Mars Colonization Discussion Thread

[tater]

On 11/4/2017 at 7:52 AM, DAL59 said:

Mars air has 100% humitidy 24/7

The fact that Mars' atmosphere holds as much water as it can (relative humidity) is true, but it can't actually hold much water, so holding all it can doesn't make that much difference. 

The density of Earth's atmosphere is on the order of 1.225kg/m³, while Mars is on the order of 0.02kg/m³. 

A cubic meter of our air has grams of water vapor, Mars would have 60X less.

3 hours ago, Green Baron said:

And take enough ketchup with you. That feeling of desperation when it runs out ...

I was talking with Sid Gutierrez (a shuttle astronaut who lives here in ABQ), and he said that you'd really want hot sauce, not ketchup. Not sure if it's microgravity, or the total climate control, but astronauts start thinking everything tastes bland, and hot sauce is like cigarettes in prison, they use it as currency when supply runs low.

[Green Baron]

Ah, okay, i'm not a chef you know, so my creations might not be everybody's taste ... :-)

[wumpus]

51 minutes ago, tater said:

I was talking with Sid Gutierrez (a shuttle astronaut who lives here in ABQ), and he said that you'd really want hot sauce, not ketchup. Not sure if it's microgravity, or the total climate control, but astronauts start thinking everything tastes bland, and hot sauce is like cigarettes in prison, they use it as currency when supply runs low.

"Dave" (or whoever is behind "Dave's Insanity Sauce") could make a killing here.  While I can't recommend eating it directly in any food (a drop makes chili roughly as hot as an entire habanero) you can turn any "lesser*" sauce into hot sauce using the base to dilute insanity sauce.  Does the ISS own its own trademark and refuse to allow items to claim "as used on the ISS"?  I'd expect others to copy TANG and use astronauts for marketing.  And of course, by now there are many "more or less entirely capsicum" products as well (but Dave's is probably the easiest to find).

* using store brand "hot sauce" often works well as you can have pepperish taste to go along with the heat.

[tater]

^^^That would kill one of the only economic forces in space, the trade of the last taco bell hot sauce packets, lol. (those are popular because they are unit doses that work well, apparently, though certainly not my favorite.

[PB666]

20 hours ago, Green Baron said:

Wow. What happened to their brains and are they still alive ? I read they lack volunteers for human experiments ... no wonder. Quite a lot of dogs were less lucky.

Mengele reborn ? No, that goes too far, but somehow at the limit of what ethics allow, or not ?

Potatos? Ketchup?  seriously people . . . .Can you grow an avocado, mango, grapes (make wine), barley (beer), hops (beer). Some of the paleoanthro folks believe that Ireland and N.England would have been sparcely inhabited if it had not been for the ability to grow barley and ferment barley. Beer and barely malt was survival once upon a time, as you needed something to tide those long winters.

Here is how to ask the question. Are you going to bring food animals or not.

 Answer is true.
    Model Chicken (they can fly away on Mars) for eggs . . . .cheapest source of animal protein (2-3 eggs per day).
    Plant crops that are rich in omega-3 fatty acids such as flax-seeds. Diet should be rich in whole grains, supplemented with green leafy vegetables.

Answer is False
   Avacodos and other plant crops rich a diverse array of fats, Crops such as quinua, lentils and legumes as a source of protein. Wheat protein can be extracted to create a protein product, but needs to be modified to reduce its toxicity (gluten has a number of proteins that should not be eaten at high levels when extracted). Coconut is a rich source of C-10- C14 saturated fats that increase body weight and sense of well being. Also peanuts are a good source of protein and fat.

In both cases.
  Lack of fish in the diet could overcome by have an cold climate greenhouse that overexpresses certain omega-3 found in fish.
  Fermentable crops are those crops that are rich in starch and generally low in protein. Barley, certain wheats, potatos (sho-chu), sweat potato,   yucca root (tapioca),  . . . . . .

 

The difference between the ISS and Mars is not so much the soil or gravity issue . . .

On the ISS they grow food to supplement what is brought frozen or dehydrated on supply ships every few months.

