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#8026 Re: Human missions » Yet another Mars architecture » 2015-05-09 10:53:00
SpaceNut,
If NASA is serious about humans to Mars, then working within their exiting budget is a top priority. It's highly unlikely that the agency will receive significantly more funding than it already gets. No matter how complex it is perceived to be, orbital assembly built ISS, a far more complicated vehicle than a ITV/MTV from an assembly standpoint, using far lighter payloads and far more expensive launches than what F9H/FH would allow for.
It's not going to cost more to assemble the Mars mission hardware at ISS than it would to fly SLS once or twice per year.
There are three use cases for SLS, all of which accomplish relatively mundane tasks at staggering expense:
1. Launch a MTV, less propulsion, in one flight
If there's no insistence on launching a massive capsule system like Orion with the MTV, then the mass of the MTV remains within the capability of a single F9H flight. Orion wasn't designed for crew sustainment during deep space flights, so there's no point in adding the mass of Orion to the MTV. If the MTV has a problem that makes it uninhabitable in deep space, the result is loss of crew and loss of mission. If the same amount of funding that we've expended to develop Orion was instead spent to develop CL-ECLSS, active radiation shield, and the systems reliability required for deep space transits, we wouldn't need a non-functional lifeboat.
2. Launch a fully fueled multi-person MDV/MAV in one flight
This use case makes the most sense of all the ways in which we could use SLS. Our astronauts need a way to get home, but apart from instant availability, bringing the mass of all the propellant required to get back to Earth from Mars is clearly the most uneconomical way to accomplish this. It can't possibly cost more to develop ISPP for use on Mars than it costs to bring it all from Earth, unless our Mars mission is the type of flags and footprints mission NASA said it didn't want to do.
3. Launch large chemical propulsion stages for orbital transfers
If NASA develops SEP systems for orbital transfer, then there's no logical explanation as to why we'd require the types of kick stages that only SLS could push to LEO. Again, F9H/FH is adequate for smaller chemical kick stages that less massive MTV's and MDV's/MAV's would require in conjunction with SEP.
#8027 Re: Human missions » Yet another Mars architecture » 2015-05-08 01:32:22
It's a little more complex than you're making it out to be, Rob.
Eisenhower was indeed concerned about the Russians launching ICBM's at the US, but he was also a forward thinking man and wanted something more for America than a giant military industrial complex that pervaded every aspect of American life. The fear of the unknown was the foundation that the military industrial complex was built on, but the scientific achievement (whether it benefited the military or society as a whole) was what has kept the institution in place. The good that it does for our country is inseparable from the bad. Fear is a powerful motivator. Problems arise when the fear controls our activities.
With respect to what lead to the Russian space program, again, fear was a powerful motivator.
There are people in Congress who genuinely care about our space program, rather than just concerning themselves with votes from their constituencies. Irrespective of how they personally feel about our space program, most of these people who make policy decisions can't balance a checkbook, much less possess the engineering background and experience required to make effective decisions on what's worth spending money to develop. In general terms, they just don't understand much of anything about what they're making decisions on when it comes to our space program. Moreover, why would they? Their job is to make legal decisions.
NASA is not blameless, either. The administrators need to be better advocates for our space program and there needs to be truth in advertising, so to speak. For example, NASA administrators needs to be honest with themselves and others about what America requires for space exploration.
Orion may very well be the most advanced space capsule system in the world, but if it costs too much to develop, is too heavy to launch on a reasonably priced rocket, or is too small for any real space exploration, then it has no utility for space exploration. Any manned space program is all about the humans. This is the one area of our manned space program that requires the most development, the one that's most lacking in terms of available technology to support stated space exploration objectives, and the one area that should receive the most funding for development.
Inexplicably, NASA and Congress have decided to create a new launch vehicle and spacecraft instead of developing the technologies that makes human space exploration possible. On the face of the issue, having a very capable rocket and a modern spacecraft would seem like a logical place to start since you obviously need a rocket to take you into space and a spacecraft for the ride up. However, we've had a reliable spacecraft and launch system, better known as the Space Shuttle, for humans to use to get to space for three decades. There was never any requirement to reinvent the taxi service (SLS), let alone the taxi cab (Orion), for space exploration. That's exactly what we've done. The end result will be no more or less reliable or cost effective than the Space Shuttle was. In short, there was no justification for replacement of the Space Shuttle and even less justification for continuing to use Space Shuttle hardware in an expendable vehicle.
This post isn't meant to be a NASA or Legislature bash. If someone from NASA (unlikely) or our Legislature (highly unlikely) reads this, take the point and not the arrow. Even to a lay person, like myself, it's blatantly obvious that Orion can't take humans anywhere into deep space, apart from the moon, and that SLS isn't required for space exploration. SLS may simplify some aspects of space exploration by negating some exploration vehicle assembly requirements, but nearly every mission architecture document I've seen from NASA involves some in-space assembly of mission hardware components. It really doesn't matter what SLS might do for NASA if the budget only allows for one flight per year. If you can't fly the rocket at least twice per year, then you don't need it because you can't afford it. If you can get funding to fly it at least twice per year, fine. If not, F9H/FH will still get the job done, even if it wasn't invented by NASA. You'll even have money left for development of payloads that actually require heavy lift. Kinda nifty, if you ask me.
With the level of funding that Orion receives every year, NASA could have a real deep space exploration vehicle, near closed loop ECLSS, active radiation shielding, and solar electric propulsion. SLS may have some future utility for space probes, telescopes, and putting a deep space exploration vehicle in LEO with one flight. Orion never will have any future utility for space exploration. There are far less expensive taxi cabs available.
In closing, there needs to be a reprioritization of available funding if we want to go back to the moon or to go to Mars.
#8028 Re: Human missions » Yet another Mars architecture » 2015-05-07 19:24:03
NASA's budget woes are a direct result of our legislators dictating procurement programs to the agency. Neither Congress nor the Senate have any vague idea of how to execute an efficient or effective procurement program, let alone how best to design a space launch system for affordability and maintainability. That NASA's administrators are forced to continue to cheerlead for the knuckleheads in the Congress and the Senate in order to try to reconstitute our manned space program is an absolute travesty.
