Mars 9 tons at a time.

[thereiwas]

I assumed we were talking long-stay (until next window) not short stay (return in same window). Long-stay needs more supplies, and I don't think surface habs will cut it due to radiation. That is where all the talk of sandbags and bulldozers comes from.<br /><br />But if the goal is a short-stay mission first that might be enough trips, though I would still send the crew 2 years after the cargo.

 

[JonClarke]

Surface habs are fine for long stay missions as well. Radiation exposures are similar to what is exprienced in LEO. You don't need bulldozers and sand bags. That is more for permanant settlements.<br /><br />However, small scale earth moving capability would be useful. Rovers should come equipped with small blades and buckets. That is where the advanced field robotic capability comes in.<br /><br />Jon<br /><br /><br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[thereiwas]

Even though LEO (at least where ISS orbits) is inside the Van Allen belt and Mars has no such belt?

 

[gunsandrockets]

This is something I wish I knew more about, but I do know a little.<br /><br />The thin atmosphere of Mars does have some radiation shielding effect (I think it also shields against MMOD), and the bulk of Mars underfoot will block radiation from that direction. But I suspect radiation from solar flare events would require additional shielding.<br /><br />I don't see why ISRU water stored in a ceiling tank couldn't be used for hab shielding. Another idea is an inflatable 'igloo' hab, an inflatable pressure vessal with the walls filled with liquid water which then freezes to perform the functions of insulation and radiation shielding. A pressurized Rover might need to store it's engine propellant (or batteries) in the roof for the extra radiation shielding even at the risk of making the rover top-heavy.

 

[j05h]

Radiation has 3 potential sources on Mars, IIRC: solar particles, cosmic rays and local radioactives. One recent piece of research suggested that Mars' atmosphere might cause just enough decay for cosmic rays to make the surface more hostile - instead of a single ray passing through a person it would spray them with a decay byproducts that are more damaging. Tenative, but needless to say, Mars has a challenging radiation environment. EVA may be a rare or underground event. <br /><br />Ceiling tanks and storage are a good idea for a surface Hab or Rover, but there are also somewhat ("sideways") omni-directional particles. Underwater/underground is the place to be. 10m of water overhead provides a better radiation shield than Earth's atmosphere according to Marshall Savage. Living in caves, lava tubes or cliff overhangs for shielding all have their own safety issues. Martian glaciers, especially equatorial Elysium Planitia's huge projected reserve, would be the ideal locations for melting/drilling into. Size a Tunnel Boring Machine to the same as all the Habs, melt them down into vertical tunnels, even right to the ancient seabed. Seal the top of the tunnel with an ice plug and airlock. Live in ice-caves and have access to an entire "core sample" of Mars history. Use the TBM to cut a pattern of tunnels, sell the water and other materials that aren't needed for the base and eventually have a sizable arcology in the ice. Once you can build Really Big, the challenge is building and balancing any domes against the mass of air inside. <br /><br />Mud-slag, water or similar composite could be the most plentiful construction material available, especially for a mining base. Even if construction is as simple as bagging a module and pumping slurry around it until it freezes or your ice-igloo. It could use a polyethylene foam in bags that inflate on arrival, similar to the inflata-foam PCs are shipped in. <br /><br />For a rover, it partly depends on vehicle size. A "Hummer" built w <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[thereiwas]

And remote control the rovers from inside the hab where possible, like on initial surveys.

 

[j05h]

<i>> And remote control the rovers from inside the hab where possible, like on initial surveys.</i><br /><br />Yes. Generally, living in space (except perhaps on Titan or Venus) will require radiation shielding. Hopefully future Martians will spend some time out on the surface instead of just being burrow-dwellers. If Mars is terraformed, any atmosphere generation will greatly improve the radiation environment. It will still probably be "hotter" than Earth, though. For real radiation protection you need to be sealed in water. <br /><br />Following up on my suggestion of poly foam in plastic: if the rover had an inflatable sleeve on top and sides, it would have lightweight shielding. It'd make heat pipes necessary but that is an advantage if a Sterling generator is used in the power train. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[JonClarke]

The vAB's don't provide any protection against galactic cosmic and gamma rays, the GCRs are the main source of radiation. Nothing is going to protect against these except several m of rock or regolith.<br /><br />The vABs do reduce the effect of solar radiation, but they can also be a liability, focussing it at high levels.<br /><br />On Mars the atmosphere provides a surprising about of shielding against solar radiation, 6 g/cm2 at datum, 12 g/cm2 on the floor of Vallis Marineris, Hellas, and Argyre. This is the equivalent to 2.2 and 4.4 cm of aluminium, respectively. Habitat structures will provide additional shielding and you can arrange consumables in a way that they provide still more, if required.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[gunsandrockets]

<On Mars the atmosphere provides a surprising about of shielding against solar radiation, 6 g/cm2 at datum, 12 g/cm2 on the floor of Vallis Marineris, Hellas, and Argyre. This is the equivalent to 2.2 and 4.4 cm of aluminium, respectively.><br /><br />Now that is an interesting factoid. <br />

 

[JonClarke]

Yeah, I was quite surprised when I discovered that. It is also the minimum shielding from the zenith. At angles of 30 degrees above the horizon you get effectively twice that thickness of atmosphere.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[j05h]

<i>>Surely they could be captured into Lunar orbit first, then transferred to Earth orbit.</i><br /><br />Jon, have you read anything about a potentially dangerous "scattering" of cosmic background radiation at Mars' surface? It'd theoretically mean crew are subjected to decay products instead of the main eVent.<br /><br />josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[JonClarke]

