Alternative Mars Architecture based on Constellation

cIclops · 2008-02-07 04:09:46

Works for sturdy equipment, but the initial impact produces 25 Gs of acceleration. That will make any astronauts chunky salsa on the back wall. Even padded acceleration couches with seat belts will not protect astronauts from that acceleration.

25G impact is survivable, according to this fascinating article: Human factors in commercial suborbital flight

What are the basic impact tolerances for well secured and well positioned humans? Work pioneered by the late John Paul Stapp and others over the past half century has established these limits for human subjects, cadavers, and assorted animal models. Plus Gz (eyeballs down) of a well-positioned (not bent forward) person is up to about +30 Gz applied at rates of up to about 500 G/sec. Minus Gz (eyeballs up) can be tolerated up to about –15 Gz applied at up to about 200 G/sec. Plus Gx (eyeballs in) can be tolerated up to about +40 Gx for up to about 250 milliseconds. Minus Gx (eyeballs out) can be tolerated up to about –40 Gx for up to about 150 milliseconds and –25 Gx for up to about one second.

cIclops · 2008-02-07 04:23:21

Having a nuclear reactor poke along behind you on a separate truck? I don't like it, the reactor still has to be extra-big to generate enough power, and the cable will be very troublesome if not dangerous. You are also eliminating a large swath of terrain you won't be able to move around in: the area behind you, as there will be too much radiation.
Also making the HAB mobile really does place unacceptable constraints on the volume of the HAB, especially with add-on modules down the road or whatnot.
A permanent base should also be higher on the priority list I think, especially to get at the one resource that is critical for the future: water. We will want to establish a drilling rig for water as soon as we reasonably can, which calls for a stationary location.
And being that Mars is such a big place, the short range of a mobile HAB won't cover much more of it than rovers could thanks to its lower speed. For that matter, nor would it be a good option for finding a permanent base site.

The mobile nuclear power plant will be integrated with the fuel ISRU. If power beaming isn't practicable, then a separate generator (fuel cell) could power the Hab using ISRU fuel. How much would local terrain be irradiated and for what distance if the power plant stayed unshielded in one spot for 100 days?

If the "permanent" base is only an ISRU facility, then there will need to be more than one. Consider that the maximum distance from a fixed base is about 10,600 kms.

cIclops · 2008-02-07 06:50:14

I feel compelled to point out that the goal of the first few launch windows, even the first decade, is not to poke at every mildly amusing rock within a 500km radius, but to assemble, fabricate, an build up a capability to support a growing human population, which can then in turn poke at rocks at will.
Towards this end, we will want to establish a handful of continuously occupied, fair sized bases on opposite sides of the planet built of both local and imported equipment, capable of producing a surplus of life support goods, like food, water, air and fuel. Smaller outposts evenly spaced in between to store supplies, and other wish serve as semi-permenent outpost for more localized exploration.
Within a decade, the entire planet will be open to the kind of purely scientific rock poking everyone seems so excited about.

This will require a massive space policy change. And to do that will require either an extraordinary event or enormous public demand. The former is a possibility, the later is probably not. Even if colonizing Mars became a policy goal, using the first few launches to support a "growing human population" is not a sound way to proceed. Basic exploration, testing of equipment (especially the transportation system!), seeing how human physiology and psychology adapt, is critical. All that has to be done before a such a base can be designed. There are too many unknowns. It will probably require a second generation transportation system before such a project becomes affordable. Mars colonization is far in the future, perhaps after a Lunar colony is established. Nice dream though.

dicktice · 2008-02-07 10:00:09

And I feel compelled to reiterate that the so-called "caverns on Mars" shouldn't be overlooked during the first phase of exploration. Why no serious discussion of this, so far?

RobertDyck · 2008-02-07 13:10:37

And I feel compelled to reiterate that the so-called "caverns on Mars" shouldn't be overlooked during the first phase of exploration. Why no serious discussion of this, so far?

With no ground water movement and no massive limestone deposits, there will be no caverns as we on Earth know them. The only caverns on Mars are lava tubes. Lava tubes are something most people aren't familiar with. What I saw on TV of explorers in lava tubes, they tend to have very rough floors, holes in the roof, and the floors are covered in razor sharp shards of lava including obsidian. Not all the rubble is razor sharp, but enough is to be a hazard. You need very good boots to walk through one.

