Fallacy of excluded choices: Moon or Mars - but what are the other choices?

[PB666]

The discussions of where to place the next station/colony has revolved around two choices Moon and Mars. Lately mars has been the choice of private foundations or corporations. Its largely a public relations move to date. Selecting astronauts for a mission to mars that will not launch for at least a decade. The Mars mission in the video (c.1990) was not to launch untill 1999, of course never launched. In not trying to discount the value of a lunar facility, or someday a martian research facility, but one thing that researchers and explorers do not want to do is lock themselves into concretized thinking, particularly when it comes to choosing future research opportunities.

1. From a scientific point of view I like Lagrangian L2

-L2 is in a small gravity well that is half in earths SOI, it is a few more dV than reaching the moon

-There is no need for rescue vehicles of the like needed for mars and moon

-We have seen the great scientific benefit of observations from these orbits, but what we really need are much larger space telescopes.

-Imagine not having to fly to Ceres or have 10-20 year missions to explore the outer solar system, just point your telescope

-We could have an array of space telescopes searching for asteroids and short period comets that can be exploited.

-It is still partially in earths magnetic shield.

-there is nothing there to exploit but it is theorized that passing NEO sometimes get trapped in the Lagrangians, so it may be possible to capture these smaller objects and collectively exploit them with out need large sums of dV.

-Problems - No gravity, radiation. Insolance is diminished

-Best Infrared observations in proximity to earth excepting the outer solar system.

- Very useful visible and UV observatory.

2. Trojan asteroids and NEO asteroids.

-Right, intersecting NEO from earth is a challenge, the logic is that if an asteroid is closes to earths elliptical, it eventually gets sucked into earth or thrown into the outer solar system.

-But with some of the new highly efficient technology coming we could actually steer and asteroid into a more favorable orbit (say between earth and mars, or earth and venus) or even park the asteroid in L2 or L1 (a dangerous proposition).

-A parked asteroid in L1 or L2 would be the best of all worlds. Close to earth energetically, close to earth in terms of distance (though still to far for a true emergency)

-A parked asteroid could shield crewmen from dangerous radiation from the sun.

-A mined asteroid could shield crewmen from all directions.

-Can also be used for observatory but the rotational velocity needs to be killed, better placed in tidally locked rotation with sun.

-Problems. Initials fuel costs, lack of gravity, initial exposures to radiation.

3. The smaller satellites (Deimos or Phobos) or planetoids of the asteroid belt.

-We already seen that Ceres is showing signs that it may have volatiles under its sooty skin, this may be the best places to search for targets that produce lots of hydrogen.

- There should be other asteroids that have similar compositions with high percentages of volatiles suitable for conversion to water and hydrogen.

-As opposed to NEO asteroids, larger belt asteroids tend to have reasonable rotations.

-Problems here include frequent impactors, but these could be intercepted.

-It is suggest that the surface of these planets is soft, which may make it easy to dig down.

[Kibble]

I think the real fallacy is thinking we have to make a choice at all - the one-legged stool. A proper BLEO infrastructure will have many aspects and probably involve most of the inner Solar System - Venus, Mars, Moon, the Minor Planets, and maybe the Asteroids (generally why they aren't discussed is because they are actually quite far away, and usually inclined relative to the Ecliptic).

Here's a link to a blog post by the legendary Hop David about it: http://hopsblog-hop.blogspot.com/2013/09/one-legged-stools.html

[tater]

The reasons for manned space flight have little to do with science. Human physiological issues in microgravity environments don't really count, as they are valuable only for the sake of putting men in that environment in the first place, not for gaining broader, basic science data about the universe at large. For that robots win.

In KSP we might rationalize a geologist astronaut picking better rocks, but in the real world, with the same budget (in both treasure and dv), you'd have a robot sample return that would simply grab more rocks (all Apollo grabbed, plus the mass of squishy stuff and the life support required to sustain them).

i think manned missions are important for the sheer adventure of it. Exploring is valuable for civilization at large psychologically, I think.

