Land Crew in large pressurized Rover

Impaler · 2012-05-20 04:32:25

I notice that most mission architecture land the crew in an immobile Habitat type structure and then if mass budgeting allows a pressurized rover is inserted somewhere else in an um-manned cargo lander, it seems the rover is the first thing to get cut when mass needs to be shaved. As the pressurized Rover is critical to making long distance excursions and field studies any performance reduction their has a big impact on the science potential of the mission. I propose that instead the Rover be scaled up until it is a FULL EDL payload (~20 mt depending on the EDL architecture) and the crew be delivered to the Martian surface IN said rover ready to 'hit the ground rolling'.

Scenario:

The Mars Rover Lander (MRL) is pre-positioned in Mars orbit in a slow cargo flight. The Habitat the crew has used for the Interplanetary Transit (ITH) would brake into Mars orbit and then dock with the MRL for crew transfer and then the ITH remains in orbit and acts as the Habitat for the Earth return portion of the trip docking with a Earth Return booster stage with a long duration consumables module (ERS) in-order to make the return. In event of failure to dock with the MRL or a determination that it is unfit the surface landing can be scrubbed and the docking made with the ERS instead with a wait in Mars orbit for the return window to open.

On successful landing of the MRL the crew is inside a functional vehicle charged with 2-4 weeks of consumables and the main stock of scientific equipment. The Rover brings the crew to the immobile Habitat lander and Assent Vehicle and can house the full crew on long duration excursions and then return to the Habitat and ISRU and/or Power sources for recharge/restocking.

Advantages:

Interplanetary transit Hab dose not need to be designed for Martian EDL and can be re-used for Earth Return. Likewise no 'throw-away' minimalist landing capsule.

The Scientific equipment can be stowed on and integrated with the rover allowing significantly bulkier, power-hungry equipment (drill-rigs?) while also elimination surface logistical work of moving equipment to-and-from another lander or a laboratory inside the immobile habitat. The Rover takes all equipment with in ware-ever it goes.

A larger 'maxed' Rover's power-train and structural frame should allow for higher speed/safety (sliding scale, pick your preferred point) during excursions.

Full Crew in Rover avoids splitting up the crew during long excursions allowing all critical skill sets (science, engineering, medical) to be present at all times for crew mutual-support (like Lunar Rovers buddy system). Also avoids difficulty of maintaining communications between Rover and distant Hab.

Rover is sufficiently robust in Life-support (weeks without recharge) that it functions as a life-boat in case of main Hab failure. Repeated Repair attempt EVA's can be made from the Rover to attempt to restore primary Habitat. With access to ISRU plant and outside power life-support could be maintained even longer, albeit at a level so cramping that it would be deleterious to the research objectives.

Rover landing touchdown can exploit the Rovers own suspension and wheels as shock absorbers, eliminating one set of landing-legs from Cargo landers that would otherwise bring all of the items now put in or on the rover. Likewise Rover seating eliminates the need for redundant gravity-couch type equipment inside habitats.

Accuracy of landing ellipses necessary for mission successes vastly reduced to levels at or below current capabilities. Only a failure of landing accuracy AND rover mobility strands the crew unable to reach the Habitat before consumables are exhausted. Adjustment to Martian gravity can also occur without haste if the crew is coming from a 0g or less then Martian g condition during transit.

Builds on Large and Growing experience base of autonomous rovers architecture, power-train and science payloads but puts Humans in the loop eliminating huge time delay and slowness of semi-autonomy, vastly increasing productivity before and during EVA's by using initial tel-operationally gathered data to decided if EVA is worthwhile.

If other Landers are equipped for towing/dragging the large Rover will have enough power to make this possible over short to medium distances should this be desirable in the mission architecture. Likewise large scale Regolith moving activities will be possible for research purposes (trenches) and for logistical purposes (burial for radiation shielding and thermal insulation, boulder clearing and grading for safety).

