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I am sure that Elon would disagree.

I know who I think is right.

https://youtu.be/cn0g0CaqofQ?si=XcQ32bq5M0cUcvSA

That was great!

Feynman is always interesting, but there are so many Youtube channels posting convincing AI resurrections of Feynman explaining stuff that it's almost impossible to know what he really thought however much like Feynman's true beliefs they may seem to be! Ditto for several other science luminaries.

I know who I think is right.

First point, wrt the impossibility of operating machines on Mars. The Perseverance rover has been operating for over 5 years. Curiosity has been operating for 13 years, far beyond it's intended life.

Second point, wrt the impossibility of being outside of earth's atmosphere for a long period. The current record spaceflight duration is 437 days. The Boeing Starliner's crew was stuck on the space station for 286 days, waiting for a more reliable Dragon craft to pick them up. Back during the cold war, we were taught food in metal cans was safe to eat, because the can itself would shield the food from alpha and beta particles, while gamma radiation would go through the can and out the other side.

I stopped watching his routine at that point.

Steve

I am sorry that I posted that link now. I thought the video was AI or maybe even the audio based of a text of Feynman's, but I can not find a link to anything like it. I should have looked at the information in the YouTube description.

What we do: Present physics concepts inspired by Feynman’s teachings using AI-assisted narration and educational storytelling.
❌ What we don’t do: Claim to be Feynman’s real voice, impersonate him, or present non-scientific theories as his work.

The problem is that as far as I can tell they are not using his actual thoughts or words, but presenting them as if they are. In the words of the Mac Mac Feegle "We wil'na be fooled again."

First point, wrt the impossibility of operating machines on Mars. The Perseverance rover has been operating for over 5 years. Curiosity has been operating for 13 years, far beyond it's intended life.

I thought this too. There's a wind in the light atmosphere on Mars. The sands in Saudi aren't good for making concrete as they're too round and smooth. River and beach sand, etc., are good for concrete because they aren't too round. They've been doing experiments with explosives and Saudi sand for concrete, I presume they're trying to fracture it.

Since our Mars machines are encased in metal, they should be covered with dust - they aren't, so the magnetic part of the dust he talks about hasn't appeared

It's late.

The space station is within our magnetic field.

There have been published studies that indicate renal failure for astronauts on a journey to Mars. So that part was correct. Astronauts would not survive a round trip.

I believe Spirit got a jammed wheel, and spent the rest of its mission dragging that wheel. I think a bearing seized, but am not sure.

We would do better focusing on the one planet we know can support our life rather than hope for something that may not be viable for a very long time, if ever.

We would do better focusing on the one planet we know can support our life rather than hope for something that may not be viable for a very long time, if ever.

So said a lot of people in the 1960’s with respect to the Apollo Moon Landings. Fortunately, we didn’t listen.

For an entertaining and informative read on the subject of life in space, let me recommend A City on Mars: Can We Settle Space, Should We Settle Space, and Have We Really Thought This Through? by Kelly and Zach Weinersmith. I found it very illuminating.

The TL;DR version is that the answer to all three questions is probably "no," at least at anything close to the level of technology we'll have in the next several decades. You can see a summary of their analyses on the wiki page:

https://en.wikipedia.org/wiki/A_City_on_Mars

The super-digested version is that it's highly unlikely that humans could survive for very long outside our magnetosphere, given exposure to radiation level (the longest time is only 12 days). It's also highly unlikely that humans could complete our reproductive cycle (conceiving, gestating, giving birth, early childhood development, and growth into adulthood) in zero- or low-gravity environments - making long-term settlement of places like the Moon or Mars nigh-impossible with current technology.

After all, Mars ain't the kind of place to raise your kids. In fact, it's cold as hell.

The space and explorations threads describe the differences between right and left in such an eloquent and profound way it’s almost sad.

https://www.sciencedirect.com/science/article/abs/...

The super-digested version is that it's highly unlikely that humans could survive for very long outside our magnetosphere, given exposure to radiation level (the longest time is only 12 days).

On re-reading my post, I need to clarify this sentence.

The longest time that a human has spent outside the magnetosphere is 12 days. That is not the longest amount of time a human could survive outside the magnetosphere - which on re-reading, might be what someone might take from my post.

The real problem is radiation. We've got good data on long-term exposure to low/zero gravity - people have spent a lot of time in earth orbit, and we have a fair amount of information on what it does to our biology. But because humans have never spent much time outside the magnetosphere, we don't know for sure how long a person could survive - we don't have a lot of data. Because once you get outside the magnetosphere, you're no longer protected from radiation - both from the sun and from cosmic rays. The latter are particularly difficult to deal with, because they're such high-energy particles that you can't really shield against them (as your shield gets thicker and blocks more particles, you actually end up increasing the secondary radiation exposure from the energies released when the shields interact with the cosmic rays).