Most importantly for Mars, a lava tube is not sealed air tight. It tends to be open at the exit end, and has holes in the roof. I don't know how strong the rock would be, can it hold pressure?

RobertDyck · 2008-02-07 13:13:17

25G impact is survivable

Huh. Still wouldn't want to do it. I want landing rockets and legs. Let me land without pushing the limits of human tollerance.

JoshNH4H · 2008-02-07 14:44:46

Back to the moving hab- Impractical, but there are many benefits that can't be ignored. I would suggest a long range rover being included (very long range, 2000+ km) or possibly a deflatible hab, so that it could be set up 2 or 3 times over the course of the mission.

RobertDyck · 2008-02-07 14:54:53

Mars colonization is far in the future

Bite your tungue! :x

GCNRevenger · 2008-02-07 18:45:06

The only caverns on Mars are lava tubes. Lava tubes are something most people aren't familiar with. What I saw on TV of explorers in lava tubes, they tend to have very rough floors, holes in the roof, and the floors are covered in razor sharp shards of lava...
...Most importantly for Mars, a lava tube is not sealed air tight. It tends to be open at the exit end, and has holes in the roof. I don't know how strong the rock would be, can it hold pressure?

And why would you want to? You could build a perfectly nice inflatable habitat by chemically combining Martian CO2 and water to make plastics. Need extra radiation shielding? Bury it with/in Martian dirt.

GCNRevenger · 2008-02-07 19:47:17

The mobile nuclear power plant will be integrated with the fuel ISRU. If power beaming isn't practicable, then a separate generator (fuel cell) could power the Hab using ISRU fuel. How much would local terrain be irradiated and for what distance if the power plant stayed unshielded in one spot for 100 days?
If the "permanent" base is only an ISRU facility, then there will need to be more than one. Consider that the maximum distance from a fixed base is about 10,600 kms.

If you are going to lug around a fuel cell power plant you may as well instead use that mass for a smaller "satellite" ISRU plant to refuel a long-range rover anyway. A mobile HAB will be difficult to design in any case, particularly accommodating the heat shield or enough volume. The HAB itself will also need extra tough construction to handle the bending and bouncing going over rough terrain. And I bet that the shaking will be rough on hardware too.

No, we should go to Mars with a stationary lander and long-range pressurized rover, preferably with a drill on board, with landing sites near areas of interest with a mind on finding a good place for a permanent research base. Again, a buildup of hardware at a central site for the purpose of a permanently manned research base, with laboratory volume, ISRU for life support/fuel/light-duty building materials should be a high priority: avoiding "Apollo on Mars" is, after all, the one thing we have to have. Right?

The list of reasons why a mobile HAB is a bad is a long one, and puts this idea to bed.

cIclops · 2008-02-08 05:18:53

The mobile nuclear power plant will be integrated with the fuel ISRU. If power beaming isn't practicable, then a separate generator (fuel cell) could power the Hab using ISRU fuel. How much would local terrain be irradiated and for what distance if the power plant stayed unshielded in one spot for 100 days?
If the "permanent" base is only an ISRU facility, then there will need to be more than one. Consider that the maximum distance from a fixed base is about 10,600 kms.
If you are going to lug around a fuel cell power plant you may as well instead use that mass for a smaller "satellite" ISRU plant to refuel a long-range rover anyway. A mobile HAB will be difficult to design in any case, particularly accommodating the heat shield or enough volume. The HAB itself will also need extra tough construction to handle the bending and bouncing going over rough terrain. And I bet that the shaking will be rough on hardware too.
No, we should go to Mars with a stationary lander and long-range pressurized rover, preferably with a drill on board, with landing sites near areas of interest with a mind on finding a good place for a permanent research base. Again, a buildup of hardware at a central site for the purpose of a permanently manned research base, with laboratory volume, ISRU for life support/fuel/light-duty building materials should be a high priority: avoiding "Apollo on Mars" is, after all, the one thing we have to have. Right?
The list of reasons why a mobile HAB is a bad is a long one, and puts this idea to bed.

Time to wake up

A fully mobile exploration system has many advantages, including flexibility, efficiency and adaptability to the unknown. An enormous amount of information will be available from satellites, many sites will be identified (MSL had 30 proposed landing sites) so the ability to send people to these will be very important. On the planetary scale a fixed base is analogous to a robot lander such as Viking, and a mobile platform to a rover. Isn't it better to design a relocatable facility given that exploration has to cover an area the same as the whole of Earth's land surface?