EVA onto the Mars surface can be made exclusively from the Rover rather then the Habitat, ware as initial crew landing in Habitat forces at-least initial EVA's to be from the Hab. Habitat should connects to the Rover by dust-excluding sleeve/tent (not necessarily pressurized) to isolate all dust contamination to the Rover itself to minimize risk to crew health or Habitat function.

Last edited by Impaler (2012-05-20 04:45:23)

GW Johnson · 2012-05-20 13:16:45

Impaler:

I quite agree with you. Leave the transfer habitat in orbit for return. That provided a huge payoff in Apollo. Why sacrifice the benefits of "lunar orbit rendezvous" at Mars?

The lander could be itself the habitat, as in Apollo. Or, maybe not, if its engines are solid core nuclear, as in NERVA. Who yet knows? Depends upon what we might get operational in the next 5 years or so.

It would be handy to have at least a small shirtsleeve environment on the surface in which to eat, sleep, and do whatever lab work supports "exploration". That last item is far more important than it might sound, and is something we did NOT do on Apollo. That surface habitat could be nothing more than the inflatable version of a Quonset hut. That engineering problem is not all that hard to solve.

As for rovers, it's design depends mostly on the size, mass, and endurance of the astronaut's spacesuit, because that is the "payload" for every astronaut being carried. Why not consider a mechanical counterpressure suit? They are 2-4 times lighter, and unbelievably more supple than the "traditional" gas balloon suits we currently use.

If we were to back off from the arbitrary NASA requirement of 1/3 atm equivalent body compression, to about 1/5 to 1/4 of an atm, we could build one today in the lab that worked (we already did, way, way back in 1969), and we could "develop" it to a usable form in about 5 years, given the "right" contractors.

A lightweight astronaut/suit requires FAR LESS of a rover, maybe even one that is unpressurized (just carry an inflatable Quonset hut with you). Such a thing might even be able to "fly" on rocket engines to very long ranges, compared to what we are used to thinking about (surface battery cars). Liquid propellants really do store more energy per unit mass than any battery ever imagined, so far.

Gotta think way outside the "traditional boxes" to really solve these problems. There are a few of us (very few) who did that professionally. From 1976 until 1994, I did exactly that, for aerospace/defense applications. And I was very good at it. Space travel stuff is really no different.

That's why I come up with these wild-seeming ideas. If you look closely, they might actually work. Maybe, they are not really so wild after all.

GW

SpaceNut · 2012-05-20 16:52:05

The idea is not new to have alarge rover for the crew to land in. Such work is currently being put together for publishment on the http://tech.groups.yahoo.com/group/marsdrivemission/ which initially was initiated by Michael Bloxham also of the same here which we did have a thread that was part of the crash which has not come back as of yet. This was also discussed on the nasaspaceflight forum...

New Mars Mission Design- Team Members Needed

louis · 2012-05-20 19:15:47

I think if you're going to land a large tonnage it makes sense. However, I favour more modest tonnages with more emphasis on ISRU. That way I think you get more bang for your bucks.

SpaceNut · 2012-05-20 20:12:58

Went exploring manually and located a few more newmars topics....

The first version of a manned mission as worked on by the Marsdrive Group over on Yahoo http://www.newmars.com/forums/viewtopic.php?id=5539

Then the question as I meantioned before by Michael Bloxham Shouldn't there be more focus on surface mobility? that this thread by Impaler is also in wonder of....

And a much older one here Combining the Rover and Hab - Go RV'ing

Rune · 2012-05-21 09:39:12

Sure, put the Hab on wheels. It is a sound idea. That way it can go after the lander, and the ascent vehicle if they are not the same (in most ISRU plans they are not). It is conceivable that they end up a few kms away from each other, and that way you can relax the landing precision requirements in the first place. But I would put it on an earlier cargo flight, and land it unmanned. Why? Well, first you wouldn't need to make it safe enough for people. Just safe enough that you think it is likely to be pulled off at the first try. If you fail, you send another and delay the whole thing two years, big-ish deal and certainly big money, but no deaths.