On Mars you have to grow just about everything . . . . .See other post . . . . .If we are going by $100,000,000 ( the stated PL for this value is not given, but assume its 18000) for 25,000 kg in LEO then on mars. Then such a craft can deliver 6260 kg to the Martain surface. However of that 6260 you have an engine (277kg) and containment structure (2500kg) which and I propose at least 33% of the weight as some type of aerobraking (2086 kg). This leaves a consumable payload of 1397 kg. Lets add another 30,000,000 for the structure cost to get to mars, target the colony and land. Final cost today for a repeat mission to resupply Mars would be 140,000,000$ for 1400 kg or $100000 per kg sterilized C14 oil (refrigeration not need), 15 dollars cost of coconut oil included. This is the highest energy density food that is safe long term to eat, completely digestable, and most efficiently burned (glucose has nasty biproducts that have to be dealt with such glycosylated proteins as it is an aldehyde . . . . .cause of diabetes).       To figure the daily cost we need to know calories in a kg of coconut oil. THere are 7850 [kilo]calories in a liter of coconut oil. The oil has a density of 0.925 translating to  8500 [kilo]calories of oil per kg. Lets say that given the gravity on Mars (and work need to main posture while sitting or standing) and given 1:1 male to female ratio an average human should consume about 2000 calories on Mars. Presupposing that of this 2000 calories 1333 will be derived from coconut oil, how frequently would a colony of 4 people need to be resupplied and at what cost.

8500/(4 x 1333) = number of days colony can survive on kg of coconut oil = 1.594days. $30k/day (cost per human per day . .$7000). How many years can the colony survive on the shipment . . . . .6.0 years. Economically this in not too good on Earth, but in space this is a reasonable cost. Disclaimer here, if the environment is very cold, humans can burn 2 to 3 times of calories per day particularly the oils. So if they are working out of doors in the Martian night, the cost of oil calories goes from 1333 to 3333 [kilo]calories per day. Another argument for using more robots on Mars.

Cost reduction strategies. First - for a colony of four, with resupply every 4 years the highest bang for the dollar is going to be in mission conservation. That is to say use proven strategies with guaranteed success. (Noting the failure of many resupply missions to ISS). Colony collapse due to malnutrition brings in magnitude higher human resupply cost.

efficient storage. I should make a note about C14 oil which goes along the same logic as metal fuels for Ion drives. C14 oils have all but no vapor pressure at STP and freeze just below room temperature. Thus if the C14 is the sole item ship we can reduce the structural cost of the payload to 0.025 from 0.1 for the food part of the payload (keeping in mind that the ISP is for cryofuels but the cost of storing cryofuels is not included in the weight, I am making the assumption that n the near future this rather simple problem will be overcome). Technically speaking coconut oil can be used as rocket fuel in a duel cycle engine, so cryogenic fuels are only needed in LEO to LMO insertion and aerobraking could be used to get ship to Mars plus 500m above landing elevation. Given this we could probably double the payload to 2600 kg. Given a maximum resupply interval of 4 years only 66% of the payload can be devoted to resupply of other items (such as essential vitamins). Thus as long as you can keep the fat cool (colder than 4'C) you basically can have blocks of fat attached to the hull of the transfer ship mounted on large aluminum screws about a central pole. Any thin solar reflector will suffice to keep the fat frozen in space (sure hope Mars reentry strategy works). This is workable for a Mars resupply mission for most items except foods that need to be eaten fresh, however with -80'C cryogenic storage, no foods technically need to be eaten fresh, not even after 4 years. One storage unit however weighs about 800 pounds and the newest models need servicing every 5 years (however if you allow the use of older CFC's the duty cycle is about 3 times longer).

efficient transfer. This is a much more insidious problem. Given that our oil is indefinitely stable (pureC14 will not go rancid like olive oil). We now have the luxury of time and with time our propulsion system variations broaden greatly. Given our transfer cost of to Mars is 3884 of which only 600 is needed to get to Mars from the most eccentric elliptical orbit of Earth. Since ION drives can be used to kick our space craft into such an orbit we can now focus on space craft with efficient engines (but huge solar panels). The basic strategy here is to start at LEO say 150,000 meters. The 3rd stage of the F9 payload is ION drive space craft (lets use magnesium as the fuel since it has low storage cost). About 1/4 of the space craft weight will be solar panels. 1/10th of the weight will be Lithium-ion batteries. The ISP is 5,100 (Exhaust velocity is 5000). One of the advantages of using metals is that there is no need to contain them, magnesium isnt the only metal that can be used and better ISPs might be obtained with graphite or Lithium-Boro-hydride or other solids that do not need pressurized containment. This is important because the aerodynamic shielding required to protect such items is a launch to LEO mass only, and the containment that is used need _only_ be physical and need not be pressurized or potentially structural. An example would be a Carbon coated magnesium nose cone (instead of a carbon-fiber) that is then consumed for ION drive fuel.

