Space Things

[ZDan]

Originally Posted by Irace86.2.0

The fastest train ever was a French train on wheels and not a Maglev train, so I don't know if wheels are limiting, so that could also be why he changed.

Wheels are no prob. The point is that "air bearings" operating in a vacuum *or low-pressure* tube was a dumb idea in the first place.

I don't know if creating a lower pressure environment is a terrible idea. It is the sole reason why planes fly so high. Are you saying it is laughable because keeping the tube lower pressure would be hard or prohibitively expensive or dangerous or all or what?

Yeah, maintaining a vacuum or "low pressure" over any decent distance is problematic. Very difficult, very expensive, very susceptible to seismic events, vandalism, terrorism, etc. Vacuum train idea has literally been around over 100 years, apparently "invented" by the father of modern rocketry, Robert Goddard. Yeah, greatly reducing drag is a great idea! But doing that by flying at 40,000 ft in an airplane is not really a problem. Creating and maintaining a vacuum or low-pressure environment in an elongated tube for miles and miles and miles, not so practical. Ol Muskie repeatedly talked and laughed about how *EASY* it is though. Far from it... High-speed rail is a totally doable thing. Hyperloop is not really workable.

A three year mission to mars wouldn't be a death sentence. Are you saying you know the risk of cancer is greater than say smoking tobacco? Around 1.3 billion smoke tobacco including more than 10% of the US population, and even more live around second hand smoke, so finding risk-tolerant people wouldn't be a problem. Several astronauts were smokers including Buzz Aldrin.

No reason to bring up or talk about smoking to muddy waters. Already said there are any number of people who would sign up for a Mars mission despite the risks.

People would be exposed to FAR greater solar radiation and also cosmic rays. All the time logged by astronauts in low earth orbit where they are protected by the Van Allen belts does not translate into survivability outside the V.A. belts. Even lunar missions on the scale of days are far far more risky as solar activity can injure or kill astronauts outside the belts. Obviously a mission to Mars would leave them exposed for much longer. Building a ship with sufficient shielding makes the mission impractical, unless we want to spend a significant portion of GDP on it for years/decades. With the tech we have now or may have in the next say 10-20 years, I don't see it happening.

Staying on mars would require tunnels, which is why there is The Boring Company.

I don't see any giant boring machines being sent to Mars any time soon...

NASA discusses using lava tubes in its mission plan for long term housing in the initial years to avoid larger radiation doses.

Hell of a lot more realistic than sending massive boring machines...

NASA will likely extend their limit on acceptable radiation levels like they did recently, so astronauts can go to Mars, but what really is going to happen is Optimus

Optimus? I don't think humanoid robots would be of much use, but anyway, I think Optimus is way behind what Boston Dynamics has been doing.

and other robots and autonomous vehicles will be sent to Mars to build tunnels, structures, mine materials, terraform the atmosphere and surface, and pave the way for humans to be able to survive on mars much easier.

None of that is happening in our lifetimes...

With that said, current age or age of death:

Again, the environment outside the Van Allen belts is far more hostile/deadly vs. ISS/low earth orbit.

People seem to think that going to Mars is just a step beyond going to the moon. It is one or two orders of magnitude more difficult. I don't think it's realistic with chemical rockets. Unless you decide that a 25% chance of survival is acceptable risk...

[ichitaka05]

Originally Posted by Unplugem

Ah, yes, the science-fiction fan is here to report me, just as I expected.

Look here, my friend. I am not trying to bash your beliefs; I am only trying to draw the connections for you, so that you can comprehend what you actually believe. Some people cannot connect the dots, even though the names are identical to Roman gods.

I'm not trying to dissuade you from believing in ancient Roman paganism. If you are going to tag a moderator to come and punish me, then let me ask: what exactly did I do wrong here? Didn't I stay on topic? Didn't I only show how "outer space," which is indeed the topic of this thread, is named after Roman gods? Is that not a fact? What did I do wrong here, that makes you want to report this discussion to a moderator? How have I wronged you?

How is posting images "spam?" I don't believe it's "spamming," but what do I know?

I’ve stated:

WARNING TO ALL: If you gonna debate, debate like an adult & not like my 7-yo nephew. No need to do pointless jabbing, taunting or calling pointless names. From this post on, idc if you’re old member or new member, if you break this rule, I WILL get you an early holiday leave (for 1 month).

You don’t need to call any member a pointless names. Spud even gave you a chance… I’ve gave a final warning, so no, not getting a second chance. I went through several pages of posts to see anyone else broke the warning, but I did not see it (maybe cuz it 6am & I’ve barely woke up, so didn’t see it).