Designing and building a true heavy lift launch vehicle wasn't a mistake, but the arbitrary decision forced on NASA to incorporate STS hardware into SLS was a profound design mistake. There's no way to make STS hardware remotely affordable or simple to maintain. F9H/FH will be the launch system of choice for the foreseeable future, if affordability is a consideration.
In any event, the money to develop payloads for SLS is most definitely gone and SLS definitely won't perform like a Saturn V. Between the poor decision making of the Congress and Senate and the indecision on NASA's part, we're not going anywhere for a long time. If it were put to a vote, most Americans would defund the manned space program. It's way, way past time for NASA to deliver.
#8029 Re: Human missions » Yet another Mars architecture » 2015-05-07 04:27:46
RobS,
SLS will probably cost between $1B and $1.5B per flight. Add in ongoing development funding, maintaining facilities, and other recurring costs and we're talking about ~$3B a year to maintain the SLS program. NASA and Congress will resort to magical thinking to explain away what SLS will really cost to fly, but $1B to $1.5B is a sound estimate.
#8030 Re: Human missions » Yet another Mars architecture » 2015-05-02 21:38:00
RobS wrote:I think at this point we are still not certain about the accuracy of landings because Mars has an atmosphere. Apollo 12 could land close to he Surveyor, but the circular error probable of the unmanned Mars probes is tens of kilometers. Zubrin worried about landing accuracy as well. We're still even sure we CAN land larger things on Mars, let alone the accuracy.
That's why you have transponders on the surface and appropriate thrusters on the lander.
IF you have enough retro-rocket thrust there is no reason why you can't land sizeable payloads on Mars.
If you generate enough thrust and have enough fuel you can make a refrigerator fly. The problem isn't thrust generation, it's the quantity of fuel required to make the refrigerator fly.
The entire point to development of HIAD and ADEPT is more efficient deceleration to increase the tonnage landed with respect to the mass of the deceleration solution required to soft land it.
#8031 Re: Human missions » Yet another Mars architecture » 2015-05-02 16:27:30
Regarding pushing the mass of a M113 to Mars using a single F9H flight, the SEP systems we're developing right now for ARM are more than sufficient for landing ~15t-17t payloads on Mars when used in conjunction with advanced EDL solutions like ADEPT. Without advanced EDL solutions like HIAD and ADEPT, we're not going to Mars.
In very simple terms, we'd need much more powerful and massive propulsion solutions, even with the ISP advantage that SEP provides, for the kinds of mission packages that send the MTV, MDV/MAV, and surface habitation module or rover to Mars together. Eventually we could develop propulsion solutions to send the entire mission hardware package to Mars, but at what cost and on what timeline?
If we opt to use far more economical launch vehicles (F9H) and more efficient propulsion (SEP) we can reasonably afford to put a lot more tonnage on Mars than slightly more capable launch vehicles (SLS) or less efficient propulsion (chemical) would allow for. Sending more tonnage to Mars does far more to lower overall mission risk than skipping orbital assembly or having multi-person combination descent/ascent vehicles.
#8032 Re: Human missions » Yet another Mars architecture » 2015-05-02 15:44:58
I really can't understand why you keep talking about "landing off target". I can't see how that could happen, unless there was a serious malfunction of the lander - the like of which never happened on the Apollo missions. The lander would be tested and tested again - hundreds of times. There is no reason to think it will land off target. Using your logic we would have to started "safety planning" for all sorts of unlikely events.
In the context of plans that land the crew together in a combination descent/ascent vehicle, or even individually as my plans call for, landing "off target" means landing them far enough away from a permanently habitable structure or vehicle that retrieval is not practical.
In my plans, the permanently habitable vehicles are electrically driven M113 variants, known as MTVL's, that travel together in convoy for normal exploration operations. For human EDL, the rovers ring the landing area and retrieve individual astronauts after a drastically simplified EDL solution has brought them, individually, to the surface of Mars.
My supposition is that if the human EDL solution is light enough, a simple ringsail, using an inflatable ring to assure deployment of the parachute, is possible. The individual EDL solution forgoes the complexity of propulsively landed multi-person combination ascent/descent vehicle and whatever improvement to landing accuracy that the more sophisticated solution provides.
I don't think any mission risk reduction benefits will be realized from dragging the mass of a multi-person EDL solution to Mars. It's a plan to spend lots of money and lengthen the timeline for humans to Mars through development of an unnecessarily complicated human EDL solution that will take money from the programs required for transit to/from Mars and the programs required for surface habitation.
Keeping the crew alive is a top priority but effort needs to be concentrated where it is effective in guarding against real risk.
There's no reason why a pressurised Rover shouldn't also be provided for use post-landing. But rather than building some huge monster, we could have a small 2 or 3 person vehicle.
Each MTVL would sustain a crew of two for approximately 250 days of a nominal 500 day surface stay. A durable rover simply will not be a soda can on wheels. Every attempt to lighten the rover will only defeat the purpose of having them, which would be durable and reliable surface transportation that can sustain the crew and shield them from the effects of solar radiation.
The alternative is establishment of an outpost that our astronauts will never venture very far from. I would prefer that our astronauts actually explore the surface of Mars when they get there. They can only do that if they're mobile.
Anyway, exploration should not be a major priority for Mission 1. ISRU experimentation should.
NASA is a space exploration agency, not a space colonization agency. We're going to Mars to explore, first and foremost. Permanent human presence is a secondary goal. ISRU is important for the establishment of a permanent outpost, but it's not a justification for going to Mars.
We could probably get plenty of exploration value using a pilotless drone - maybe rocket powered - steered by the first colonists.