Second, you can actually test that all the hab systems work before you commit yourself to a surface stay remotely. It is also good to test that your ascent vehicle looks good before you land, that is why I like the rotation of landers in Mars Direct. I wouldn't make them the return vehicles all the way to earth (makes them big, and non-reusable or single stage), but otherwise I like the concept of having one ready and bringing another in case that fails.

You also do need a manned ship to take off, period, and it has to land at some point, so it makes sense to put the astronauts in that one, and since it has to take off again it makes sense to make it light. A lander crew compartment in one of my scenarios would look more like a soyuz's than anything else.

So, Hab on wheels, that I agree. But I wouldn't call that a rover... in fact if the mobility system was detachable (I'm thinking something like ATHLETE, which is already built and everything), it could transport the astronauts in a light inflatable tent on short trips around the area, while the hab stays put, with it's heavy equipment like labs, supplies, long-term-redundant-as-hell ECLSS and power systems. Probably turning the atmosphere into fuel for the mobility system (I'm thinking methane/LOX fuel cells make sense here, you get the best of both worlds, electrical power and chemical energy density) and the lander that just came down if you have a working ISRU system, too. That would be cool to develop, and you can prove it works without endangering anyone if you have an unmanned flight two years before carrying the hab and the return lander ahead of the crew. The fact that the landers would transport the hydrogen for the sabatier reactors on theirs way down in their empty fuel tanks, eliminating the need to dig anywhere for water and lots of equipment with it, is quite important and drives the architecture a bit, too.

Rune. Remember, doing it in a single flight doubles the size of the propulsion system to push it to mars. Why not use both "MOR" AND "MSR"? (I think those would be the acronyms for Mars Orbit Rendezvous and Mars Surface Rendezvous)

MatthewRRobinson · 2012-05-21 11:59:13

Impaler wrote:

I notice that most mission architecture land the crew in an immobile Habitat type structure and then if mass budgeting allows a pressurized rover is inserted somewhere else in an um-manned cargo lander, it seems the rover is the first thing to get cut when mass needs to be shaved. As the pressurized Rover is critical to making long distance excursions and field studies any performance reduction their has a big impact on the science potential of the mission. I propose that instead the Rover be scaled up until it is a FULL EDL payload (~20 mt depending on the EDL architecture) and the crew be delivered to the Martian surface IN said rover ready to 'hit the ground rolling'.
Scenario:
The Mars Rover Lander (MRL) is pre-positioned in Mars orbit in a slow cargo flight. The Habitat the crew has used for the Interplanetary Transit (ITH) would brake into Mars orbit and then dock with the MRL for crew transfer and then the ITH remains in orbit and acts as the Habitat for the Earth return portion of the trip docking with a Earth Return booster stage with a long duration consumables module (ERS) in-order to make the return. In event of failure to dock with the MRL or a determination that it is unfit the surface landing can be scrubbed and the docking made with the ERS instead with a wait in Mars orbit for the return window to open.
On successful landing of the MRL the crew is inside a functional vehicle charged with 2-4 weeks of consumables and the main stock of scientific equipment. The Rover brings the crew to the immobile Habitat lander and Assent Vehicle and can house the full crew on long duration excursions and then return to the Habitat and ISRU and/or Power sources for recharge/restocking.
...

The thing that I don't like is that this is extremely unsustainable. It's that lack of valuing reusability that led to Apollo dying so quickly, as opposed to the Space Shuttles, which despite being extremely expensive, kept going for 30 years. Not only would you need to design a large, lightweight spacecraft that can survive EDL, but it also has to do it and then start driving around afterwards? It's not too much of a leap, unless you plan for the thing to take off again. But that's exactly the problem; it can't take off again.