One study gives a max time in space at around four years - which would make a round-trip to Mars theoretically possible (you'd still up your lifetime risk of cancer somewhat with the 18 months in space, though).

https://www.science.org/content/article/humans-ret...
https://newsroom.ucla.edu/releases/safe-for-humans...

The space and explorations threads describe the differences between right and left in such an eloquent and profound way it’s almost sad.

I'm not sure I understand that statement - or your link. The biological limits on deep-space exploration come from cosmic rays, not X-rays. Completely different types of radiation. And what does this have to do with left vs. right?

So said a lot of people in the 1960’s with respect to the Apollo Moon Landings. Fortunately, we didn’t listen.

That was a) exploration, and b) part of the Cold War oneupsmanship. Scientifically, there was little reason to put people on the moon. They were (in 1969) more versatile, of course. The modern rovers we've sent to Mars are generally superior at this point, being able to do anything a human could do (in scientific activities).

Adding humans to the Mars equation is an unnecessary, even detrimental, complication, that requires a LOT more resources to sustain and protect them. And then, their kidneys will start failing by the time they get there. They won't survive the journey back. Without radiation-proof shelter, they wouldn't last that much longer on Mars. I linked a few articles about that last year, though probably on the Science board (since it seemed less like "US Policy").

I'm all for exploring the planets. I'm against the notion that we should just give up on the Earth, and try to colonize someplace else. Earth is the one place that WILL support us, if we take moderate care of it. No place else will, that we know of.

And what does this have to do with left vs. right?

Nothing, of course. But, you know the old saying, "to someone with a hammer, everything looks like a political question."

Pete

I'm not sure I understand that statement - or your link. The biological limits on deep-space exploration come from cosmic rays, not X-rays. Completely different types of radiation. And what does this have to do with left vs. right?

Taking your questions in reverse order:

1. Plenty

2. Aerogels are cool. And very versatile. Ask yourself what problem radiation shielding represents to a space vehicle. One must balance protection effectiveness with weight (because every gram matters when launching things).

3. And finally, we can definitely tell who’s a problem solver vs. somebody who points them out, then jumps up and down.

“Hey - Bob?”
What’s up, Jim?
“You know, up in space the astronauts’ tools and gear are going to floating around in zero G. How are they going to handle jobs with multiple tools if they’ll just float away?”

Lemme think…what if we made a re-usable adhesive?

“Might outgas in space or lose effectiveness. Static electricity won’t work either.”

What if we made a ‘zipper’ of sorts, except instead of metal we hook a bunch of stiff fibers together? This Swiss dude was trying to replicate seeds sticking to his pants and has a cool idea.

And thus…Velcro was popularized.

The space and explorations threads describe the differences between right and left in such an eloquent and profound way it’s almost sad.

I absolutely agree with Dope1’s statement above.

The right believes in fantasies and the left believes in scientific facts.

That was a) exploration, and b) part of the Cold War oneupsmanship. Scientifically, there was little reason to put people on the moon.

lol. Other than understanding our nearest celestial neighbor?

I'm all for exploring the planets. I'm against the notion that we should just give up on the Earth, and try to colonize someplace else.

You’re aware that at some point in the future the sun will eventually consume the Earth and that at multiple points in the last asteroids have had significant influence on the development of life here, yes?

1. Plenty

What, exactly?

2. Aerogels are cool. And very versatile. Ask yourself what problem radiation shielding represents to a space vehicle. One must balance protection effectiveness with weight (because every gram matters when launching things).

I have no doubt that they are cool and versatile. But cosmic rays have different physics than other types of radiation.

The problem that radiation shielding for cosmic rays presents to a spaceship is that they can't be blocked with shielding. They are so high-energy that they blast through everything - and when they do interact with something, that interaction creates a secondary radiation emission that is also very dangerous. Ironically, if you provide more shielding it becomes more dangerous for the occupants inside, because the damage from the secondary radiation increases faster than the reduced exposure from the cosmic rays. We can't shield against cosmic rays with any currently-existing technology, nor are there any real prospects for developing a material that can do so over the next few decades.

3. And finally, we can definitely tell who’s a problem solver vs. somebody who points them out, then jumps up and down.

Solving problems isn't always just a matter of optimism vs. pessimism. Some problems simply can't be solved with then-existing technology. You couldn't have launched a space mission in 1880, no matter how much you might have wanted to. You couldn't develop self-driving cars in 1968, no matter what. The general level of human knowledge wasn't far enough along.