Edited March 9, 2015 by tater

[kStrout]

VENUS. Lets face it, we are on the KSP forums, we know a lot more about how space works than most people. We know that it makes a lot of sense to stay near earth for now, but the public will not be satisfied unless the next step is interplanetary. The solution, Venus.

wonderfully explains why Venus is so much better than Mars. If the space program was totally unaffected by the public, we should build a moon base, then use the rock mined from that base to build a space colony in LEO. Edited March 9, 2015 by kStrout

[Newt]

In KSP we might rationalize a geologist astronaut picking better rocks, but in the real world, with the same budget (in both treasure and dv), you'd have a robot sample return that would simply grab more rocks (all Apollo grabbed, plus the mass of squishy stuff and the life support required to sustain them).

In the Real World, we also would have a team of geologists sitting at control station on Earth picking out the best looking rocks, for less than the manned missions cost.

Kibble. I agree. The idea of Mars as the 'Next Logical Step' for manned spaceflight irks me, just as much as any other one track sort of missions. Why go to Mars? There are dozens of reasons. Why go to the Moon, or Venus, or Jupiter? The same. We should send orbiters to the next two large planets, perhaps look into building an orbital space colony/orbital power stations. And build Space Telescopes, and look more seriously into SSTO's, and go build a base on the Moon, and, and....

This has sort of been what we are doing, in unmanned flight. If we could expand it to manned, it would be ideal, but probably costly or very long term. But this overemphasis on Mars seems, silly.

[tater]

^^^ True enough, it's not like the landing sites are picked at random, and with the moon, they can pick and choose via remote control.

[SargeRho]

For now, there aren't really any other destinations. Sure, Titan might be nice, but it's also -157°C, and Europa only has a tenuous atmosphere of oxygen hardly worth the name. They are also all years away.

[Scotius]

They are also all years away.

And there is the main obstacle in the way of manned exploration. And getting something really big going. We need engines able to take human crew to Mars (or somewhere else) fast enough for astronauts to not catch too much radiation, and their bones decalcify, and their muscles turn into jelly.

[crubs]

And there is the main obstacle in the way of manned exploration. And getting something really big going. We need engines able to take human crew to Mars (or somewhere else) fast enough for astronauts to not catch too much radiation, and their bones decalcify, and their muscles turn into jelly.

Centrifuges bro. At that point the problem is complexity and the amount of money the government is willing to fork over.

[Voyager55]

Money is really the only issue standing in the way of exploration. Technologically we could have gone to Mars in the 80's.

And is anyone else skeptical about the SLS? It's extremely expensive, when comparing it to their annual budget, it seems they will only be able to launch one per year.

"Centrifuges bro", I second that.

[PB666]

The reasons for manned space flight have little to do with science. Human physiological issues in microgravity environments don't really count, as they are valuable only for the sake of putting men in that environment in the first place, not for gaining broader, basic science data about the universe at large. For that robots win.

In KSP we might rationalize a geologist astronaut picking better rocks, but in the real world, with the same budget (in both treasure and dv), you'd have a robot sample return that would simply grab more rocks (all Apollo grabbed, plus the mass of squishy stuff and the life support required to sustain them).

i think manned missions are important for the sheer adventure of it. Exploring is valuable for civilization at large psychologically, I think.

Playing the devil's advocate here. Humans were a hell of alot more time efficient on the moon than the Mars rovers, the samples they have brought back from the moon are unmatched for any mission to any celestial in the solar system. The amount of science done from the Moon rocks is nothing less than incredible.

The mars rover can do meters per day, it requires all this back and forth communication with earth. For human, tell them to go pick up 20 lbs of rock that human can scour the area of several football fields. And there is compromise, because if he is mounted with a camera, and computers or people back on earth see something of interest, they can ask for a refetch. Seriously, if we did not care about the lives of the astronaut at all, you would simply put 1 astronaut down where you placed curiousity. Give him enough food and water for 20 days in an isolation suit have him pick up rocks and carry them back to an a launch site which obtains minimally stable LMO and then dock with a vessel to get it back to earth, in earth orbit dock with ISS and put the rocks back on the next mission down to earth. You'de have scientist analyzing those rocks for the next 40 years. Don't underestimate the value of humans, they are many fold better at dealing with complex 'black swan' circumstances than computers. Just imagine if you had an astronaut right now walking up to the Beagle . . . . . . You would hear some Brits saying "Hail mary, mother . . . . .