I would say, I like the proposal... Conditionally. If, it is only used for one or two missions, and the rest use a different architecture. The MRL would be a great asset on the ground, there's no argument there, but as a lander I consider it a serious failure because it can't take off again. Just imagine if in Apollo we had to launch two Satun V's for every mission, one to land a LEM, and another to land a big rover. Now hopefully you see where my objections are coming from.

Also, consider that you're lobbing around a lot of extra weight carrying the MPS used for landing on the rover. It's not a problem on the HAB, but on the rover you need an engine to move the whole thing, so that extra weight is really going to hurt your range, which will have a huge impact on what science can be done.

Alternatively, I would propose giving the rover standardized "racks" and slots where different scientific packages can be carried. Instead of taking all the scientific equipment with you wherever you go, just take some of it. If you're driving off to do scientific mission X, there's no reason to carry the big scientific package to do scientific mission Y, that's a waste of rover range. Especially when it comes to equipment like drills. No reason to carry that big rig along when you're doing an unrelated mission; you can just leave that at the immobile hab and give yourself more range with the weight savings.

And I's also suggest some way of getting rid of the MPS and other such weight. It could probably be very easily done in a way it's been done before; put all the MPS and such lander, non-rover mass on a pad that the rover sits on, like like what's been done here. Or, alternatively, you might even use a sky crane system like MSL, or maybe even a combination of the two. But however you do it, I highly recommend somehow getting rid of lander MPS mass.

Impaler wrote:

Advantages:
Interplanetary transit Hab dose not need to be designed for Martian EDL and can be re-used for Earth Return. Likewise no 'throw-away' minimalist landing capsule.

Personally, I'd favor an architecture where you don't have to throw-away anything. Though, like I said, I can't argue that such a rover would be an enormous asset.

Impaler wrote:

The Scientific equipment can be stowed on and integrated with the rover allowing significantly bulkier, power-hungry equipment (drill-rigs?) while also elimination surface logistical work of moving equipment to-and-from another lander or a laboratory inside the immobile habitat. The Rover takes all equipment with in ware-ever it goes.

I already replied to this one, and I do agree, except that the rover should take some equipment, depending on how much mass savings it can turn up. If most the packages are pretty light, then I'd go ahead and let them stay on the rover. But heavy rigs like a drill rig, should be detachable to allow for longer-ranged missions.

Impaler wrote:

A larger 'maxed' Rover's power-train and structural frame should allow for higher speed/safety (sliding scale, pick your preferred point) during excursions.

That's an advantage? It sounds like extra weight. Extra weight that's worth what it brings (a mobile lab almost), but I wouldn't list that as an advantage.

Impaler wrote:

Full Crew in Rover avoids splitting up the crew during long excursions allowing all critical skill sets (science, engineering, medical) to be present at all times for crew mutual-support (like Lunar Rovers buddy system). Also avoids difficulty of maintaining communications between Rover and distant Hab.
Rover is sufficiently robust in Life-support (weeks without recharge) that it functions as a life-boat in case of main Hab failure. Repeated Repair attempt EVA's can be made from the Rover to attempt to restore primary Habitat. With access to ISRU plant and outside power life-support could be maintained even longer, albeit at a level so cramping that it would be deleterious to the research objectives.

Definitely agree there. If used in combination with the ERV architecture, that means there'd be three entirely separate redundant life support systems. NASA's rule of three. They'd be happy with that, as would anyone else in the aerospace industry.

Impaler wrote:

Accuracy of landing ellipses necessary for mission successes vastly reduced to levels at or below current capabilities. Only a failure of landing accuracy AND rover mobility strands the crew unable to reach the Habitat before consumables are exhausted. Adjustment to Martian gravity can also occur without haste if the crew is coming from a 0g or less then Martian g condition during transit.

If you use an ERV with a powered descent phase, then that problem is handled. You could even package a very small unpressurized moon-rover like "buggy" with the ERV in case somehow you land a few too many km's away to walk.

