Mars Colonization Discussion Thread

[DAL59]

There's still MOXIE. WAVAR

 

Edited November 12, 2017 by DAL59

[PB666]

4 minutes ago, DAL59 said:

There's still MOXIE.

 

Random jargon throw? How is oxygen purification going to get that water out of the Martian poles.

[DAL59]

Oh, wrong acronym.  I meant WAVAR.  

https://www.lpi.usra.edu/publications/reports/CB-955/washington.pdf

Edited November 12, 2017 by DAL59

[kerbiloid]

54 minutes ago, PB666 said:

You are not familiar with gamma, I worked with gamma for 35 years, I was an RSO.

I'm impressed.
My skills of a poor janitor cannot be compared, I see.

54 minutes ago, PB666 said:

1. Gamma is all around you all the time. Most people are surprised to find there is more radiation already in a room than when they open a vial of isotope and start working with it. You actually have to be using millicurie amounts before you can see noticeable effects in ambient gamma rise.

Lyrics.
Radiation everywhere, yes. Typically 10..20 mkSv/h. I know this.

54 minutes ago, PB666 said:

2. Studies in N. Iran have demonstrated that people who have a 10 fold higher level of exposure to background gamma radiation are at no increased risk for birth defects or cancer. They instead increase the rate of DNA damage and repair and compensate. In fact at the sublethal dosage levels, it is not really clear what level of gamma is dangerous. Injestion of any isotope however carries increased risk

Belletristics.
N.Iran studies may demonstrate whatever they want, radiation shielding is calculated according to official standards, not to articles.
0.5 rem/year for civilians, 5 rem/year for personnel, unless in your country the values differ.

54 minutes ago, PB666 said:

3. In an atmosphere gamma just doesn't travel that far, certainly not through a heterogeneous substrate. As I stated early tinting a 1 inch thick piece of plexiglass with a small amount of lead suffices to knock out almost all gamma radiation. Of course a mixture of metals is more effective but why do you need to, a heterogenous construct like the hull of such as ship will capture most of the gamma without any extraordinary effort, a good soil is compose of complex material.

1.Btw, that's you suggest to use heterogenous constructs (carbon fibers with lead addons). I suggest the solid steel.
2.Cosmic rays are not air. They don't float around, they are bombing the outer surface of the hull.
As you can see, when a carbon nucleus absorbs such proton, it produces gamma, unless you can show another physics.

54 minutes ago, PB666 said:

4. In the area surrounding Chernobyl in Belarus there was a study done to find out why there was an increased level of radiation effects in some areas versus others after the fall-out was at ground level. The ground in these areas was radioactive, but that in-and-of-itself was not sufficient to increased risk of blood pathologies. Observers went to several farming communities, what they found was there was almost no risk in people ambiently exposed to radiation, but when people worked in the fields if they gathers stubble and burned it there was much higher risk. As it turns out the risk came not from exposure to the volatile salts liberated into the air by the piling and especially the burning process, and the risk turned out to be almost entirely an inhalation risk.

See p.2. Belletristics.
Several tens old (post-reproductive age) people are not a sampling. Nobody tells that a bird falls dead crossing the 30 km zone. Risk of diseases gets higher.

54 minutes ago, PB666 said:

5. I used to work with so much radioactivity that if you sat a one side of a room (Geiger counter running) and me at the other with a , the radiation source I was working with while facing the other direction could ping that meter on the x/100 scale. It used to burn my finger where I held it for several days on occasion.

You should better study the difference between the general and local exposure. The first one would kill you after hundreds rem, the second can be cured even after thousands.

Spoiler

54 minutes ago, PB666 said:

Gamma is not the danger that you think. READ

 

Nice picture, I don't know what's that.
Gamma biological coefficient is 1, alpha 20.
I.e. for gamma 1 gray = 1 sievert, for alpha 1 gray = 20 sievert.
LD50 is (in different sources) 350..450, LD100 ~600..800.
Different organs have their own different coefficients, of course, but here we speak about general exposure, so that doesn't matter.

54 minutes ago, PB666 said:

Second. Objects don't suddenly stop in space unless they collide with something mass. Rollers do not need bearing replacement they are only present to deflect imbalances, they otherwise are not moving because they are not touching (magnets are maintaining position, not the rollers). If the internal cylinder needs servicing just bring it to a stop

Objects suddenly stop when something appears inside a bearing and prevents their further rotation. No matter, in space or on ground.
If you are going to deflect imbalances from time to time, that means your cylinder will be shaking. If constantly, that means you use roller mechanical bearings.

What does mean "bring it to stop"?!
Don't you forget about happy peasants dancing between the trees on the riverside? If you stop it, they fly into the nearest wall or up, drowning in huge but weightless water blobs.
You can not stop the cylinder, it must keep rotating whatever happens. That's why any kind of bearing is not an option at all.

