Nessary Validating Missions

Impaler · 2012-06-05 17:01:40

Under the notion that any manned mission to Mars will require considerable tech that hasn't been developed or validated yet. Those techs will need validation missions in-order to be incorporated into following manned missions, and the great number of outstanding challenges and outstanding technologies mean were looking at a lot of missions. There's a ton of debate over the 'which-rock-next' in the community and NASA but their seems to be very little acknowledgment of the necessity of validation missions in the achievement of ANY major goal. I'd like to look at this problem by listing hypothetical missions and exploring what they would or could validate.

I'm going to list Missions and what kinds of validations result. A 'WOULD' validate means that mission success is dependent on the tech, if the tech fails it's a catastrophe, this should be done only with robots. A 'MIGHT' validate means the attempted solution might not work but this failure doesn't result in a catastrophe. A 'COULD' validate is like might validate but that the tech is basically piggy-backing on the overall mission and isn't really core to the mission so it could be omitted.

Long Duration Human in LEO: This is certainly the simplest possible mission as we already have a fully operational station. The Russians are interested in doing year long durations on the ISS and health studies on the ISS are ongoing. Hypothetically a mix of drugs, exercise, diet could push the limits of endurance to a point ware the transit to Mars is viable at Zero-g. Unfortunately this has been tried for years without success so it's unlikely to work.

Would Validate: None
Might Validate: Zero-Gravity survival of long duration
Could Validate: Closed-Loop life-support

Long Duration Human at EML: This is on the horizon of viability, a small station could be assembled and moved to EML1 via SEP or a standard rocket booster and the supplied regularly as the ISS is. The same mix of zero-g survival therapies could be attempted here as well but the main issue would be radiation determining just how damaging it is to health over long duration and how much shielding is adequate to reduce the risk to an acceptable level.

Would Validate: Radiation survival of long duration
Might Validate: Zero-Gravity survival of long duration
Could Validate: Closed-Loop life-support

Robotic Lunar Polar Rover Landing: Another very low cost mission that will almost certainly preceded any manned return to the Moon, would almost certainly examine the Polar volatile deposits.

Would Validate: None
Might Validate: Regolith ISRU
Could Validate: None

Short Duration Lunar Landing: The 'Apollo on Steroids' concept, short duration here means ~1 week. Because brief landings have already been conducted this mission is very low in validation value, the actual landing itself would validate nothing and auxiliary experiments would need to be brought to achieve any new validations.

Would Validate: None
Might Validate: None
Could Validate: Regolith Contamination management, Regolith ISRU

Long Duration Lunar Base: A far more extensive mission then temporary landings, this would be an attempt to build a habitat of the size and mass of the ISS and keep it inhabited permanently as a research outpost.

Would Validate: Intermediate-Gravity survival long duration, Regloith Contamination management, Surface habitat construction
Might Validate:
Could Validate: Regolith ISRU, Closed-Loop life-support

Manned Near Earth Asteroid visit: An idea which has been talked about a great deal lately due to its low Delta-V requirements. This mission has all the risks of the EML station plus it's own unique elements involving the Asteroid.

Would Validate: Radiation survival of long duration, Heavy Tough-down on micro-gravity Body
Might Validate: Zero-Gravity survival of long duration
Could Validate: Closed-Loop life-support, Asteroid ISRU

Manned Phobos/Demos Visit: A more ambitious version of the Asteroid visit by going into the Martian gravity well but not all the way to the surface. Again this mission builds on what the NEA visit would validate with unique elements associated with reaching and returning from the Martian gravity well.

Would Validate: Radiation survival of long duration, Heavy Tough-down on micro-gravity Body, Heavy Trans-Mars Propulsion, Heavy Earth-Return Propulsion
Might Validate: Zero-Gravity survival of long duration
Could Validate: Closed-Loop life-support, Asteroid ISRU

Heavy Robotic Rover Mars landing: A robot massing >10 mt would be landed and conduct various research experiments, possibly sample return, deep drilling or other high energy high mass experiments that can't be done with existing rover masses. The key validation here would be that of heavy landing as currently landing technologies are maxed out at the 1 mt size and an order of magnitude more would be needed for a Human mission. Atmospheric ISRU could be utilized to fuel a sample return stage as well or equipment to test extraction of water and or oxygen from the regolith.

Would Validate: Heavy Trans-Mars Propulsion, Heavy Mars Entry Descent and Landing
Might Validate: None
Could Validate: Regolith ISRU, Atmospheric ISRU

Last edited by Impaler (2012-06-06 01:37:15)

Impaler · 2012-06-05 17:11:53

Now we can look at the mission suite and try to determine a minimum necessary group or groupings that validate all the techs needed for any particular long term goal. Not all possible technologies are necessary, for example closed loop life-support is considered optional my most experts for an initial Mars exploration mission because open-loop life-support is well understood and not prohibitive in mass.

The grouping for Manned Mars landing validation that I think is most likely to be conducted would be something like be this and in this order

EML Station
Lunar Polar lander
NEA Visit
Lunar Base
Phobos/Demos Visit
Heavy Mars Rover landing

At that point we would have validated all the tech necessary to do a Human Mars landing. But other mixes of missions could also occour with more or less risk involved as more or less techs are being validated in each mission.

If you think their are other good missions that you think should be included or validations I've missed on the existing missions please do post them and I'll edit the listing, perhaps creating a matrix as well that can visually organize everything.

Last edited by Impaler (2012-06-05 17:17:04)

louis · 2012-06-05 17:40:36

Impaler wrote:

Now we can look at the mission suite and try to determine a minimum necessary group or groupings that validate all the techs needed for any particular long term goal. Not all possible technologies are necessary, for example closed loop life-support is considered optional my most experts for an initial Mars exploration mission because open-loop life-support is well understood and not prohibitive in mass.
The grouping for Manned Mars landing validation that I think is most likely to be conducted would be something like be this and in this order
EML Station
Lunar Polar lander
NEA Visit
Lunar Base
Phobos/Demos Visit
Heavy Mars Rover landing
At that point we would have validated all the tech necessary to do a Human Mars landing. But other mixes of missions could also occour with more or less risk involved as more or less techs are being validated in each mission.
If you think their are other good missions that you think should be included or validations I've missed on the existing missions please do post them and I'll edit the listing, perhaps creating a matrix as well that can visually organize everything.