There are then the dynamic concerns of ION drives. Efficient use of fuel requires the pulsing of engines at pE that then drives the extra-systemic elliptical into an intersect orbit. The problem here is that ION drives cannot produce the output required to pulse once leaving LEO on intercepting transfer orbit and pulse a second time to place the ship in orbit. So we have to examine the benefit of ION drives.
1. Enough dV so that we never have to relaunch - have a repair bot in LOW earth orbit replace the grid and replace fuel, you can also have repair bot in LMO that likewise replaces grids.
2. Engines are very light weight, but they produce little thrust, they typically can operate a few years before maintenance is required. Lets say for a 26000 kg space craft you need dV of lets say 7000 over a year (I will get into this later). Only 15% of the ships transfer and insertion to circularization weight needs to be fuel. So the assumption here is you have ISS2 which is more like a train station than a science station. A transfer ship waits in the station, this ships includes a Mars-brake and land ship and an ID-circulator that travels back and forth between the station and LMO carrying the Brake and land which carries the PL. Lets say the ION drives are active for 1/4th of the trip and inactive over the rest. The F9 rocket transfers 26,000 payload to the transfer ship (replacing drive grids and adding fuel). This means that gross mass is higher how much higher we have to calculate. The minimum amount of thrust is approximately 25N. Seems like a little but its actually alot

The drawbacks of ION drive circulators.
1. From the above we need at least 25N of thrust to get us from LEO and a psuedo transfer orbit that adjusts prior to mars SOI intersection to lower insertion and circularization dV (because of low-light and thrust issues).

The amount of thrust an ION drive can generate is 2 * efficiency * wattage / V_e = 70.58824 KW. This can be achieved with 2 ION drives weight 50 kg each. So we now have 100kg of ION drive. We also need structure to carry 26000 lbs of fuel and payload, at least 15 percent (lets say another 5 percent to return home). 0.025 x .20 * 26000 = 130 kg of circulating fuel containment structure. Another 20kg for fuel transfer mechanisms. Then we have the srtuctural frame for the landing ship, lets say 0.05 of weight of landing ship. 26000kg - (ID fuel) = 20800 =. 20800 x 0.05 = 1040 kg. Next we add solar panels. This is where we get hit hard. 70 KW at 30% efficiency and considering that such a ship spends its orbit halfway between Earth and Mars (Average(149 Gm, 228 GM) = 188.5 GM. Now we are going to go near future and argue that have to consider that 40Eff solar panel can output 1.26E25 / O_sun²  where O is the orbits semimajor axis in nearly solar orbits. Next argument is weight in our near future technology the extra-cylindrical mass per unit area is 0.5kg/m3 for Solar panel surface area. mass = 70/2 * output/m2 The mass of the solar panels is then 12,351 kgs (this is 2 panels 62 meters in radius) . We now have to add vessel structural mass of 0.05% to accommodate the new stresses for a total of  12948, this drops our thrust/kg and increases our power requirement. We also need to add a third engine. The third engine which all-things-being-held-equal approximates the derivative of thrust requirement brings the panel requirement to 18500 kg. This brings total Circulator dry mass to 150 kg of engine mass,  2000kg of structural mass not including structure devoted to Panels, 18500 kg of panel mass ~21000 kg of circulator dry mass (one F9 luanch) noting that the grid weight per 3 35kw drives is trivial (You could actually have a low mass maintenance bot that replaces these in route and improve average efficiency, paying for itself). So now we know what we need on this 50000 Ve (5100 ISP) ION/Solar panel driven circulator (sparing the math). 21000 kg Circulator, 13200 kg of Circulator Fuel, 12800 kg of gross lander mass. The gross lander mass is composed of 1000kg (100 kN) 375 ISP Metholox engine (the circulator stores and conserves liquid oxygen and liquid methane during the trip and loads tanks prior to orbital entry the circulator also provides low pressure ammonium based cooling for any perishable foods on the ship via a solid copper semi hexagon seat that the lander ship sets into via passive heat transfer, temperature is maintained at -55'C). 4268kg of detachable mars aerobrake, 500dV of fuel requires 1193kg of Fuel and tanks, lets say another 91% of the remaining mass is devoted to food. This leave 5700 kg of food from one F9 supply mission to a transfer station in LEO about earth. The variable cost is  $15604 per kilogram of food.