What would another rocket powered robotic vehicle tell us about Mars that all the other rocket powered robotic vehicles haven't already told us? We've done about as much as we can remotely. Sooner or later we need to land some geologists, meteorologists, and microbiologists to try to determine whether or not humans could conceivably live there. After a few mobile surface exploration missions, we can concern ourselves with establishment of a permanent outpost there.
#8033 Re: Human missions » Yet another Mars architecture » 2015-05-02 11:37:42
Put another way, under normal operating conditions, the crew is aboard the descent/ascent or descent and ascent vehicles for less than 24 hours. The minutes spent during descent and ascent are critical to the outcome of the mission, but should we devote a major portion of available funding to those few minutes because of what might happen afterwards or account for what might happen afterwards with the design of the rest of the mission hardware?
If there's contention about what our general landing accuracy on Mars is or contingency scenarios that have to be accounted for, should we design a propulsively landed solution that necessarily has significant mass and complexity, or should we develop surface transportation solutions that can retrieve our astronauts if they land off target? What solution has the lowest level of technical complexity, small single man capsules with pressured rovers to retrieve astronauts who land off course or a multi-person propulsively landed capsule that lands the entire crew in one operation? What problems or contingency scenarios does landing the entire crew at the same time solve?
Obviously the propulsively landed solution is capable of some degree of course correction to land as near to the target as feasible, but what happens if even that solution lands a little off target? For example, let's say that a propulsively landed multi-person capsule lands 10km from where intended. Does that mean our astronauts have to carry the oxygen and water to walk back to the habitat module? I think you still need a rover of some kind to retrieve the astronauts. You don't need a pressurized rover and perhaps don't even need a rover that carries the astronauts, but you still need a small robotic rover to carry oxygen and water.
For any real surface exploration effort, a pressurized rover that provides some measure of shielding against SPE's is a requirement. Supposedly, we're going to Mars to explore. A substantial pressurized rover is therefore a requirement if we're to accomplish that stated mission objective.
Establishment of a base on Mars is a far future goal that would require some level of cooperation between the various space agencies. It would be really nice to have, but it's not required for surface exploration and shouldn't stand in the way of a surface exploration mission.
#8034 Re: Human missions » Yet another Mars architecture » 2015-05-02 09:12:08
The ascent vehicle/descent vehicle safety issue can be avoided, but not at minimum mass. I think it is wrong to let minimum-mass as a constraint drive you into a corner with no outlet.
If you have real surface mobility, which is only provided by a substantial pressurized rover, you can land up to a 100km off course and not suffer the consequences. Where do you draw the line and say, "No matter what your equipment does, this is your task and if you can't accomplish it, we can't help you." Obviously we have to repeatedly test the equipment under realistic operating conditions ahead of time. That can only be accomplished by sending the mission hardware to Mars.
It is fairly easy to show that a single stage chemical rocket vehicle capable of a two-way trip to the surface and back from LMO is quite possible. Its only drawback is low payload fraction, meaning many tons of fueled vehicle must be sent to Mars to land a handful of tons on the surface, and still ascend. There is no way around that.
We certainly can do that if we deem it necessary, but is that really the best way to design ascent/descent systems?
But the advantage is that this vehicle could be refueled either on the surface or in LMO, and thus be reusable. It could make many such trips, very important for constructing some sort of base on that first mission. This becomes very attractive indeed, if in-situ propellant production proves practical at massive production rates.
I don't think ISPP is nice to have. I think it's a hard requirement. Can we design vehicles that are reusable after reentry? We certainly could, but is that the best use of limited available funding? How much would it cost to design a reliable reusable lander versus the cost of another comparatively inexpensive F9H flight? If F9H achieves first stage reusability, will it be less expensive to launch the F9H again?
The safety issue also goes away if you bring more than one of these landers to Mars with you. All it needs is a temporary-occupancy abort capsule for its command cabin, in which the entire crew rides. The other vehicle(s) can be rescue birds if descent or ascent abort becomes necessary. That capsule looks an awful lot like Red Dragon in its characteristics, actually.
Safety issues don't exist, except between peoples' ears. On the other hand, failures in complicated systems like propulsively landed reentry capsules are very real. The frequency of the failures can be mitigated by thorough testing in as many different conditions as is feasible and not making any particular piece of hardware more complicated than it absolutely has to be to achieve design objectives.
The problem I see with the combination descent/ascent vehicles is that this type of EDL solution attempts to account for such a wide range of potential problems that the end result is fairly complicated. I think it's unrealistic to think a thorough testing program can be conducted with one or perhaps two descents/ascents at Mars.
The only problem with all of this is the mass of payloads that must be sent to Mars. Those are large enough to require assembly in LEO, not direct shots to Mars. No way around that, either.
The number one problem we currently contend with is the incredible cost of getting to LEO. If launch costs were between a quarter and half of what F9H promises to deliver, we'd have no problems sending the more massive combination descent/ascent vehicles to Mars. Heck, a lot of problems are solved if launch costs drop to between $250/kg to $500/kg.
But as launch prices have fallen from the $25,000-30,000/lb we had with shuttle to the $2500/lb we have with Atlas-5 and Falcon-9, and to the $1000/lb we will soon have with Falcon-Heavy, this is not an objection that would rule out this kind of mission architecture.
Only the high costs associated with SLS would preclude this approach as unaffordable.
SLS was clearly designed to maintain STS status quo, with respect to launch costs and complexity. There are some payloads, due to dimensions or mass, that would best be lofted with SLS. As long as we have SLS, we may as well use it where it makes other aspects of space exploration, like orbital assembly, less complicated.
So far, the only real downside I see to this approach is the need to do LEO assembly of those landers. Their diameters are typically around 10 m, too large to put together on the ground and ride up. The real choice is (1) do we need an SLS to launch these landers (a minority of the tonnage to send)? or (2) do we learn how to provide the assembly bay and spacesuits necessary to do on-orbit assembly of this type?
We're already assembling the MTV at ISS, so why not assemble the landers there, too? If there wasn't such a fixation on landing the astronauts together, this wouldn't be a problem. If everyone involved can't get past that fixation, then ISS assembly is the solution.