INteresting posts.

I am still of the Apollo mindset. You plan for everything but you don't become bewitched by the problems.

I think there certainly have to be validation missions, as there were for Apollo, but they should be of a minimal nature.

Radiation protection can be achieved in lab conditions on Earth in my view. We know how to protect against radiation, to the extent we can.

We certainly need long mission in zero g. Would multiple figure of 8 passes between Earth and Moon not be a good idea? Then we need to test the zero g crew both on Earth and the Moon to see how quickly they can adapt to operational conditions.

Most importantly, I think we need a Mars Replica Environment on Earth - a big pressurised "warehouse" with Mars-type soil, the same temperature, atmosphere and so on, and a sol night-day sequence. It can have corners with 3D projections for "exploration". We would learn a lot that way.

I think Phobos and Deimos are a complete distraction and potentially quite dangerous.

Rune · 2012-06-05 19:20:17

Why not a sample return from mars? Refueling with the same ISRU method that the manned mission uses. It would validate EDL of large payloads, atmospheric ISRU, and return to earth, all in one mission (yeah, it's risky, so build several and be prepared to lose some... I know, I'm preaching heresy). So the only missions on that list that would develop something else are the ones that commit you to long terms outside of LEO. Which automatically means that you are committed to your return engine working wherever you are. The only safer thing some would offer is more frequent return windows, if the return propulsion fails you are screwed wherever you are. If you pick your destination by minimum effort, lunar obit /L1 sounds nice. If you add scientific return to the mix, I'd say a carbonaceous asteroid rates higher. Phobos and Deimos win on the PR front, because they actually have names, and they sound cool, and are close to Mars.

Oh, and TMI/TEI propulsion gets plenty of validation if you do cargo flights, like 100% of the contemporary proposals do. Also, I somehow don't see chemical rockets as something needing validating. Perhaps a SEP would need some testing, but as you say those fly unmanned. So by your stated opinions elsewhere... why the heck do you need to validate anything related to engines? You are not seriously considering long term H2/LOX storage, are you?

Just one other thing: exploring what dose of radiation is unhealthy with humans means giving astronauts cancer on purpose. I think that's a no-no, and I think the only way they get away with miro-g nowadays is because you can recover from that somewhat. No way people get put outside the Van Allen belts without knowing how much damage they are going to receive. Do that with rats on the ground and measurements on probes, please? Radiation is radiation wherever you are, and the radiation environment is pretty well understood because, among other things, it is also crucial for unmanned systems, and interesting from a scientific viewpoint. Plenty of people can give you a sufficiently accurate estimate of how much you get fried in the usual mission in an unshielded tin can with the also usual radiation shelter for solar storms, and the answer is about the career limit for an astronaut. So not really much to investigate there.

So out of your list, I would just pick two missions, and one of those I added. Some (any) long duration flight for ECLSS reliability validation, and an unmanned sample return for the rest. Minimum effort, maximum return, and the risk concentrated in an unmanned mission that you can retry until you get right.

Rune. So doing all the list? Wasteful. IMO, if you really want to do something, then go do it and not something else.

RobS · 2012-06-05 21:21:55

I don't think we need a lot of these.

ISS: Astronauts have already stayed there longer than 6 months; Russian astronauts have stayed in space close to a year. A 6-month flight to Mars in zero-gee is not a serious problem; we know what people need to do to adjust back to gravity. According to Zubrin, the Russians who stayed in LEO close to a year also were exposed to as much radiation as astronauts would be on a 6-month flight to Mars.

Long-term health in Martian gravity: This can be simulated by astronauts on the moon wearing weights as they walk around the station and do EVAs. If they mass 80 kg and carried 80 kg of weights around with them, their effective weight would be close to Martian; it's be a bit less in terms of vertical force, but more in terms of momentum (because they'd have twice as much mass to accelerate and decelerate as they move around).

Phobos and Deimos: Not needed before the first manned landing on Mars, but useful as additions to later missions, especially if the moons have ice.

Equipment testing: Perhaps a run to a Near-Earth object would be useful, and you'd need to land a spare return vehicle on the Martian surface. I wouldn't send 10 tonnes of rovers because you don't need them. If you want to test a large landing you land a spare return vehicle or a cargo vehicle with a surface vehicle, consumables, an inflatable, etc.

EML1 and 2: Unnecessary unless you are using solar electric or solar thermal engines for moving cargo; then you might need a station where they can rendezvous.

Additional precursor robotic surface missions: definitely. Apollo was preceeded first by Ranger, then Surveyor, and they were essential. You want a rover to explore several potential landing sites and you want one at the final site. You may even want a pressurized vehicle with remote-controled manipulator arms already at the landing site when the astronauts arrive. It may be able to set up the inflatable hab before they arrive or drill for water.

Manned Mars flyby before landing: Not necessary. Such missions were needed on Apollo because they had no other ways to test out the equipment.

Impaler · 2012-06-06 02:49:10

I disagree that the initial stages of cargo landings in support of the first Manned landing can be considered validators. The start of the Manned mission would not be green-lighted until it's all it's key technologies are validated on prior missions, the lander foremost among these. NASA isn't going to get put itself in a position ware those cargo landers are at serious risk of failing because it would immediately scrub the whole mission for something like a decade while they go back to the drawing-board on the lander. Meanwhile all the other mission hardware for delivering the crew is collecting dust or worse has to be scrapped because it's incompatible with the new lander.