Utilizing Advanced Transportation as a source of food and soil micro-nutrients

Having previously established the daily cost in calories for a 4 year period 66% can come from Oils (C10 to C14). The remainder of calories (666 per day x 4 individuals x 365.25 days/year x 4 years approximates 4 million [kilo]calories) would come largely from proteins of a perishable nature, the reason I say this is that slow carbohydrates are the easiest to grow, nature is very good a producing these (and humans are very good at refining these to fast carbs). Protein is expensive, but it has a dual function since the nitrogenous waste (urine) of a low sodium diet that is filtered produces a R/O decant that when added to compost rapidly becomes usable nitrogen. The compost can come from a combination of inedible plant waste and human feces. Proper containment of the gases (CO2 makes up the overwhelming end produce, but other nitrogenous gases are produced and includes hazardous microbial spores).  Protein contains about 8500 usable [kilo]calories per kilogram (Eggs are 100% usable, Collagen is poorly digested).  This means we need 470 kg for four years of dehydrated protein. Adding back the 1000 kg amount of Oil needed by 4 individuals for 4 years this brings the total cost of food in grams to 1500 kgrams for a 4 year cycle per 4 individuals. Given we have a payload of 5700 to play with we could add  another 11 people. However I would suspect that the additional 4200 kg of PL would be utilized for bringing personal items (clothes, toothbrushes, ipads, feminine products, makeup, first-aid kits and with kids  . . . . . . . ). Colonist could for-go luxury items for building materials for expaning there colonies. This might include husbandy kits (for laying hens) and might also include cryogenically preserved eggs for brood stock. Greenhouse expansion kits. Drilling equipment for excavating martian tunnels for the purpose of permanent enclosures. In Situ Manufactoring (includes iron alloy structural framing and aluminum alloy enclosure pressure walls, LED and wire manufactoring) Cotton could be grown for textile production. . . . . . . . . Thus you need at least one, probably two skilled laborers. If the colonies are relatively closely spaced their could be a devision of specialized labor. Reducing the dependency of Earth.

This then opens up a third efficiency facilitation: To make that ship capable of hauling 6000 kg and use it to resupply calories to 4 colonies. This really reduces the cost of transportation.

Fixed Cost of a Circulator System.

The cycle time of a circulator with maintenance lets say is 25 years. (1/4th of the panels) at the current cost the most efficient panels are guessing about 1000$ to $5000 per meter. So lets argue that the circulator has a 5 year cycle time. That roughly comes out to 1/5th of its total life cost per cycle. 21000 Mass to LEO is 64,000,000 million dollars. Then we have to consider the cost of the space station, arguing its completely robotcized but with periodic human repair missions. The transfer windows to Mars can be rather wide for ION drives since they do not burn completely to their target but adjust their orbit to match that of the target as they approach its SOI. So we could have  vehicles leaving all the time some going in the direction of Venus then burning up to mars, some taking a more direct orbit. In a duty cycle the station could service 10 colonies on Mars or 10% of the yearly cost of the station being born by a single colony. Assuming a modest size station that last 50 years this breaks down into a few 100,000,000$ per year with 20,000,000 going to the cost of each colony. The transfer ship needs then 100,000,000/25 years or 4,000,000 years of capitalization (assuming no depreciation) with depreciation. The Lander and Payload run 10,000,000 per year. This translates to a total of 34,000,0000 per colony or 8,500,000 per person per year. If the cargo only supplies the caloric needs of the colony and can resupply 4 colonies each 4 year visit then the cost goes down to 2,300,000 per individual per year. The optimal macro colony size is therefore 12 to 15 individuals being resupplies every 4 years from the calories brought on one F9 launch either expendible (15 individuals) or non-expendible (12 individuals).

Summary

The basic answer to the trivial responses regarding pleasure foods. You grow in your greenhouse that which most greatly reduces your resupply cost. The green leafies are the most expensive because they are mostly water and provide little caloric nutrition and they are simply the easiest to grow and you get the most benefit from eating these fresh. Next you want to grow whole grain crops and complex/carb protein crops. Carbohydrates are 5 times more expensive (As high as 50000$ per individual per day) to ship from Earth relative to purified C14 oil as a major source of calories. But the other part of this is that whole grains are the primary source of dietary omega-6 fatty acids, which have a safe shelf life of only 1 year and go rancid. Therefore the whole grains for two reasons should be grown in-situ. A third reason is that the chaff from grain crops are soil-building compostable materials. Remember those perchlorates in martian soil . . . . .mix that into composting human feces and urine in a chaff waste compost heap (cooking at around 50'C) AND forget about it, in three weeks it will not be of any concern. Need a source of heat in the winter, turn on the compost heap. When mixed with the desalinated components of urine put compost into overdrive, rapidly break down and increase the heat (&CO2) production of the heap.    This is not perchlorate bioremediation, such as treating soil with microbes, the bioremedial rate of soil is two orders of magnitude slower than a compost heap, as long as the compost is well mixed and the proper seed of microorganisms are provided the cellulases in the compost drive heat formation and provide an abundance of sugar for microbial growth. So there is no benefit to supplying sugar from Earth if a greenhouse is available on Mars, there are only detriments.

