What we need to go to Mars - short term projects

RobertDyck · 2016-10-11 23:50:52

Tom Kalbfus wrote:

direct CO2 electrolysis to recover O2 from CO2 currently dumped in space
This won't replace the current life support system, it will augment it. Currently 50% of CO2 recovered from cabin air is dumped in space. The other 50% goes to the Sabatier reactor. Direct CO2 electrolysis only recovers 40% of O2 contained in the CO2, but 40% is better than 0%. This could replenish recycling losses.
Why can't you recover all of the oxygen? If you heat it to a high enough temperature, you can break any chemical bond and recover all of the oxygen!

I'm talking about the device described in "The Case for Mars". That same device was built as the MIP (Mars ISPP Precursor) instrument on Mars Surveyor 2001 Lander. Unfortunately that was one of the instruments removed to convert it into Phoenix. It works by heating CO2 gas to +900°C, then uses a thin wall ceramic tube as the catalyst. CO2 is inside the tube, electrolysis causes O2 to pass through the wall of the tube to the outside, but CO2 and CO stay inside. This converts 80% of CO2 into CO. So that means only one oxygen atom from CO2 is recovered, the other remains attached as carbon monoxide. So 80% of 50% = 40% of the oxygen atoms.

It takes a lot more energy to break the remaining oxygen atom free. What you describe would be highly energy intensive. Then there's the problem of how you separate oxygen from carbon. And once you have just carbon, that will be carbon soot, which is a lot more difficult to handle than a gas. Carbon monoxide can be dumped in space. Or on Mars it can be dumped into the atmosphere. Carbon monoxide is a natural constituent of the atmosphere of Mars, so a single lander or a single permanent base is not going to alter the environment. If you had 7 billion people doing this, it would significantly alter the environment. But not 4 people on an entire planet. Or 100 people.

Antius · 2016-10-12 05:28:02

Not to mention the fact that carbon monoxide is a valuable feedstock for making plastics and reducing metal ores. Carbon dust is used in a few processes, but is more easily produced by stripping methane.

There are a few gas-cooled nuclear reactors capable of reaching outlet temperatures of 900C, but materials issues makes it difficult to achieve outlet temperatures much greater than 700C, basically because steels lose most of their strength beyond 700C and few other materials provide the right properties in terms of fission product retention, corrosion resistance and strength at these temperatures, without also providing an unacceptable cross-section to neutrons. The Chinese are experimenting with graphite and silicon carbide kernels, but the performance of these materials under high burn-ups reached in real reactors is uncertain.

That said, a nuclear reactor capable of pre-heating the CO2 to 700C would dramatically cut the electricity required to provide the remaining boost to 900C. It means that 75% of the energy needed can be provided by nuclear heat, with the remainder provided by electricity.

Last edited by Antius (2016-10-12 05:30:40)

Oldfart1939 · 2016-12-14 19:35:09

OK, I'm reopening this dormant thread, as it had a few tweaks of my topics and experise.

Bone decalcification in microgravity. I started working on this problem independently back in 2007 in the hopes of a NASA request for proposals under the SBIR program. Alas, nothing even resembling a request for this type research ever came along...much to my dismay; shortly thereafter my wife became ill and consumed most of my available free time caring for her. But...I digress.

I began collecting professional medical and biochemical peer reviewed papers in order to familiarize myself with the nature of bone biochemistry, and the medical resources available. As I did this study, I was using as the start point treatments for the common disease prevalent in post menopausal females: osteoporosis.

Here's something of a recap of what I'd surmised before I abandoned ship: this is a problem which can be addressed through an endocrineological approach. Calcium uptake in mammals and indeed, all vertebrates, is regulated by a oligopeptide hormone, Calcitonin. This hormone is made synthetically in various Pharma labs today, and has been found very effective in reversing calcium loss in bone structure.
There are two types of cells involved in modelling bone architecture: osteoblasts and osteoclasts. Osteoblasts are responsible for rebuilding bone structure by replacing old and dying cells; osteoclasts, on the other hand, are responsible for sculpting the architecture by removing dead and dying tissues. There are other hormones involved as growth factors, but these are not well understood or being investigated for the zero-G problem.
So--is anyone aware of the status of dealing with bone loss at NASA? Do they even have a clue that help is available?