Basically you must consider 'loss of mission' as well as 'loss of crew' in assessing mission risk and failure to consider lose of mission is a huge over-sight in most Mars mission designs, while they bend-over backwards to avoid loss of crew (usually by organizing available assets such that any failure can become a loss of mission) they ignore loss of mission entirely (All Zubrin's work and a lot of the casual Aerospace industry stuff has this flaw running through it). But the political and public perception costs of loss of mission are extremely high, so high that it justifies getting firm validation of all the tech going in so the loss chances are kept to a minimum even when using a robot ware loss of mission is the only consideration.

As for more specific issues:

Radiation: While most of the radiation issue is a 'known' their are still some 'known unknowns' in their. Cosmic radiation is a bit different from the Fissile-material stuff were mostly dealing with here in our historic experience on Earth. Cosmic Rays are mostly protons, electrons and some high energy heavy nuclei, it's possible these are not equivalent to the weak non-penetrating Alpha particles were familiar with. If the Cosmic rays are worse then expected then our shielding numbers will be inadequate and we will have possibly killed a human crew. The Solar storm stuff is even less understood but we are sure we need some kind of heavily shielded storm shelter to survive, I can't see any deep-space mission until such a shelter have actually been through a storm and a some data points collected even if its with animals. I see EML as the closest location to test radiation mitigation at, and it has the key advantage that it can be evacuated (back into the magnetosphere) before a storm hits given the warning window we have now.

Phobos/Demos Visit: Lots of dismissal of this mission which I don't think is valid. This mission would be of the full duration of the landing mission with the same outbound and inbound duration and the landing duration replaced by an orbital stay. The moons are approached and landed on mainly for the benefit of reducing the crews radiation dose, they shield half the sky, more if your in a crater. It's the duration and propulsion that's mainly being validated here, I don't care what kind of return propulsion is being used it's the reliability and restartability after ~500 day hibernation that's at issues. The only problem I forsee is if zero-g limits that might make such a mission untenable, in that case I'd expect a complete un-manned shakedown of all the key interplanetary propulsion stages that are going to be used.

Mars Sample Return using ISRU: I'd consider this to be a 'Could validate' on the idea of the Large Rover Landing. ISRU equipment and power supply is going to be of that kind of size and mass. While its a good ISRU validator, and perhaps the Mars Assent stage fueled from it I don't see it validating the Heavy Earth return propulsion because a Sample return would bring back such a small amount.

louis · 2012-06-06 14:14:53

Impaler wrote:

I disagree that the initial stages of cargo landings in support of the first Manned landing can be considered validators. The start of the Manned mission would not be green-lighted until it's all it's key technologies are validated on prior missions, the lander foremost among these. NASA isn't going to get put itself in a position ware those cargo landers are at serious risk of failing because it would immediately scrub the whole mission for something like a decade while they go back to the drawing-board on the lander. Meanwhile all the other mission hardware for delivering the crew is collecting dust or worse has to be scrapped because it's incompatible with the new lander.
Basically you must consider 'loss of mission' as well as 'loss of crew' in assessing mission risk and failure to consider lose of mission is a huge over-sight in most Mars mission designs, while they bend-over backwards to avoid loss of crew (usually by organizing available assets such that any failure can become a loss of mission) they ignore loss of mission entirely (All Zubrin's work and a lot of the casual Aerospace industry stuff has this flaw running through it). But the political and public perception costs of loss of mission are extremely high, so high that it justifies getting firm validation of all the tech going in so the loss chances are kept to a minimum even when using a robot ware loss of mission is the only consideration.

As for more specific issues:
Radiation: While most of the radiation issue is a 'known' their are still some 'known unknowns' in their. Cosmic radiation is a bit different from the Fissile-material stuff were mostly dealing with here in our historic experience on Earth. Cosmic Rays are mostly protons, electrons and some high energy heavy nuclei, it's possible these are not equivalent to the weak non-penetrating Alpha particles were familiar with. If the Cosmic rays are worse then expected then our shielding numbers will be inadequate and we will have possibly killed a human crew. The Solar storm stuff is even less understood but we are sure we need some kind of heavily shielded storm shelter to survive, I can't see any deep-space mission until such a shelter have actually been through a storm and a some data points collected even if its with animals. I see EML as the closest location to test radiation mitigation at, and it has the key advantage that it can be evacuated (back into the magnetosphere) before a storm hits given the warning window we have now.
Phobos/Demos Visit: Lots of dismissal of this mission which I don't think is valid. This mission would be of the full duration of the landing mission with the same outbound and inbound duration and the landing duration replaced by an orbital stay. The moons are approached and landed on mainly for the benefit of reducing the crews radiation dose, they shield half the sky, more if your in a crater. It's the duration and propulsion that's mainly being validated here, I don't care what kind of return propulsion is being used it's the reliability and restartability after ~500 day hibernation that's at issues. The only problem I forsee is if zero-g limits that might make such a mission untenable, in that case I'd expect a complete un-manned shakedown of all the key interplanetary propulsion stages that are going to be used.
Mars Sample Return using ISRU: I'd consider this to be a 'Could validate' on the idea of the Large Rover Landing. ISRU equipment and power supply is going to be of that kind of size and mass. While its a good ISRU validator, and perhaps the Mars Assent stage fueled from it I don't see it validating the Heavy Earth return propulsion because a Sample return would bring back such a small amount.

I think you're living in the past if you think NASA are going to be leading this mission. It will be Space X in the lead.

What validation was done before putting someone on the lunar surface? Answer: v. little. I think if in the 1960s sensible planning could prove so successful I think it can with Mars as well. The challenge is bigger but our resources are much more developed as well in terms of computers, knowledge of what we will be facing and materials we can use.

I think if you do the long haul in space and maybe a simulation on the Moon with the additional weights as suggested, then you are ready to go, assuming your EDL has been tested with cargo to Mars and in other ways. Testing the radiation protection at EML might be good as well.