We're almost certainly at a similar position when it comes to long-term settlements outside the magnetosphere. We do not have any technology that can possibly provide both: i) earth-level gravity; and ii) protection against cosmic rays. You can get gravity by spinning in a spaceship, but we don't know how to protect a spaceship from cosmic rays. You can get protection from cosmic rays by being deep underground, but we don't know how to generate gravity under those conditions. These are not "we don't know how" like we didn't know how to develop velcro before we did it - these are "we don't know how" in the sense that nothing we know about the physics of the material world suggests a possible solution at current levels of knowledge about the universe.

You’re aware that at some point in the future the sun will eventually consume the Earth ……

Absolutely true. In about 5 billion years. I wonder what my portfolio will be in 5 billion years?

Of course, the Milky Way (where we live, not the candy bar) will be merging with the Andromeda galaxy in about 5 billion years, too.

Personally, I’m a lot more concerned about Earth surviving Trump’s presidency.

By the way I whole heartedly support space exploration. AI might be a huge help. As a kid in the 60’s, my best friend and I were space junkies. Our parents let us skip school to watch space shots. We wrote to NASA weekly and they sent us a boatload of great stuff. I still have a large box of the collection. Ms. Wolf is constantly asking me to get rid of it. No way! Very cool stuff.

By the way I wholeheartedly support space exploration.

As do I. I think it's fanciful that we might have permanent human colonies outside the earth's magnetosphere any time within the next fifty years, but space exploration in general is certainly a worthwhile pursuit. I expect it will mostly consist of unmanned exploration, other than perhaps a lunar facility similar to Antarctica (ie. someplace that's manned all the time with short-term workers but with no permanent inhabitants who continuously live there).

We can't shield against cosmic rays with any currently-existing technology, nor are there any real prospects for developing a material that can do so over the next few decades.


And there it is. “We can’t”.

You want to know the difference between those who want to see us head out to the stars and those who want to stay put?

Those 2 words. Says it all.

You’re aware that at some point in the future the sun will eventually consume the Earth

The Sun is expected to engulf the Earth in approximately 5 to 7.6 billion years. Near as I can figure it, that only gives us 200 million to 300 million generations to come up with a plan and the technology

It’s not like we’re wasting time.

But that’s not the biggest nor the most immediate threat to human life on earth.

Sometimes I get the idea that the most avid voices for colonizing Mars are simply trying to evade addressing the problems here at home.

But as the old song goes:

Wherever you go, there you are

lol. Other than understanding our nearest celestial neighbor?

Exploration. Yes, a good thing.

You’re aware that at some point in the future the sun will eventually consume the Earth and that at multiple points in the last asteroids have had significant influence on the development of life here, yes?

Yep. I'm also aware that sometime after that, the universe itself will die (either Big Crunch or Cold Death). The time scales of both are enormous. Also, when the Sun dies, Mars goes, too. Won't matter if we managed to tech our way into a colony on Mars at that point.

Asteroids are a problem. We should be devoting more resources to finding, tracking, and defending against them. Wouldn't you agree?

Asteroids are a problem. We should be devoting more resources to finding, tracking, and defending against them. Wouldn't you agree?

Certainly. Wouldn’t it be nice to have space ships robust enough to head out and intercept them rather than having to do it from Earth?

Those 2 words. Says it all.

Because you're only looking at two words. The full sentence was:

We can't shield against cosmic rays with any currently-existing technology, nor are there any real prospects for developing a material that can do so over the next few decades.

If you misread what other people are saying, then you won't be able to have a productive discussion with anyone.

You know the difference between those who want to see us head out to the stars and those who will be doomed to stay put? People who can accurately assess what the current level of technology is, figure out what changes have to occur to current levels of technology in order to make deep space travel, and thus actually develop a plausible roadmap for getting there. The people who blind themselves to the existing state of technology will never be able to accomplish anything, because they won't be able to accurately identify what has to happen for the goal to be fulfilled.

We do not currently know how to shield astronauts from cosmic radiation. We will need to figure that out before we can have a Mars colony. Pretending that's not true because you think it's inconsistent with a "can-do" spirit would be foolhardy.

BTW,
On your moon point:

https://www.esa.int/Enabling_Support/Preparing_for...

Helium-3 is a VERY interesting material to mine and use.

We can't shield against cosmic rays with any currently-existing technology, nor are there any real prospects for developing a material that can do so over the next few decades.


And there it is. “We can’t”.

Except you cut off the most important part of his response:

with any current technology

That leaves the future open to the development of the necessary technology.

Might take 50 years.
Might take 100 years.
Might take 1000 years

Or it might only take 10 years.

Regardless, we’ve got roughly the same amount of time left to develop that technology as has elapsed since a celestial gas cloud coalesced into the orb known as earth.


(Unless we continue to ignore the threats to life here and now, of course)

If you misread what other people are saying, then you won't be able to have a productive discussion with anyone.