We have about 5-10 more years before we need to freeze the design for the Mars mission for the 2030-2035 time frame. Which do you believe would be easier to do in 5-10 years: (1) get SLS flying, or (2) learn how to do assembly in space and develop a supple spacesuit?
GW
We don't have to learn how to do assembly in space. We have decades of experience with that. SLS will fly, the only question is whether or not the solution will be retained for those rare instances where using SLS solves so many other problems that the cost penalty for flying it is worth it. SLS has plausible uses for real space exploration, even if it is prohibitively expensive to actually use it, whereas Orion has no plausible uses for anything other than astronaut transfer to the moon.
If SLS Block IB can be developed in any reasonable amount of time, I think a SLS upper stage derived MTV (Skylab II) should be flown to ISS for testing. Although Skylab II is not a minimum mass and volume ITV design, such as the ISS derived hardware DSH is, it makes the transit to and from Mars a lot more comfortable for the astronauts.
We do need a MCP suit for EVA's on Mars. The Z-2 suit will suffice for exoatmospheric EVA's. Development programs for both of those suits could be completed in five years with sufficient funding.
#8035 Re: Human missions » Yet another Mars architecture » 2015-04-30 13:35:45
I was thinking of a smaller pressurized habitat. Basically enough for all 4 astronauts in spacesuits to sit in seats. Think of a minivan, not an RV.
Initially I tried to reduce mass to the minimum. That plan didn't include a pressurized rover at all, just an unpressurized rover with the habitat. As Robert Zubrin said, in case the hab lands too far from the ERV (or MAV). Instead have an open, unpressurized rover similar to a lunar rover but designed for 4 astronauts. And carry a pressure tent. Just a tent. I came up with a simple tent design for one astronaut, that used the spacesuit PLSS for life support. A 2 meter diameter dome tent, with aluminized polymer walls, and a polymer window with flap to cover the window. The floor would be an integrated air mattress; obviously round for a dome tent. With multiple layers of polymer within the air mattress, and a light fan (about the size of a computer case fan) to circulate air within the air mattress. This fan would be controlled by a thermostat. A tent on Mars would lose more heat to the ground than atmosphere, so the fan is for temperature control. Carry a bottle of pressurized oxygen to inflate the tent. The tent would only pressurize to suit pressure. And connect the PLSS to the rover to recharge the battery, and continuous power when sleeping at night. CO2 sorbent in PLSS for EMU on ISS is no longer lithium hydroxide; now they use silver oxide sheet metal. That can be regenerated simply by baking CO2 out in an electric oven. But I have a paper from the mid-90s, from the NASA technical support server, about silver oxide granules regenerated with a microwave oven. The granules have more surface area per unit mass of silver oxide, so it reduces mass. And the granules are compatible with microwave regeneration, which uses less power than an electric oven. (duh!) So include a portable regeneration oven on the rover; about the size of a toaster oven. That means losing CO2, but this is Mars, the hab can always harvest more CO2 from Mars atmosphere. The current EMU has activated charcoal integrated in the same cartridge, it's called "contaminant control cartridge". Activated charcoal removes bad smalls, and it can be thermally regenerated as well. So the whole cartridge is regenerated in an oven.
By the way, "activated charcoal" is just charcoal foam. It has very thin walls to the bubbles of the foam to maximize surface area. Bad smells bond to the surface.
How about tenting instead of RV-ing?
Rob,
I still think a much larger and heavier rover, like the MTVL concept I put forth, is required. All the minimum mass surface mobility options seem to have a lot of ways in which they could fail. I totally blanked on the fact that Martian dust storms can just about kill solar panel output. A reactor like SAFE-400 may be required for my rover concept, even though I was trying to avoid placing a reactor anywhere near the astronauts. I didn't budget for the extra mass of the reactor, either. The F9H + SEP tug + MTVL + EDL hardware solution I spec'd were designed to fulfill requirements for habitation by two astronauts for approximately 250 days and the propulsion and descent solution was designed to land ~17t on Mars using hardware that's already in the development pipeline. The mass of my solution is right at the limit of what can reasonably be done, though, and doesn't leave much room at all for mass increases.
I don't know what the right answer is, but I prefer solutions that don't test the limits of human endurance or technological innovation. Actually living in an inflatable tent or a rover the size of a minivan is a lot different than briefly using one for temporary shelter or transportation.
#8036 Re: Human missions » Yet another Mars architecture » 2015-04-29 16:18:21
Terraformer wrote:3 kWe, for 214 kg? Would it not be better to investigate the use of strontium nuclear batteries? I'm sure they could achieve much better power density than that, and without the issues that typically arise when talking about nuclear reactors IN SPACE?
Ok. I looked at the nuclear battery on Curiosity. The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) generates 125 watts Beginning-Of-Life (BOL), 100 watts End-Of-Life (EOL), contains 4.8kg of plutonium, and total mass 45kg. Energy density is much lower than HOMER-15. Producing 6 kWe (EOL) would require 60 of them, totalling 2,700 kg. A pair of HOMER-15 reactors would total 428 kg. If you know something better, I'm all ears. (Or eyes on the forum)
A SAFE-400 reactor weighs 512kg and provides 100kWe and presumably provides waste heat that can be used to keep metallic components of the rover at more reasonable temperatures than Mars' frigid environment would otherwise allow. A 100hp electric motor would presumably provide all the speed required for your rover, would it not?
Shielding would have to be increased since the astronauts may spend a fair amount of time in close proximity to this thing, but it does solve a lot of other problems with power requirements for redundant ECLSS and reserve power for charging batteries and dashes to rescue injured or wayward astronauts.
If there was a way to halve that weight and reactor volume, presumably using better nuclear fuels that requires far less fissile material to achieve criticality and a far lighter moderator, you'd really be on to something.
Just a thought.
BTW, Rob, how much IMLEO for your plan?