54 minutes ago, PB666 said:

Third. By building reasonably size communities it is not neccesary to build thermonuclear power plants, particularly since the outside hull is moving at a reasonable speed on can have Solar Panels. Fission power plants can be shielded, but the bigger problem is that they have maintanence issues so scrub these until better plants. If you spin a ship at 1g on the outside edge then adding more solar is problematic because of the g-forces. At 0.1g you can increase the area point at the sun by 3 fold.

You can easily calculate total cross-section area of you cylinder and divide it by the population.
Don't forget the magnetic bearings, btw, they eat a lot.

54 minutes ago, PB666 said:

We have already discussed the fact that you do not understand cosmic radiation.

That's not the only thing which I don't understand.

54 minutes ago, PB666 said:

Hydrogen is the best absorbent

For nucleons. Protons and neutrons. Physically.
Technically - only when you can replace the depleted hydrocarbon pellets or blankets where it is.
A cryostat with liquid hydrogen as a surface shielding is beyond the good and evil, sorry.

54 minutes ago, PB666 said:

Antimatter in cosmic rays are rare

The only antimatter which I have mentioned are positrons which appear when cosmic protons hit your carbon fiber nuclei.
Other gamma in my and Sun's example appears due to the irradiated carbon decay.

54 minutes ago, PB666 said:

Finally I am not going to deal with your what ifs, since you don't seem to read the literature.

Exactly, I don't. Words come into my mind themselves.

 

Btw, did you ever calculate some mechanical device with bearings or high-temperatre gaseous reactor?

(Please, don't tell me about radon, btw, its measuring was my secondary work for two years)

Edited November 12, 2017 by kerbiloid

[PB666]

Cosmic rays are radiation of the massive type not of the massless type. When they decay the decay products are short lived and exhibit some quantum and relativistic traits. Because of this they can pass right by a heavy nucleaus like lead and couple with lighter nuclei like hydrogen.  Even in 1943 they were detecting cosmic rays that passed through 15 cm of lead. That was the point of the article. You still continue to pretend that cosmic rays have an unusual sensitivity to iron and lead.

If a proton hits carbon fiber then it degrades. The level of cosmic radiation is 10⁴ to 10⁵ per meter squared per second, however those with energies capable of nuclear fussion are in the 100 to 1000 fold fewer. Carbon Fiber has a density of 1.7 grams per ml. It is largely composed of carbon with some nitrogen. The level of carbon is about 80% making the carbon density  1.36 gram per ml. Avagadros number is 6.0223 x 10²³. This converts to   6.82E22 C per cubic centimeter. That translates into 6.82E28 per cubic meter of carbon fiber at a 0.1 M in thickness that translates into 6.8E27 C per meter of carbon fiber hull. Lets argue that a hull has twice the rated stress limit, and that a strand is structural if a million atom constituants are integral. So that in order for the wall to fail it means that roughly  1.364E23 carbons degrade per square meter of hull.

In the original calculation give 10² to 10⁴ how long would it take for the cosmic radiation take to 'f-up' the hull  T = 1.364E23/10E4 = 1.364E19 seconds = 430 trillion years. Assuming that the vessel has 100 year life (and cannot be resurfaced) the carbon fibers would have to be fatally sensitive to one damage in 10E18 carbon molecules.

So you can stop with the fluffy just so arguments. We got you Kerb, we know where you are coming from.

[kerbiloid]

That's nice. Does carbon emit gamma-radiation if absorbs a proton? How does the former proton energy get lost?

[PB666]

23 minutes ago, kerbiloid said:

That's nice. Does carbon emit gamma-radiation if absorbs a proton? How does the former proton energy get lost?

At that level not alot. The biggest problem is secondary cosmic radiation getting into the living areas. It is almost always the case that adsorption, inhalation or ingestion of radiation is going to be far more toxic than EM radiation. There are exceptions, such as ultrahigh energy gamma. You need magnitudes more damaging ionizing radiation that you do the source of that radiation to get significant damage.

There are situations where gamma radiation is a factor, for example, if the males in the colonies wait until their 40s and 50s to have offspring, in that case gamma radiation could be problematic.

[DAL59]

 

[PB666]

38 minutes ago, DAL59 said:

 

350,000 tons of end transfer spaceship, which at present no launch system could put into orbit around earth, let alone transfer from earth Orbit to mars. To leave earth to Mars from LEO requires about 10,200 dV to get to LEO . . .LEO to Mars transfer start of 3884 dV. If the fuel use with Metholox fuel at ISP 375 requires the rocket leaving orbit of 872 kT. At Space X current efficiency they would need a launch of about 8 mT.

Here are the current launch systems.

https://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems

Note that Space X has 150 kT with Trans Mars Injection after refueling. Very ambitious, even empty this ship has 175,000 tons so . . . . . .

[tater]

It’s 75 tons dry mass, they assume 85 t due to mass creep, however, not 175t. 

Its 350,000 kg, not tons. 350 metric tons wet at entry looks like.

[tater]

Couldn't quote with phone.

3 hours ago, PB666 said:

350,000 tons of end transfer spaceship, which at present no launch system could put into orbit around earth, let alone transfer from earth Orbit to mars. To leave earth to Mars from LEO requires about 10,200 dV to get to LEO . . .LEO to Mars transfer start of 3884 dV. If the fuel use with Metholox fuel at ISP 375 requires the rocket leaving orbit of 872 kT. At Space X current efficiency they would need a launch of about 8 mT.