What you need for a geologist on mars is a mobile facility (with much more robust wheels) that can be assisted along behind him as he forages for "science".

The problem with humans in the post Vietnam era is that you cannot treat them as fodder. Second that rock collector is probably going to be a trained geologist, so he has value beyond just collecting rocks, and third if you have a resource on mars that can cover 10 km per day, that is a very valuable thing to keep going. All of that should mean we have a manned mission to Mars - but the critical problem is keeping that one trained geologist alive its all about MASS and Landings and return vehicles.

If mars is too hard, phobos is not, we could have a manned moon to Phobos that brings back a bunch of rocks. If we can get enough Station on Phobos then the emergency problem for Mars is much improved, since an emergency on Mars does not have to wait 9 months for a return window to earth.

[Mazon Del]

Really, my thought about the Mars mission is that in a way it is a pretty great method of giving us a tool to go elsewhere. If you have a rocket capable of launching a ship over to Mars, down the gravity well, stick around for a couple months, then rocket itself back up (even if it had to do some ISRU) and then back all the way to Earth. You can use that same rocket (with between 0-100% redesign of the human capsule/ship part, I'd say around 30% if they wanted to do it cheaply) in order to get to other destinations, such as asteroids or whatever. And imagine if we decided to use that rocket to lob cargo at the moon!

In short, just because the launcher/capsule are designed to go to Mars, doesn't mean you cant reappropriate the system to go somewhere else.

[Nibb31]

In short, just because the launcher/capsule are designed to go to Mars, doesn't mean you cant reappropriate the system to go somewhere else.

That depends. It's a bit of a waste to design an aircraft carrier and use it go shopping.

Spacecraft are expensive, so an underutilized one is just as bad as an underperforming one. You design them for a set of requirements. If those requirements don't match the actual use, then you have pretty much wasted resources. The opposite example is Orion, which was originally designed for lunar missions (21 days of life support, dV and reentry speed calculated for lunar orbit). Since Constellation was canned, they are now trying to shoehorn it into a Mars architecture, where it really doesn't have much purpose, other than as a lifeboat. Consequently, it will ultimately cost more than if they had designed a spacecraft from the start for Mars missions.

[Mazon Del]

In the case of an actually underutilized system, certainly. I am assuming that what would be done is instead of taking the mega rocket to lob X number of people and Y tons of cargo at Mars and instead point it at the moon to launch X+? number of people and Y+? tons. You still fully utilize its capacity as far as a launcher is concerned. Now as far as the capsule goes, that certainly can be an issue. But if they are sneaky they could poke at their requirements to make it easier for this sort of thing.

[PB666]

In the case of an actually underutilized system, certainly. I am assuming that what would be done is instead of taking the mega rocket to lob X number of people and Y tons of cargo at Mars and instead point it at the moon to launch X+? number of people and Y+? tons. You still fully utilize its capacity as far as a launcher is concerned. Now as far as the capsule goes, that certainly can be an issue. But if they are sneaky they could poke at their requirements to make it easier for this sort of thing.

When you are thinking of creating a base you are thinking of how long you can use T+? of the same number of people, actually 'on the base doing stuff' instead of 'inflight waiting to do stuff'.

The moon is 3 days away, mars is minially 6 months so you save alot of time and time = f(N, (food,water,disposables,etc))

Presumably if you get folks on the surface of the moon, the could dig down or cover up to block radiation, the could add weights in order to fight off the effects of low gravity on thier muscles and thier heart. So with these two disposed of you have mission length/individual is going to be a function of food, water and waste (which is really not a problem on the surface of the moon, yet).

[Mazon Del]

For the most part I imagine the vast majority of the 'extra' mass budget that NASA would gain from using a Mars rocket to fly to the moon would be utilized to send cargo to aid in construction/experimentation. Presumably they would math out how much of that should be devoted to extra food (if any, given what the crew module was already going to store for a Mars trip).