#8037 Re: Human missions » Yet another Mars architecture » 2015-04-28 16:15:23
Rob,
The concept sounds great, but how much IMLEO?
Why are you going to aerocapture the ITV with the lander attached? Why not just capture first and then rendezvous with the lander? What type of thermal management requirements would the ITV and/or lander have to attempt what you're asking? Maybe GW can provide an indication of what type of thermal flux this thing is going to be subjected to when it aerocaptures. Is the lander's heat shield so large that it acts as the brake for the ITV and lander stack?
The ECLSS NASA is currently working on is significantly more compact, capable, and reliable than what's aboard ISS right now. It's going to be at least several more years before that's ready for prime time, maybe even five or six years with current funding. I'd prioritize that project, but I don't run NASA.
#8038 Re: Human missions » Yet another Mars architecture » 2015-04-28 13:37:48
Your mission plan is not the only one.
Good to know.
Claiming every other plan constitutes "killing the crew" is hyperbole and bullshit.
If you put the entire crew in one capsule, which probably would not have been tested on Mars more than once due to the mission hardware and launch costs, and that capsule has a problem that inhibits a successful landing, what else would you call that?
If NASA had a budget 25% greater than what it currently receives, I'd be all for a multi-person lander. There'd be more than enough funding to devote to EDL hardware and launch costs associated with testing. Funding has already been allocated where it has and current commitments have survived two administrations from opposing political parties. The next administration is not likely to kill Orion or SLS, given how far along those projects are in development.
My plan includes pre-landing a laboratory. And include a pressurized rover with that lab, with recycling life support. Crew lands with the habitat. Normally, the lab will be connected to the hab; the hab will provide all life support. But if something goes wrong with the hab, then the pressurized rover will be connected to the lab, which is the backup habitat. If crew have to use the lab as hab, then expect laboratory equipment will have to be removed in favour of living space. So using the lab as the hab means loss of mission, but not loss of crew.
Landing the crew in the habitat module is certainly an option, but that also means the entire EDL solution has all the attendant baggage that a man rated system carries with it. In other words, it will take NASA an inordinate amount of time, cost beaucoup bucks, and be heavier than absolutely necessary. How many crew members do you intend to send and what's the target mass of the solution?
What's your plan for transferring the crew to the lander? Do you favor an orbital rendezvous at Mars or does the lander + habitat + rover have to be connected to the MTV? What will your IMLEO be for the MTV + lander + habitat + rover?
If something goes wrong with the primary habitat module, do you have a method worked out to transfer consumables from the primary habitat module? In other words, does the rover or habitat module have an airlock that can accommodate a cargo container or two and a suited crew member? How many crew members can the rover's ECLSS handle, long-term, does it have ECLSS redundancy, and how big is that rover?
#8039 Re: Human missions » Yet another Mars architecture » 2015-04-28 11:12:21
The Mars Rover expeditions have shown there are many places on Mars where there are large plains scattered with rocks of manageable size.
The pre-landings could serve several purposes:
Yep.
1. Laying guidance transponders.
This certainly helps improve landing accuracy and needs to be seriously pursued.
2. Clearing a safe landing zone.
This requires serious earth moving equipment. Perhaps a nuclear powered robotic Bobcat could be used?
3. Manufacturing rocket fuel for an ascent vehicle (or maybe on a first mission, storing such fuel).
This solves landed payload mass requirements and needs to be seriously pursued.
4. Providing long term consumables for a two year stay.
This is definitely required for exploration.
5. Providing mining robots to mine for water, iron ore or other resources.
This is a long term permanent human habitability goal that's not required for surface exploration.
6. Establishing a surface hab for the first colonists to transfer into.
This is a long term permanent human habitability goal that's not required for surface exploration.
7. Providing an automated farm hab to grow food on the surface.
This is a long term permanent human habitability goal that's not required for surface exploration.
8. Mapping of the surface - down to 10s of cms.
I believe we've already done that, but I'll have to go back and check with the resolutions were.
#8040 Re: Human missions » Yet another Mars architecture » 2015-04-28 11:04:51
Reliable lightweight aeroentry is vital to landing large masses on Mars. And I'm not suggesting it be developed later rather than sooner. Seriously, I'm not. It just doesn't matter as far as the crew goes. It will always be safer to land the crew separately (And indeed that is what you're suggesting if you have the kind of mission where the crew arrive 2 weeks later).
Wow! I was beginning to think, based on all the other responses I've received in other threads, that everyone else was in favor of killing the entire crew if something goes wrong with human EDL on Mars.
I will differ on one issue and that's I think you don't need to land anything on Mars larger than about 15 tonnes. Practically anything you can think of can be built up from that scale. I see Mars drive as a response to the "big lander problem" but I believe they're going a bit too far in the other direction. In any case they don't really make the landing problem go away either.
A 15t landed payload corresponds to what a single F9H flight could deliver to Mars using a SEP tug and ADEPT. If NASA wants to give a SEP tug "something to do", perhaps they could land a mobile habitat on the surface of Mars.
You're defending Mars direct. Fortunately I'm not
Mars Direct looks a lot like flags and footprints to me because the proposed HLLV costs so much to develop and operate and the landed payloads are so massive. Mars Semi-Direct looks like a more plausible, and certainly more affordable, way to get humans to Mars.
What I do see though is a lot of frustration people have with NASA coming up with ridiculously large mission mass. And thus a lot of architectures that are attacking the problem from particular directions. Mars direct is largely a response to the NASA overkill. I kinda like it in some ways. Its got a certain minimalism. But, for me the solution ultimately lies in something a bit more considered, a bit more conservative, but still not wasteful either.
Yes, lots of us are frustrated that NASA says it wants to conduct a meaningful surface exploration campaign of Mars, but the only proposed mission architectures from NASA and most everyone else are essentially establishing a base, which de-facto means all operations would be conducted at or near the base. Establishing a base of operations on Mars may require much larger landed payloads and it may be a worthy long term exploration or colonization goal, but it's guaranteed to be so that we simply won't go to Mars to begin with.