Here are the current launch systems.

https://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems

Note that Space X has 150 kT with Trans Mars Injection after refueling. Very ambitious, even empty this ship has 175,000 tons so . . . . . .

150 tons to LEO (payload, not counting vehicle). Vehicle is 85 t dry, so 235 tons to LEO. That gets refilled with propellant, and it's around 1200t filled. According to that, it's landing at 350t, so assuming a full payload of 150 tons, that leaves 115t of props left for landing.

 

EDIT:

I assumed that was a video of the current BFR/BFS, not the old ITS, which is not a thing.

My values were for the current version, not the ITS. You can look up the old version data, which is more massive than the values I gave. My bad.

Edited November 14, 2017 by tater

[DAL59]

SpaceX has its own launcher specifically for this craft.  The craft will use some of its own fuel to circularize into orbit, then more ITSs will refuel it in orbit.    

[tater]

9 minutes ago, DAL59 said:

SpaceX has its own launcher specifically for this craft.  The craft will use some of its own fuel to circularize into orbit, then more ITSs will refuel it in orbit.    

Huh?

The booster is suborbital, like the F9 booster, and likely has a very similar flight profile to RTLS F9 missions now. It gives the upper stage (the BFS) something like 2-2.5km/s. The spacecraft (BFS) then achieves orbit expending most all the fuel. Similar launches are then done with the tanker (an empty cargo version, such that it makes orbit with substantial propellant remaining). Multiple tanker flights refill the BFS (I really like the use of "refill" by SpaceX since you want to say "refuel," but it's not just fuel, it's also oxidizer). The BFS then burns for Mars in this case. 

[DAL59]

That's exactly what I said...I meant the ITS ship will use some of its own fuel to circularize.  

[tater]

2 hours ago, DAL59 said:

That's exactly what I said...I meant the ITS ship will use some of its own fuel to circularize.  

The BFS (ITS is no longer a thing) will use pretty much all of the fuel to achieve orbit at all. It gets to orbit effectively empty, except for the landing fuel reserved.

[PB666]

So the question is why are we @DAL59 feeding Videos of [no longer a thing] here.

I was skeptical anyway, the lander burned out 900 dV of thrust but not change weight at all. It was a rather sophomoric video.

Let me be specific, the way they are turning the lander while under 5 g of drag force without evidence of thrust input seems like complete fantasy.

Edited November 14, 2017 by PB666

[tater]

That video was from nsf, right? It was an attempt at characterizing EDL. The recent BFS video was actually by spacex.

[DAL59]

 

[PB666]

On 11/17/2017 at 2:55 PM, DAL59 said:

 

Really, traveling around in fake space suits is preparing people for mars, more or less fancy toys for over grown 5-year-olds.

[kerbiloid]

Even IT zergs in hardware shops use power drills instead of manual screwdrivers.
Why use those hammers on Mars? They may damage the spacesuit and make the arm tired.
Why not use some kind of pneumatic drill?

[Nibb31]

3 hours ago, kerbiloid said:

Even IT zergs in hardware shops use power drills instead of manual screwdrivers.
Why use those hammers on Mars? They may damage the spacesuit and make the arm tired.
Why not use some kind of pneumatic drill?

Because in space, simple is usually better.

These simulations are mostly designed to develop procedures, so it's perfectly valid to evaluate various tools to find out what is practical and what isn't.

Edited November 19, 2017 by Nibb31

[kerbiloid]

2 hours ago, Nibb31 said:

Because in space, simple is usually better.

I.e. after a hi-tech spacecraft had delivered them to Mars, and they are living in a hi-tech planetary base, the manual hammer is a critical point of the whole enterprise?

[Canopus]

14 minutes ago, kerbiloid said:

I.e. after a hi-tech spacecraft had delivered them to Mars, and they are living in a hi-tech planetary base, the manual hammer is a critical point of the whole enterprise?

Both the ship and the Habitat will ideally be designed to be as simple as possible too.

[kerbiloid]

59 minutes ago, Canopus said:

Both the ship and the Habitat will ideally be designed to be as simple as possible too.

With manual pumps?

[Nibb31]

6 hours ago, kerbiloid said:

I.e. after a hi-tech spacecraft had delivered them to Mars, and they are living in a hi-tech planetary base, the manual hammer is a critical point of the whole enterprise?

Don't be stupid.

Any high-tech spacecraft is going to be designed with reliability in mind. That means the less possible moving parts and manual backup for most vital equipment.

5 hours ago, kerbiloid said:

With manual pumps?

As a backup, why not ?.,

How would a pneumatic hammer be superior to a normal hammer or screwdriver ? The ISS uses special zero-torque screwdrivers for EVA because zero-G, but on Mars, they will be likely to have power tools with manual tools as a backup.

Evaluating how practical it is to perform various tasks with various tools is pretty useful work.