No comments on the other 4 advantages, other than a nod.

Also, this whole time you've seen me keep mentioning an ERV. I agree with the idea of landing a rover, or even landing the crew in a large rover, but I think doing away with an ERV is a big mistake. IMO it's just outright nonsensical to use ISRU and make it a mission-critical aspect in the sense that the MAV requires it, but not use it to produce the propellant used for TEI. It's even a little comical. It's like MRDM managed to get the disadvantages of both without getting the advantages of either.

ISRU/ERV
+ Much lower mission mass
- New Technology becomes mission critical

All-up Propellant
+ Safer
- Much more mission mass

ISRU MAV + All-up ITH
- Compromised mission mass (Because aerocapture is impossible, the compromise is far towards the "heavier" side)
- New technology becomes mission critical

If you're going to bring along the ISRU equipment, you'd might as well use it for everything; it's not going to make any difference in safety, and it's going to save an absolutely tremendous amount of mission mass. Not to mention, it means your ITH (which is now an ERV) is already equipped with a heat shield to allow for aerocapture into Mars orbit. And, to add another point, as opposed to a MAV, the ERV would be another backup life support system on the surface that could be not only used for an emergency, but used for months, during which time the crew could continually attempt repairs on the HAB and Rover.

GW Johnson wrote:

Impaler:
I quite agree with you. Leave the transfer habitat in orbit for return. That provided a huge payoff in Apollo. Why sacrifice the benefits of "lunar orbit rendezvous" at Mars?

Because in Apollo we didn't have ISRU to save mission mass.

GW Johnson wrote:

The lander could be itself the habitat, as in Apollo. Or, maybe not, if its engines are solid core nuclear, as in NERVA. Who yet knows? Depends upon what we might get operational in the next 5 years or so.
It would be handy to have at least a small shirtsleeve environment on the surface in which to eat, sleep, and do whatever lab work supports "exploration". That last item is far more important than it might sound, and is something we did NOT do on Apollo. That surface habitat could be nothing more than the inflatable version of a Quonset hut. That engineering problem is not all that hard to solve.
As for rovers, it's design depends mostly on the size, mass, and endurance of the astronaut's spacesuit, because that is the "payload" for every astronaut being carried. Why not consider a mechanical counterpressure suit? They are 2-4 times lighter, and unbelievably more supple than the "traditional" gas balloon suits we currently use.
If we were to back off from the arbitrary NASA requirement of 1/3 atm equivalent body compression, to about 1/5 to 1/4 of an atm, we could build one today in the lab that worked (we already did, way, way back in 1969), and we could "develop" it to a usable form in about 5 years, given the "right" contractors.
A lightweight astronaut/suit requires FAR LESS of a rover, maybe even one that is unpressurized (just carry an inflatable Quonset hut with you). Such a thing might even be able to "fly" on rocket engines to very long ranges, compared to what we are used to thinking about (surface battery cars). Liquid propellants really do store more energy per unit mass than any battery ever imagined, so far.

Flying rovers; an idea worth looking into, maybe, but that's a lot of extra mass for MPS. And just look at the range of a car 2-ton SUV with a 20 gallon gasoline tank, and try to get that same range with a 2-ton rocket with a 20 gallon gasoline tank. No reason that the rover needs to be battery-powered. You're right in that liquid propellants store more energy, so the rover can just use an internal combustion engine designed for CH4/O2. Liquid-fueled internal combustion engines are something we have plenty of experience with
The only disadvantage, is that you can charge a batter with solar panels or nuclear powerplants that provide semi-continuous and continuous power, respectively. But internal combustion is a different story. For that, I'd imagine the same ISRU plant that produced our ERV's propellant could also fill some large storage tanks with propellant for our rover.