However we get to Mars, its going to take a decade or two. And that's time enough to for everyone to sit around and bang heads together and not get too wedded to their particular approach.
If it takes more than ten years, it's probably not going to happen. Each successive political administration has their own personal proclivities and NASA, Congress, and the President are all deeply afflicted with NIH syndrome.
NASA isn't the only body that theoretically could do this. I think ESA has the resources to do this eventually. Japan, China could all play the part.
I agree. No one else has an EDL tech program to land anywhere but Earth. However, ESA, Russia, and China could eventually complete successful tele-robotic surface exploration campaigns from manned platforms orbiting Mars.
The thing about the US is that if you've got a great architecture, whose going to build it. If its NASA then you've got to get through its strange meld of hard core rationality, plain old fashioned bureaucracy, and US style corporate welfare. Not that the ESA doesn't have its own politics at play.
NASA has to develop and manufacture the human habitability and EDL solutions in house. There's no current commercial interest in the systems required for long duration space flight or landing on another planet. NASA can contract with SpaceX for launch services and crew transfer services.
Point is, even the most spartan Mars architectures are not pocket money. Eventually the big space agencies will have to be won over. And if that's the case they're going to be won over with with architectural proposals that don't just save launch costs, but also simplify development effort and most of all don't make them look like they're taking unnecessary risk with their crew.
Easier said than done. NASA constantly and literally tries to reinvent the wheel and if someone already invented something that works really well, they don't seem to show much interest in it. The one big exception are the JPL guys. They're constantly trying to figure out what they can do with what they have and what they know.
And that's about as far into politics as I dare venture. I'm interested in this as a problem worth solving that hasn't been solved well by anyone, yet.
For me, politics is a lot like watching paint dry. That said, it may be necessary to get into the game to get the kind of support required for a project like this one.
We do have time to get the technology right, to scrutinize what we're doing in unprecedented detail and do it safely, and I might add, in style.
One would think that. There doesn't appear to be any coherent program at NASA or any other government sponsored space exploration agency with that objective.
#8041 Re: Human missions » Yet another Mars architecture » 2015-04-28 06:03:59
Louis,
I've never thought that landing accuracy was a particularly challenging aspect of the mission. JPL is trying to call a snow day on manned Mars landings due to their aerocapture entry accuracy, which is still less than 10km. No manned mission needs to use aerocapture. Any manned EDL should start in LMO.
Until your explanation of what you wanted to do, I thought you'd suggested littering the landing area with supplies to ensure that the astronauts would have consumables once they'd landed. We already have high precision surface maps. We need to test a transponder system or GPS that permits two or more vehicles to rendezvous on the surface.
If you want to set up a base of operations as soon as you get there, then you can have the robot or robots start deploying structures for a base. Understand that as soon as you establish a base, you're never going very far from that base.
Pushing rocks and debris out of the landing area is an excellent idea but that could take a long time, if it's even possible, without real earth moving equipment.
#8042 Re: Human missions » Yet another Mars architecture » 2015-04-27 16:40:58
Louis,
Reusing Red Dragon for subsequent landings is not possible. It's wishful thinking. No spacecraft ever built has been reused after reentry. The months of refurbishment work to re-certify the orbiters for flight after each reentry in enormous specialized terrestrial facilities that employ hundreds of workers doesn't count.
You either land a really small and light one man capsule for a human or you land as big a cargo package as your lift vehicle and EDL solution allow with a single launch. That'd be between 15t and 17t for F9H if you use SEP to send the payload to Mars. The key to survival on the Martian surface is mobility and complete redundancy. If you land far off course in Red Dragon or any other EDL solution that does not include a fully fueled ascent vehicle and you're not mobile, you'll probably be a permanent resident. If you design a mobile mission architecture that's required for any real surface exploration effort, a side benefit is that you can screw up landings something fierce and live to tell the tale. You still have to land within a hundred kilometers or so of a waiting surface rover, but landing 20km away from a habitat module doesn't equate to loss of crew and loss of mission.
Put another way, what typically happens here on Earth when you miss the runway? The same thing will happen on Mars. Some things you just have to get right. EDL on Mars is just one of those things.
Littering the landing area with supplies won't help, either. You can't throw supplies all over the landing area and hope you land near them unless money is not a problem. If money is not a problem, you can afford to land the most massive multi-person lander your heart desires, complete with a fully fueled ascent vehicle and habitat module. Money is a major problem. That's why scattering extremely expensive payloads all over the Martian surface isn't an option and neither is designing massive EDL vehicles.
#8043 Re: Human missions » Yet another Mars architecture » 2015-04-26 15:44:01
I think you're overengineering.
We are there on all fronts now I would say, given development time. Any leaps required are as nothing compared with what was achieved in the five years between Apollo going from design to a lunar-capable system.
Your first statement there pretty much sums up the problem. If only development time and funding that is not available due to the congressionally mandated Orion and SLS projects was made available, a manned Mars mission would be achievable. The statement "We think we have the solutions to mission requirements for a manned Mars mission" and "We have flight rated hardware sitting over there waiting to be launched to Mars" are two entirely different statements. We can't make the latter statement because we don't have a single piece of hardware ready for a manned Mars mission. More than four decades after the stated goal was publicized by NASA, we still have no flight rated hardware for that purpose.
We could continue to pump money into the manned space program for another two decades to give NASA's corporate partners "something to do". We won't have anything to show for it, but we could do that. Alternatively, we could issue an ultimatum with a timeline attached to it. Either NASA figures out how to get humans to Mars in ten years or less with the existing budget or we pull the funding for the manned space program. My first six years of employment were spent working for Uncle Sam. Sometimes you have to light a fire if you want something accomplished.
The solution to many of the supposedly "insurmountable" problems is pre-landing of supplies a landing zone.
