Mars Direct Rethought - Fixing the potholes in Zubrin's plan

Nirgal82 · 2002-08-11 13:09:57

Okie dokie, I'm sure this has been discussed here before but, here goes...
I was looking over the details of the Mars Direct plan and noticed a few holes. This being the case I found my head was comming up with numerous questions.
Here's a few

Firstly, Zubrin clearly states that a tether be used to connect the hab/aeroshell combo to the spent rocket stage that pushed the whole thing on the way to Mars.
What is this tether going to be made of?
I've heard that tethers have problems with oscillations.
Can mid-course corrections be made using precision computer controlled propellant firings?

Next, the whole plan rests on in-situ production of rocket fuel for the return trip. How effective and fail proof is the storage process for keeping the fuel for the duration of the wait for the crew as well as the duration of the proposed 500 day stay?
Speaking of fuel production, the power source suggested by Zubrin is a small nuclear powerplant. How likely is this?
And what reasonable alternatives are there? Also, keep in mind that it also has to power the Hab reliably for the 500 day stay. (unless the Hab comes with its own power)
OK, lastly (for now, mwa ha hah hah...sorry)
Is there actually enough to do during the long 500 day stay?
I was wondering if you could pack an M-year's worth of experiments into the tunacan that is the Hab while still meeting wieght requirments.
I hope we can fix these little problems. Perhaps these are some of the reasons why NASA, ESA, or Russia hasn't picked up this obviously ingenious plan.

Your friendly neighborhood Martian...
-Matt

Nirgal82 · 2002-08-11 13:24:40

Sorry, thought about this about 2 seconds after hitting the "add reply" button.
Zubrin says that a "closed loop life support system" is to be used with an inflatable greenhouse structure attached to the hab.
Ok, so what materials can be used for such a greenhouse?
Also, we would be depending on the successful harvest of plants grown an extra half AU away from the sun for survival.
How sure can we be that we will get yeilds from such conditions, even if you up the CO2 percentage of the greenhouse atmosphere?
I've read and have participated in discussions on other forums about the effectiveness of growing plants in Mars ambient light. The current consensus seems to be that arrays of white LED lights be used rather than ambient light.
Perhaps a major precursor mission to Mars Direct would be to send a group of greenhouse landers to Mars, each set up with different configurations, one with an inflatable greenhouse garden, another closed to ambient light using LEDs, and even one with an inflatable structure with a rotating mirror array that could help concentrate Martian ambient sunlight.
This would probably require two or more landers (only two if you make the inflatable greenhouse a double experiment, first try it without the mirrors then have the mirrors come out for duty once the first experiment is completed)
The data from these experiments will prove to be very very valuable.
I'd hate to go all the way to Mars only to find out that we cant grow our food. Dry rations aren't all that appetizing, and I doubt that Zubrin's claim of bringing enough to survive the duration of the stay is very strong.

Your friendly neighborhood Martian...
-Matt

Phobos · 2002-08-11 15:33:41

Next, the whole plan rests on in-situ production of rocket fuel for the return trip. How effective and fail proof is the storage process for keeping the fuel for the duration of the wait for the crew as well as the duration of the proposed 500 day stay?
Speaking of fuel production, the power source suggested by Zubrin is a small nuclear powerplant. How likely is this?

I've wondered the same myself. The mere mention of launching nuclear reactors in space is likely to result in a vicious wave of Luddite scare mongering. And on top of that the public seems to think it's hip to be anti-nuclear even if nuclear power is used for peaceful purposes so I'm not to hopeful about the prospects of launching a small nuclear generator into space either.

Is there actually enough to do during the long 500 day stay?
I was wondering if you could pack an M-year's worth of experiments into the tunacan that is the Hab while still meeting wieght requirments.

Yeah, 500 days seems like a long time to stay in the same place. I liked the early Russian plan better of having a train of big rovers land at one pole and slowly proceed toward the next. The 500 days though would give a lot of time to do things like greenhouse experiments and various engineering type projects. Hopefully when the hab lands it'll be in a place with a lot of various geological features within reach, things like dry riverbeds and old craters that will maximize the chance of finding evidence of life and doing geology research.