Alternatively, or maybe even in addition, you could put solar panels or an RTG on the rover and give it unlimited range. Albiet, once you run out of liquid propellant, you'd be moving a lot more slowly, though it does mean in the event of an emergency you'd eventually get back to the hab, MAV, or ERV.

GW Johnson wrote:

Gotta think way outside the "traditional boxes" to really solve these problems. There are a few of us (very few) who did that professionally. From 1976 until 1994, I did exactly that, for aerospace/defense applications. And I was very good at it. Space travel stuff is really no different.
That's why I come up with these wild-seeming ideas. If you look closely, they might actually work. Maybe, they are not really so wild after all.
GW

At the very least they're thought-provoking

Impaler · 2012-05-21 14:56:15

Some folks seem to have taken my lack of discussion of the method of Assent from Mars and other elements of typical Mars Direct-ish scenarios as an indication these elements are omitted. This is incorrect, I refrain from talking about the Mars assent because it is irrelevant, no reasonable rover would contribute to to that phase of the mission other then to drive the crew to the assent vehicle.

I'm operating under a few constraining assumptions that should help make my logic more clear.

1: The Martial EDL technology along with the TMI stages and ultimately the Launcher we have available constrains each landing to a modest standardized payload size.
2: The Crew must reach the surface in one of these EDL modules and because they are essentially identical the risk to the crew from EDL failure is equal what ever they go in.
3: A Habitat capable of comfortably housing the full crew and providing all their consumables for the surface stay can be fit in this payload size but only just and it will be desirable to have this already on the Martian surface before the crew arrives ruling it out as the crew landing vehicle.
4: A Mars Assent Vehicle either ISRU based or pre-filled (take your pick) can also be built within this payload limit but again only JUST. Indeed the mass budget on Mars Assent is the main driver for ISRU so their is going to be no way to put cargo here. Again this asset should be in place before the crew arrives ruling it out as the crew lander.
5: A pressurized vehicle is necessary for good science return and such a vehicle would necessitate at-least one additional lander due to the mass and physical dimensions of such a vehicle.

When I put these assumptions together I conclude that it would be better to make the Rover as large as possible and Fill an entire landing mass budget with it, rather then to send a small rover along with a mixed set of equipment/supplies/consumables etc. Furthermore I conclude that because the crew is under equal danger in EDL if landing in an immobile Habitat vs the Rover the Rover's advantages in immediate mobility and the ability to re-use the Interplanetary transit Hab means the Rover should be the crew lander. Effectively we get the advantages of a 'Max' rover (the maximum lander payload mass) over a more modest rover at virtually no cost in Initial Mass LEO.

I attempt to provide an estimate on how much performance such a Maxed Rover might provide but these area admittedly just estimates, I can be sure that even the Max Rover can't provide the life-support duration that an equal mass immobile habitat could provide and I don't think it's reasonable to expect a rover of any size to be the one and only mission habitat and to just 'gypsy' around in it. Thus the necessity to periodically return to the main Habitat to recharge both the crew (more space and comfort in the Hab) as well as the life-support capability of the Rover (Food, air, water, fuel).

Last edited by Impaler (2012-05-21 14:58:09)

SpaceNut · 2012-05-21 20:32:02

Much like the other thread that MatthewRRobinson has ask with regards to and on the benefits of ERV, MAV and MTV the elements surface Habitats, ect.... These are all parts but until you link them together with the right words is just an alphabet soup.... even the athlete is just another piece to use in another manner for a set of mission words.

The large RV habitat is meant to minimize the exposure to the elements for the first crew while exploring greater distances..

Throw away pieces of mission designs versus reuseable as well is not as important as to going as starting to go....
You reuse by going back to the same spot over and over again....