[GreenWolf]

Deimos.

Deimos is actually closer to Earth (in terms of delta-v) than the surface of the Moon. And there's a pretty good chance that there's significant quantities of water ice there. And if you have ice, you have remass. And if you have enough remass, you can go anywhere.

(The incredibly informative site, Atomic Rockets, has tons more info about a potential Deimos base here: http://www.projectrho.com/public_html/rocket/appcapedread.php)

On the subject of using large rockets for everything, I would argue that you really shouldn't be using large rockets at all. It's easier to build your big ship/station in orbit instead of launching it in one go. It's why Lunar Orbit Rendezvous was chosen over Direct Ascent for Apollo. Doing Earth Orbital Rendezvous instead of LOR would have allowed them to use an even smaller rocket, but would have required more launches per mission.

[tater]

Playing the devil's advocate here. Humans were a hell of alot more time efficient on the moon than the Mars rovers, the samples they have brought back from the moon are unmatched for any mission to any celestial in the solar system. The amount of science done from the Moon rocks is nothing less than incredible.

No doubt, but I said the same amount of treasure spent. That basically means delivering the same throw weight to the surface of whichever body as the reference manned mission would be. The moon rocks collected were largely so valuable because of the choice of sites to land, and the sheer mass of rocks (hundreds of kgs). The question is how many kg of moon rocks could had been returned for the cost of the entire Apollo program? I imagine a comparable amount, though to be fair in the 60s men might actually have been easier than good robots.

The mars rover can do meters per day, it requires all this back and forth communication with earth. For human, tell them to go pick up 20 lbs of rock that human can scour the area of several football fields. And there is compromise, because if he is mounted with a camera, and computers or people back on earth see something of interest, they can ask for a refetch. Seriously, if we did not care about the lives of the astronaut at all, you would simply put 1 astronaut down where you placed curiousity. Give him enough food and water for 20 days in an isolation suit have him pick up rocks and carry them back to an a launch site which obtains minimally stable LMO and then dock with a vessel to get it back to earth, in earth orbit dock with ISS and put the rocks back on the next mission down to earth. You'de have scientist analyzing those rocks for the next 40 years. Don't underestimate the value of humans, they are many fold better at dealing with complex 'black swan' circumstances than computers. Just imagine if you had an astronaut right now walking up to the Beagle . . . . . . You would hear some Brits saying "Hail mary, mother . . . . .

What you need for a geologist on mars is a mobile facility (with much more robust wheels) that can be assisted along behind him as he forages for "science".

I was taught some of my lunar geology by on the only geologist to actually do that (though only on the moon). I get the idea. Still, instead of a small rover we'd be effectively talking about a manned MAV type vehicle, and the rovers could collect hundreds of kgs of samples. Robotic equipment has certainly improved over the years. Also, for sample return the rovers don't need to "do science" while they are there. They don't all need drills, maybe none do. They pick up rocks, and drop them in a hopper that vacuum seals them in a bag with the sample location serial number on it, and move on. Send a few per MAV, and they need not be quite as careful, have one drive carefully, another a little faster, and one can be sort of reckless

The problem with humans in the post Vietnam era is that you cannot treat them as fodder. Second that rock collector is probably going to be a trained geologist, so he has value beyond just collecting rocks, and third if you have a resource on mars that can cover 10 km per day, that is a very valuable thing to keep going. All of that should mean we have a manned mission to Mars - but the critical problem is keeping that one trained geologist alive its all about MASS and Landings and return vehicles.

If mars is too hard, phobos is not, we could have a manned moon to Phobos that brings back a bunch of rocks. If we can get enough Station on Phobos then the emergency problem for Mars is much improved, since an emergency on Mars does not have to wait 9 months for a return window to earth.

If you can design a rover for men that can drive far afield, you can design a robot that can do the same mechanically---the terrain avoidance bit is clearly the limiting factor for mars. For the moon the 5 second round trip lag is not so bad. Or you could take your topic title and allow that missions need not be either only robot, or only manned.