  That ketchup, take those tomato and onion seed with you and make quick friends with the botonist in the colony. Vinegar in ketchup is slightly higher cost than oil (you will receive glacial acetic acid which you will have to hydrate).   Grow tomatoes, remove skins (of course grind, cook and eat), remove seeds, grind cook and eat. The pulp of the tomato is cooked until color changes, added onions, salt (from your urine, btw), and acetic acid, the sugar will be squeezed from cane and dehydrated on an electric stove, the molassis (also edible) removed and sugar crystalized ground and dried. The sugarcane pulp will be growned using a metate to produce a fiber that will be treated with cellulases and fermented with yeast used to make ethanol. The Ethanol will be saved to make return home fuel. The yeast extract will be used to make food thickeners. The oxygen produced by the greenhouse will be saved on site to make pressurized oxygen which is cryogenically concentrated to make return home fuel. Theoretically the landers could be reloaded with fuel, sent back to the ID-circulators and sent back to earth (absent the martian air brakes) but the cost utility of this is not good.

Although Potatoes are good there are many other greens in which the whole crop is edible.  Change your cravings to things that are coconut flavored . . . . . .

Just because I know how to do Martian-life stuff is not a suitable reason for me to want to go there. The first Moron to step into his roboticized martian colony has a world of misery and hard work in front of him.

Yes - I have an LED lit greenhouse, make my own compost, know a little about the chemistry of the heap, know how to make soil from sand,  . . . . . . .there is a reason why men of old laid down the plow and took to the sword, as to the fact they make fun of farmers trying to squeeze out an existence off the land. The primary reason is for each pound of grain you have to grow 10 pounds of plant, 15 dried pounds considering the roots system. When you consider that the average human needs 2000 [kilo]calories per day. And if we break that down into  1800 calories per dried kg of grain translating into 1.1 kg/day, this means that the average human needs to generating about 50 lbs on living biomass per day just to sustain himself. The botonist in a colony of 4 individuals 200 lbs of day of living biomass. After you're done harvesting your crop you need to compost about 20-30 lbs of that green per day. Doesn't seem like much until you realize that the Heap needs to be turned every few days (grab that shovel) and it would take 4 or so weeks to get into its rest state. So that at times youre daily chore is moving around a ton (on mars 600 lbs) of compost on a routine basis. After that you want to mix the compost into the maintenance substrate which is 4 times the weight of the compost. That rocket ship your fueling, you get about 1 part ethanol for every 20 parts of cane chaff you grind to a pulp. You are going to be grinding for years to get enough pulp to make the alcohol to return back to Earth. But not only this, you will put on that EnvSuit and go out and chisel rocks or fix drill bot that are hammer a tunnel into martian sandstone so that you can build housing and greenhouses that are safe from Martian faux-pas (such as cosmic radiation) and that is going to be the substate that you take back home and grind into soil. You are not ready for living on Mars. When you can farm and prepare all what you eat with your own hands, then. . . . . . .

 

 

 

 

 

 

[DAL59]

7 hours ago, Green Baron said:

These data show that the combined effects of at least three components of the Martian surface, activated by surface photochemistry, render the present-day surface more uninhabitable than previously thought, and demonstrate the low probability of survival of biological contaminants released from robotic and human exploration missions.

However, there still could be life deeper underground.  

7 minutes ago, PB666 said:

Disclaimer here, if the environment is very cold, humans can burn 2 to 3 times of calories

It won't be cold inside the habitat!  

[Nightfury]

@PB666 this is one of the longest text's I've ever seen in this forum

Edited November 6, 2017 by Nightfury

[DAL59]

What about hydroponics?

A robotic hydroponic farm isn't very far off with our current technology.  

3 hours ago, tater said:

A cubic meter of our air has grams of water vapor, Mars would have 60X less.

There is still plenty of ice in the soil and in glaciers.  Not nearly as much as on Earth, true, but still plenty for open cycle water.  

On 11/4/2017 at 5:14 AM, Green Baron said:

Morning :-)

Nor do i, i can't judge the significance or know the source of the table but it fits well into the (in my eyes overhasty) thinking that a Marsian colony can somehow be a real thing in the medium future (i say 30 years).