I cannot see the advantages of Phobos and Deimos. We will have ways of dealing with the radiation threat on the Mars surface e.g. ice shelters for the habs...

RobS · 2012-06-07 06:16:22

Cosmic radiation is quite well characterized, as far as I know, Impaler. Astrogeologists date meteoroids using cosmic ray tracks, the damage that cosmic rays do to crystals, so we know the cosmic ray flux and the various energy levels of them. So I don't think there are serious unknowns. One of the probes on the Martian surface has a radiation measuring device, so we have a good characterization of the radiation environment there, too. Solar radiation is well known, too, because it degrades solar panels, and the degradation can be predicted pretty well now.

I agree that cargo landers are not a sufficient test of the system by themselves. We will have to land at least one spare Mars ascent vehicle before we land astronauts, and that will be a test of that piece of equipment. But the cargo landers will provide a test for the landing of large masses on Mars, and most likely the landing stage of the cargo lander will use many of the elements of the Mars Ascent Vehicle. It is even possible that the cargo landed will be roughly equal in mass to the ascent stage, and that both vehicles will use variants of the same landing stage. So the experience of landing cargo will be useful.

Phobos and Deimos: I'm not sure anyone would advocate spending 18 months on them; that's the problem. And there's no way with existing technology we can give astronauts on the moons centrifugal gravity. The best way to visit the moons is to spend a few weeks or a month on one after aerobraking into Mars orbit, or before trans-Earth injection. Considering their potential ISRU resources, they need to be explored at some point. Phobos, however, adds 1 km/sec to your total delta-vee and Deimos adds 1.4 km/sec.

GW Johnson · 2012-06-07 10:14:33

I think the enabling-technology boundary you are discussing here is not a sharp boundary. It depends very strongly on how much hardship and risk one is willing to endure, once the thing is feasible at all.

500 years ago it was possible for the very first time to cross the mid-Atlantic with ships from Europe. Magellan even took a fleet trans-Pacific, but about half his ships and men were lost, including Magellan himself. It took months to cross the Atlantic, years to cross the Pacific. Crews were dying of diseases like scurvy, and of spoiled food, all the time.

300 years ago the same Atlantic voyage took weeks, the Pacific took only months, and they had banished scurvy with citrus fruit. The ships were better and faster. Explorations and colonizations became far easier, so there were more of them. That's the way it worked.

We had the basic rocketry and capsules and a lander to go to the moon by the late 60's. In the 1970's, there was considerable experience with space station living with Skylab and the Salyuts. The remaining challenge that was recognized was a lander vehicle for Mars. The microgravity disease and radiation dangers went largely unrecognized or ignored back then. Long-term food storage and cooking was still unresolved.

But, from a simple technological feasibility standpoint, it had become possible to send men to the surface of Mars in the 1980's. That very mission had been on NASA's books for the 1983 opposition in the late 60's, and had been pushed back to the 1987 opposition at the time Apollo was cancelled and all manned flight beyond LEO forbidden in 1972.

In hindsight, we know the crew would more likely have died than survived, of microgravity disease, if not radiation. But we had an agency and an astronaut corps willing to go, back then. I know, that 1987 mission was my target via naval aviation and flight test school. It all went by the boards in 1972.

We know a lot more today, and have a lot more relevant experiences under our belt. There is a well-known work-around for microgravity disease, although most people still believe you have to build some "Battlestar Galactica" monstrosity to employ it. No, you don't. Nor do you need complicated cable crap, or gigantic space trusses, or any of that junk.

The same 20 cm thickness of water shielding that protects from solar flares also halves the cosmic ray exposure, without secondary showers. The "biggie" that we now have is experience at LEO assembly via docked modules - that's what's required to build the ship or ships that take men to Mars. We did that, it's called the ISS.

We still lack a viable lander. But that could be done, in about 5 years if a national priority. (That's just how we did the Apollo lander.) Mars is very hard to land big things upon, but there is a solution. It's called low-thrust rocket braking during hypersonic entry, followed by low-thrust rocket braking during chute or ballute descent, followed by a throttle-up to high-thrust rocket braking for the touchdown. You have to burn all the way down, at one thrust level or another. Multiple slightly-canted engines solves the retro plume instability problem during the hypersonics. The rest is tinkertoys we already have, we just never put them together for that application before.

If it were a national priority, if we as a people actually had the collective will, we could easily send men to the surface of Mars before 2020, and very likely get them home safely, not some "sometime in the 2030's” or later (which really means “never”, by the way). At today's launch prices, which are about 15 times cheaper than the shuttle, I do believe we could likely do it for under $100B.

We are in the analogous situation now relative to Mars, as were sailors 300 years ago trying to cross the Pacific. 300 not 500 years ago, when it was much more likely to fail. But it is still difficult and dangerous. No doubt about that.

I do not see the sanity of going all that way to Mars and not landing. What's the point? This is not a technical or science thing, this goes to the very heart of who and what we are. And what we have been, ever since that first migration out of Africa, maybe a million years ago, before we even became the species we are today.

Nope. If we go at all, we land. That's not even a proper topic for debate.

But on the other hand, I don't see the sanity of being hung up on the one trip - one landing model we used for Apollo. There's no such restriction on designs that rely on orbital assembly in LEO. Make several landings while at Mars, and visit the moons, too! But, you don't have to build "Battlestar Galactica" to do this, contrary to what most folks seem to believe.

You build a modest manned transit ship, and you build modest vehicles that take landers and the landing propellants, separately. You rendezvous all this fleet in Mars orbit, and then go to work exploring multiple sites, with rover cars that have drill rigs on them.

You go to find out “what all is there?” and “where exactly is it?”, and you try out your best “live-off-the-land” equipment while you’re there. That’s what we’ve always done, ever since that first migration out of Africa. Unless you get that done on the first visit to Mars, then any future base or colony will be “iffy” at best, and more likely fail. Same is true anywhere else we might go, too.