SpaceNut · 2016-12-14 20:01:58

So far its just regerous exercise and data collection studies....on board the ISS....

RobertDyck · 2016-12-14 20:38:03

NASA is providing astronauts with vitamin D and calcium. Beyond that, I don't know. I believe there has been research into hormones. I know for a fact they have collected blood samples to analyze hormones. Don't know if they've tried any hormone therapy.

I do have a hypothesis regarding clinical osteoporosis on Earth. I believe it's a nerve condition. If nerves in bones are not producing enough signal to the system, then hormones to trigger osteoblasts are not produced. There has been a lot of research into hormones, but I don't think any research into condition of nerves within bones for patients suffering osteoporosis.

Last edited by RobertDyck (2016-12-14 20:39:28)

Oldfart1939 · 2016-12-14 23:38:50

There is a very large commercial opportunity going to waste here. Robert, I agree that there has to be some mechanism of signaling the pituitary to stop stimulus of production of another yet to be discovered growth factor. A similar disease is anemia, which can be treated by erythropoietin or EPO, which itself is a protein based growth factor type hormone. If a osteoblast growth factor can be found and identified, I have a good friend and former research colleague who could also design the genetically engineered pathway to make it; after all his name is on the patent for EPO.

NASA is missing the boat on this one.

RobertDyck · 2016-12-15 10:26:28

Oldfart1939: Write a formal proposal to NASA and submit it. They may not be pursuing this because they don't know anyone with the skills to do it. If you and your colleges do, you may get it.

NASA: Guidance for the Preparation and Submission of Unsolicited Proposals

NASA Acquisition Internet Service (NAIS)

Oldfart1939 · 2016-12-15 11:09:02

Robert-

I just contacted my buddy about this. He's also "retired" and losing his mind; was the 1st Organic Chemist ever hired by AMGen. as well as the smartest.

Last edited by Oldfart1939 (2016-12-15 18:35:34)

SpaceNut · 2016-12-15 18:14:48

The recent ISS twin study should yield quite a bit of information as urine as well as blood were drawn from both the control as well as the experimental subject during the year long study on weightless conditions.

Oldfart1939 · 2016-12-20 10:38:23

Spacenut;
The problem is knowing what to look for in these samples, and doing any form of experimentation is impossible; this recently concluded experiment simply gives a baseline for future studies.

A fairly recent paper, www.pnas.org/cgi/doi/10.1073/pnas.0606805103, indicated that bone loss in osteoporosis may be somewhat modulated by a diet high in ascorbic acid (Vitamin C). This could be the basis of an ISS borne mouse or rat experiment, with a corresponding control study done on Earth. This addition to diet affects the hormone action in post menopausal females w/r osteoporosis.

SpaceNut · 2016-12-25 19:10:27

Lack of vitamin C has been known for centuries as a bone desease issue parameter....(Scurvy) Edit: correction provided by Terraformer, thanks....error just no excuse for being tired when posting....
Vitamin D as well plays an important part in bone growth which was (Rickets) Thanks again....

Like you elude to its more than just bone as its the whole body hormonal and imuninization systems that are in play....

Terraformer · 2016-12-26 07:00:21

You're thinking of scurvy. Rickets is vitamin D deficiency.

Speaking of which, how long do they spend under sun lamps on the ISS?

SpaceNut · 2016-12-26 08:57:55

Yes as related to seasonal depression... onboard the ISS Testing Solid State Lighting Countermeasures to Improve Circadian Adaptation, Sleep, and Performance During High Fidelity Analog and Flight Studies for the International Space Station (Lighting Effects) - 12.07.16
aims to determine if the new lights can improve crew circadian rhythms, sleep, and cognitive performance.