 

 

My general thoughts:

This is all based on a few presentation slides of a visionary guy who surely has his successes (F9 is a giant leap imo), but in general tends to dream a little ahead of reality or communicate without a real plan ("steal underpants").

I mean in KSP you slab together an ISRU ship, fly to wherever, timewarp till the tanks are full and then fly back. Jeb's moronic grin will be with you all the way and F5/F9 if you landed at the wrong spot is routine. Reality is a little different, right now there is no prototype, little to no knowledge about density or concentration (heck even availability) of resources.

Even on earth with its rich crust and resource pools everywhere the exploration is a work for geologists and geographers, then engineers to judge the how, when and with what before work can begin. In my opinion, thinking that one just lands, hangs out too funnels one tagged CO2 and the other H2O, suck in whatever and do some blackbox magic that fills your tank will not work. It might just be that H2O once was there but now is gone or out of reach. Or there are traces but in the next valley over yonder.

If you want to do exploration to check the feasaibilty for a colony to support more than a few specially trained people for more than a few years you must do more than send probes and automated laboratories. You'll need data, charts, analyses, blabla, like how much of what is where and how can it be obtained. Technologies to actually obtain things and do something with them to make them useful. That's a universities job and one for a huge industry !

Even Jeb looses his facial features for a second when thinking of it :-)

Actually, in ksp, its good practice to send a probe with a resource scanner...

And why not carry a couple hundred drones on a cargo ITS and have them swarm around looking for resources?  (like in Nat Geo

s Mars series)

Note:  The Nat Geo Mars Spacecraft looks nothing like the ITS...

 

 

[PB666]

46 minutes ago, Nightfury said:

@PB666 this is one of the longest text's I've ever seen in this forum

Then you haven't been here very long.

47 minutes ago, DAL59 said:

What about hydroponics?

A robotic hydroponic farm isn't very far off with our current technology.  

There is still plenty of ice in the soil and in glaciers.  Not nearly as much as on Earth, true, but still plenty for open cycle water.  

Actually, in ksp, its good practice to send a probe with a resource scanner...

And why not carry a couple hundred drones on a cargo ITS and have them swarm around looking for resources?  (like in Nat Geo

s Mars series)

Note:  The Nat Geo Mars Spacecraft looks nothing like the ITS...

 

 

This design is only useful for a landing site that has already been closely surveyed. The landing struts are too close together relative to the height. Any landing site on Mars can be off by hundreds of meters from that actual landing site. With a grade of 10% or higher this thing is on its side.

As for the probes good idea, I made 1/2 scale satellites that can land on a site and gather information (of course they use the faux-pas KSP Ion engines so   . . . . ). I can take these small satellites with me.

My Currrent mission to Mercury has a combination Satellite based surface scanner and Relay station. Not sure yet whether I have enough dV to make it.

 

 

[DAL59]

I know.  I was talking mostly about the drones, but I couldn't find a good picture.  

[Green Baron]

No problem with fictitious spacecrafts of all sorts, dreams of habitats and abundant resources, easy to obtain, refine and use. But none of it survives a reality check right now.

Moar data ! If all goes well we might have a closer idea in 10 or 20 years of what it takes and if it is possible at all to send people to Mars. Until then we'll have to rely on robotic missions and their data and a whole lot on the interpretation of what they send home.

[tater]

I think a manned Mars mission isn't completely improbable in the next couple decades, but colonization talk without having any data on the human factors of 0.38g is pretty absurd.

[DerekL1963]

21 minutes ago, PB666 said:

Any landing site on Mars can be off by hundreds of meters from that actual landing site.

True for the more-or-less "guided" probes we've sent to date.  Not necessarily true in the future and emphatically not true of a guided and piloted vehicle departing from orbit (rather than dropping straight in as had been the general practice to date).
 

1 hour ago, tater said:

I think a manned Mars mission isn't completely improbable in the next couple decades, but colonization talk without having any data on the human factors of 0.38g is pretty absurd.

Quoted for truth.

[DAL59]

1 hour ago, tater said:

without having any data on the human factors of 0.38g is pretty absurd.

How to we get that data?  By sending humans to Mars!  

[PB666]

44 minutes ago, tater said:

I think a manned Mars mission isn't completely improbable in the next couple decades, but colonization talk without having any data on the human factors of 0.38g is pretty absurd.