GW

louis · 2012-06-07 13:47:40

GW Johnson wrote:

I think the enabling-technology boundary you are discussing here is not a sharp boundary. It depends very strongly on how much hardship and risk one is willing to endure, once the thing is feasible at all.
500 years ago it was possible for the very first time to cross the mid-Atlantic with ships from Europe. Magellan even took a fleet trans-Pacific, but about half his ships and men were lost, including Magellan himself. It took months to cross the Atlantic, years to cross the Pacific. Crews were dying of diseases like scurvy, and of spoiled food, all the time.
300 years ago the same Atlantic voyage took weeks, the Pacific took only months, and they had banished scurvy with citrus fruit. The ships were better and faster. Explorations and colonizations became far easier, so there were more of them. That's the way it worked.
We had the basic rocketry and capsules and a lander to go to the moon by the late 60's. In the 1970's, there was considerable experience with space station living with Skylab and the Salyuts. The remaining challenge that was recognized was a lander vehicle for Mars. The microgravity disease and radiation dangers went largely unrecognized or ignored back then. Long-term food storage and cooking was still unresolved.
But, from a simple technological feasibility standpoint, it had become possible to send men to the surface of Mars in the 1980's. That very mission had been on NASA's books for the 1983 opposition in the late 60's, and had been pushed back to the 1987 opposition at the time Apollo was cancelled and all manned flight beyond LEO forbidden in 1972.
In hindsight, we know the crew would more likely have died than survived, of microgravity disease, if not radiation. But we had an agency and an astronaut corps willing to go, back then. I know, that 1987 mission was my target via naval aviation and flight test school. It all went by the boards in 1972.
We know a lot more today, and have a lot more relevant experiences under our belt. There is a well-known work-around for microgravity disease, although most people still believe you have to build some "Battlestar Galactica" monstrosity to employ it. No, you don't. Nor do you need complicated cable crap, or gigantic space trusses, or any of that junk.
The same 20 cm thickness of water shielding that protects from solar flares also halves the cosmic ray exposure, without secondary showers. The "biggie" that we now have is experience at LEO assembly via docked modules - that's what's required to build the ship or ships that take men to Mars. We did that, it's called the ISS.
We still lack a viable lander. But that could be done, in about 5 years if a national priority. (That's just how we did the Apollo lander.) Mars is very hard to land big things upon, but there is a solution. It's called low-thrust rocket braking during hypersonic entry, followed by low-thrust rocket braking during chute or ballute descent, followed by a throttle-up to high-thrust rocket braking for the touchdown. You have to burn all the way down, at one thrust level or another. Multiple slightly-canted engines solves the retro plume instability problem during the hypersonics. The rest is tinkertoys we already have, we just never put them together for that application before.
If it were a national priority, if we as a people actually had the collective will, we could easily send men to the surface of Mars before 2020, and very likely get them home safely, not some "sometime in the 2030's” or later (which really means “never”, by the way). At today's launch prices, which are about 15 times cheaper than the shuttle, I do believe we could likely do it for under $100B.
We are in the analogous situation now relative to Mars, as were sailors 300 years ago trying to cross the Pacific. 300 not 500 years ago, when it was much more likely to fail. But it is still difficult and dangerous. No doubt about that.
I do not see the sanity of going all that way to Mars and not landing. What's the point? This is not a technical or science thing, this goes to the very heart of who and what we are. And what we have been, ever since that first migration out of Africa, maybe a million years ago, before we even became the species we are today.
Nope. If we go at all, we land. That's not even a proper topic for debate.
But on the other hand, I don't see the sanity of being hung up on the one trip - one landing model we used for Apollo. There's no such restriction on designs that rely on orbital assembly in LEO. Make several landings while at Mars, and visit the moons, too! But, you don't have to build "Battlestar Galactica" to do this, contrary to what most folks seem to believe.
You build a modest manned transit ship, and you build modest vehicles that take landers and the landing propellants, separately. You rendezvous all this fleet in Mars orbit, and then go to work exploring multiple sites, with rover cars that have drill rigs on them.
You go to find out “what all is there?” and “where exactly is it?”, and you try out your best “live-off-the-land” equipment while you’re there. That’s what we’ve always done, ever since that first migration out of Africa. Unless you get that done on the first visit to Mars, then any future base or colony will be “iffy” at best, and more likely fail. Same is true anywhere else we might go, too.
GW

Thanks for that informative summary, GW.

Thankfully we don't have to rely on NASA to deliver a Mars landing. Musk is determined to get there and will use Space X to realise the dream.

clark · 2012-06-07 16:35:10

To gw, but the rest can chime in, you mention national priority. I think the failure in the argument is that there is some burning need to do this now, or in five years or in some accelerated fashion, but there isn't a definitive reason to do this now or in five years or in ten or in 50. It seems if we wait, technology gets better, costs go down, knowledge increases. Why not wait, or take a slow and steady approach?

SpaceNut · 2012-06-07 18:18:45

I do agree that a mission profile as such which includes real hardware for the duration at least but how would we simulate the landing of mass?

Glandu · 2012-06-08 02:56:39

GW : Best pro-Mars message I've ever read. Better than Zubrin's book.

louis · 2012-06-08 03:22:23

clark wrote:

To gw, but the rest can chime in, you mention national priority. I think the failure in the argument is that there is some burning need to do this now, or in five years or in some accelerated fashion, but there isn't a definitive reason to do this now or in five years or in ten or in 50. It seems if we wait, technology gets better, costs go down, knowledge increases. Why not wait, or take a slow and steady approach?

You obviously subscribe to the "Slacker's Code" . LOL

Of course, why bother doing that marathon?....why bother landscaping your garden?...why go to all that trouble of doing up an old house?...why make a play for that member of the opposite sex when you might get hurt in the process?....

