: Mars Is a Hellhole

Tue Mar 09, 2021 6:01 pm

danrjones wrote:
Tue Mar 09, 2021 2:34 pm
It would be like you swinging a string with a rock tied to the end, that rock pulls on the string and keeps it taught. Now imagine a small ant walking that string up and down. That ant would not impact the stability of the system, as the rock has a lot of force pulling outward on the system keeping the string tight.

The Physics are fine, the materials science and money is another matter.
Materials science is a problem due to the physics. Any musical instrument has strings that are under a great deal of tension. They obviously vibrate quite easily since that is how they make sound. Having a 50 mile long (or whatever length it actually needs to be....) thin structure with no intermediate support would behave like that string. It would vibrate at multiple frequencies unless some material science miracle occurred that created a material of nearly infinite stiffness.

DaveinOlyWA
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Re: Mars Is a Hellhole

Tue Mar 09, 2021 9:29 pm

DougWantsALeaf wrote:
Tue Mar 09, 2021 8:15 am
I thought the space elevator required long strand carbon nanotubes to be commoditized.
Strength of the tube not withstanding, the issue is the drag when "anything" is pulled thru the tube. It would literally yank that satellite out of the air. A geosynchronous orbit does not negate the fact that the ground station is moving pretty fast.

Remember the bird on the wire problem? The forces are simply way beyond anything we have available.
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LeftieBiker
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Re: Mars Is a Hellhole

Tue Mar 09, 2021 11:25 pm

Strength of the tube not withstanding, the issue is the drag when "anything" is pulled thru the tube. It would literally yank that satellite out of the air. A geosynchronous orbit does not negate the fact that the ground station is moving pretty fast.
The designs I've seen have external elevators, not internal. And I don't see a big chunk of extremely massive rock being 'literally yanked out of the air' by a relatively small load on the tether. The idea is to have enormous masses at both ends of the tether: Earth at one end, and something along the lines of a fair-sized asteroid (probably with a station built around or inside it) at the other.
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Re: Mars Is a Hellhole

Tue Mar 16, 2021 12:03 am

We're going to Mars because it IS a hell hole and reachable without a warp drive today.

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Re: Mars Is a Hellhole

Tue Mar 16, 2021 3:24 am

If 'inhospitality' were something we desired, we'd be all over the Moon by now. Mars is actually the least inhospitable planet we can currently reach to explore.
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Re: Mars Is a Hellhole

Tue Mar 16, 2021 6:45 am

LeftieBiker wrote:
Tue Mar 16, 2021 3:24 am
If 'inhospitality' were something we desired, we'd be all over the Moon by now. Mars is actually the least inhospitable planet we can currently reach to explore.
I don't claim to have the smarts and hard working ethics of Elon Musk.

Musk has built the only proven EV company on this planet. He has built the only proven reusable rocket engines on this planet. SpaceX ls the only company flying people to and from space today. When a man will spend all of his money to realize his vision of the future is believable in my world.

Read why Mars and deep space may becoming less of a hell hole.

https://www.sciencealert.com/four-bacte ... -space-pla

And perhaps has some kind of water.

https://time.com/5947142/water-on-mars/

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Re: Mars Is a Hellhole

Tue Mar 16, 2021 12:41 pm

We know that Mars has subsurface water. It's just a question of how much, where the smaller deposits are, and whether any of it is in liquid form. (That last is mainly relevant in the search for present life.)

Musk is not entirely sane, judging from his tweets and some of his actions. He may simply want to be the Founding Father for a whole planetary colony, or he may be looking at using Mars as a shipyard/home base for exploration of the outer planets. Or something less grandiose, like claiming the minerals there...
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Re: Mars Is a Hellhole

Tue Mar 16, 2021 4:05 pm

As I understand matters, Mars has apparently lost a large fraction of its estimated water from the time of formation, but still possesses very large quantities not only at the poles but at considerably lower latitudes too. MAVEN, our most recent orbiter, is expressly designed to investigate and quantify how water and other volatiles get lost to space there. I think the European orbiter is also pursuing this line of research.

I gather that most of the water presently near the surface but not at the poles is in the form of dust-covered ice.

It's clear that Mars has many resources that would facilitate construction of a scientific base, and perhaps, much much later, something bigger. I see no business case for building anything much on Mars though. There is nothing there we can't get here for a fraction of the price. This is the issue with all space-based industry as far as I can tell.

There are some chemical processing operations like electrophoresis and crystal growth that work better/differently in microgravity, so in a world where the cost of launch services has collapsed (thank you SpaceX), that might open up some new business opportunities. Scaling that up, however, is an unsolved problem. One that doesn't benefit from human presence either I might add. it will all be robotic.

I find the case for human exploration of Mars a difficult one to justify. I might add that as a member of the "Apollo generation" I have always been fascinated by space exploration and related science activities. Hugely fascinating and also worthwhile. What we have learned in the past 20 years alone about the early solar system formation, the formation and evolution of Earth and the rise of life here is mind boggling. Finding a second genesis anywhere would completely re-write our understanding of our place in the universe, at least for those of us willing to entertain those findings. No doubt there would be no shortage of skeptics.

As I noted in an earlier post, pursuing the exploration of Mars in the name of elucidating our understanding of our evolution and history is a worthwhile enterprise. But unlikely to be one that garners Apollo-like funding. No, I don't believe that you have to send astronauts to do this research. Clearly not. Every rover generation sets a new standard for what we can do remotely. Human spaceflight is oversold.
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GRA
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Re: Mars Is a Hellhole

Tue Mar 16, 2021 10:27 pm

LeftieBiker wrote:
Tue Mar 16, 2021 3:24 am
If 'inhospitality' were something we desired, we'd be all over the Moon by now. Mars is actually the least inhospitable planet we can currently reach to explore.

When it comes to in-reach inhospitability, Venus. By comparison, the moon or Mars are vacation resorts!
The surface of Venus is not where you'd like to be, with temperatures that can melt lead, an atmosphere so thick it would crush you, and clouds of sulfuric acid that smell like rotten eggs to top it off!


https://www.nasa.gov/audience/forstuden ... s_5-8.html
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

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