That depends. Manned landing mission is not going to be like Apollo, the return window requires a wait, which means colonization aspect means the first men landing on Mars may have to colonize unless a better source of Power in flight can be obtained. My argument is this, we cannot even think about a manned landing mission without proper preparation of the infrastructure on Mars. Footprints and flags only mission is essentially a suicide mission. 0.38 g maybe survivable even long-term, it is more survivable than micro-gravity. We tend to think as colonization as being permanent, but the first colonies in the new world were frequently abandoned or moved. Some were abandoned only to be later reoccupied. It may be the case that that first colonies on Mars are only occupied for a few months at a time until the safe infrastructure for permanent settlement is in place.

The question that I posed in the previous long post is that 'can a Mars colony be made feasible enough such that only trivial resupply missions suffice'. I devised a strategy for transporting materials brought by common commercial rocket to LEO. Circulator to LMO, and landing ~6T on mars. The true question here is how much can we expect inhabitants to supply of their food calories and raw materials. If the answer is less than 30% then there is no long term feasibility of a Mars colony. If, OTOH, they can supply 70 or 80% of both, then a single resupply ship can service dozens of colonies within a certain proximity.

On the issue of Power these are my thoughts. If you have a High ISP ION drive (5000+ sec), then on circulation back to earth you can afford to be wasteful and chase Earth versus Hohmann intercept. The problem is Power.
-Solar panel absortion to power efficiency is creeping slowly from 30, I have seen efficiencies as high as 45, but a circulator will require a very durable solar panel. And still we are talking huge amounts of power. Once the Earth has passed Mars no transfer orbit can catch it until Earth is once can following Mars. As a consequence an Earth intercept transfer has to burn so hard that its periapsis falls below the orbit of Venus and then rises to intercept Earth with positive radial velocity.  This will require several thousand more DV than a direct transfer orbit. 

- If you have a 10,000 ISP engine granting all the extra dV you have to either increase the size of solar panels or the efficiency <------. Because adding solar panels makes the absolute thrust issues more problematic, efficiency. There is a marginal utility of gain when adding ISP (payloads must shrink). So a normal mars return is within the bounds of what ION drives can current do, but beyond the bounds of what current solar panels can do (both efficiency and size). If you replace 30,000 kg of solar panel with a 1 megawatt fusion reactor all your problems except cooling immediately go away. First ION drives are low weight and you can add many. The cost of fuel shrinks. You now have both thrust (interplanetary worthy no launch to orbit worthy) and you can plow to a mercurial orbit and back to earth and stop at a reasonable altitude, transfer the pilot to a return station and go back to Mars again. The problem is not so much a strategy for getting to Mars, getting Elon to Mars is doable, even landing him there alive in a coffin is doable (he would survive, pretty sure) keeping him alive for more than a few months or longer with resupply is not much of a problem either (still not a colony though) . We simply lack the power to get him back in a timely manner.

Assuming a transfer ship and a coffin (1000 kg) plus a passenger and his EVA suit. A lander that used 500dV to land and 4200 dV to orbit . . . . . 4700dV with the most efficient engines Metholox engine 375 sec means that you need to get a return rocket of 7 tons on Mars just to hook up to a ID Mars return vehicle . . . . . IOW Musk walks into the coffin at time X, pushes a button, it travels up to orbit and parks next to the return vehicle. He gets out, space walks to the return ship, boards it. The reason why this makes sense more than any of the other concepts is the smaller the return craft, the easier it is to design a return vehicle. A single person lander only needs a few hundred dV which means aero braking is relatively easy (provided they have a place to stay). This return vehicle is at the very limit that a F9 rocket, with the help of a LEO to LMO circulator can provide. That one launch and orbit leg requires one F9 AND is not a ride any of us want to take.

The problem is that the dreamy-eyed mars folks are not thinking about just how hard life will be once you leave Earths SOI in the direction of Mars. They keep thinking about USS Enterprise that can warp from point A to B using space ships with nicely decorated personal cabins.  Thats why I said a month ago, I though about it for a millisecond and the answer is no-go. Nasa will no-go, I think in the end Space-X will no-go.

 

[DAL59]

1 hour ago, PB666 said:

Footprints and flags only mission is essentially a suicide mission.

Why?  You can easily carry enough food for a 2.5 year mission, and as Zubrin constantly points out, the radiation isn't that much.  

1 hour ago, PB666 said:

30,000 kg of solar panel

MIT scientists have made a far lighter solar panel.  If that was used, or beamed power, that mass would leave.  Also, chemical rockets work fine!  

https://www.nasa.gov/pdf/376589main_04 - Mars Direct Power Point-7-30-09.pdf

[tater]

Flags and footprints isn't a suicide mission. 