Perhaps these are some of the reasons why NASA, ESA, or Russia hasn't picked up this obviously ingenious plan.

Could be, but I have a hunch NASA and ESA doesn't wholeheartedly approve of Mars Direct because it's to cheap and wouldn't "utilize" all of their various competing and expensive projects and related teams.

Adrian · 2002-08-11 15:54:19

I've wondered the same myself. The mere mention of launching nuclear reactors in space is likely to result in a vicious wave of Luddite scare mongering. And on top of that the public seems to think it's hip to be anti-nuclear even if nuclear power is used for peaceful purposes so I'm not to hopeful about the prospects of launching a small nuclear generator into space either.

There were protests against Cassini, sure - Cassini carried an RTG I think. However, it still flew and I don't think that the greater public were overly concerned. If the only concern about a human Mars mission was the fact that it would carry a nuclear reactor, I don't think that would be enough to derail the mission - providing that it could be shown that it really was the best option and the alternatives were significantly inferior. Don't get me wrong, there'd be vocal protests against the use of a nuclear reactor, but the protestors would be in the minority.

Nirgal82 · 2002-08-11 21:34:51

Yeah, I figured Cassini had to have some sort of nuclear power source, solar electric doesn't work that far out, and its not like its burning coal, heh heh...
Anywho, a lesser concern of mine is the fate of the aeroshell.
Is it jettisoned once the hab or ERV reach subsonic speeds, and if so, perhaps a sortie during the human stay could go retrieve it.
Might seem an exersize in futility, as it would have likely broken up during its crash into the surface. Although it may have enough practical value to put parachutes on the sucker.
Anyone ever thought of it as a radiation shield that could be "draped" or rather set up like an umbrella over the hab?
Might afford just a little bit of extra protection during a dangerous event such as a particularly large solar flare...
Just a thought anyway...more to come later...

Your friendly neighborhood Martian...
-Matt

Nirgal82 · 2002-08-11 21:50:38

In regards to the greenhouse lander experiments, perhaps we should get together and actually draw up some sort of proposal, including all the technical aspects, and petition one of the world's space agencies to actually do it.
Unfortunately I lack the technical skill, however I am very good at brainstorming and coming up with feasible ideas. Perhaps we could, together, write up something that could be taken seriously out there.
Its times like this that I wish I had a website, then I'd simply draw up some simple diagrams for you all to look at. However this is not the case, so as an alternative, I'll draw up some simple bitmap images later on and send them to you people upon request. (maybe someone out there with a site will to share a little space for some small bitmap files {; ) hmmmm?)
Anywho, anyone willing to take on some of the technical aspects of this project, your help will be much appreciated.
Maybe, just maybe, over time, we can do this.
I think the M.S. is a little too tied up in its FMARS project and the artificial G experiment to lend a hand in sending landers to Mars right now, unless someone can prove me wrong...
I hope I'm not being too ambitious...

Your friendly neighborhood Martian...
-Matt

Phobos · 2002-08-12 00:42:49

There were protests against Cassini, sure - Cassini carried an RTG I think. However, it still flew and I don't think that the greater public were overly concerned. If the only concern about a human Mars mission was the fact that it would carry a nuclear reactor, I don't think that would be enough to derail the mission - providing that it could be shown that it really was the best option and the alternatives were significantly inferior. Don't get me wrong, there'd be vocal protests against the use of a nuclear reactor, but the protestors would be in the minority.

I forgot about RTGs on space probes. I think the more cynical side of my nature has taken over tonight. Even if people in one particular country oppose launching a nuclear reactor, we could probably find another participating country that would do it.

In regards to the greenhouse lander experiments, perhaps we should get together and actually draw up some sort of proposal, including all the technical aspects, and petition one of the world's space agencies to actually do it.

