Sorry, all I’ve got are a couple of ICBMs. No heavy lift.
One would hope they’re going to experience some significant fraction of gees both accelerating to get there and decelerating to stop.
Personally, I don’t think we should be sending people to Mars until we have the kind of engines that ensure those acceleration/deceleration portions are most of the trip, with only a few days of turnaround at most.
Do you expect to have that capability within the next 100 years outside of sci-fi?
Nope. Why, is Mars going somewhere soon?
No, and apparently, nor are we if we follow your advice.
Why would you impose such an arbitrary and ridiculous standard?
Spin gravity is complicated and adds some engineering challenges. Continuous acceleration to Mars is a whole different level, if it is ever possible at all.
Not to speak for @MrDibble but it’s probably because there’s nothing in Mars that requires human presence in the next few decades, we can explore with robots to our heart’s content.
That said, I’m a nerd and a crewed mission to Mars, unnecessary and wasteful as it would be, would make me absurdly happy.
Well, from a purely practical standpoint, we shouldn’t send people off the surface of the Earth at all. At the very least until we have robotic systems robust and smart enough that they have prepared the way for us.
Personally, I would hold out till we have a cycler in place to send a manned mission to Mars, which would probably be quite a while off, at least decades, quite possibly 100 years or so.
But technology that allows continuous acceleration is not even on a realistic horizon. Even very efficient fusion wouldn’t be able to achieve that. You’d need antimatter or other form of total matter to energy conversion.
Not sufficiently robust. A minimum of three and preferably more. That is, prefereable in terms of avoiding capsule separation, but not in terms of other things.
The more cables there are, the complex the system. For example, to maneuver the ship, it’d likely be required to kill the rotation and then wind the two halves together. Winding up three cables is going to be a more complicated job than just winding up one. At some point adding more cables will cause too many other problems. So I expect them to settle for about three or four cables as optimal.
Impose? I didn’t know I was God-Emperor of Space Travel.
As for “arbitrary”, if desiring a safer transit is arbitrary, I’ll happily embrace that.
You think maybe you want to dial it back a bit, there?
Yep.
I mean, I’d love to go to Mars, too. But I’m not going to kill myself to do it.
If others want to, that’s up to them. But I was saying what I thought was sensible and safer.
There are practical reasons to send people into orbit. Mostly to see what happens to them, admittedly. Even the Moon is in that realm.
To Mars? Not so much. Practical, I mean.
We already have constant-acceleration engines now. Just stupidly low acceleration.
I didn’t say that you had the power to stop anyone, but you did say what your preferences are. So, yes, this would be assuming that you have your way.
There are other ways of creating a safe transit that don’t rely on technology that only exists in sci-fi.
I do think that calling for a requirement that can’t be met is ridiculous. I’m not sure what other word there is for it.
I’m not going to Mars until there’s a Starbucks there. Not saying I want the Starbucks for myself, but that’s the level of development that I’d want to see before I contemplated the trip.
That’s the entirety of the reason for manned space presence at this time, solely to study how to keep humans in space, healthy and safe.
Okay, if that’s what you meant, if you meant that they should constantly accelerate at something like .00001G, then sure. Don’t see how that helps with the physiological problems, which is what the actual focus is on.
So, in fiction, then?
Apparently it’s not the tether, according to this thread.
Is it the rotating ring, which is just as much a sci-fi-only tech.
No, what’s ridiculous is insisting on an arbitrary timeline of 100 years. What skin is it off anyone’s nose if we only set human feet on Mars in a thousand years’ time?
No, in my original post I meant something with real effect, like, say, 0.5g.
Now, I was just nitpicking. Like I’m going to nitpick that it’s g, not G.
I don’t see how you got either of those from this thread or anywhere else. Both are entirely viable technologies. Both will probably be used where appropriate.
I didn’t make any sort of arbitrary timeline, not sure what you are talking about. I was simply trying to get an idea as to your thoughts on what kind of timeframe you were talking about.