The Power of Light

Most people function regularly on a 24-hour cycle known as a circadian rhythm. However the space station environment creates a departure from the cycle of light and dark astronauts are used to at home. A high workload, the need to work ‘nightshifts’, the excitement of spaceflight, plus the unusual environment can disrupt astronauts’ circadian clocks. These factors can combine to disrupt sleep, which can in turn effect performance.

GW Johnson · 2016-12-26 15:11:44

There is another problem cured with a bright light, one that no one wants to admit to, because it's inconvenient. Some folks can tolerate dim light, others cannot. They get seriously depressed without bright sunshiny days. It's a very real effect, related to mental health. I suspect that confinement interacts badly with this bright-light-in-the-face effect.

GW

RobertDyck · 2016-12-26 15:59:26

Repeating from my initial post, I would still argue for a demonstration of maneuvering while rotating in tethered flight. My proposal is to tether a Dragon v1 cargo ship filled with garbage to a Dragon v2 with astronauts. Rotate, and make course changes while rotating. Just to prove you can. With any test you have to prepare for success, but also have to prepare for failure. The reason for a cargo ship filled with garbage is it's destined to burn up in the atmosphere anyway. If something goes wrong and you have to decide which ship to sacrifice, it's a no-brainer.

This demonstrates the ability to make course corrections in transit between Earth and Mars, with artificial gravity using Robert Zubrin's idea.

Instead of Dragons, you could do this with CST-100 tethered to Cygnus, or Soyuz tethered to Progress. Or Dragon v2 tethered to Cygnus, etc.

GW Johnson · 2016-12-26 16:12:20

If you use a semi-rigid connection instead of cables, there is nothing left to demonstrate. That's both cheaper and more sure.

Use your propellant tanks and unmanned items linked together as a long baton, at the end of which is your habitat for men. Then spin it head over heels. Very stable, as demonstrated in Friday night half-time shows for many decades now. And you can push on it without despin, if you wish to risk that.

Why risk cables that do not resist bending, nor can you push on them? The dynamics are just easier and more certain with a semi-rigid structure. There is no tangle risk, either, if something goes wrong. (And it always will: Murphy's Law.)

GW

elderflower · 2016-12-26 16:24:48

I have a bright lamp with tubes that emit UV to combat my tendency to get a bit depressed and hibernate during prolonged grey spells of the British winter. A flight south also helps. A couple of hours exposure to bright light of a suitable spectrum overcomes this problem.

Void · 2016-12-26 18:22:05

I go to the gym and do a bit of tanning there. Trust me it is just a little. It is healthier in moderation, and then you also don't scare other people with your vampire skin.

I read an article that said that sure enough, Swedish women who got more sun, got more cancer, but the reason they got more cancer is that they lived longer. Skin cancer in many cases is highly treatable anyway if you get it early I believe.

RobertDyck · 2016-12-26 20:20:09

GW: you keep talking about rigid connection members. Acceleration is represented by the formulae

1G acceleration = 9.8 m/s²

solving for radius

R = A * T² / (4 pi²)

For 2 RPM, rotation period = 30 seconds

R = 9.8 * (30²) / (4 pi²) = 223.4132 metres

That's radius, or distance from habitat to centre of rotation. Actually, you would calculate acceleration from floor of the upper level of the habitat, so subtract height of the dome ceiling, and height of the upper story. But then add tether length to the counter weight. If that's the spent upper stage, it will be less mass than the habitat. Force must be the same, so length from centre of rotation to spent upper stage will be significantly longer.

Do you realize how much mass it would be for a truss that long?

::Edit:: corrected calculation. Radius = 223.4something, not 2234.something
Oops! Just recalculated, and you're correct. Don't know how that happened because I use the Windows calculator.