Kennedy said it best when he said "not because it is easy but because it is difficult".

The analogy from the body is probably a good one here - your body does need to be exposed to microbes, to danger, to develop its immune system. I think a healthy society does need to attempt difficult and somewhat risky things to keep alive its spirit, its creativity. Of course, if you want to live in Sleepy Joesville, that's fine...it's an existential choice.

Personally I just find life a lot more interesting when interesting things are going on around me and, as a taxpayer, I am quite prepared to pay for that bit of excitement and engagement with the big world out there.

GW Johnson · 2012-06-08 17:47:06

Well, I’m glad to see I provoked some very relevant discussion with that over-long post of mine. Sorry about the length, but it’s really hard, actually impossible, to reduce something that complex to a sound bite. (Actually, I hate sound bites.)

One issue I seem to have provoked some discussion on, is “when-to-go”. One of my points in that long post was that the longer you wait (and your technology and experiences accrue), the easier and more reliable an exploratory voyage becomes. So, how long do you wait? There’s no definite (or easy) answer. But, if you wait too long, you never go (we’ve seen that before, too).

There’s a problem with never going or ceasing to go, another lesson taught by history. Cultures that cease to explore, will fade to obscurity, or even die. It just takes a while for the dead dinosaur to fall over. Example 1: China quit voyaging around the Indian Ocean and Western Pacific. Within a few centuries, China was no longer a regional power, and hasn’t been again, until recently. Example 2: About 280 AD, Rome began pulling back from exploration and colonization (we might all disagree with their subjugative methods, but the point is, they quit), starting in Britain. That’s what Hadrian’s Wall was really all about. By 2 centuries later, they had split their empire in two, and the western half had already fallen. (It took another millennium for the eastern half to end: big dinosaur.) That’s just two examples, there’s more.

I don’t have an answer about when it’s “best” to go to Mars, or even what “best” means in that context. It’s not a rational thing, anyway. I do know it was feasible at very high risk in the 1980’s. It’s easier, and a whole lot more likely now, that we could send a crew to Mars and get them home in good health. Personally, I’d say go as soon as you think you think you can get them home healthy maybe 98+% of the time, because of the “nothing is more expensive than a dead crew” problem we have already seen. But that’s just me. I think we’re just about there, if we design the mission, vehicles, and equipment right. (“Designs-done-right” are the topics of other discussions we have been having.)

I’d like to see what the rest of y’all would recommend for the answer and “rationale” (remember, this isn’t a logical thing, it’s a cultural thing) to the question “when do we go to Mars?”

GW

GW Johnson · 2012-06-08 17:52:18

Oops, forgot. The Earth's land is largely explored and settled now. There are only two places left where cultures can go to explore and colonize: (1) the deep sea, and (2) space. Both are very worthy and viable destinations, and I love what we have done in both arenas. In the "short" term, we need to be doing both IMHO. In the longer term, the sea is finite while space is infinite. So what does that tell you about long term objectives?

GW

clark · 2012-06-08 18:39:11

This is pretty much what I thought.

I would like to avoid the diachotomy of explore/don't explore argument that is often the knee jerk reaction to a question like mine. If you look carefully, I am not questioning the merit of exploration. Some (not GW) seem to miss that point because my question speaks to a fairly fundamental problem in the pro-space exploration argument- the need for speed. Sorry to make you uncomfortable.

And this is not a cultural thing. This is a simple, straight forward objective look at the situation. Why do we need to go to Mars at a faster rate than what we are doing now? Sure, it is technically feasible- and easier today than previously, but why go now? Why not focus on other space exploration tasks that increases or expands our capabilities beyond just Mars (as a destination)? Or invest in science objectives that have a far more liklihood of returning more value to Earth science?

The main problem with setting Mars as the primary focus of our space exploration is that it will cause us to invest less, or come at the cost of other ongoing space science research that is not centered on Mars.

I guess what it comes down to is, why make Mars the center piece of our space exploration efforts? All the heavens in our grasp and we only grab for Mars? Look what happened when we did the same thing with the Moon.

Impaler · 2012-06-08 23:56:09

This notion that at 'Lets just do it' program that sends people to Mars would NOT conduct a number of validating missions first is absurd. As I've said even the 'go directly to the moon' Apollo program was preceded by Mercury and most importantly by Gemini. And Apollo was by no means a 'slow and lazy' program, nor was it risk-averse. If your an advocate for an aggreisive development program that aggressiveness is going to come in the form doing the validation missions at a fast clip with the various project dove-tailing together and replacing each other rapidly as the Apollo capsules rapidly replaced Gemini capsules.

Allusions to the age-o-sail are profoundly dis-honest, when Columbus sailed across the Atlantic it was in boats that were already common, affordable and which had been validated by a century of usage. That's why it was possible to RENT (as Columbus did) a Caravel cheap, the cost per week was equal to price of two cows! The first voyage was an absolute drop in the bucket for the state, which is why Spain could immediately follow it up the very next year with a flotilla of 17 ships and 1200 men which had the goal of establishing outright colonies, now that their was a justification for spending "real money". These vessels were not the Space-craft of their day they were the 747's of their day.

Arguing that our ability to send a 1 ton robot to Mars means we have the capability to send a human NOW at ANY price is again just absurd. The Viking landings can not possibly be construed to mean we have the capability to send a human 'since the 1980's'. Just because a mission would use rockets and heat-shield based entry is like saying that after the Wright brothers flew at Kitty-hawk it was then possible from a 'simple technological feasibility standpoint' to fly across the Atlantic. Your ignoring the need to mature a technology to higher levels of capability and reliability, work which can easily exceed the cost and complexity of just developing and demonstrating the core technology. Just as the American-Soviet space race was mostly technology maturation on existing ICBM technologies even the most intensive Mars mission would require a huge amount of maturation of the present space technology, and that maturation will need validation and time.