The ideal solution would be a fully relocatable outpost, the question then is how to transport it. By "air" will be much harder than across the surface, so that leaves one option, by ground. An outpost needs energy & supplies and has to provide shelter and lab equipment. A mobile design was considered for the Lunar Outpost based on the ATHLETE platform. It had the capability to move elements 1000 kms or more with only an 8% mass overhead. On the positive side there will be 20 more years of new technology to use. Clearly if the technology isn't ready then this approach won't work, yet it surely should be fully discussed. There's plenty of time

So the level and extent of local irradiation from a reactor isn't known? Perhaps sufficient shielding can be added from local materials.

Commodore · 2008-02-10 20:05:53

I feel compelled to point out that the goal of the first few launch windows, even the first decade, is not to poke at every mildly amusing rock within a 500km radius, but to assemble, fabricate, an build up a capability to support a growing human population, which can then in turn poke at rocks at will.
Towards this end, we will want to establish a handful of continuously occupied, fair sized bases on opposite sides of the planet built of both local and imported equipment, capable of producing a surplus of life support goods, like food, water, air and fuel. Smaller outposts evenly spaced in between to store supplies, and other wish serve as semi-permenent outpost for more localized exploration.
Within a decade, the entire planet will be open to the kind of purely scientific rock poking everyone seems so excited about.
This will require a massive space policy change. And to do that will require either an extraordinary event or enormous public demand. The former is a possibility, the later is probably not.

It is a huge change in policy. But all it requires is leadership that looks beyond the next election. Oh wait, does that count as an extraordinary event. I try not to be that cynical.

Even if colonizing Mars became a policy goal, using the first few launches to support a "growing human population" is not a sound way to proceed. Basic exploration, testing of equipment (especially the transportation system!), seeing how human physiology and psychology adapt, is critical. All that has to be done before a such a base can be designed. There are too many unknowns. It will probably require a second generation transportation system before such a project becomes affordable. Mars colonization is far in the future, perhaps after a Lunar colony is established. Nice dream though.

It depends on how its done. The only thing we really need to establish a base is an assessable supply of sub-surface water. Anything else will be well tested on the lunar surface, long before entering interplanetary space.

Also, I don't consider such an effort to be colonization, but exploration in the purest sense. On Earth, exploration is piece meal, and not automatically needed to formally colonize. On Mars, you got to know where everything is to plan a colony cause there is no room for error. Of course to do that you have to put a sizable number of people on the ground. Thats difference between the kind of flags and foot prints missions that poke around isolated areas, and a long term, sustained campaign that give purpose to it.

SpaceNut · 2019-06-01 11:34:25

Wow a topic that started before 2008's great crash with boiloff of hydrogen discussion. Long-duration cryogenic storage of propellant and life support liquids is an enabling technology within the critical path of nearly all envisioned human planetary missions.
Microgravity Zero Boiloff Tank experiments provide data for Pressure Control Systems

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#26 2008-02-07 04:09:46

Re: Alternative Mars Architecture based on Constellation

#27 2008-02-07 04:23:21

Re: Alternative Mars Architecture based on Constellation

#28 2008-02-07 06:50:14

Re: Alternative Mars Architecture based on Constellation

#29 2008-02-07 10:00:09

Re: Alternative Mars Architecture based on Constellation

#30 2008-02-07 13:10:37

Re: Alternative Mars Architecture based on Constellation

#31 2008-02-07 13:13:17

Re: Alternative Mars Architecture based on Constellation

#32 2008-02-07 14:44:46

Re: Alternative Mars Architecture based on Constellation

#33 2008-02-07 14:54:53

Re: Alternative Mars Architecture based on Constellation

#34 2008-02-07 18:45:06

Re: Alternative Mars Architecture based on Constellation

#35 2008-02-07 19:47:17

Re: Alternative Mars Architecture based on Constellation

#36 2008-02-08 05:18:53

Re: Alternative Mars Architecture based on Constellation

#37 2008-02-10 20:05:53

Re: Alternative Mars Architecture based on Constellation

#38 2019-06-01 11:34:25

Re: Alternative Mars Architecture based on Constellation

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