Impaler · 2012-05-22 05:46:27

Actually returning to the same spot is a bad idea in my opinion, I know many scenario's do that but your just going to be re-examining the same ground and to get good scientific data your going to want to explore several places far apart with each mission. This is how they did it in Apollo and it's the logical approach if your looking for knowledge. I think many scenario's involve repeated landings in one spot is because they are in a 'colony' building mind-set and want to accumulate hardware towards some kind of permanent base. This is false, the first missions will be scouting parties not the toe-holds of future colonies, their job is to learn as much as possible about Mars and scout for more attractive places to explore and resources that can be useful. Making camp on the first land you see is always a mistake, that's how the Pilgrims off the Mayflower ended up in freezing cold Massachusetts rather then their intended destination Virgina.

Btw with regard to Rovers, if our mass budget allows perhaps 2 rovers each massing 10-15 mt each could be brought in on one lander, that would make them each the size of a large Unimog but you would be looking at a fairly large payload fairing maybe 7 m to accommodate 2 side by side 5 m rovers.

Rovers are theoretically movable from one landing sight to another by topping off the fuel tank and sending them autonomously to the next landing sight if its within the vehicles maximum one-way range. You probably wouldn't want to count on it though, high likelihood of getting stuck in difficult terrain. A bit of Solar power that allows them to move at a slow but steady pace but with nearly unlimited range might be desirable if the future landing sights are known years in advance.

Last edited by Impaler (2012-05-22 05:52:18)

GW Johnson · 2012-05-22 15:47:20

Returning to one spot is a bad thing only if you decide to confine yourself to the one landing during the mission. Why not make more than one landing? After all, unlike the moon, it's a very long way to Mars and back with men.

GW

SpaceNut · 2012-05-22 19:28:32

Apollo was classed as Flag and Foot prints with the sortie definition used for the missions duration and science that was done....With landings of just 6.... ranging from a few days on the surface to ...not sure memory fails me.... but that said Mars is a 2 plus year cycle and when looking at how many years we covered the moon before cancellation we were done in what..6 years with no more follow on missions....robotic or otherwise...

Even if we used the 6 years for missions to go then we only get 2 or 3 mission before we wll be bored again and not go....So we do need to have multiple landing for each mission trip or we will not go to stay....

Impaler · 2012-05-22 22:54:53

Entry Descent and Landing will be the single most dangerous step in any Mars mission, once a crew is safely on the surface it would be far too dangerous to put them back in the air again even on a sub-orbital flight.

SpaceNut · 2012-05-23 05:17:24

Agreed that the same parachutes and shields would not be good.

Should the rover then be sized for 2 or 3 crewmem and be of a 2 unit concept per mission with a central insitu MAV that they rondevou for return Earth.. and for the big bang for the buck go with a twin MAV mission crew size of 12 split up equally into seperate landing zones...

MatthewRRobinson · 2012-05-23 20:20:20

SpaceNut wrote:

Much like the other thread that MatthewRRobinson has ask with regards to and on the benefits of ERV, MAV and MTV the elements surface Habitats, ect.... These are all parts but until you link them together with the right words is just an alphabet soup.... even the athlete is just another piece to use in another manner for a set of mission words.
[...]

Well, it's really two different mission architectures, that specifically focus on how the crew gets to and from Mars, irrelevant of how the hab and other cargos get there:
ERV: Earth Return Vehicle,
Unmanned ERV sent to Mars. At the next launch window, a manned ERV is sent to Mars. The ERV lands, and the crew ride either one back home at the next return window.
It's essentially Zubrin's ERV from Mars Direct, except I would personally prefer something reusable (and thus single-staged) and that can perform an aerobrake in Earth's upper atmosphere so it can be reused.

MAV+MTV refers specifically to the architecture used in MRDM 5.
MTV: Mars Transfer Vehicle
Large, trans-habbed equipped spacecraft that cannot enter an atmosphere, to serve as a habitat for transit in-between Earth and Mars orbit.
MAV: Mars Ascent Vehicle
Small spacecraft that only goes from martian surface to Mars' orbit, and possibly back again.