Enjoy your 1 month holiday break. Hope to see you come back more calm without calling names & have an adult discussion or debate.

& this is still a warning to ALL in this thread. I’m not asking everyone to hold hands & sing kumbaya. All I’m asking for is not to yippee ki yay each other.

[Spuds]

Originally Posted by Unplugem

Ah, yes, the science-fiction fan is here to report me, just as I expected.

Look here, my friend. I am not trying to bash your beliefs; I am only trying to draw the connections for you, so that you can comprehend what you actually believe. Some people cannot connect the dots, even though the names are identical to Roman gods.

I'm not trying to dissuade you from believing in ancient Roman paganism. If you are going to tag a moderator to come and punish me, then let me ask: what exactly did I do wrong here? Didn't I stay on topic? Didn't I only show how "outer space," which is indeed the topic of this thread, is named after Roman gods? Is that not a fact? What did I do wrong here, that makes you want to report this discussion to a moderator? How have I wronged you?

How is posting images "spam?" I don't believe it's "spamming," but what do I know?

No, you are preaching and trolling. If you don't understand what that means you should really get off the internet and go experience the real world if they will still take you. Annoy the people geolocated near you before you take your crusade global, maybe they will have more patience. You know as well as I do that nobody here is going to suddenly change their mind, so why keep coming back. It's pointless except to be annoying.

Edit: Apologies to Ichi, I didn't see that you dealt with it before posting.

[Dadhawk]

Originally Posted by ichitaka05

Enjoy your 1 month holiday break. Hope to see you come back more calm without calling names & have an adult discussion or debate....

Oh man, and just as I started a different thread to try and redirect this discussion away from the space exploration thread....typical of me, always just "that to much" late!!!

[Irace86.2.0]

Originally Posted by Unplugem

If you do a test and rotate something (such as a large picture) above your head, you will see that the rotation appears to flip directions depending on if you are facing toward the center of rotation versus away from the center. So, both rotations actually do work on a flat earth if we assume the cameraman in the southern hemisphere is actually still facing toward the North Pole while the cameraman in the northern hemisphere was facing away from it.

No it doesn’t. Nice try.

But I love that you said southern hemisphere and north pole.

[Irace86.2.0]

Originally Posted by ZDan

Wheels are no prob. The point is that "air bearings" operating in a vacuum *or low-pressure* tube was a dumb idea in the first place.

Which part? The part where air is suppose to be used in an "airless" environment? This is where a perfect vacuum and a low pressure environment is an important distinction. I believe the idea was to replicate the lower pressure environment of flying at altitude, but we all know there is plenty of wind resistance at high speeds, even at high altitudes where there is lower pressure. As you know being an aerospace engineer, wind resistance goes up by the square of the velocity, so I could imagine a situation where the pod was on wheels until it reached lift when enough ram air pressure built up on the nose that it could be diverted to the air bearings. The design of the pod wasn't like that of a typical MagLev train where the nose is tapered. It was blunt and filled the tube, essentially becoming the mouth/inlet of something like a jet engine that feeds air to make air bearings.

Originally Posted by ZDan

Yeah, maintaining a vacuum or "low pressure" over any decent distance is problematic. Very difficult, very expensive, very susceptible to seismic events, vandalism, terrorism, etc. Vacuum train idea has literally been around over 100 years, apparently "invented" by the father of modern rocketry, Robert Goddard. Yeah, greatly reducing drag is a great idea! But doing that by flying at 40,000 ft in an airplane is not really a problem. Creating and maintaining a vacuum or low-pressure environment in an elongated tube for miles and miles and miles, not so practical. Ol Muskie repeatedly talked and laughed about how *EASY* it is though. Far from it... High-speed rail is a totally doable thing. Hyperloop is not really workable.

I think the safest solution would be underground tunnels/tubes. This would essentially solve the seismic events, vandalism, terrorism issues, etc. It would also allow it to be straight, without needing to snake through the countryside, so it could be fast, and it would mean it wouldn't be subject to local taxes, lawsuits and environmental/wildlife claims. It would decrease the hurdles and complexities and time of trying to build/suspend a train in the air through cities, and it would decrease the sound and disturbances associated with a high-speed train.

According to this RAND article from 1972, a half bar of pressure is more than achievable:

https://www.rand.org/content/dam/ran...2008/P4874.pdf

Originally Posted by ZDan

No reason to bring up or talk about smoking to muddy waters. Already said there are any number of people who would sign up for a Mars mission despite the risks.