Caching supplies on the surface doesn't solve any problems unless you're close enough to reach the cache. Being highly mobile on the surface of Mars lowers landing tonnage requirements, not caching supplies. You can always litter landing areas with supplies if you want to, but that increases tonnage requirements.
Entry is not a problem - it is clear to me that the Space X cantilevered design will work. We just need a minimal descent/ascent vehicle. Once people get to the surface they can then transfer within 3 days to a full functioning hab that has been pre-landed.
I agree with need to have minimalist descent/ascent solutions for humans, but what does the SpaceX "cantilevered design" have to do with that?
We don't need anything bigger than 50 tonne loads as we can assemble the transfer vehicle in LEO from multiple parts.
Having true heavy lift vehicles reduces the number of assembly operations required, but it's not a show stopper.
The health effects of a long term mission can be tested in a lunar orbiting and lunar landing test run.
We already know what the long term health effects of microgravity and radiation exposure are, but for whatever reasons NASA has devoted no funding to implementation of artificial gravity and there's no serious funding devoted to active radiation shielding.
#8044 Re: Interplanetary transportation » Forget NTR, SEP is the Future » 2015-04-26 13:10:27
There are intelligent ways to use SEP in conjunction with chemical rockets to minimize the mass of the propulsion systems required for a manned Mars mission.
In my DRM, chemical rockets (F9H only) are used to lift the individual pieces to ISS for assembly and testing as well as transfer crews to MTV's at L1.
There are some reasons why this works well and it requires an explanation of how mission hardware is assembled and utilized:
Individual mission hardware components are launched using F9H for assembly at ISS. The SEP system is integrated with the MTV rather than being a separate module mated to the MTV. The total mass of the MTV is low enough for this to be practical since no massive multi-person lander or heavy capsule system is attached to it.
A chemical kick stage with storable propellants is mated to the MTV at ISS as part of final assembly. Once assembly and checkout have been completed, the unmanned MTV is transferred to L1 using a SEP tug. This eliminates crew time for the transfer from LEO to L1, eliminates crew radiation exposure problems associated with spiraling out through the Van Allen belts, and permits the MTV to protect its solar arrays during its transit to L1.
The crew boards the MTV at L1 using Dragon/F9H. The Dragon capsule would then be returned to ISS using the SEP tug that brought the MTV to L1.
The chemical kick stage sends the MTV to Mars from L1, eliminating the time required to spiral out. The MTV's onboard SEP propulsion system is only responsible for LMO insertion, transfer to L1 from LMO, and L1 insertion. If a SEP tug mated a chemical kick stage to the MTV in LMO for the MTV to use to depart LMO, then all we require our SEP system to accomplish is LMO insertion from L1 and L1 insertion from LMO.
After the MTV returns to L1 another Dragon capsule takes the crew from the MTV to ISS to return to Earth with a departing ISS crew or the MTV crew can simply return to Earth. A SEP tug would take the MTV back to ISS for repairs, refurbishment, and refueling.
The synergistic use of chemical and SEP can keep mission hardware component masses within the lift capability of single F9H flights. Refraining from adding the mass of multi-person landers and capsules to the MTV permits use of integrated SEP hardware.
The point to all of that is that there are ways to make SEP work for manned missions, but only in conjunction with chemical rockets and only for missions that don't start in LEO (neither of which is a big deal, IMO). If you don't use chemical rockets with SEP, your transfer times go up dramatically or your ISP takes a big hit. From NASA's own DRA 5.0 presentation, using NEP resulted in the lowest IMLEO and using NTR resulted in the greatest number of days on Mars. Combined chemical and SEP resulted in missions with the longest duration, with the fewest days on Mars. However, IMLEO was on par with NEP and we're all aware of how launch costs affect mission costs.
Using an Americium fueled reactor, gas core for NTR or thin film for NEP, would make the comparison more favorable for the nuclear options. The insistence on using Uranium fueled reactors that require large core diameters and heavy moderators to sustain fission is what makes nuclear power unattractive in terms of power density. There's such an extreme difference in volume and mass between a reactor fueled with Uranium vs Americium that there's no case to be made for continuing research into using Uranium fuels for space nuclear power.
#8045 Re: Interplanetary transportation » Forget NTR, SEP is the Future » 2015-04-25 23:42:50
NTR doesn't receive any funding because stupid people are deathly afraid of anything with nuclear in the title and that's all there is to it. The fact that no one has been killed in the US by nuclear power generation, for the entire history of our use of nuclear power, does not dissuade the stupid people from associating nuclear power with nuclear weapons.
There is no comparison, none whatsoever, between the energy density of nuclear fuels and the theoretical maximum energy density of solar panels. There is a real problem with converting all the energy released in fission into electricity, though. That's a different problem.
Uranium, even HEU, is not an optimal fuel for space power and propulsion applications. Naturally, NASA has decided to spend what little money it devotes to NTR research on producing sub-optimal nuclear fuel rod assemblies for sub-optimal methods for using nuclear reactors for propulsion. Space nuclear reactors wouldn't be nearly as big and heavy as they are if Americium was used instead of Uranium.
SEP is a technology worthy of continued development because it's ISP is better than chemical and the nuclear thermal alternative, which provides both high thrust and high ISP, is unpopular with stupid people. That does not mean that nuclear power and propulsion are not worthy of future development.
I'm not holding my breath, but if Lockheed manages to produce a working fusion reactor of the size and power they're currently working on within the next five years or so, this debate will be entirely academic. Fusion research receives plenty of funding from a variety of universities, corporations, and governments.
#8046 Re: Human missions » Yet another Mars architecture » 2015-04-25 21:43:44
I'm still frustrated. SLS is the shuttle ET, SME, SRB, and upper stage uses J-2X which is an upgrade of the J-2 used by Saturn V. J-2 was upgraded to J-2S in 1965-1972. So why is it taking so long, so expensive?
Rob,
What don't you get about this?
SLS is not STS hardware. It's an all-new, untested rocket.
The avionics are all-new.
They have to develop a new payload shroud.
The upper stage program was never completed.