Fly the PEOPLE to orbit, then land ROBOTS to collect samples. Robots controlled from low orbit with near zero delay. Best of both worlds. You need not land, then ascend with heavy life support, so more useful cargo to and from. The risks associated with landing, etc become zero.

[Kibble]

It's easier to build your big ship/station in orbit instead of launching it in one go. It's why Lunar Orbit Rendezvous was chosen over Direct Ascent for Apollo. Doing Earth Orbital Rendezvous instead of LOR would have allowed them to use an even smaller rocket, but would have required more launches per mission.

There are more costs to orbital assembly than just having to pay for more rocket launches. It means you can't use high-energy fuel, because boil-off. So your stuck with lower-efficiency storable fuels. It means more failure modes, especially because of so much rendezvous and docking, and if the launch of just one of the modules fails the entire mission has to be aborted, and the modules already on-orbit are wasted effort doing nothing. Also in most cases you're going to have to use fairly big (Proton-class) rockets anyway, or even bigger if you don't want your stack to be a stupidly long chain of 20mt rocket stages.

Either way the program would end up with a similar cost and complexity to the assembly of Space Station.

[Bill Phil]

Deimos.

Deimos is actually closer to Earth (in terms of delta-v) than the surface of the Moon. And there's a pretty good chance that there's significant quantities of water ice there. And if you have ice, you have remass. And if you have enough remass, you can go anywhere.

(The incredibly informative site, Atomic Rockets, has tons more info about a potential Deimos base here: http://www.projectrho.com/public_html/rocket/appcapedread.php)

On the subject of using large rockets for everything, I would argue that you really shouldn't be using large rockets at all. It's easier to build your big ship/station in orbit instead of launching it in one go. It's why Lunar Orbit Rendezvous was chosen over Direct Ascent for Apollo. Doing Earth Orbital Rendezvous instead of LOR would have allowed them to use an even smaller rocket, but would have required more launches per mission.

They want to balance the total number of launches. When you have too many, there's a lot of risk. When you have fewer, there's less risk.

- - - Updated - - -

Either way the program would end up with a similar cost and complexity to the assembly of Space Station.

They could have then constructed it to go to the Moon on more than one occasion, amortizing the construction costs... As cost per flight would be lowered.

Plus, if they could've modularized it, then the failure of one module wouldn't mean failure to all. So, it might have resulted in a better overall program with more intensive exploration.

Anyways, it's better to have a big ship than a bunch of small ones. If it can be reused after each flight.

EDIT:

Come to think of it, Apollo Program cost in today's money would be about 109 billion USD. Comparable to the 150 billion USD of the ISS. They're already similar. And using a multi-flight deep space vehicle to amortize the cost per flight would be ideal.

Assuming 9 flights to the Moon, Apollo works out at about 12 billion USD per mission, in today's money. If we assume that the built on orbit spacecraft took 10 years to make, and can only be in space for a total of 30 years, as well as it taking, oh, a whole year to refurbish the vessel and do a mission, costing about as much as the ISS, we get about 7.5 billion USD per mission (flight, in this case). That's a bit generous, so it would most likely be much more.

Edited March 11, 2015 by Bill Phil

[GreenWolf]

There are more costs to orbital assembly than just having to pay for more rocket launches. It means you can't use high-energy fuel, because boil-off. So your stuck with lower-efficiency storable fuels.

Boil-off isn't nearly as bad once you get into space, since vacuum is a really great insulator. And if you're going to Mars, you probably want to use methane as your fuel (to take advantage of ISRU), reducing boil-off even further.

It means more failure modes, especially because of so much rendezvous and docking, and if the launch of just one of the modules fails the entire mission has to be aborted, and the modules already on-orbit are wasted effort doing nothing.

Multiple launches also spreads the risk around. If one of the launches fails, you can delay the mission until the next launch window without having to relaunch everything. If a single rocket mission fails at launch, there goes your entire mission.

Also in most cases you're going to have to use fairly big (Proton-class) rockets anyway, or even bigger if you don't want your stack to be a stupidly long chain of 20mt rocket stages.

Rockets don't scale linearly with payload. A rocket that can lift 75 metric tons is far less than half the size of one that can lift 150 metric tons.

