New Mars Forums

heh, shieldiness  <!--emo&:D

Zubrin noted (briefly, as always) in The Case for Mars that the astronauts could fill sandbags with regolith upon arrival and lay them over the roof of the hab. The practicaility of this would depend on the condition of the astronauts on landing (It would be a shame if a weak astronaut fell off the roof of the Hab on M-Day 2 and broke a leg.)

Using regolith in some fashion would be appropriate and efficient, and suit the 'living off the land' theme of the exploration. The pressurised Rover could have a backhoe / shovel attachment for excavating and displacing regolith.

Gregory Benford noted in his novel The Martian Race that hab water was stored in a distributed fashion through the hull, to provide an addition layer of radiation coverage.

If water can be produced in-situ from permafrost or other sources it would be a good shielding material. The Astronauts could inflate bladders (either separable or built in) mounted on the roof or walls.  It could not be assumed however that Astronauts could be able to find and extract water on the first mission though. Water has the advantage that it can be pumped from one location to another, albeit in a heavily insulated hose.

--Merp.

Thanks RobS

One thing I have always wondered about cyclers is how easy would it be to 'jump on' as it went past? Additionally, if the maneuver for whatever reason failed, what abort options would be available?

I'm not sure I like the idea of separating the MAV and ERV since it introduces two significant complications - the need for an orbital rendevous and the maintenance issues you mentioned, including long term storage of cryogenic fuels in orbit. The reusability of a MAV you mention is very promising but would require an integrated landing capability that would drive up the mass.

On the other hand, For both ERV and Hab missions I really get the feeling that we could do with more space. The MAV/ERV should have enough space for the reactor, a chemical plant (of greater flexibility and adaptability than Zubrins' ) and other missions supplies for both scientific and engineering experiments.

The pressurised Rover should definately arrive with the Hab, to provide the mobility required in the case the landing places the crew far away from the ERV. Apart from this I think the weights Zubrin quotes are bit optimistic.

All of which suggests we should use alternate propulsion to increase the mass delivered to the surface. This isn't as big a deal as it was when Zubrin wrote The Case for Mars.

I wonder if we could modularize certain pieces of equipment to make them common between both the ERV / Hab?  eg If both the Hab and ERV have three 'stages'.

Hab - standard Hab section(HAB), mission section (MIS), and Lander sections (LND) (Re-entry rockets and struts on the bottom, aeroshield, parachute, solar energy and communications gear on the top). 

ERV - standard Hab section(HAB), standard Lander section (LND)  and earth return section (ERN) (delivers the Hab to mars orbit or earth)

This obviously isn't a perfect concept (where does the chem plant go?), but I think investing in designs with common elements would be worthwhile,  saving money, simplifying production and allowing flexibility in mission by swapping out sections.

Just a thought

PS. Does anyone know where I can find out information on using the TransHAB in a Mars mission?

--Merp

I don't know if the doom and gloom over 0.38G is justified. 0.38G is greater than 0G by a factor of... (work it out). Its a substantial difference and the truth is we don't have research on long-term low gravity exposure to say either way.

My own feeling is that any (non-zero) gravity well might stop bone decalcification, which is the real demon. As far as I know muscular deterioration is thoroughly reversable, and in 0.38G, 5psi, heavy physical activity environment would probably be negligible.

I agree with Zubrin that hosting humans in LEO just for the purpose of discovering how bad the effects of zero G are is entirely unethical, as is the lack of research into artificial gravity.

--Merp

After doing some research on the net, I've been pleasantly surprised by 2 things

1) non-US government development in the space sector is tanglible and growing. ESA's Mars Express / Beagle 2, France's Netlander, Japan's Nozumi(sp?) and the Plantary Society's Cosmos Solar Sail project are all in the works right now.

Nasa is throwing money into a blackhole with the ISS at the moment. At the same time countries like China are developing a manned spaceflight capability while other agencies are targeting Mars with robotic science missions. The launch vehicle market is saturated at the moment, driving down prices. Russian infrastructure provides a cost-effective alternative to that in the US.

How long will it take the average US Congressman to realise that the US technical advantage is being eroded?

2) Nasa's Smaller, Faster, Cheaper approach is obviously not achieving our goals for human exploration, but it is providing an excellent scientific payoff. Does any one doubt that the confirmation of large permafrost deposits on Mars help our cause?

The highly successful Discovery and Scout class missions have introduced competitiveness into some parts of NASA operations. The New Frontiers program proposed by the administration will extend this to larger scale (<= $650m)missions. There is a problem, however, with this cheaper robotic approach to exploration of the solar system. As noted recently by the National Academy of Sciences, less money per mission means less technology development is achieved.

I'm all for NASA's scientific exploration of the Mars.

I have a question, however. If you are going to end up spending billions of dollars over 20+ years sending robotic missions to Mars, all the while NOT generating much public interest, culminating in a sample return mission,  why not just bite the bullet - Develop a manned mission architecture that not only achieves the science goals, but that also pushes technology and human endeavor forward.

It is frustrating, but perhaps in the long run the lack of US progress towards moving man out of LEO will allow other nations to start catching up, and inadvertantly reignite some vision and drive within the US government. I blame NASA for a lot of the current situation, but responsibility must be shared across all industrialised nations.

--Merp

Hi all. This is my first post... I thought I would cut my teeth replying to Matt

You could use carbon nanotubes as the tether material. They are mentioned in a recent Space.com article about current groups with designs on a terrestrial space elevator. I imagine the same issues would be applicable to both applications, except for scale.

On this issue of mid-course corrections... I think it would be quite possible. After all, nearly every correction must be well timed anyway. I would advocate carrying some small amounts of reserve propellent and hydrazine just in case rotation or course needs further refinement (owing to the lack of experimental data on such).

What risk factors do you imagine? Storage of a propellent that doesn't need cryogenic storage should be relatively simple - or at least a lot simpler than imported alternatives. In fact I think a bigger risk factor would be the transit and storage of the small amount of H2 feedstock that Zubrin specifies. 

The hab, according to Zubrin's fitout, has an independent 5kWe Solar power source. Presumably this includes batteries and is operable on the surface (pg 94 TCFM certainly talks like it is).

On the nuclear issue, the NRC's recent SSE survey highlighted the requirement for nuclear power generation in space. Also featuring prominently is the development of advanced RTGs:

Onward and upward...

Once again, Zubrin's weight allowance for science and field equipment is 1 tonne. I don't know how much equipment this buys, but it is probably important to remember that the astronauts can use the same equipment to do the same experiments across their entire accessible range. Boring for the astronauts, maybe, but probably very valuable science-wise. In comparison to robotic visits, 1 tonne is a huge amount, and it is leveraged by the fact that humans can use such equipment a lot more flexibly, and in different situations than a robot.

Also, remember that time will be taken up by travelling (in the rover), day to day maintainence, R&R and communications and reports to Earth. If the next Hab were deployed elsewhere on the planet, the explorers would only 500 days to explore as much as possible of it. This doesn't seem like a lot to me.

I know.. I keep thinking that there must be some pretty serious flaws in the design for the agencies to ignore it like they have. Does anyone know the rationale behind Nasa's Mars Semi-Direct? Perhaps if we can work out why they changed the architecture we could discern what they perceived its faults to be?

My guess is that if Mars Direct is perceived to have flaws they could be:

1) that the weight allowances might be way off
2) that maintainence issues might be under-represented - What are the consequences of dust contamination of the hab and vital machinery, etc?

Cheers.