People would be exposed to FAR greater solar radiation and also cosmic rays. All the time logged by astronauts in low earth orbit where they are protected by the Van Allen belts does not translate into survivability outside the V.A. belts. Even lunar missions on the scale of days are far far more risky as solar activity can injure or kill astronauts outside the belts. Obviously a mission to Mars would leave them exposed for much longer. Building a ship with sufficient shielding makes the mission impractical, unless we want to spend a significant portion of GDP on it for years/decades. With the tech we have now or may have in the next say 10-20 years, I don't see it happening.

As I understand it, the Van Allen belts don't protect astronauts. They are a consequence of earth's magnetic field, but not a shield from it. They are concentrated regions of radiation that are themselves a barrier to space flight, as astronauts must fly through these high radiation zones, but as I understand it, they do so quickly, so their exposure of radiation through the Van Allen belts on a three year mission to mars will be a small percentage of the total radiation they receive. The ISS is inside the Van Allen Belts, but to the point I think you were trying to make, they are inside the protection of the earth's magnetic field, which diverts radiation to the poles. Well, mars would be about 2.5 times higher than the ISS(Source), but again, do you know or does anyone know that such a difference is deadly or increases the rate of cancer or side effects to levels that justify concerns, beyond concerns of the unknown? You say it is "far, far, more risky" without really backing this up with what the risk is. You say we would have no problem finding risk prone people to go, so I shouldn't ask to compare the radiation risk to smoking and the cancer risk from that, but then you say we are 10-15 years away from tech that would allow us to go to mars when you just agreed that we would have no problem finding people who are willing to accept the risks. You seem to be contradicting yourself.

Do you know the risks, or do you just know the radiation dose is higher and just assume a high risk? Do you think people will accept this risk and go, or are you saying that no government in the world will allow people to take this risk?

Originally Posted by ZDan

I don't see any giant boring machines being sent to Mars any time soon...

[On lava tubes] Hell of a lot more realistic than sending massive boring machines...

Why does it have to be anytime soon? PrufRock was assembled here, and it could be assembled there in a dozen or so payloads from Starship. SpaceX launched around a hundred rockets this year of Falcon 9 and Falcon Heavy, so at SpaceX and globally, things will ramp up from there. It took 300 years to build Notre Damn, so nothing needs to happen soon. We will need an energy source before PrufRock goes anyways. I feel like we haven't even gone for a day, and you are jumping the gun and saying how we can't resort there or something.

Originally Posted by ZDan

Optimus? I don't think humanoid robots would be of much use, but anyway, I think Optimus is way behind what Boston Dynamics has been doing.

None of that is happening in our lifetimes...

I don't know how old you are, but I'm 42, and I could die tomorrow or live to 102 like by great grandmother, but if I live to 102 like her or into my 90's like the rest of my family, in 60 years, we will have a lot going on the moon and mars if we maintain this pace. You say nothing like what I mentioned will happen? We already have the mars rover, an autonomous vehicle on mars, so it won't be long until we have more autonomous vehicles and robots on mars laying the groundwork. We won't have the planet terraformed at all, but we will have robots and autonomous vehicles on mars, and we will producing energy and creating materials/products, and I would be shocked if we didn't have a rotating colony of humans living in some type of shielded structures, be it above or underground.

Originally Posted by ZDan

Again, the environment outside the Van Allen belts is far more hostile/deadly vs. ISS/low earth orbit.

People seem to think that going to Mars is just a step beyond going to the moon. It is one or two orders of magnitude more difficult. I don't think it's realistic with chemical rockets. Unless you decide that a 25% chance of survival is acceptable risk...

The moon is not protected from the sun, and it is barely covered by the wake of the earth's magnetic field when the earth is between the sun and moon, so conditions on the moon's surface, especially the dark side of the moon is worse than on mars, that at least has a thin atmosphere. Radiation dose is higher because the trip is longer, but a three year stay on the lunar surface would likely be worse than on mars. Again, don't just say we would get a higher dose of radiation; what do you know would be the results or the increased risk of cancer specifically mortality and morbidity?

Now you are saying you don't think it is possible to go to mars with chemical rockets, but we have put landers and rovers on mars over a dozen times going back to the 70's, so this statement confused me, along with your 25% survivability risk. The success rate in the last twenty years has been high, so I don't really understand your risk assessment from a technologic assessment, even if health risks were thrown in there in an arbitrary number.

[Irace86.2.0]

[Irace86.2.0]

Lockheed Martin Selected To Develop Nuclear-Powered Spacecraft

https://news.lockheedmartin.com/2023...red-Spacecraft

[ZDan]

Originally Posted by Irace86.2.0

Which part? The part where air is suppose to be used in an "airless" environment? This is where a perfect vacuum and a low pressure environment is an important distinction.