I'm not arguing that we need radically new Propulsion technology to actually Do a mission, Zubrin is right on that one point but ignores the fact that the cost to develop that massive hardware necessary for such a mission would requite so much time and money that the this development process would be indistinguishable from our current space program development path involving alternative near-term destinations like the Moon, Asteroids or Lagrange points. Their is nothing left but to advocate for budget increases that are never going to happen, even in a good economy. Technology developed and validated that can bring down the cost of a mission is what anyone who is serious should be advocating for, not this childish 'do it now at any price and suicidal risk' attitude.

Last edited by Impaler (2012-06-09 00:01:46)

louis · 2012-06-09 07:09:07

Impaler wrote:

This notion that at 'Lets just do it' program that sends people to Mars would NOT conduct a number of validating missions first is absurd. As I've said even the 'go directly to the moon' Apollo program was preceded by Mercury and most importantly by Gemini. And Apollo was by no means a 'slow and lazy' program, nor was it risk-averse. If your an advocate for an aggreisive development program that aggressiveness is going to come in the form doing the validation missions at a fast clip with the various project dove-tailing together and replacing each other rapidly as the Apollo capsules rapidly replaced Gemini capsules.
Allusions to the age-o-sail are profoundly dis-honest, when Columbus sailed across the Atlantic it was in boats that were already common, affordable and which had been validated by a century of usage. That's why it was possible to RENT (as Columbus did) a Caravel cheap, the cost per week was equal to price of two cows! The first voyage was an absolute drop in the bucket for the state, which is why Spain could immediately follow it up the very next year with a flotilla of 17 ships and 1200 men which had the goal of establishing outright colonies, now that their was a justification for spending "real money". These vessels were not the Space-craft of their day they were the 747's of their day.
Arguing that our ability to send a 1 ton robot to Mars means we have the capability to send a human NOW at ANY price is again just absurd. The Viking landings can not possibly be construed to mean we have the capability to send a human 'since the 1980's'. Just because a mission would use rockets and heat-shield based entry is like saying that after the Wright brothers flew at Kitty-hawk it was then possible from a 'simple technological feasibility standpoint' to fly across the Atlantic. Your ignoring the need to mature a technology to higher levels of capability and reliability, work which can easily exceed the cost and complexity of just developing and demonstrating the core technology. Just as the American-Soviet space race was mostly technology maturation on existing ICBM technologies even the most intensive Mars mission would require a huge amount of maturation of the present space technology, and that maturation will need validation and time.
I'm not arguing that we need radically new Propulsion technology to actually Do a mission, Zubrin is right on that one point but ignores the fact that the cost to develop that massive hardware necessary for such a mission would requite so much time and money that the this development process would be indistinguishable from our current space program development path involving alternative near-term destinations like the Moon, Asteroids or Lagrange points. Their is nothing left but to advocate for budget increases that are never going to happen, even in a good economy. Technology developed and validated that can bring down the cost of a mission is what anyone who is serious should be advocating for, not this childish 'do it now at any price and suicidal risk' attitude.

That's all way too pessimistic and defeatist. I think you have been mesmerised by all the talking up of difficulties that has gone on over the years. Really the problem of getting people on to Mars is in reality several discrete problems and you need to break down the project into those discrete areas:

1. Launch
2. Orbital assembly
3. Long exposure to zero G and one third G
4. Protection from cosmic radiation/solar flares in transit and on Mars
5. Transit mode
6. Life support in transit
7. EDL for Mars
8. Return from Mars
9. Life support on Mars
10. Mars ISRU

In terms of technology maturation I think 1, 2, 3, 5, 6, 9 and 10 are really pretty much there, or - at most - existing technology needs to be tweaked and put in place (e.g. Mars ISRU - we already have independent energy production and rock drilling on Mars - it's really just an extension of things we can already do).

Some significant work needs to be done on 4 (more in terms of design it seems from what GW says), and on 7 and 8 (perhaps the trickiest element).

What is missing is a properly funded and focussed project, similar to Apollo (but far less costly). If we started now on a 10 year project we could mature the EDL technology while we worked on other design and build elements.

After the initial landings I believe Mars colonisation - although relatively slow to develop - will be self-funding so cost will no longer be an issue.

GW Johnson · 2012-06-09 08:41:55

This is a good discussion amongst folks with differing viewpoints. Too bad it is not taking place nationally in any meaningful way when NASA and the rest are getting their objectives set.

I rather like Louis's list. It's a good startpoint.

1. Launch
2. Orbital assembly
3. Long exposure to zero G and one third G
4. Protection from cosmic radiation/solar flares in transit and on Mars
5. Transit mode
6. Life support in transit
7. EDL for Mars
8. Return from Mars
9. Life support on Mars
10. Mars ISRU

and to it I would add one more item:

11. a supple, mobile space suit

I think that with orbital assembly, launch is no longer the problem it once was, and prices are coming down fast.

If you want a really good mission to do before going to Mars, try determining how much fractional gee is therapeutic in LEO.

Another would be a satellite outside the Van Allen belts with a radiation counter inside 20 cm thickness of water. It would give a good test of halving the cosmic ray risk, and on those erratic opportunities, a test of how good the 20 cm of water really is against solar flares. More of a design concept validation test, based on what we already know.

A third would be to check out frozen food storage and cooking under the presumption of artificial gravity for maybe 5 year missions in flightweight hardware designs. That can be done right here on the ground.

If you want to talk about validating missions, these would be necessary milestones along the way to a goal. With Apollo, we had a specific goal to land men on the moon and return them safely. That goal does not need to be specific as long as it is to send men to other celestial bodies to explore. Mars is an obvious choice among many that will come within range over time as we get more capable.