It's achievable with some effort. The NASA version of Mars Direct addresses the problems via redundancy, sending the MAV ahead, etc. I don't think it's a problem other than money, really. The lynchpin issues are the life support (with requisite spares), and working out the landing issues ahead of time (unmanned).

[PB666]

4 hours ago, tater said:

Flags and footprints isn't a suicide mission. 

It's achievable with some effort. The NASA version of Mars Direct addresses the problems via redundancy, sending the MAV ahead, etc. I don't think it's a problem other than money, really. The lynchpin issues are the life support (with requisite spares), and working out the landing issues ahead of time (unmanned).

If money = power then its money. But given the fact that only truely viable deep space power source is one that has yet to have proven itself on Earth (fusion energy). While solar materials are getting more weight efficient and conversion efficient the problem is that these are not stationed arrays, they are flipping out in space. The Russians tried using fission reactors in space, that proved to unweildy because of the plumbing issues involved.

Think of the problems that could be solved with power. . .+ radial transfers and - radial stop vectors. (So called 39 days) also limits the travel of Mars past earth making travel back easier. The 39 days (VASIMR) was an ION drive based system, the only problem was they 200 kw required to operate it does not exist.

I think the biggest stumbling block at present is the return trip (A Mars launch/orbit) is expensive, even to carry one individual and transfer to another ship (factoring cost from earth) and the additional time required to transit back to Earth. The way Mars looks compared to the lunar mission.

1. More dV for intercelestial transfer.
2. More dV to insert into orbit
3. More mass required to land
4. A whole mission just to supply the return vehicle greater than a single Apollo mission with lower capacity
5. A return mission with a capsul much heavier and elaborate than the command module/capsule.

At each point along the way the mars mission is more risky, expensive . However the last two are the most problematic.

 

[tater]

The NASA DRM (with both NTR and chemical versions) puts the MAV on the surface well ahead of time to make propellant. The older profiles land a stage with a return vehicle that can make martian orbit without refueling.

I'm not sure what the problem is you are referring to, yeah, it requires a lot of launches, and prepositioning elements at times vs all up in 1 go, but it's not impossible.

[DAL59]

14 hours ago, PB666 said:

1. More dV for intercelestial transfer.
2. More dV to insert into orbit

Not correct actually.  It takes equal delta vee, because Mars has an atmosphere.  Also easier ISRU.  

14 hours ago, PB666 said:

A return mission with a capsul much heavier and elaborate than the command module/capsule.

Especially with Bigelow, that could be easily doable.  

8 hours ago, tater said:

The NASA DRM (with both NTR and chemical versions) puts the MAV on the surface well ahead of time to make propellant. The older profiles land a stage with a return vehicle that can make martian orbit without refueling.

I'm not sure what the problem is you are referring to, yeah, it requires a lot of launches, and prepositioning elements at times vs all up in 1 go, but it's not impossible.

Zubrin's plan calls for only three launches: A hab, and ERV, and a manned lander.  

[tater]

5 minutes ago, DAL59 said:

Zubrin's plan calls for only three launches: A hab, and ERV, and a manned lander.  

Zubrin can have all the plans he likes, he lacks his own space program.

NASA has not, and will not do Mars Direct, they will do whatever version they think is best (assuming they ever have more that money for white papers). NASA is risk averse, and their version---the only version you should bother thinking about in the context of NASA---adds complications in the name of safety.

The recent LockMart proposals: their lander, and transit ship to be (notionally) assembled at DSG, has 2 of everything, some of which is sent ahead to Mars, for example. This is not a NASA DRA, but it's closer to the spirit of what NASA might actually think about doing.

 

[DAL59]

The problem with Lockheed plan is that it will enable only 2 week stays for only 4 astronauts.  For a lander to be sustainable, it should be able to carry at least a couple dozen people to the surface and stay for a few years.  

It also requires a dozen launches just for a 2 week surface stay!  

[DerekL1963]

1 minute ago, DAL59 said:

For a lander to be sustainable, it should be able to carry at least a couple dozen people to the surface and stay for a few years. 

Exactly what is your definition of "sustainable"?

[DAL59]

2 weeks isn't very long to explore, let alone build a colony.    

[tater]

31 minutes ago, DAL59 said:

2 weeks isn't very long to explore, let alone build a colony.    

Then why do you bring up Zubrin? He proposes a flags and footprints mission, not colonization.

You can't argue that we could send an Apollo-style mission for cheap as an example of why colonization is cheap.

Colonization is a multi-trillion $ thing.

33 minutes ago, DerekL1963 said:

Exactly what is your definition of "sustainable"?

He seems to conflate flags and footprints with colonization?