Who is misunderstanding who? You’re the one making definitive statements about what technology exists or does not exist. Or can not exist.

No offense, but you’re in no position to judge. Or make sweeping generalized conclusions of that nature especially in regards to current or future research.

I posted the aerogel paper to see if anyone would try to engage in a thought experiment. That would require someone to question what an aerogel is, what it’s used for and think about why having something with the density of air, near zero thermal conductivity and oh-by-the-way-can-be-custom-configured-to-block-different-types-of-radiation would have an incredible potential for space travel.

And then juxtapose that with the Mars space travel problem to see if there might be ways to leverage what we already know about aerogels to make them better.

Alas.

Pretending that's not true because you think it's inconsistent with a "can-do" spirit would be foolhardy.

Who did that? Nobody. In fact, which one of us gave a narrative about how NASA worked out a very cool solution to a challenging problem back in the 1960s? I could have chosen Tang or a dozen other examples.

Again, there were voices in the 1960s who said Apollo was a waste of money. Ironically if they’re still around those same people probably use the tech developed for the space program every day and don’t realize it.

Also, when the Sun dies, Mars goes, too

Well….. there’s that.

But they might be able to tack on an hour or two to the aforementioned 5-7 1/2 billion years before they get swallowed as well.

Think of it as a cast party after the last performance

“We can’t” is a state of mind. One that’s sadly prevalent in this board.

Too bad. I’d suggest all of you Google up the little kid talking to the CNN reporter about the Artemis mission.

Then ask yourselves why you aren’t excited.

You guys might learn something about yourselves. Or not.

I posted the aerogel paper to see if anyone would try to engage in a thought experiment. That would require someone to question what an aerogel is, what it’s used for and think about why having something with the density of air, near zero thermal conductivity and oh-by-the-way-can-be-custom-configured-to-block-different-types-of-radiation would have an incredible potential for space travel.

Which is very different than actually providing an explanation of how aerogel could actually be used to block cosmic rays.

Cosmic rays aren't electromagnetic radiation. They are instead extremely high-energy particles that travel through space at very nearly the speed of light. Completely different physics.

There's no implied "thought experiment" here - it's like posting an article about some new antibiotic and asking people to think about how it might be used to treat a virus or radiation poisoning. The fact that some technology exists to solve problem X does not mean that it has any applicability to solving problem Y - and posting an article on something irrelevant to the problem being discussed isn't "seeing if anyone would try to engage in a thought experiment," it's just profoundly misunderstanding the vast difference between X-rays (and other types of electromagnetic radiation) and cosmic rays.

Who did that?

You did, when you truncated my sentence to just "we can't" from "we can't shield against cosmic rays with any currently-existing technology." If you think there's current technology that can provide spaceships with shielding against cosmic radiation, then just explain how. Otherwise, you're just engaging in wishing away the actual impediment to space exploration.

We can’t” is a state of mind. One that’s sadly prevalent in this board.

But nobody is saying that.

Any more than you saying a year ago that solar technology without more efficient battery storage could not be a significant base load source of power…… was an absolute statement of “We can’t”.

Which is very different than actually providing an explanation of how aerogel could actually be used to block cosmic rays.

Simple. Dope it with something else. Like polyethylene, hydrogen or titanium carbide.

Some references for you
https://www.sciencedirect.com/science/article/pii/...

https://ntrs.nasa.gov/citations/20130012682

https://newatlas.com/materials/aerogel-lightest-el....

…along with many others.

And this is…existing research. I’d suggest you modify your tone on these subjects.

Otherwise, you're just engaging in wishing away the actual impediment to space exploration.

lol. Hey, if you say so.
Thank you for proving my point that curiosity and problem solving are endemic in folks who just don’t care for the space program. It explains a lot.

But nobody is saying that.

Sure about that? Al is as rude as he ever gets when it comes to technical subjects. And I’m taking it easy on him.

Any more than you saying a year ago that solar technology without more efficient battery storage could not be a significant base load source of power…… was an absolute statement of “We can’t”.


Hmm. What all have I said about energy? I’ve said that energy is the ballgame. I’ve saved more mW adding up to MW than most human beings in the planet. You jokers who use a PC or a Mac - my fingerprints are in both - are welcome.

Battery tech today isn’t great. But what I’ve also said is that silicon anode technology and solid state batteries (which are in development today) will help fix that.

What I also said was that government mandating this crap was bad idea when the tech wasn’t ready.

Which is a completely different thing than this topic.

Gold star to you for trying, brown star for the results.

And this is…existing research. I’d suggest you modify your tone on these subjects.

So, more articles about how this stuff is useful for blocking electromagnetic radiation - which cosmic rays aren't.