This might be a good idea to for that Mars project Adrian mentioned in another message. Personally, I think we'll have to use systems of giant mirrors outside of the greenhouse area to concentrate light on the plants to compensate for the intense sunlight food crops love. Somewhat similiar to your project, I was kind of designing a hypothetical recreational garden for Mars and was looking for plants that would do well in relatively cool environments that weren't in full sun. I found some alpine plants that might work well. I imagine having large enclosed areas that are landscaped to look like natural areas on earth with ponds and plants for people to kick back would be good additions for a colony. Being creative with rocks could add a lot of atmosphere to.

Mark S · 2002-08-12 09:03:20

Is a 550 day surace stay too long for Martian explorers? I don't think so. In fact, it might not be long enough. The purpose of such a long stay is for the astronauts to visit as many different sites as possible and conduct experiments in Martian geology, biology, and meteorology.

The only way to truly see what Mars has to offer during the 550 days is with long-range vehicles. In Zubrin's original plan, the hab would be fueled by Martian carbon dioxide in a nuclear-thermal rocket. This would allow the hab to hop all over the surface of Mars. When NASA picked up the idea in 1993, the hab grew wheels to replace the NTR. Zubrin has also suggested methane-fueled, pressurized rovers, although they will not come close to the versatility of a hopping hab.

Keep in mind, though, that the astronauts will not be conducting EVA s for their entire stay. Dust storms and solar activity will probably keep them indoors for a significant amount of time. They will also be occupied with experiments that will be conducted inside the hab's laboratory. But I guarantee that there will be no shortage of activities for the original explorers of Mars.

turbo · 2002-08-12 09:04:10

Folks, I'm weeks away from a Bachelors degree in Electronics Engineering Technology. I don't see how LEDs are going to anything for plants but illuminate them while they die. LEDs do use less power than regular bulbs, but no off-the-shelf LEDs radiate with the same frequencies the Sun does. I must have been paying attention in Environmental Science that night, since I recall ultraviolet radiation is used for photosynthesis by plants. LEDs radiate in mostly visible light, some are even strictly infrared (the ones in remote controls) so may I suggest some sort of focusing lens?

Uh, Matt, since Mars already has 95% CO2 atmosphere, why try to make a greenhouse environment higher in CO2?

Inflatable greenhouse? How about automated and smaller version of good old chain-cutter to make a trench to just roof over for a green house? (long line of coal miners would like to know why we must bring walls with us when solid rock is already there)

Okay, standing on soapbox is giving me altitude sickness, I'm getting down.

Be Well All!
turbo, student that learned to take the power off before putting my hands in the gizmos

Bill White · 2002-08-12 09:18:26

At another forum we have discussed the sulfur light - I believe one is now being used to light parts of the Smithsonian.

It is a full spectrum light - very durable - and draws power similiar to LEDs.

Nirgal82 · 2002-08-12 09:18:32

Well, in regards to LED's, I have no experiencee or knowledge in that, it was merely a suggestion based on discussions from other forums...
And the C02 garden thing, I meant raise the percentage based on the assumtion that people would want to fill the greenhouse with an air mixture breathable by humans...
Back to the greenhouse lander experiments, I feel that an experiment carried out on Mars, using different growing conditions, must be performed before trying to do agriculture there ourselves. Not only will it give us data based on how plants grow in Mars ambient light, but also give us valuable data on how they grow in less gravity...

Your friendly neighborhood Martian...
-Matt

Bill White · 2002-08-12 09:18:33

At another forum we have discussed the sulfur light - I believe one is now being used to light parts of the Smithsonian.

It is a full spectrum light - very durable - and draws power similiar to LEDs.

turbo · 2002-08-12 09:46:23

At another forum we have discussed the sulfur light - I believe one is now being used to light parts of the Smithsonian.
It is a full spectrum light - very durable - and draws power similiar to LEDs.

Thanks Bill!

Since I've had to recently mess with LEDs as part of my Senior Project, I'll definately look up the sulfur light!

Hmmm, LED is usually 2.5 Volt draw, but has quite an attitude if put in the wrong way. Send one kilo sulfur or one kilo "I'm really a diode but don't tell Edison" to Mars?