Last edited by RobertDyck (2016-12-27 02:20:41)

kbd512 · 2016-12-27 02:11:40

Rob,

Did you mis-place a decimal point somewhere?

SELECT ROUND((9.8 * POWER(30,2)) / (4 * POWER((22/7),2))) AS len FROM dual;

len
---
223

SELECT ROUND((9.8 * POWER(15,2)) / (4 * POWER((22/7),2))) AS len FROM dual;

len
---
56

This online calculator seems to confirm my figures:

http://www.artificial-gravity.com/sw/SpinCalc/

RobertDyck · 2016-12-27 02:54:43

I would like to say "now calculate length from centre of rotation to spent upper stage". That "spent upper stage" would be the "Exploration Upper Stage" for SLS. After all, SLS block 2 is the Ares launch vehicle from Mars Direct. Current plants are to use 4 RL-10 engines instead of a single J-2X. Ares in 1990 used a single J-2S because that was the newest latest version of J-2 available at that time. Now the newest is J-2X. However, they're planning to use RL-10, so just go with that. I'm having difficulty finding the dry empty mass of EUS. That's necessary to calculate force during rotation. Force from a Mars Direct habitat on the tether must equal force from the counterweight.

We're still talking about hundreds of metres. A truss that long would be unreasonably heavy. A rope that long would be reasonable. So in this case I argue for Robert Zubrin's original idea.

kbd512 · 2016-12-27 04:41:04

Rob,

According to NSF Forum, EUS (4 RL-10C-2 configuration) should have a 26,133lb dry mass and a 262,752lb total mass. TMI should be 34.4t for SLS Block IB. No conventional 223m truss structure that I'm aware of would be remotely within the mass constraints that EUS could TMI. I seem to recall that GW wanted to use an upper stage or two in conjunction with the habitat module to form a baton between 50m and 100m long. It's technically feasible, but it would require some orbital assembly. It's not a deal breaker, but those rockets get pretty expensive, pretty fast.

I just don't understand why we can't use tethers. If the tether snaps, the habitat module contains the RCS, so it would re-orient itself and then we're simply back to microgravity for the rest of the transit. I don't know what the tether would weigh and maybe there's some sort of material constraint I'm not aware of. Fabrics and polymers is your area of expertise, Rob. Enlighten us. How much would a 56m Spectra tether weigh that could withstand a 20t habitat tugging on a 11.9t counterweight? How long does it have to be? Is 56m even feasible or do we need a 223m tether?

GW Johnson · 2016-12-27 11:06:31

I want to spin at 4 rpm (OK for unacclimatized civilians) or at most 8 rpm (requires training at acclimatization). At 4 rpm, a 56 m radius gives you one full gee. 56 m is just not that many items strung together. At 8 rpm, you only need 14 m radius, but the gradient and coriolis effects are far stronger. The tension is 4 times higher, too.

I did not use the word truss. I do not favor truss-based spin structures for ships vs stations, because the truss is inert weight, and very quickly makes mass ratios infeasible. You use as your "truss" the other modules of your ship: things like propellant tankage and modules containing supplies.

Your habitat is part of the baton length: put the daily work stations nearest the 1 gee end, put the sleeping quarters nearer the zero-gee center, since in prone sleep there is no medical benefit to gravity. Put the recreational spaces in between. Partial gee is better than no gee medically, plus it's part of the fun in the recreational spaces.

I know we can devise cables that likely will not break, mostly by redundancy, that issue does not worry me too much. What worries me is control after the unexpected meteor strike on one module but not the other. Or a stuck-on thruster, like what happened on a Gemini mission. Or any of thousands of foreseen or unforeseen asymmetric disturbance accidents.

With a semi-rigid structure, this is just not very serious in terms of the excited dynamics, the biggest effect after the vibrations are controlled being a precession-induced change of spin plane orientation. The semi-rigid article is just far easier to control. There is no way around that little fact of life.