And it’ll be the skin off the teeth of the people who live and die in those thousand years who don’t have a manned Mars presence. Just because you don’t care doesn’t mean no one else does.
That’s beyond the capabilities of pretty much anything short of an antimatter drive.
What reason would you have that a rotating craft providing 0.5g is any less safe than your magitech 0.5g continuous acceleration?
Now, if you are just saying that you wouldn’t go until we had this, that’s fine. But you said we shouldn’t send anyone until we have these capabilities.
Now personally, Mars doesn’t interest me at all. The moon is useful only because it’s so close, but asteroids are where real development can and should occur, and those will certainly be using spin gravity. The only planet that’s really worth developing is Venus as a source of Nitrogen, Carbon, and Phosphorous that will be needed to create biomass on these settlements.
Caring is not the same as suffering actual harm. Which is what “skin off your nose” means.
Then you could have just asked me that, rather than throwing your own numbers out there. And I would have said “something like a thousand years, probably”. Asking it as you did does set an arbitrary timeline for reasonableness, as your subsequent mocking responses have only served to reinforce.
Sure, probably. Certainly nothing else in the works, like the various fusion projects, would do it.
And? Like I said, are we on a deadline here?
Because the rotating craft crawling at low gees is going to be in transit for much, much longer. That’s cumulative unsafety. I’m not saying the method of generating the gees is the inherently unsafe part, I’m saying the long trip is less safe than the quick one.
The being flung off into the dark by a breaking tether doesn’t sound like a picnic either, but that’s just gravy.
Sure. You can read that as “I won’t support it materially or by vote of confidence”, if you like.
I’m not saying anyone who wants to try should be stopped, or anything, which seems to be what you think I’m saying.
I do think that humanity and the Earth will suffer harm if we don’t get our asses off this planet. Not necessarily to Mars, but that’s also not the subject of this thread. The subject of this thread is over how practical spin gravity is, and how long till we should expect to see it.
I’m sorry that you misunderstood me. But yes, waiting a thousand years before we have any sort of permanent manned presence in space is both way too long, and also, probably not nearly long enough to get the kind of engines you are looking for.
You can interpret it that way if you choose to. As far as mocking, I don’t see anything I said as mocking, only trying to clarify your position. If calling a requirement that won’t be met for milenia “ridiculous” is mocking to you, then your threshold there is too low to be meaningful.
A bit, yes. If we don’t learn to use the resources in space, and instead just waste everything down here, we will die on this rock. Do you really think we can do another thousand years like we have been doing and survive as a species? I don’t.
And once again, we aren’t talking about going to Mars, we are talking about any sort of manned presence in space. Even if the technology was there to do it, would you say that a space station should be constantly accelerating to maintain comfortable gravity for the occupants?
A long trip in a robust cycler, dug into an asteroid, with plenty of legroom and radiation shielding is going to be safer than zipping through the solar system in a ship stripped down to the minimum in order to achieve that sort of acceleration.
There can be a number of redundancies to prevent that from happening, but if it does, you are flung off at a few tens of miles per hour. Certainly an inconvenience, and one that should be planned for, but not catastrophic at all. This is opposed to hoping that your engines fire back up after your turnover maneuver, if they don’t, then you are going fast enough to escape the solar system and become interstellar. Hope you packed for it.
It’s not like we have the power to go, no-go any of these ideas. However, when discussing speculatively, then it makes sense to pretend that we do, otherwise, what’s the point at all? And if you say, “we shouldn’t send people to Mars until…” then that is speaking as though you have the power to make that decision, even though everyone in this thread knows that none of us do.
If you said, “I won’t get on a ship to Mars until…” that’s a different story. Like I said, I’m not planning my trip to Mars until it has reached a level of development that they are putting in Starbucks. But I recognize that other people need to go there to get it to that point, and that other people want to go there before it gets there.
So, to the point of the thread…, do you have objections, in that you "won’t support it materially or by vote of confidence” to building a space station in the Earth-Moon system that uses spin gravity to keep the occupants healthy?