Imagine operating an air-hockey table in a "low-pressure" environment. It's not going to work as well as the mass of the puck hasn't changed, but the available air to lift it has been reduced. Anyway, suffice it to say that after his people studied the idea for a bit, they canned it and reverted to wheels.

I think the safest solution would be underground tunnels/tubes. This would essentially solve the seismic events

Um, no it wouldn't! Earthquakes are not a surface-only thing, far from it.

Also, hundreds of miles of underground vacuum tunnels would be a massive undertaking. Anyway, judging from just how far different enterprises have run with this "original" idea (from 1906), and how much test tunnel has been made operational, I'm thinking that the impracticality of the idea has been made apparent to those trying to develop it.

but to the point I think you were trying to make, they are inside the protection of the earth's magnetic field, which diverts radiation to the poles. Well, mars would be about 2.5 times higher than the ISS(Source),

Yes, the point is that beyond the Van Allen belts, outside the magnetosphere, astronauts are in a MUCH harsher radiation environment, and it was well known during Apollo that if there happened to be unforeseen solar activity it could cost the crew their lives. And that's just over a few days.

but again, do you know or does anyone know that such a difference is deadly or increases the rate of cancer or side effects to levels that justify concerns, beyond concerns of the unknown? You say it is "far, far, more risky" without really backing this up with what the risk is.

Taking your 2.5x factor and stretching it over an 18-month mission to mars and back, I mean, yeah, that's obviously far far more risky. The health effects just from LEO for relatively short amounts of time are significant already.

You say we would have no problem finding risk prone people to go, so I shouldn't ask to compare the radiation risk to smoking and the cancer risk from that, but then you say we are 10-15 years away from tech that would allow us to go to mars when you just agreed that we would have no problem finding people who are willing to accept the risks. You seem to be contradicting yourself.

Just because people are willing to take the risk doesn't make it ethical to send them on the journey.

Why does it have to be anytime soon?

Believe me, it won't be any time soon...

Now you are saying you don't think it is possible to go to mars with chemical rockets, but we have put landers and rovers on mars over a dozen times going back to the 70's, so this statement confused me, along with your 25% survivability risk.

Landers and rovers can be designed against susceptibility to radiation exposure. Humans can't. Sending humans to mars will require significant shielding, and the added mass in addition to all the mass for life-support, food, water, everything just multiplies and it becomes a MUCH bigger project than you might think, vs. sending even SUV-size rovers and helicopters.

[Ultramaroon]

I think few people really appreciate how many things had to happen "just so" for life to evolve the way it has here.

Mars is a total pipe dream. Learned folks who promote this fantasy are disingenuous at best, more like fraudsters.

[Irace86.2.0]

Originally Posted by ZDan

Imagine operating an air-hockey table in a "low-pressure" environment. It's not going to work as well as the mass of the puck hasn't changed, but the available air to lift it has been reduced. Anyway, suffice it to say that after his people studied the idea for a bit, they canned it and reverted to wheels.

I don't know if you are confused or I am, but just so we are clear, the Hyperloop isn't a giant air hockey surface with air coming up from the walls of the tube. It is a reverse air hockey table with air coming from the puck pushing down on the surface like how an air bearing does. The air levitating the pod comes from the pod, not the surface, and it comes from the environment inside the pod, so it wouldn't be filling the Hyperloop tube with air; i.e., there isn't a net change in air molecules in the system.

There would be plenty of air molecules because, as I said before, the air resistance goes up with the square of the velocity. The propulsion comes from magnets. The pod moves on wheels until it hits enough velocity that the ram air creates enough pressure to drive the pod away from the walls, as air that is channeled from the nose is compressed and is pressurized through the feet of the pod to the smooth surface of the tube. Say we have a train going 400mph, and we take it up to 1600mph; speed increased by a factor of four, but air resistance increased by a factor of sixteen, which means if you drop the air pressure to 0.5 bar, you still have the air resistance going up by a factor of eight. You definitely won't be short of air to generate lift pressure in a low pressure environment because the speed will be so high.

Originally Posted by ZDan

Um, no it wouldn't! Earthquakes are not a surface-only thing, far from it.

Also, hundreds of miles of underground vacuum tunnels would be a massive undertaking. Anyway, judging from just how far different enterprises have run with this "original" idea (from 1906), and how much test tunnel has been made operational, I'm thinking that the impracticality of the idea has been made apparent to those trying to develop it.

The saying goes, would you rather be in a submarine or in a boat during a tsunami? An underground train in a tunnel surrounded by solid rock, especially one that is pinned to the sides of the tube, is much sturdier than a train moving on the surface on tracks or that's elevated. The risk isn't zero, but we have been building underground subway systems, tunnels for mining, service tunnels, etc for long enough, and they do better than the surface.