There is some secondary radiation - gammas and neutrons emitted by the martian surface as a result of cosmic radiation striking it. This has been mapped by MO of course, to give composition. I have not seen anthing saying that it is, or is not, a hazard to crews on the surface. I would guess that it is quite low, less than the Moon, but don't know.<br /><br />sorry <br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[solarspot]

Just to throw an idea out there regarding the crew...<br /><br />Would it be beneficial to send dwarfs as the first crew? If the spacecraft to carry the crew to Mars is really so mass-restricted, perhaps it would be easier to send people who can survive with less food/drinking water/oxygen and potentially cabin space than regular hight people...<br /><br /><br />

 

[scottb50]

I know a few dwarfs that could eat you under the table and drink you under it at the same time.<br /><br />Maybe you have boiled the thread down to a realization it's more complicated to get to Mars then Zubrin, etal., have proposed.<br /><br />I think what we need is a Cycler, Earth-Mars, Earth-moon, orbit to orbit. Moon Cyclers could prove durability before a Mars Cycler. A four year TBO, would be good.<br /><br />You could also take a Cycler to any NEO, or FEO(?), and back, what you do there is your choice.<br /><br />A Cycler would use a fixed Core. All Cyclers would be identical and provisions would be made to make them identical except they would be updated in software, until hardware changes can be made. Various Modules would dock to the Core, or to each other around and behind the vehicle.<br /><br />Boosters return to LEO. Propellant Modules needed to get into Mars orbit, transfer payloads from orbit and back to orbit and back to Earth orbit are refueled enroute or in orbit. <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

No, not cyclers. They are about the worst possible way to do it. Long flight times, inefficient trajectories, large masses, high entry velocities, narrow windows, nasty failure modes, the list of reasons wjhy you should not use cyclers is very long.<br /><br />The original Mars Direct studies of Zubrin have informed almost every Mars mission study since 1991, and underpinned many of them. It is a very robust concept.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Interesting idea.<br /><br />The problem is that most forms of dwarfism are accompanied by physical problems that would preclude someone from a Mars mission.<br /><br />People have suggested all female crews for reasons of smaller body mass. <br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[arkady]

Fascinating thread, keep going at it!<br /><br />I will probably post something irrelevant out of sheer enthusiasm at some later point, but right now I got some reading up to do. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> "<font color="#0000ff"><em>The choice is the Universe, or nothing</em> ... </font>" - H.G Wells </div>

 

[j05h]

<i>> No, not cyclers. They are about the worst possible way to do it.</i><br /><br />Please, not cyclers! Nor Scott's favorite LEO staging with HLVs. Can we explore and develop Mars with existing rockets? <br /><br />What is the best way to use existing medium-lift rockets using a direct-throw to Mars? Would you stage in orbit after aerobraking, or go in hot for a Zubrin-type direct landing? Which system makes more sense for what payloads? Any suggestions on the lander?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[j05h]

<i>> Would it be beneficial to send dwarfs as the first crew?</i><br /><br />Probably not. The crew needs to be medically average (healthy, active adult). I'm not sure how many dwarf doctors or dwarf geologists there are (Tolkien aside). Finding a qualified short Soyuz pilot might be a problem. Tooling might be an issue, too. The best solution for a "low consumption" crew are very light adult women, but even that sort of restriction is unnecessary. Human-consumption resources shouldn't be a problem during initial stages of exploration, and less-so for any development sites. A lifetime's worth of freeze-dried food only weighs several tons and ISRU water should be abundant. <br /><br />The goal is to throw a lot of mass, incrementally, at Mars. It just gets there in small packages. For resources, an undetermined amount of food, kit and backups would be pre-emplaced on the surface. Some robotic site prep could occur, as would initial methane production, before the first crew arrives.<br /><br />What would you bring?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

About Mars Cyclers:<br /><br />I've made the same mistake. When scottb50 talks about 'cyclers' he doesn't mean the Mars Cycler concept as is commonly used and as we understand it.<br /><br />Scottb50 merely uses the term 'cycler' when refering to the conventional concept of a reusable interplanetary rocket, that's all.

 

[gunsandrockets]

total crew mass vs individual crewmember mass<br /><br />Total crew size and therefore total crew mass is a vital aspect of the total mission mass. Crew is the vital kernal from which all other calculations are made. A mission with two crew should mass 1/3 of what a mission with six crew would mass. Therefore it's worth considering the possible trade-offs of reducing individual crewmember mass in order to increase the total number of crew per mission.<br /><br />

 

[kelvinzero]

Not dwarves.. Oompa-Loompas!<br />Very hard working and live on cocoa beans. The singing may be a problem.<br />...<br />Sounds like some design questions can't be answered without more prospecting. I still like the idea of a commitment to sending a continual tonnage.<br /><br />How about some sort of robotic workhorse, in decent numbers, that can handle the inital prospecting but also remain a valuable asset once we send humans? In fact perhaps the first manned mission could be to phobos while using the oportunity for better teleoperation of the mars robots.

 

[JonClarke]

A lot depends on what you want to do when you get there and how long you have got to do it. Also the skills mix.<br /><br />With only two crew you would be looking and two mechanic/enegineer types, who do some science on the side. Much like Apollo.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[scottb50]

Scottb50 merely uses the term 'cycler' when refering to the conventional concept of a reusable interplanetary rocket, that's all...<br /><br />Absolutely, I'm talking about a Vehicle that travels between LEO and LMO, or LEO and LLO, over and over again. Aerobrake where possible and enter an elliptical orbit, refining it with subsequent burns. <div class="Discussion_UserSignature"> </div>

 

[thereiwas]

All the crew does not have to go in the same vehicle. And the way they go need not be the way they come back.<br /><br />I assumed that multiple launches to LEO and assembling a large transit vehicle there is outside the parameters of this exercise.