Can Private Space Travel Take us to Mars?

Well, maybe not just a couple of kg, but equally, I don't mean an entire inflateable habitat.

The "inflateable habitat" I cited as my example is the smallest test module made by Bigelow for flight. It's dimensions are 8 foot by 10 foot (whether those are inside or outside dimensions, I'm not sure).

DKH

Remember, we don't want blithering mad(wo)men landing on Mars, we want sane human beings. Even the Apollo astronauts griped slightly about being stuck in a fairly cramped space for just a few days. Since you're talking about either a low-thrust or single-impulse vehicle, you're dealing with a travel time of weeks, at least. You have to take into account their mental health, as well as their physical.

Let's not start repeating Korolev, here.

It looks like the article says that the technology only removes CO2 from the air.

"Die Idee, CO2 aus den Abgasen zu entfernen und anschließend unterirdisch zu fixieren"

It does not recover the oxygen from that CO2. In that respect it is not so different from CO2 scrubbers already used in space.

What rpspeck seems to be talking about is recycling the astronauts exhaled CO2 back to breathable oxygen so he doesn't have to carry hundreds of kilograms of oxygen just to keep the astronaut alive.

I provided a link in the post you are responding to. That link points to a post of mine in the Technology section - and in that point I am mentioning that something will have to done with the output of that new technology and that the article doesn't provide all informations I would find interesting about that technology.

And I wasn't referring to the issue you are quoting - its different from that issue and reads "...Zwei Firmen aus Tucson (Arizona), haben den Bau eines "Windschrubbers" angekündigt. Der Prototyp ist eine etwa zehn Quadratmeter große Konstruktion, die das Kohlendioxid aus der Luft aufnimmt. ...". "Luft" isn't identical to "Abgase" by far.

Please read my post in the Technology section I have provided a link to in the post you are quoting.



One additional relevant point concerning rbspeck's thoughts and ideas - this is the Financial Barriers section and rbspeck might be arguing his way simply to work out the least cost way for a manned Mars mission. If he would be posting in the Public Perception section he might post quite different thoughts and ideas - this would be valid for the Technology section and the Regulation section too. The aspect of the section titles should be taken into account perhaps. rbspeck might be talking theoretically - in Economics that wouldn't be unusual any way: it simply illustrates a difficult topic.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)

Yes I know that. I already read your post in the Technology section and followed the link you posted there to see the article.

You have left out the most important part of that quote. Here is the complete quote, including the part you left out,

"Zwei Firmen aus Tucson (Arizona), haben den Bau eines "Windschrubbers" angekündigt. Der Prototyp ist eine etwa zehn Quadratmeter große Konstruktion, die das Kohlendioxid aus der Luft aufnimmt. In dem Filtersystem befindet sich eine Natriumhydroxid-Lösung. Diese reagiert mit dem CO2, im Ergebnis entsteht Kalk, den man in den Ozeanen lagern will."

The improtant part of the quote is, "in den Ozeanen lagern ". This says that the captured CO2 will be disposed of and not recycled into usable oxygen.

The issue "...in den Ozeanen lagern" is not part of the technology but a possible decision or intention under consideration. For this reason that issue must be separated from the informations about the technology - from the technology you get lime but the technologx doesn't place the lime anywhere and so the people must do it. The people in turn CAN place the lime at the ground of the oceans but they can place it elsewhere if they want or find that advantageous.

For this reason I can leave away "...in den Ozeanen lagern..." and think about placing it within a chamber of another technology that might break the oxygen off the output of the reported technology. The "another technology" can and should be looked for now - it perhaps may be using the energies free available in space.

Such articles are mixing technological informations with decision-oriented informations, economical infromations and so on. The "... in den Ozeanen lagern ..."-part simply is off-topic in this board and this section as well as in the Technology section.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)

Hi rpspeck,
I should have read your posts more carefully before replying



I couldn't find another mention of the "Water Gas reaction" in this thread so I googled it. I found a lot of information about running the process the other way, using CO and water to produce H2 and CO2. In fact this seems to be the often mentioned steam reforming method that is used to make industrial quantities of hydrogen gas. However I found nothing on running the reaction the other way to recover oxygen from CO2. I would be interested in any additional information you can supply on this topic. Especially has anyone made a prototype CO2 -> O2 recovery system based on this reaction?

(EDIT) It would still seem to me that you need a scrubber to remove the CO2 from the cabin air before it can be fed to the water gas reactor. The system now used on the ISS for this purpose weighs over 45 kg, not including the sorbent canister. http://www.hsssi.com/Applications/Space ... moval.html
Also, you need another system to separate CO from O2 since the water gas reaction produces both.

(ANOTHER EDIT) I found a really good paper on this subject.
http://flightprojects.msfc.nasa.gov/book/chap2.html
or the pdf version
http://flightprojects.msfc.nasa.gov/book/rp1324.pdf
I'll need to research the ISS oxygen generators. The ones that are always in the news for the problems they have. They may be recovering O2 in the ISS after all. That would be good news, but I bet the equipment is very heavy.

(YET ANOTHER EDIT) The appendix of the above document referred to a system that directly converts CO2 to O2 and solid carbon as an oxygen generator, but that does not seem to be related to the ISS oxygen generator at all.
http://www.jamesoberg.com/elektron2_tec.html
So we still need a scrubber plus water gas reactor to make CO and water for the oxygen generator. (Now that I think about it, CO gas should be easy to separate from liquid water.)