I'm not sure why you're cranky about my tone. I made a simple statement that we do not have existing technology to provide shielding against cosmic rays - and you decided to misinterpret that into being some broad "we can't" statement about space exploration generally. Which is just foolhardy. Shielding against cosmic rays and finding a way to replicate the protective effects of the magnetosphere is one of the big known deficiencies in space exploration technology.

That doesn't mean that we'll never be able to solve it! Just that we're not especially close to solving it. Because cosmic rays aren't electromagnetic radiation. They're a different category of problem, and so the solutions to shielding against electromagnetic radiation you keep linking to (like aerogels) aren't able to be "doped" into doing it.

We very well may one day be able to provide such shielding. For some reason, you keep wanting to convert a point about an existing technological obstacle to long-term spaceflight (which might one day be solved but hasn't been solved yet!) into either a moral or philosophical failing. I'd suggest you modify your tone on these subjects. Or provide a link to existing technology that can actually shield against cosmic rays, rather than other hazards of space, like electromagnetic radiation or solar wind (which is also comprised of particles rather than radiation but travels as much lower velocities than cosmic rays).

we can definitely tell who’s a problem solver vs. somebody who points them out, then jumps up and down.

You are definitely NOT a problem solver. Your responses document that fact.

I worked at a company that designed and built high-end surface analytical instrumentation. Lots of Ph.D. physicists working there. So, I would look at what THEY have/use--not what someone claims on an Internet chat board. The machines they build use ultra-high vacuum chambers with pumps (worked in that dept) AND radioactive energy sources-in each machine--to generate the laser beam(s) shooting inside the vacuum chamber. I also worked with the people designing and building the machines. They VERY MUCH were interested in the full range of radiation to which they--AND whatever they were doing--was exposed AND was highly relevant.

If there existed even a *hint* of an EFFECTIVE radiation shield(s) being available (even theoretically), they would be "all over it" in an instant to design/build it because it would *directly* impact them personally AND professionally. They would be able to figure out if it was practical, or if the current technology was "not yet there" to do more. BUT, they would be aware of WHAT THEY WERE SEEKING in order to make radiation shields realistic.

Management would be "all over it" and allocating resources to develop radiation shields because they would mostly eliminate the risk of radioactive contamination if a radioactive spill or exposure would happen--at the company, at a customer site (that had bought a machine for in-house use), or anywhere else radiation needed to be contained.

LOTS of profit to be made by offering such a product and/or service (radioactive spill/waste containment and disposal). How about a company manufacturing nuclear warheads? Would the US (and other) govt(s)--plus any other related industry--be interested ??

And there it is. “We can’t”.

You want to know the difference between those who want to see us head out to the stars and those who want to stay put?

Those 2 words. Says it all.

He said we "can't...with any currently-existing technology". That is absolutely correct. He did not speculate on future technologies.

I worked on an atmospheric Cerenkov detector for my grad work. We measured -among other characteristics- energies. We cannot at this time shield against particles of those energies. And organic tissue would not fare well with bombardments of those energies (TeV).

Well...we can shield if we start digging. Hard to take a cave into space, though. Albaby mentioned a moonbase. It would have to be sub-lunar. Not sure how many meters, but I would guess at least 10 meters. Otherwise the inhabitants would get their DNA shredded. The few realistic designs I have seen for such an installation usually had the water tanks above the habitation to increase shielding.

Then ask yourselves why you aren’t excited.

You guys might learn something about yourselves. Or not.

Because I was in the space game for a time. Plus, I remember the Apollo missions. They aren't novel for me. I remember the last few missions, including the famous Apollo 13. At the time it was very exciting. Today, it's "I've seen this before". It's good that little kids are getting excited. They haven't seen this before, so I get their excitement. I remember it from when I was that age.

If exploration is the stated goal, then robotics is vastly cheaper than constructing human habitations (and packing them with food, water, air, plus recyclers and scrubbers, and all the other fun stuff people would need to survive). You get a lot more science-bang for your buck sending a rover to Mars (or an atmospheric penetrator to Jupiter) than trying to mount a manned mission.

Cosmic rays aren't electromagnetic radiation. They are instead extremely high-energy particles that travel through space at very nearly the speed of light. Completely different physics.

OK...I don't want to get into the weeds here, but that isn't entirely correct. At our project we had to parse Cerenkov airshowers into photonic and hadronic. Both are "cosmic rays" (though we don't generally call them that...we call them alphas, or gammas, or whatever they are). Our specific goal was weeding out the hadronic showers and analyzing the photonic (gamma ray) showers.

Gamma rays can be excruciatingly energetic, and will rearrange your DNA (and other biology) pretty effectively. Our energy regime was about 500 MeV to about 4 TeV. There are detectors that go even higher.