Hey Matt, do you know the name of the algae that only grows in the polar regions the Brits were thinking of bombarding Mars with back in the 70s? I thought I still had that old book around but haven't found it yet. Might be nice to have something to tease a PhD with in Environmental Science!

Be Good!
turbo, not everyone's favorite martian but if I can put a PhD on spin cycle first maybe the hab would be easier?

Nirgal82 · 2002-08-12 09:54:08

Gee, heh, I must be a youngin, or at least not as well read as I thought I was, heh heh...
I had no idea that the Brits had plans like that, at any point in time.
So to answer, no, I don't know the name, but I'm guessing its the stuff Vishniac was looking for when he met his unfortunate demise in the antarctic. Probably something that grows underneath the rocks in the dry valleys.
If you, Turbo, or anyone else has a link to info. about this former British endeavor I would definately appreciate it...
By the way, do you know why the plan fell through, I imagine it was ethical concerns...

Your friendly neighborhood Martian...
-Matt

turbo · 2002-08-12 11:16:58

<Hey Matt, do you know the name of the algae that only grows in the polar regions the Brits were thinking of bombarding Mars with back in the 70s? I thought I still had that old book around but haven't found it yet. Might be nice to have something to tease a PhD with in Environmental Science!>
Gee, heh, I must be a youngin, or at least not as well read as I thought I was, heh heh...
I had no idea that the Brits had plans like that, at any point in time.
So to answer, no, I don't know the name, but I'm guessing its the stuff Vishniac was looking for when he met his unfortunate demise in the antarctic. Probably something that grows underneath the rocks in the dry valleys.
If you, Turbo, or anyone else has a link to info. about this former British endeavor I would definately appreciate it...
By the way, do you know why the plan fell through, I imagine it was ethical concerns...
Your friendly neighborhood Martian...
-Matt

I think the algae idea was shelved about the same time as the Daedalus starships. I'll have to keep looking and see what I can find.

Be good!
turbo

Bill White · 2002-08-12 15:21:02

Sulfur lamp links:

http://www.sulfurlamp.com/tech.htm

http://www.thelightingcenter.com/fusion/fusion.asp

2 FAQ from the 2nd link:

How frequently will you need to change the bulb?

The bulbs may, in fact, never need to be changed. Because there is no filament or electrode in the lamp itself, there is nothing to burn out or break. It is possible to consider the bulb to be useable for many years.

* * *

What are some of the more exotic uses you have considered?

There are almost too many to mention. The lamp has been well received by the Department of Agriculture where scientists are looking for ways to use this energy-efficient source of near-sunlight to grow plants in the laboratory. We are also looking at other applications where solar simulation is important.

GOM · 2002-08-12 19:54:40

My prior post in "Wonderland" - - There it is and there its gone - once someone else posts I will delete this placeholder :0

Is this board playing tricks again?

Shaun Barrett · 2002-08-13 02:05:50

I must be living in a time warp or something, but believe it or not, this is the first I've heard of sulfur lamps! And I'm ashamed to admit it because I'd always imagined myself as being reasonably up to date on new technologies.
A nagging concern about Martian colonisation in the recesses of my mind has always been light intensity and potential depression from the dimness of everyday sunshine.
This light source will surely go a long way towards alleviating or even eliminating the problem.
Thanks, Bill, for dragging me into the 21st century! At last, I've seen the light!! (Sorry! )

Phobos · 2002-08-13 15:51:21

I just realized that Bill isn't talking about sodium lamps. I kept thinking how the hell a sodium lamp could be used for growing plants. Anyways, I'm not sure how well these sulfur lamps will do on a very large scale. Plants are very energy hungry machines. Large orbital mirrors that are aimed at domed crop fields might produce better results on a big scale.

RobS · 2002-08-13 18:31:10

In the little bit of research I have done, I don't see any reason to assume that ambient Martian light is insufficient for plants. Corn grows when there'a a month of cloudy weather; it doesn't happen often, but every decade or so it happens. If you had a cylindrical greenhouse with its long axis oriented north-south, in the morning you could lower the insulation on the east side and let in the sunlight; the west side would still have its insulation blanket up, and if the insulation blanket were silvered, it would reflect additional light inside. In the late afternoon you could reverse the process, raising the insulation blanket over the east side of the greenhouse and lowering it on the west side. That would increase insolation maybe fifty percent, making it close to terrestrial normal.