That won't work in space because, "in the zero-gravity environment of outer space, gas bubbles don't rise within a liquid — so a process that is trivial for earthly high-school chemistry labs becomes devilishly difficult".
Here is the complete article where I got that quote.
http://www.msnbc.msn.com/id/6800245/

So put it in some sort of a slow-spinning centrufuge. That should separate the liquid from the gas.

I thought of that too. I wonder if the Elektron system on the ISS uses a centrifuge internally. I haven't found any details on the inner workings of the Elektron unit, but it may be a centrufuge. If we thought of it then I bet several hundred real aerospace engineers did too. They are either using that method already or they know some good reason that we don't know why it wouldn't work.

The Fuel Cell I referenced is not a standard electrolytic cell, since it is intended to CONSUME H2 and O2, not produce it. It isn’t easy to push bubbles down into the electrolyte. The gas actually reaches a catalytic surface which feeds ions into the liquid. Since these are equivalent to what was used on Apollo, they work fine in zero “g”. It happens that all such systems work well in the other direction, and are sometimes used that way. (Buy the "Fuel Cell Kit" $119.95 from "hoptustore" to try this in both directions.)(http://www.hoptustore.com/fuelcelcaran.html)

Yes, a recyclable mole sieve or similar CO2 scrubber is needed (as well as a condenser for metabolic water in expiration and that from evaporation). Even the hydroxide/carbonate process is thermally reversible. Details remain to be worked out.

Has anyone looked into my “Algae from Food” (1953 Scientific American) ref. and any updates? Hydroponics should at least BE TRIED outside science fiction. A few small pumps, aquarium supplies and Plexiglas tubing are all that is called for to duplicate the 1953 work. (A GREAT idea for a SCIENCE FAIR PROJECT). I am in fact counting on school kids to finish the work NASA didn’t do!

But not in 0 G. I don't think you and I are any smarter than all the hundreds of real aerospace engineers that have already worked on this problem. If there was a way to do it as simply as you claim, at least one of those guys would have noticed that. If his boss didn't permit him to work on it, he would quit, form his own company and make it anyway. That is exactly what Shockley's team of engineers did. When he wanted to make point contact transistors, several of his engineers quit, started Fairchild semiconductor and started the current electronics revolution.

Hello, rbspeck,

concerning the CO2- and O2-problem a financial problem may be hidden in quite another requirement - there has to be got rid of the carbon. Second the carbon has come somewhere - it may have to be moved there perhaps. ...

What I am trying to say is that the CO2- and O2-problem is part of a greater recycling environment which will be unpreventable incorporated into your thoughts posted in this thread.

May be a minor question - which way would you solve it at least costs?



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)

Regarding fuel cell operation in 0 g, it worked in Apollo. About reverse mode (electrolysis):

1, getting Oxygen gas to flow out of the dry, back side of the catalytic cathode/anode assembly is no harder than getting Oxygen gas to flow into this in the standard power generation mode. (Same applies to Hydrogen side)

2. Getting water to flow into the electrolyte chamber under a bit of pressure is easier than disposing of the water generated there in the power producing mode (without diluting the electrolytes).

3. Someone else’s failures only make me think twice about a problem, and then move on. As a result I have earned a few patents and created a number of innovative (niche market) products. “Why hasn’t it been done before?” Cause I just got around to it. (Same for all inventors)

4. For referenced $119.95 you can join me in laughing at everyone who pretended to work on this problem and failed. You will get an electric car which uses this reversible cycle to run across the floor as well. You can then turn it upside down, shake it , roll it over and over etc. to see that bubbles rising in a gravitational field have nothing to do with a real fuel cell. (I do hope the manufacturer didn’t add some quirk to make tipping impractical, since this has nothing to do with what is essentially an Apollo chemistry fuel cell). Fuel cells don’t use some tricky technology to push bubbles down into the liquid continuously.

Now admittedly, my practical experience to date has been with the Titanium Dioxide fuel cell, which involves no liquid since it runs hot. In this case, the water in or out would be in the form of steam. This is another of several established fuel cell technologies, and would also supply the Oxygen generation need. (The Oxygen in and out passes through a porous Platinum film to reach the ceramic “electrolyte” surface. The Platinum film takes care of the electron transfer to or from the oxygen atom or ion – depending on direction- as well as providing an electrical circuit to collect the current in or out.)

Regarding Carbon input and output: The carbon input comes in the only form we know how to use – food. I suggest the “All butter diet” for light weight, and noted a backpacker who reportedly came close to it. I would personally prefer the all M&M™ diet, since these candies are now known to be the preferred food of terrestrial astronauts. (Reeses Pieces, as I recall, were the extraterrestrial favorites).

Carbon will be recycled only by hydroponics – as needed for starflight.

The Carbon is eliminated, in my model, either as carbon dioxide or preferably as carbon monoxide. I have confirmed that reduction to elemental carbon is practical, but we don’t need the extra Oxygen (since a lot of Oxygen is included in all usable foods). Rather I have a good use for the carbon monoxide (or dioxide): It would be stored and used for attitude control jets. “Cold gas jets” (preferably warm) are entirely adequate for spacecraft control when you don’t need to do things in a hurry (as demonstrated on SpaceShipOne). Thus the endpoint of the recycling would solve another operational need.

Hydroponics would reduce my maneuvering fuel (and the food supply that produces it) but the best diet would probably use 1/3 to ½ Earth food to round out the hydroponics product.