OK, I’m done with replying to you. You can’t even not mock when you’re saying how you’re not mocking.
We obviously don’t heed spin gravity to send people to Mars. We’ve put peoole in the ISS for longer than a Mars trip and they come back to Earth with minimal rehab. Mars would only be 1/3g, so the travelers should be able to get around fine.
A bigger issue is if Mars’ gravity is still too little to avoid bone density loss. In that case, a 2-year trip to Mars and back could leave peoole pretty messed up.
All the more reason to go to the Moon first. Long duration stays at 1/6 g would give us data that would allow us to learn how well humans tolerate low gravity for extended stays, without the risk and development of an orbital centrifuge. We can also use the moon to prove out technology for keeping humans alive and fed on another planet. Closed ecosystems, greenhouses, etc.
As for centrifugal gravity in space, if you were using something like two Starships connected with a cable, you’d probably want to connect them by the thrust pucks on bottom, so that the forces are absorbed vertically where the rocket is strongest. attaching them at the midpoint would require the rocket to take huge side loads, which would make it much heavier.
That means when you take off you would be sitting upside down to the interior fittings with the ‘floor’ over your head… Not a problem, but interesting.
As a born engineer, I can’t not design! 
To make the interplanetary Bola, you have four separately launched parts. Part one is a roughly cylindrical craft with the main interplanetary drive and fuel tank. Part two is a Mars lander and reascent vehicle.The other two parts are launched separately, and are a roughly matched set of crew modules. makes these as large as you can afford or justify. Each one has enough thrusters for spinning up and slowing down the Bola, and for rescue should the tether break.
At each end of the mission, when changing to a Mars transfer orbit, and at Mars deceleration, the two crew modules are rigidly attached to the drive module and landing craft combo. The rest of the months and months long mission is coasting. During this time, the two models are unreeled from the drive module using their tethers. The crew module thrusters are used to spin the assembly up to maybe 2 rpm. When getting close to Mars, the modules rotation is stopped using the thrusters, and reassembled for orbit and landing. Do it all again for the way home, without the lander, which is left in orbit, maybe to be used again, if it can be refueled.
Sure there’s a lot of things that would need to be solved. Like life support. Micrometeroid defense. Radiation shielding. But you’d need to solve those for any mission.
At least this way you can avoid bone loss, for a relatively low cost. And does anyone think that we can’t make a cable (and it’s multiple redundancies) that can last two years of spinning? The only time it would break is in cheesy sci fi movies.
The bad part is you have two crew halves that can’t interact for a year. But you do have full crew redundancy should some catastrophe happen.
You could put the crew in one half, and “stuff we’ll need when we get there” in the other half.
Yes, there would be some engineering needed for a cable strong enough to hold the weight of a crew module, and long enough for comfort, and reliable enough that human lives could depend on it for months or years on end.
Engineering would be needed… but it wouldn’t be new engineering. We already have structures here on Earth that meet all of those constraints. Why would this be any more difficult than a suspension bridge?
The separate crews will grow apart and come to despise each other. Eventually, they will realize they can’t share the same planet. One of them has anticipated this set of events, and saved all of its waste products onboard, ending up with a higher mass than the other module. They concoct a plan to spin up the bola as they approach Mars, just to the point where the heavy module will have a barely low enough velocity to make it back to the lander with its maneuvering thrusters (discarding the trash at that point), and then cut the cable. The light module, traveling faster, simply won’t have enough delta V to make it back.
What they didn’t anticipate is not only had the other module mostly faked their own waste disposal, they had already turned on themselves. Those who were simply killed were the lucky ones. The rest were eaten alive. Less than a tenth of the crew remained.
The handful of psychotics remaining discarded the corpses and excess equipment once the bola was cut. They had more than enough delta V to make it back to the lander first and lock the doors. But burning up in the Martian atmosphere instead of encountering whatever the other crew had turned into was a blessing in disguise.