As for the "dim" light bothering astronauts, I don't think anyone would notice. I remember in 1970 I experienced a 95% total eclipse of the sun (I wish I could have gone to the area of totality, but I was too young!). At the height of the eclipse I was experiencing about as much sunlight as Jupiter's moons receive; it was a bit errie, but barely noticable as a fainter background. Next time there is a partial eclipse of the sun in your area, go outside when about half the sun is covered. You won't even notice the drop in insolation. But when its about 95% covered it is noticeable; yet even then, its about like the brightness at sunset.

RobS

Bill White · 2002-08-14 07:36:38

In reply to Phobos:

I just realized that Bill isn't talking about sodium lamps. I kept thinking how the hell a sodium lamp could be used for growing plants.

Anyways, I'm not sure how well these sulfur lamps will do on a very large scale. Plants are very energy hungry machines. Large orbital mirrors that are aimed at domed crop fields might produce better results on a big scale.

There is short term - medium term - long term.

If a settlement has 150 people, designing and deploying orbital mirrors seems rather fantastical to me, especially when sulfur lamps can be purchased at retail - today - and are a better value than much of the commercial lighting that now exists, and draw relatively little power to boot.

1.5 million people growing food with nukes and sulfur lights? Okay - I see the point Phobos is making.

Next, I say hope for the best but plan for the worst. . .

In the little bit of research I have done, I don't see any reason to assume that ambient Martian light is insufficient for plants. Corn grows when there'a a month of cloudy weather; it doesn't happen often, but every decade or so it happens. If you had a cylindrical greenhouse with its long axis oriented north-south, in the morning you could lower the insulation on the east side and let in the sunlight; the west side would still have its insulation blanket up, and if the insulation blanket were silvered, it would reflect additional light inside. In the late afternoon you could reverse the process, raising the insulation blanket over the east side of the greenhouse and lowering it on the west side. That would increase insolation maybe fifty percent, making it close to terrestrial normal.

I agree 100% settlers will want to maximize their use of Martian insolation, if only to reduce the power needs of a settlement. Yet I have heard that Mars receives 50% of Terran levels due to additional distance from the Sun with another 50% loss due to greenhouse materials - leaving 25% Earth normal for growing plants.

Mirror concentrators will help but there will be dust storms and "what if" 25% - 40% Earth normal is not enough to grow healthy crops, efficiently?

Sending a nuclear reactor - for power - and a few sulfur lights (or other light source) with the first settlers seems merely prudent. If natural light is enough for particular crops, well, use the lamps to grow roses!

Phobos · 2002-08-14 21:49:03

If a settlement has 150 people, designing and deploying orbital mirrors seems rather fantastical to me, especially when sulfur lamps can be purchased at retail - today - and are a better value than much of the commercial lighting that now exists, and draw relatively little power to boot.
1.5 million people growing food with nukes and sulfur lights? Okay - I see the point Phobos is making.

When I was thinking massive I was thinking of cropfields that were very large, like modern commericial crop fields. I agree that it would be overkill to build orbiting mirrors if only a 100 people were living on Mars. As for the light requirements of the plants, I really think it depends on the plants your using. Some plants will likely do fine with the reduced light, others will just be puny unproductive space wasters. We might have to build plant specific greenhouses. If at all possible we should just go ahead and use the sulfur lamps. Even plants that can produce in the reduced light will likely be more productive if they have higher light levels.

As for the "dim" light bothering astronauts, I don't think anyone would notice. I remember in 1970 I experienced a 95% total eclipse of the sun (I wish I could have gone to the area of totality, but I was too young!. At the height of the eclipse I was experiencing about as much sunlight as Jupiter's moons receive; it was a bit errie, but barely noticable as a fainter background. Next time there is a partial eclipse of the sun in your area, go outside when about half the sun is covered. You won't even notice the drop in insolation. But when its about 95% covered it is noticeable; yet even then, its about like the brightness at sunset.