As the RAND article mentions, this would be a massive task, but the economics would pay out over a ground/elevated train, and the benefits over commercial air travel would be clear. Why hasn't it been done? Same reason we don't have any high speed trains: money. Local, state and federal governments are lobbied against public transportation, so we have a terrible public transportation system in this country. Part of that is the bureaucracy of trying to run trains through cities where every municipal along the path wants to either tax the project or wants to save an endangered turtle. You presume it to be a feasibility problem, but that is really only loose conjecture. Meanwhile in China: Image.

Originally Posted by ZDan

Yes, the point is that beyond the Van Allen belts, outside the magnetosphere, astronauts are in a MUCH harsher radiation environment, and it was well known during Apollo that if there happened to be unforeseen solar activity it could cost the crew their lives. And that's just over a few days.

Taking your 2.5x factor and stretching it over an 18-month mission to mars and back, I mean, yeah, that's obviously far far more risky. The health effects just from LEO for relatively short amounts of time are significant already.

Just because people are willing to take the risk doesn't make it ethical to send them on the journey.

Believe me, it won't be any time soon...

Landers and rovers can be designed against susceptibility to radiation exposure. Humans can't. Sending humans to mars will require significant shielding, and the added mass in addition to all the mass for life-support, food, water, everything just multiplies and it becomes a MUCH bigger project than you might think, vs. sending even SUV-size rovers and helicopters.

It would be nice if there was more hard data on the actual risks, but it is just speculative because no one has gone, and we are inferring based on what we do know about radiation dosing. We know that cumulative, higher doses of radiation can damage tissues, and NASA sets the standard for REID at 3% and are planning to raise it
(Source), and this study suggests that the REID for the planned mars mission of 940 days to be 2-8% depending on the gender and race (Source). This means this trip would be a one and done trip for astronauts for their career in space, but it would be a risk most would take. The risk assessment for REIC and REID can't predict the future of cancer detection and treatments, and neither measure seems to be predicting whether a 35 year old who is exposed will die at 45 of cancer or at 90.

Lockheed Martin developed an AstroRad vest that has been tested in space and is suppose to help block vital organs from radiation (Source). I don't know how effective it is compared to lead vests, but I think it is meant to be more comfortable than lugging a lead vest; even in a weightless environment, a led vest would be cumbersome. (Side fact: We don't use them for patients anymore in the hospital). Lockheed Martin is also contracted to develop a nuclear propulsion rocket, which could cut the time to mars from seven months to forty-five days. We will see.

Unless people die in space on the mission to the moon, I think we will have people on the moon in less than five years, and we will have people on Mars in less than ten years.

[Irace86.2.0]

Originally Posted by Ultramaroon

I think few people really appreciate how many things had to happen "just so" for life to evolve the way it has here.

Mars is a total pipe dream. Learned folks who promote this fantasy are disingenuous at best, more like fraudsters.

Going to mars, colonizing mars or terraforming mars?

There are lots of theories on terraforming mars, including creating a magnetic field with studies showing mars may one day enable its own magnetic field, but really, this is all fun talk and science fiction until we first go and then return with materials to build.

We can go camping on mars and do experiments. I don't think you would doubt that.

We could bring small/micro nuclear reactors, vehicles, equipment for infrastructure, etc, so we can have an outpost and small colony. Over time, it would grow into something bigger, but Total Recall style. Pending some crazy technology like controlling gravity, I don't think we will be able to terraform mars into something earth-like that can sustain an atmosphere and significant amount of life, but I leave the possibility open.

[NoHaveMSG]

Originally Posted by Unplugem

Ah, yes, the science-fiction fan is here to report me, just as I expected.

Look here, my friend. I am not trying to bash your beliefs; I am only trying to draw the connections for you, so that you can comprehend what you actually believe. Some people cannot connect the dots, even though the names are identical to Roman gods.

I'm not trying to dissuade you from believing in ancient Roman paganism. If you are going to tag a moderator to come and punish me, then let me ask: what exactly did I do wrong here? Didn't I stay on topic? Didn't I only show how "outer space," which is indeed the topic of this thread, is named after Roman gods? Is that not a fact? What did I do wrong here, that makes you want to report this discussion to a moderator? How have I wronged you?

How is posting images "spam?" I don't believe it's "spamming," but what do I know?

The point was start your own fucking thread and let people discuss what they want to discuss in this one. You are pretty easy to ignore until you spam a bunch of large posts that make it hard to follow any other discussion.

[Irace86.2.0]

This is a nice explanation for why NASA also chose a longer route for Artemis 1.