(Hadronic showers are the result of hadrons striking the upper atmosphere, hadrons being anything comprised of quarks, which include protons, neutrons, alpha particles -ionized helium-, and the like.)

I would not want to be struck by any "cosmic rays", photonic or hadronic. Over time it will kill you.

You can get protection from cosmic rays by being deep underground, but we don't know how to generate gravity under those conditions. These are not "we don't know how" like we didn't know how to develop velcro before we did it - these are "we don't know how" in the sense that nothing we know about the physics of the material world suggests a possible solution at current levels of knowledge about the universe.

Passive (dead mass weight) is not the only method that can block cosmic rays. They can be deflected with magnetic fields in the same manner that the Earth does it. We just need a large source of power. Advances in fusion that will hopefully occur over the next decade or two could provide the needed power generation, and until then, the risk can be mitigated by shorter trips and stays as long as there are humans willing to put themselves at risk. At least, this is my optimistic - perhaps rose-colored glasses level - outlook.

There are many methods of blocking space radiation. They include active and passive methods of radiation shielding. Active methods of space radiation shielding employ electric and magnetic fields to deflect the charged particles away from the crew volume before interacting with the spacecraft material. The result is very similar to the protection we enjoy due to Earth’s magnetic bubble.

Theoretically, active shielding is the best possible solution since it reduces the likelihood of secondary particle generation. However, the application of active shielding in space-like conditions is challenging from an engineering point of view: the amount of electric and magnetic fields required to deflect highly energetic charged particles is in the range of hundreds of megavolts.

Although some advanced research is ongoing to reduce the requirements for such fields to be effective, active shielding is not yet a reality, leaving us with passive shielding for now.

See https://stemrad.com/blocking-space-radiation-in-de...

There's also talk of "radiation vests" - AstroRad - there that use special materials. See https://stemrad.com/astrorad-4/

The shielding itself in the AstroRad is comprised of a polymer with a high abundance of hydrogen which is advantageous for shielding against space radiation because it minimizes the generation of secondary radiation. Individual solid shielding elements are organized into a scale-like architecture to allow for uninhibited, comfortable movement of the astronauts while wearing the AstroRad. StemRad is currently exploring the use of recycled plastics materials generated onboard future spacecraft for use in the shielding elements which would dramatically decrease the payload mass associated with the equipment.

Yep. I'm also aware that sometime after that, the universe itself will die (either Big Crunch or Cold Death). The time scales of both are enormous. Also, when the Sun dies, Mars goes, too. Won't matter if we managed to tech our way into a colony on Mars at that point.

That's why the true ideal place for humans to colonize is one of the "water" moons of Jupiter or Saturn. They're far enough out to escape the death of the Sun. Still have to deal with the low gravity problem however!

“We can’t” is a state of mind. One that’s sadly prevalent in this board.

This is insignificant blather. I was an avid scifi fan in my youth. Isaac Azimov, etc. I appreciated when a writer actually explained science in his story. Scifi is great, but to enjoy it, you "suspend your disbelief", in fact the mark of a bad scifi movie is when you're bored enough to find fault with the science, like a tree cast out into the void burning for a long time.

But at some point you learn the harsh science lessons and come to terms with the reality, the speed of light is formidable, and there may be no worm holes. Andromeda Galaxy is going to ram our galaxy. There may be no alternate universes passing through our space unnoticed. The sun will expand and engulf earth if Andromeda doesn't get us. The universe could rip apart as it expands or we could just expand into cold space as all the suns burn out. And we are fragile - space travel can fry us. It sinks in that the human race may end some day with little chance of a revival. I had trouble with that.

Samuel Butler in The Way of All Flesh says 'all animals, except man, realize that the principal basis of life is to live it'. Headed down to Key West this month. Anyone been to Kruger Park in Africa?

I'd suggest you modify your tone on these subjects.

Erm, okay. I think we're done in this thread.

That's why the true ideal place for humans to colonize is one of the "water" moons of Jupiter or Saturn. They're far enough out to escape the death of the Sun. Still have to deal with the low gravity problem however!

If we have descendants that survive, they probably won't be human anymore. And we'll still have the problem of no energy source in the solar system. Assuming Europa or Enceladus actually has liquid water (theorized, not assured), the life cycle is solar powered. No sun, no life. I can't rule out some as-yet unknown technology, but that does seem to be a basic limitation. Maybe we'll evolve into Vorlons, and not have to worry about such mundane things. :-)

Well...we can shield if we start digging. Hard to take a cave into space, though. Albaby mentioned a moonbase. It would have to be sub-lunar. Not sure how many meters, but I would guess at least 10 meters. Otherwise the inhabitants would get their DNA shredded. The few realistic designs I have seen for such an installation usually had the water tanks above the habitation to increase shielding.