The dim light might pose a problem for people who are susceptible to seasonal depressive disorders. Really though, I think some people might even prefer the dimmer light. I know it's blasphemy to say it, but I actually like dark cloudy days.

RobertDyck · 2002-08-20 22:53:09

The inflatable greenhouse is a great idea. I am chair of the Winnipeg chapter, and members here want to build an inflatable greenhouse for Earth. The idea is to do a study for Mars, but build a very realistic analogue for Earth. The Earth greenhouse would be inflatable and designed to grow plants in Canada in winter. (As well as North Dakota and Alaska.) That would prove we can control temperature in a cold environment, but it also permits selling them to grade schools as an education/outreach project. The school year is mostly in winter, so winter operation is important. We should design it to have a low shipping weight, relatively low cost, and deployable on a grass or other unprepared ground. That is ground that is flat, level, and free of sharp rocks that could cut through the envelope. This could also be sold to farmers to grow vegetables in winter. Sale to farmers could raise money for the Mars Society.

I would like to include everyone interested. I mentioned this on the GreenCELSSTaskForce list, and at the Town hall meeting at the conference in Boulder. I really need 2 individuals: one who knows how to do a thermal analysis, and a geologist who knows how to do a CIPW analysis.

The geology is for the second part: an accurate Mars soil simulant. I have the analysis of JPL's Mars soil simulant. I also talked to the primary investigators for the Alpha Proton X-Ray Spectrometer on Sojourner (the rover carried on Mars Pathfinder). I also have a paper from the TES instrument on Mars Global Surveyor. This shows JPL's soil simulant is way off. I would like to do a CIPW analysis of Sojourner's results to estimate minerals, then find minerals sources on Earth to blend an accurate simulant. The result could be exposed to Mars atmosphere, pressure and UV in a Mars jar to create the super-oxides. I also have a paper describing how to do that. We really need a geologist to ensure we create an accurate simulant. The simulant could be used for greenhouse as well as In-Situ Resource Extraction experiments.

The idea so far is to use Tefzel film. That is strong yet light-weight and Dupont claims it is UV stabilized, at least for Florida. (Penney Boston claims it won't withstand UV in Utah). The idea I have to control temperature is to use 2 layers and "Heat Mirror" or "Solex applied window film". That is a spectrally selective film that will transmit visible light but reflect IR and block UV. If that isn't enough, we can fill the gap between layers with argon gas instead of air. Argon is used for high-efficiency windows since it conducts less heat.

The last part is ideas to insulate the floor. We need a simple yet light-weight way to insulate the floor from frozen winter ground that gives you a durable walking surface.

So who is interested?

Robert Dyck

RobertDyck · 2002-08-20 23:17:46

White LEDs:

I'm in favour of using a transparent inflatable greenhouse. That is far simpler than any mirror or electrically illuminated design. As for light details, I'll let the agronomists argue.

I would like to point out that plants like visible light, they get sunburn from UV just like you and me. For more detail about light spectrum and plants see Photosynthesis - Estrella Mountain Community College. Scroll down to the chart "Relative rate of photosynthesis". Anything less than 400nm is ultraviolet, and larger than 750nm is infrared.

Robert Dyck

RobertDyck · 2002-08-20 23:24:18

Anyone doing work on a greenhouse, either a real one for Mars or analogue, can send me a copy. I'll post it on the greenhouse page Winnipeg chapter web site. You can then post the link here.

Robert Dyck

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#1 2002-08-11 13:09:57

Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

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Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

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Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

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Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

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Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

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Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

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Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

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Re: Mars Direct Rethought - Fixing the potholes in Zubrin's plan

#15 2002-08-12 11:16:58

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#16 2002-08-12 15:21:02

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#17 2002-08-12 19:54:40

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#18 2002-08-13 02:05:50

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#19 2002-08-13 15:51:21

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#20 2002-08-13 18:31:10

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#21 2002-08-14 07:36:38

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#22 2002-08-14 21:49:03

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#23 2002-08-20 22:53:09

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