But, to say that visiting an NEO or a Martian moon is a necessary prerequisite to landing on Mars is setting up an unnecessary obstacle. The same vehicle that can take you from LEO to an NEO can take you to Mars orbit, or Venus orbit, or even orbit about Mercury, maybe even the asteroid belt with a bit hotter propulsion retrofitted to it. You look at an orbit-to-orbit transit vehicle, and it naturally becomes one design that does all those jobs. That's the analog to the caravel ship, or the clipper ship, or the DC-3, or the B-747.

Landing on Venus is a bit out of the question, but the same lander that can set down on Mars would work on Mercury, the moon, or even the moons of Jupiter and Saturn. And more. To visit small asteroids or moons, simple rendezvous with a propulsive backpack suffices, since the gravity is negligible. You don't need the big lander. Again, anything that will work on Mars will likely work on the other destinations. That's the analog to the barges and lighters that unloaded the caravels and later sailing ships, when no deepwater dock was available. It's pretty much all the same design problem; Mars makes a good set of design criteria and conditions.

The long pole in the tent is probably that lander, but we ought to be working on hotter propulsion, always.

GW

SpaceNut · 2012-06-09 20:51:35

I agree that a list does help but as I see he problem with launch and orbital assebly both of which comeback to the impact of numbers with 3,4 impacting the subassembly in orbit with the latter 9, 10 doing the same to the EDL which further does ripple back to the assembly in orbit.....

GW Johnson · 2012-06-10 09:53:01

No list is perfect, for sure. But the launch and orbital assembly thing is pretty much a demonstrated item now, after learning how to do it with 25 ton modules delivered by the shuttle. That was about $27,000/pound. Atlas-V-HLV can deliver 29 tons at about $2500/pound now, according to what I read. Pretty soon, Falcon-Heavy will be delivering 53 tons at near $1000/pound.

An ISS under these circumstances would be closer to $10B than the $100B we paid. So why not think of building whatever-we-need the same way, with what we have for launch rockets that double as commercial launchers, so that in turn there is a routine reason for their existence. To me, that seems the smarter solution, by far.

That is what NASA's old Constellation program should have been, but never even came close to being. Their thinking was way too corrupted by the perceived need to preserve existing contractors doing what they previously did during shuttle, and by illogical mandates from a Congress not competent to make those detail decisions (by definition).

If you think outside the box of the Apollo model (one mission-one launch, and one mission-one landing), then the orbit-to-orbit transit vehicle model, with landers as needed, immediately pops out as the most practical way to do this manned exploration thing (or some of the unmanned, for that matter). And it's not new: the same ideas were proposed by the Germans (von Braun, et al) ca. 1930's, 1940's, and 1950's. In the inner solar system, the very same transit vehicle can take you to orbit or rendezvous with any planet or moon or NEO inside the main asteroid belt. The same lander design would work on Mars, the moon, or Mercury, the only places we even need one.

One transit vehicle design, one lander design, do it modular to tailor the propellant supply to the particular mission, the other components being "common" universal designs. Now assemble them in LEO out of modules sized to fit rockets you have anyway, and reuse the hell out of whatever you can return home with (habitat and engines at least). What's so hard about that concept? And it is not, I repeat not, "Battlestar Galactica". We're talking an assembly far smaller than ISS for these missions.

Habitat modules (inflatable or otherwise) we can build, weve been doing it since 1973. Capsules we have or can build as crew return (or emergency return) vehicles. Engines (chemical, nuke, electric, etc) we have or could very soon have. Artificial gravity can be had during coast by spinning the ship end over end, and we know how to live in zero gee already.

Short-term zero gee is no problem. Radiation? Try 20+ cm worth of water around the designated shelter, as the water and wastewater tanks you already know you gotta have anyway. Make that shelter the flight deck, so critical maneuvers can be flown, no matter what. No problems or show-stoppers there. Just routine design and development testing.

The lander is the toughie. If we are serious about going to Mars, that is the critical enabling technology. We ought to be working on it. No one is, to my knowledge, but I am no insider. I think I know how to do it. There's no real show-stoppers, but it does require some combined techniques we haven't yet done together. Separately, yes; together, no. Not so very big a hurdle, that.

The artificial gravity is a major design constraint (how big a stack-up at whatever spin rate is tolerable?). Somebody ought to be looking at that seriously in LEO. We've had 40 years to do it, and no one has. The medical centrifuge of the ISS was cancelled. Very bad move. I suspect that the min therapeutic partial gee is a nonlinear function of required mission duration. But that's just a hunch.

The supple spacesuit is not being seriously worked, either. There’s a funded effort at MIT for a mechanical counterpressure suit design, but no major development effort at a real contractor who might actually build the thing. Yet, we have known since 1969 that this thing would work. It’s been relegated to academic research, and saddled with an unnecessary design constraint that today’s materials still cannot reach. How stupid is that?

All of the public policy and NASA program objectives I have seen, for decades now, says the government program does not really want to go to Mars (a radical departure from the NASA of the 1960's). I rather think they're afraid to go to Mars, because they cannot accept any significant risk any more. If they could, Spacex's Dragon would carry an astronaut a lot quicker than they plan to allow. When Glenn went up in his Mercury-Atlas in Feb. 1962, the Atlas was not yet man-rated, and ultimately it never really was man-rated. It just happened to work for 4 manned flights. Enough flights, and we would have killed somebody. It is just harsh statistics.

We were lucky with Mercury, but it worked. The Titan for Gemini wasn't any closer to man-rated, either. And the Saturns for Apollo certainly weren't man-rated, not by today's standards, and never were. Today it’s entirely different. I think they’re (NASA) gun-shy because of 3 lost crews. There’s demonstrably nothing as expensive as a dead crew, and now, no one in control of that agency is willing to do anything that might risk the loss of another one. Yet, we all know it will occasionally happen. It's just a matter of time and circumstance. Statistics.

There's a multiplicity of political and cultural problems holding us back here, but not so very much any technical obstacles anymore. See what I mean?

GW

Last edited by GW Johnson (2012-06-10 11:59:29)

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