That's right - which is why it's devilishly hard to solve for a long-term habitation on Mars with existing tech. We have a very difficult choice. We can shield from cosmic radiation and high energy particles by going underground - but we don't yet have a way to create artificial gravity underground. We can create artificial gravity in orbit around Mars (using rotating spacecraft) - but we don't yet have a way to protect against cosmic radiation and high energy particles in space.

Those two things together create a very difficult obstacle to having space children. Because you might need both (radiation protection and gravity) to raise humans to physical maturity. While adults can protect against the health problems of low gravity, you can't put a baby on a treadmill. (Well, you can - but it won't have the effect you're looking for).

Our species evolved in gravity, and all our physical development and growth processes operate using gravity. Babies in particular experience much of their muscular development by acting against gravity - lifting their head, lifting their limbs and bodies, etc. It's entirely possible that this won't be a problem, but there's far more reason to be concerned about it than with biological functions like swallowing (which you can do standing on your head) that were initially concerning to scientists.

Erm, okay. I think we're done in this thread.

I literally just copied what you said to me. Did you mean it as something so egregious that it would cause the conversation to stop?

Assuming Europa or Enceladus actually has liquid water (theorized, not assured), the life cycle is solar powered. No sun, no life. I can't rule out some as-yet unknown technology, but that does seem to be a basic limitation.

If Europa has liquid water, it's probably due to tidal heating rather than solar energy. Jupiter's gravitational pull pushes a ton of energy into the planet through those tidal influences, both directly into the liquid water (if it exists) and through vulcanism in the core. That can theoretically last far longer than the billion years the earth has left in the habitable zone. Plus, Jupiter itself emits a ton of radiation, which would be lethal to any life like ours on the surface but could provide energy for subsurface life.

https://en.wikipedia.org/wiki/Tidal_heating

Assuming Europa or Enceladus actually has liquid water (theorized, not assured), the life cycle is solar powered. No sun, no life.

Not true. The energy needed for life there would/could be powered by tidal heating by Jupiter or Saturn and chemically sustained. In theory. The tidal forces would remain even if the Sun vanished.

That can theoretically last far longer than the billion years the earth has left in the habitable zone.

OMG! Time’s a-wasting!

But seriously….. a billion years ago, green algae was the going life form, just beginning to branch out int what would become the plant kingdom. Still hundreds of millions of years in the future lay the age of dinosaurs.

Who/what will our evolutionary descendants be in a billion years?

At the rate we’re going, it could be cockroaches….. or even green algae.

Shielding against cosmic rays might not even register on their list of things to be concerned about, assuming they can form a thought.

Mars could be a one way trip for the following reasons:

1. If they couldn't even get the on board toilet facilities right, who knows what else is wrong with NASA's quality control.

2. This mission is a DEI mission. Guess NASA didn't get the message or DEI was already too baked into the NASA cake to change anything for this mission. NASA is glorifying that this will be a series of "minority firsts"--first black man to the moon, first woman to the moon, first Canadian to the moon. That's a pretty effed up set of priorities for a mission like this to have. It might explain why they couldn't even get the sanitary facilities to work correctly. They're more concerned about bending the knee to DEI than to competence. At some point someone's going to pay the price for that kind of thinking. Hopefully not on the current mission. But on a 2 year Mars mission? Fuggehdaboutid. No one's coming back alive if they try that. Not with the current worldview solidly in place.

The energy needed for life there would/could be powered by tidal heating by Jupiter or Saturn and chemically sustained...The tidal forces would remain even if the Sun vanished.

Sure. That's the theory. However, the basis of life on this planet is photosynthesis. Without that, this would be a dead world. That requires illumination (sun light, preferably). We are talking about an era when we don't have this lovely fusion reactor emitting broad-spectrum light at the center of our solar system.

Plus, we haven't discussed what happens during the death of the sun. Sorry about getting into the weeds here. Occupational hazard. :-)

The sun will expand into a red giant. It is believed it will be large enough to actually engulf the Earth, and possibly Mars. Jupiter will become super-heated because of the proximity of the new solar surface to the planet. It's atmosphere is primarily hydrogen. It won't burn (no oxygen), but we can expect Jupiter to transform significantly. Meanwhile, the icy moons of Jupiter will almost certainly shed their icy layers. No telling how much sublimation of those moons' water will occur.

Then the sun is expected to blow off it's outer layers (a nova, but NOT a supernova). That will be a solar wind on steroids...lots of radiation, blowing off of at least some of the atmospheres of the outer planets. This will not be a benign thing, and seeking refuge of one of the icy moons probably won't save us.

If we don't have some sci-fi tech like warp drive, our species will be doomed. Again, I can't predict future technology. We may very well have a way to move a lot of people vast distances in a relatively short time. We would have to find a suitable planet (class M, if you're into Star Trek). And then hope that its biology is somewhat compatible with ours, and preferably we wouldn't be displacing some native sentient species (though that isn't a technical problem, just an ethical one).