They've completely replaced the control unit for the RS-25. May as well be a new untested engine.
The SRB's are 5 segment, not 4 segment, and they constructed slightly differently. May as well be a new untested SRM.
The mobile launch platform had to be upgraded because it wasn't designed for the crushing weight of SLS.
The existing pad facilities had to be redesigned and upgraded because the exhaust from the RS-25's is not diverted in the same manner and the facilities were literally crumbling after three decades of continuous use.
The VAB integration hardware had to be refurbished, replaced, and/or redesigned to accommodate a very different vehicle from STS.
In every way that matters, SLS is a completely new and untested rocket that required numerous infrastructure changes to support operations.
Retiring Saturn V was a mistake of SLS proportions. That's what happens when you let stupid people, like the overwhelming majority of American politicians, decide which projects live and die. That's our system of governance, as dumb as it is, and we have to live with it or start a revolution to change it. We'd be having a conversation about colonizing Mars or going to Jupiter right now if NASA was appropriately funded and permitted to use its resources as it saw fit. That's not the world we live in.
#8047 Re: Human missions » Yet another Mars architecture » 2015-04-25 21:22:07
SpaceNut,
I disagree about near-readiness, unless that's defined as ten years down the road. It should be taken for granted that anything NASA does these days will have been tested to perfection before they ever stake the lives of humans on the readiness of a particular technology or system. The whole "going to Mars with the hardware you have" idea is quaint, but deep space is a completely unforgiving environment.
I don't think deep space testing is going to produce any heretofore unknown issues with ISS-derived mission hardware, but we're still farting around in LEO more than four decades after we did send men into deep space. The worst part is that we already have the hardware for deep space transit.
At this point, I see no reason why we couldn't attempt a manned Mars flyby with existing hardware or hardware scheduled to be flown in the next few years.
* ISS laboratory module outfitted with avionics, RCS, ECLSS, PE water tank for SPE shielding, and five berthing ports
* 4 BEAM modules attached to the lab-hab to hold consumables (to provide slightly more pressurized volume than a MPLM, split the consumables between four modules instead of one, and not require development of a "utility tunnel")
* Assembly at ISS (finally using ISS for what it was originally intended for)
* Use Dragon for crew transfer (it's going to be man rated before Orion is)
* Chemical kick stage for orbital transfer (no advanced propulsion required)
This mission would require 2-3 F9H flights. The cost for the mission hardware would likely be equivalent to the cost for a SLS rocket. Total mission cost would likely be double or triple what a SLS rocket costs. In other words, mission costs for the flyby are within the realm of NASA's current manned space flight budget and not something far out in fantasy land, as the Purdue mission architecture is.
That'd be a darn good test of the various habitability elements required to support future deep space missions. If there's funding available for more advanced inflatable habitat modules, Skylab II style modules, and/or artificial gravity modules, fine. If not, we'd have a vehicle capable of ferrying humans around the inner solar system that we've actually tested in deep space. The SEP and EDL tech would still be required for achieving orbit and landing, but we'd be a heck of a lot closer to manned Mars exploration than we are today.
#8048 Re: Human missions » Yet another Mars architecture » 2015-04-25 17:50:56
GW,
It would seem that someone in Congress forgot about, perhaps ignored, or more likely never read Part Deux of Akin's Law #39 since none of those morons are aerospace engineers.
I think we've blown too much money on SLS to throw everything away. There's no explanation that passes muster as to why it wasn't originally designed as a 125t to 150t rocket, though.
Why do so many mission architectures put forth by big name universities, astronauts, and scientists rely on hardware that only exists on paper? Shouldn't these people know better than to rely on paper hardware? More money from heaven nonsense?
#8049 Re: Interplanetary transportation » Super-heavy Space Rocket Project in Russia(Successor to Buran/Energia) » 2015-04-25 11:49:31
We could always cooperate with each other instead of this "every man for himself" crap, but that'd probably make way too much sense. Humans to Mars in the next ten years would be completely doable with existing budgets if every space faring nation collaborated on the task. I was really hoping that manned Mars exploration would be the first task that we collectively undertake.
#8050 Re: Human missions » Yet another Mars architecture » 2015-04-25 09:58:23
Dream big, but be prepared to be confronted with reality. We lack fundamental technologies required for human habitation. There's no budget to do what the kids from Purdue want to do, either, but that's a minor technical detail.
* CL-ECLSS
* Active Radiation Shielding
* SEP tug
* Interplanetary Transit Vehicle
* HIAD and ADEPT
All other elements of any deep space mission are a question of what you want to do when you get to wherever you want to go. The five enabling technologies listed above are hard requirements. If ARM was taken seriously, we'd have CL-ECLSS, a SEP tug, and Interplanetary Transit Vehicle. We may get a proof-of-concept SEP tug and one deep space test of Orion from ARM.
We're going to need a real HLLV if we want to lift that much tonnage. If SLS was a 150t capable vehicle by 2022, that works out to roughly 2.5 launches per year between 2022 and 2040. The current budget would support no more than 1.5 launches per year. I seriously doubt that SLS will be much more than a 105t capable vehicle in its most capable configuration. At 115t-125t, SLS is pretty near to the practical limit of what that vehicle's design would be capable of without a complete redesign to add a 5th RS-25 (confirmed by ATK) or liquid boosters (something that there's no infrastructure or even room on the pad to support).
If F9H could be developed into a 100t class vehicle with a significantly larger payload shroud while not simultaneously dramatically increasing launch costs, the launch schedule would be supportable from a budget perspective. That would mean a redesign of F9H, though.
The flight schedule alone is a bit unrealistic with existing rockets. Ten years from now, who knows? Anything's possible.
Start really small. That means small capsules, small ITV's, and small landers. We can concern ourselves with colonization and whatnot after we get there. We have to get there first. I think we need to stop pushing the master colonization plans until we get there. That doesn't mean we stop thinking big, but in the near term we must focus on all the incremental technology advancements and test objectives required to realize the dream.