Impaler wrote:

Actually returning to the same spot is a bad idea in my opinion, I know many scenario's do that but your just going to be re-examining the same ground and to get good scientific data your going to want to explore several places far apart with each mission. This is how they did it in Apollo and it's the logical approach if your looking for knowledge. I think many scenario's involve repeated landings in one spot is because they are in a 'colony' building mind-set and want to accumulate hardware towards some kind of permanent base. This is false, the first missions will be scouting parties not the toe-holds of future colonies, their job is to learn as much as possible about Mars and scout for more attractive places to explore and resources that can be useful. Making camp on the first land you see is always a mistake, that's how the Pilgrims off the Mayflower ended up in freezing cold Massachusetts rather then their intended destination Virgina.
Btw with regard to Rovers, if our mass budget allows perhaps 2 rovers each massing 10-15 mt each could be brought in on one lander, that would make them each the size of a large Unimog but you would be looking at a fairly large payload fairing maybe 7 m to accommodate 2 side by side 5 m rovers.
Rovers are theoretically movable from one landing sight to another by topping off the fuel tank and sending them autonomously to the next landing sight if its within the vehicles maximum one-way range. You probably wouldn't want to count on it though, high likelihood of getting stuck in difficult terrain. A bit of Solar power that allows them to move at a slow but steady pace but with nearly unlimited range might be desirable if the future landing sights are known years in advance.

I think the best shot would be to save all those extra launches and rovers by just launching one, and maybe a second as backup, and put all the landing sites within one-way range of eachother, giving a good margin of error so the rover doesn't have to go to the very edge of it's range.

There's really no greater chance of it getting stuck on the Martian terrain transiting from one hab to another than there is a chance of it getting stuck in any other situation.

Unlike the MER's, we really can just send a guy with a shovel and/or jack out there if it does get stuck. But, once again, all issues faced transiting from one hab site to another are no different than any other excursion.

One interesting idea might be to have the wheels run on motors - the internal combustion engine is used to generate electrical power to charge the batteries. Effectively, the liquid fuel serves as an energy reserve to charge the batteries with. But you only burn CH4/O2 enough so that the batteries are always just slightly below a full charge.
That way, even if you don't run out of liquid fuel, the solar array will boost your range by providing some drive power even when the internal combustion engine is running, and it would make using the solar array as a backup much easier, since the solar arrays partially power the drive system all the time anyways. Not to mention, motors aside, an electrical drive system should be easier to repair and maintain than one that involves shafts and large moving parts. Mainly I say that because the area that has the best chance of getting scraped up badly is the chassis/undercarriage. A direct drive system from the internal combustion engine with large shafts and such would be extremely difficult to repair. But if all that's on the undercarriage is cables, then field repairs should be relatively easy.

That's something different designers of a Mars mission must face than the Apollo missions - the stuff doesn't just have to work and work well, but also should be easy to repair, even if worse comes to worse, because unlike Apollo the crews will be there for more than a year.

SpaceNut · 2012-05-23 21:29:49

Then you propose that the ERV be sent after a human mission is already gone and must wait for another cycle before it can be used is puts the crew on mars for way longer than its safe to do.

http://www-istp.gsfc.nasa.gov/stargaze/Smars3.htm
The window opens for a period of a couple months and it occurs every 25.6 months....if we launch and look at the period for a return of only 100 days on the surface with no EVR there we have to wait 25.6 more months plus...

Or are you saying to launch the ERV during the open 2 month window after the crew has left for Mars?

GW Johnson · 2012-05-24 10:10:00

So, are these plans for exploration or planting bases? Whether you put your earth return vehicle on the surface or in orbit depends in great part upon the answer to that simple question. Those two things are different missions entirely.

GW

SpaceNut · 2012-05-24 19:28:57

Also it changes the length of the surface mission as well depending on that key point....Suttle changes of preloading of the landing site with a habitat, rovers, extra supplies, ect... can and will change the duration....

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