If we don't have some sci-fi tech like warp drive, our species will be doomed. Again, I can't predict future technology. We may very well have a way to move a lot of people vast distances in a relatively short time. We would have to find a suitable planet (class M, if you're into Star Trek). And then hope that its biology is somewhat compatible with ours, and preferably we wouldn't be displacing some native sentient species (though that isn't a technical problem, just an ethical one).

Yep.
And we might as well get started with things now.

However, the basis of life on this planet is photosynthesis. Without that, this would be a dead world.

Maybe. One theory is that life predated photosynthesis, and that the very earliest life forms derived their energy chemically from deep sea hydrothermal vents rather than from sunlight:

https://en.wikipedia.org/wiki/Abiogenesis#Deep_sea...

Plus, we haven't discussed what happens during the death of the sun. Sorry about getting into the weeds here. Occupational hazard. :-)

The sun will expand into a red giant. It is believed it will be large enough to actually engulf the Earth, and possibly Mars. Jupiter will become super-heated because of the proximity of the new solar surface to the planet. It's atmosphere is primarily hydrogen. It won't burn (no oxygen), but we can expect Jupiter to transform significantly. Meanwhile, the icy moons of Jupiter will almost certainly shed their icy layers. No telling how much sublimation of those moons' water will occur.

Sure - but not for a very long time after the earth is uninhabitable.

AIUI, the habitable zone pushes out past the earth's orbit sometime in the next 1-2 billion years. That's when the sun's gradual increase in output burns off all surface water. Meanwhile, the sun won't evolve into a red giant until about 5-7 billion years. Prior to then, the habitable zone stays well short of Jupiter's orbit, and Europa will still be frozen. That's a massive amount of time when the Earth will be uninhabitable but Europa will still be more or less unchanged, with whatever water resources still protected from sublimation by the icy surface.

The red giant phase probably does mean the end of any Jovian habitable areas - but that's much further out than the end of the Earth.

Sure. That's the theory. However, the basis of life on this planet is photosynthesis. Without that, this would be a dead world. That requires illumination (sun light, preferably). We are talking about an era when we don't have this lovely fusion reactor emitting broad-spectrum light at the center of our solar system.

Humans don't use sunlight directly. We just eat plants and animals that eat plants. And plants use sunlight.

But, even on Earth now, there are creatures that live near "black smokers" at the bottom of the sea where sunlight doesn't reach. These creatures might not taste great, and I'm not even sure they wouldn't be poisonous to us, but even if they aren't, I'm sure we could engineer similar creatures that were edible in the not too distant future.

See https://www.encyclopedie-environnement.org/en/zoom...

Black smokers’ ecosystems

- Pierre Vauclare, Institute of Structural Biology, Grenoble, France

Covering nearly two thirds of the Earth’s surface, the abyssal regions of the oceans have long been considered as spaces totally devoid of life due to the absence of light. However, the discovery in 1977 of the existence of hydrothermal vents, called black smokers, located on the Galápagos Ridge, totally modified our knowledge of ocean biology, but also our vision of the origin of life. This fascinating ecosystem is located along the mid-ocean ridges (Atlantic, Pacific and Indian Oceans), between 700 metres and more than 4000 metres deep, in areas with high volcanic activity. These sites then produce fluids with very high temperatures up to 410°C. It is in contact with cold oceanic water (< 4°C), that dissolved metals precipitate with sulphides to form the complex mineral structures known as black smokers. However, despite particularly hostile environmental conditions (lack of light, high temperatures and extreme pressures that can exceed 420 kg/cm2), these hydrothermal springs shelter, in their vicinity, an exceptional marine ecosystem among the most productive. This discovery has generated numerous exploration campaigns that have led to the discovery of new species known as extremophiles with high endemism rates. Indeed, clam colonies measuring nearly 30 centimetres (Calyptogena magnifica and Bathymodiolus thermophilus) coexist with white crabs, shrimps (Rimicaris exoculata) and giant worms up to 2 metres long (Riftia pachyptila). Like any ecosystem, those of the hydrothermal springs of the abyss exchange matter and energy. At the base of the food chain of this complex ecosystem are very diverse thermophilic microbial communities (bacteria and archaea) with sulfo-oxidizing properties. Indeed, thanks to the energy not of light (photosynthesis [1]), but of the oxidation of hydrogen sulphides (H2S) which are rejected by hydrothermal fluids (chemosynthesis [2]), these microorganisms synthesize carbonaceous molecules. These are the primary source of organic matter essential for the development of the many animal communities living in this extreme environment, which is not conducive to life.

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