Either way the program would end up with a similar cost and complexity to the assembly of Space Station.

A large amount of the cost of the ISS is due to politics, and the use of the space shuttle (which had so many problems, I could dedicate twenty pages to describing how stupid it was as a launch vehicle). MIR is probably a better estimate of the costs of building an orbital station or large interplanetary ship.

[Reddragon]

And is anyone else skeptical about the SLS? It's extremely expensive, when comparing it to their annual budget, it seems they will only be able to launch one per year.

Quite many people but so far that's what NASA only has for deep space exploration (manned). It is also close to be finished so only appointed missions are missing for it.

[cpast]

Multiple launches also spreads the risk around. If one of the launches fails, you can delay the mission until the next launch window without having to relaunch everything. If a single rocket mission fails at launch, there goes your entire mission.

That doesn't work if the multiple parts are mission-critical; it only helps if you can last through the time it takes to prepare a replacement for launch (which, unless you have a pipeline, will be a fairly long time). If the multiple parts are mission-critical, and one fails, you lose everything. That's one of the major reasons EOR wasn't chosen for Apollo: by the time a failed manned launch was rerun, the previous unmanned launch would have fallen from orbit (and so failure of rocket 2 would lead to total writeoff of the mission; that, in turn, is why the people would be launched last). If you make sure the station can miss a launch without issues you're fine; however, your pieces must all be fairly capable, because the loss of one piece cannot result in mission failure. And it turns out that fairly capable pieces aren't small.

[Kibble]

Boil-off isn't nearly as bad once you get into space, since vacuum is a really great insulator. And if you're going to Mars, you probably want to use methane as your fuel (to take advantage of ISRU), reducing boil-off even further.

But it doesn't eliminate the problem. To use high-energy fuel you will need to launch the stage last, which means the astronauts might have to wait for a very long time. But even if you launch it last, and try for a first orbit rendezvous, the rendezvous might not be a success and it would take days for the phasing orbit to catch up, and by then the boil-off would be significant enough to affect mission operations. AKA mission abort.

Plus you can only launch one stage,or in the time you launch, rendezvous, and dock a second one all the hydrogen leaks out. And limiting the stack to one Earth departure stage is a problem when you're trying to use small rockets.

If one of the launches fails, you can delay the mission until the next launch window without having to relaunch everything.

Its not that simple. The on-orbit stack will be an extremely complex multi-module human-rated habitable space laboratory. You need to service it, or it will stop being habitable. That means large-scale logistics for the many months until the next launch window, on the scale of the logistics for any other piloted space facility.

Rockets don't scale linearly with payload. A rocket that can lift 75 metric tons is far less than half the size of one that can lift 150 metric tons.

I'm talking about available launch vehicles. 20mt-to-LEO rockets exist in abundance because that is about what you need to put a good-size satellite at GEO. Any payload class larger than about 30mt will be dedicated to BEO missions anyway, because no other missions need such a large capacity. And operating and manufacturing a unique rocket will cost about the same whether it lifts 75mt or 175mt.

That's the reason orbital assembly is favourable (for large piloted space laboratories) - you can use launch vehicles that are already in production, amortized by their other missions.

[Bill Phil]

That doesn't work if the multiple parts are mission-critical; it only helps if you can last through the time it takes to prepare a replacement for launch (which, unless you have a pipeline, will be a fairly long time). If the multiple parts are mission-critical, and one fails, you lose everything. That's one of the major reasons EOR wasn't chosen for Apollo: by the time a failed manned launch was rerun, the previous unmanned launch would have fallen from orbit (and so failure of rocket 2 would lead to total writeoff of the mission; that, in turn, is why the people would be launched last). If you make sure the station can miss a launch without issues you're fine; however, your pieces must all be fairly capable, because the loss of one piece cannot result in mission failure. And it turns out that fairly capable pieces aren't small.

Would it be that hard to make a facility in orbit last a few months?

Heck, during Gemini they could launch every 6 weeks. It was smaller, though... Not to mention a replacement rocket in a few DAYS for the failed Atlas-Agena Target Vehicle (on one particular mission...)