With cables, the excited dynamics are very severe (so many modes to excite!), and could far more easily become unrecoverable. Cables could easily become twisted and entangled, leading to breakage of multiple cables all at once. I reiterate: why risk this?

Please note that I did NOT say you "could not use tethers", I just said that a semi-rigid approach is far safer and nearer-term developable, and for a variety of reasons, some having to do with Murphy's Law, an effect that has already killed multiple crews.

If such a vehicle is too big for launch by a single rocket, then so what? Launch the chunks with rockets we already have that will carry them to LEO, and then just dock them together in LEO. Orbital assembly seems to have an undeservably-bad reputation with too many correspondents on these forums. I suspect that derives from the ISS.

Orbital assembly by docking is indeed exactly how we built the ISS. That project's gigantic cost wasn't due to the assembly method, it was due to the costs of an expensive launcher (shuttle $1.5B per flight delivering only something like 15 tons) plus the usual giant boondoggle costs associated with a giant government-run project. This was further complicated to yet another level by international diplomacy, well-known to be expensive for very little effect in most other applications.

But none of that applies to what we are discussing here!

Docking a Mars ship together in LEO should actually be cheaper than things launchable in one shot with gigantic rockets, the only one of which might exist anytime soon being just as expensive to use as shuttle was.

If I am right, the docked-module semi-rigid approach is also far safer because it is more proof against the Murphy's Law stuff. It is certainly demonstratable far sooner and with less costs than a cable-connected thing we have never before flown.

I'm just arguing for applying common sense: avoiding foresee-able risks, avoiding foresee-able expenses, and taking advantage of what you already have working.

GW

Last edited by GW Johnson (2016-12-27 11:14:17)

SpaceNut · 2016-12-27 22:36:53

Since we need spaces that must have useable area with in them, why not design it to be that way....

The length of the cargo delivery units
Dry Mass to Length
1,500 kg (3,300 lb) at 5.1 m × 3.07 m (16.7 ft × 10.1 ft) (Std)
1,800 kg (4,000 lb) at 6.3 m × 3.07 m (20.7 ft × 10.1 ft) (Enh)
Volume
18.9 m3 (670 cu ft) (Std)
27.0 m3 (950 cu ft) (Enh)
Cargo Mass dependant on launch vehicle
2,000 kg (4,400 lb) (Std)
3,200 kg (7,100 lb) (Enh on Antares 230)
3,500 kg (7,700 lb) (Enh on Atlas V 401)
Power 3.5 kW

Since we need cargo, life support, living spaces, and power then these make sense to utilize with the unit closest to the capsule as the living sleeping space. Add as many to get to the desired length from center to approximate the radius of spin that we would like. If we need other docking ports for the landers make use of a node module in between the living and life support or cargo areas of the length. Then couple the departure and return stages if that is the desire for journey and lets spin the batton about its center.....

All of this is launchable with the current rockets.

Antius · 2017-01-01 21:47:00

It would be useful to test human adaptation to the effects of short rotation, high spin rate artificial gravity. This can be done here on Earth, since normal g simply adds a non-variable vector to the effective g. A set up to test adaptation would be a carousel shaped centrifuge providing a self-contained simulated spacecraft environment. Spin rate could be varied and the adaptation could be monitored for various groups at different spin rates. This should be a relatively cheap thing to do.

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#51 2016-10-11 23:50:52

Re: What we need to go to Mars - short term projects

#52 2016-10-12 05:28:02

Re: What we need to go to Mars - short term projects

#53 2016-12-14 19:35:09

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#54 2016-12-14 20:01:58

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#55 2016-12-14 20:38:03

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#56 2016-12-14 23:38:50

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#57 2016-12-15 10:26:28

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#58 2016-12-15 11:09:02

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#59 2016-12-15 18:14:48

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#60 2016-12-20 10:38:23

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#61 2016-12-25 19:10:27

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#62 2016-12-26 07:00:21

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#63 2016-12-26 08:57:55

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