DBowman

Minimal Manned Mars Mission - 2*Briz = doable! + a NEA

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I've got a variant Minimal Manned Mars Mission idea. Please give me your criticisms, suggestions, validations, help, useful resource references, etc

 

[edit: an index into 'highlights'

]
 

Over the past year or so I've been reading all sorts of Mars Mission proposals.
 

The most recent proposal at the Humans to Mars conference (http://h2m.exploremars.org/) is designed to be within the existing CPI indexed NASA budget and have continuity with current programs - and so it is methodical, incremental, and expensive. NASA's DRA 5 is ambitious and even more expensive. Mars One cuts down on scope (cost!) by skipping the return, it is optimistic and speculative in the near term but hazy about the long term and the funding. I liked Zubrin's Mars Direct, a bodacious plan but at the same time small and controlled. Tito's Inspiration Mars skips the landing altogether and does a two man flyby for $1 - 5 billion.
 

All these plan involve a huge amount of money, the more they cost and the longer they take the more likely they are to be dropped or stillborn. So I wondered what was the least you could possibly spend and still be a Manned Mars Mission - it seemed like the mission plan would have to be a one man seat of the pants flyby.
 

Originally I wasn't a big fan of the flyby, but decided to ignore the reasons not to do one and just think about how to do it quick, cheap, and safe.
 

The goals / rules are:

  • Simple is safe and cheap.

  • Use the simplest thing that could possibly work.

  • Off the shelf components/systems.

  • Flight heritage.

  • Minimise first, if it ends up under mass budget then start adding things to make it safer, more useful, or more fun.

For example the Mars Society held a student Inspiration Mars mission design competition. Team Kanau's proposal is a great read (http://members.marssociety.org/inspiration-mars/finalists/Kanau_Updated_Report_V2.pdf). They budget drinking water at 2 kg/day and hygiene water at 7 kg/day. They plan to use ISS style life support to reclaim water from urine etc - ECLSS is budgeted at 8,600 kg. Seat of the pants says; 1 man 600 days is 1,200 kg water, drink from a bottle, then pee into it, wash when you get back.

 

Current state of the Minimal Manned Mars Mission 'plan':

  1. Trajectory: Tito's team did some trajectory analysis and found every 15 years there are two 'magic' trajectories; 501 days, survivable Earth reentry velocity, reasonable TMI deltaV. Probably we'd miss the current 2018 chance and have to wait until 2031. That leaves:
    1. Tito's 'Plan B' 2021, 589 days Venus & Mars flybys.
    2. Otherwise http://trajbrowser.arc.nasa.gov/traj_browser.php:
      • depart trip time    km2/s2    init+tweak
      • 2020 1.40yr 511, C3 58.7, dV 5.63+0.28 km/s, re entry 14.37 km/s
      • 2022 1.93yr 705, C3 26.7, dV 4.38+0.06 km/s, re entry 12.72 km/s
      • 2022 1.80yr 657, C3 51.8, dV 5.37+0.32 km/s, re entry 13.62 km/s
      • -.22yr 80d if it can re enter at 19 km/s and cost near 7km/s dV
    3. Maybe there are other Plan Bs in later years, or maybe other near magic trajectories if one looks hard enough...
  2. Staying Alive:
    1. Mission Time: The flyby is long but in the ballpark with other space or solo voyages. It will be longer than the current time in space record 437 days Valeri Polyakov, but possibly shorter than 658 day triple round the world solo yacht trip https://en.m.wikipedia.org/wiki/Jon_Sanders
    2. Prep: aggressive prophylactic dentistry and medical.
    3. Meds: not sure what yet, but pain can be debilitating.
    4. Shielding: Water supplies, stored urine, food, etc. It looks like around a cubic metre or water is required, pack it in daily ration PET bottles / plastic bags. After launch reconfigure their distribution as a shield, for a solar flare reconfigure again to make a more compact and higher shielding temporary shelter.
    5. Respiration:
      1. No fancy recycling: oxygen recycling via Sabatier etc - ISS experience is that it's troublesome (breakdowns, mystery smells, fire hazard, nasty chemicals are part of the device). Similarly for Elektron electrolysing H2O. Maybe the ISS zeolite bed and vent to vacuum for CO2 removal might be okay.
      2. Pressure bottled oxygen: Cryostorage is probably more compact and lighter but pressure storage should be almost as good mass wise and is much simpler. Oxygen candles sound cool (as it 'burns' it generates oxygen, how the emergency oxy on a passenger plane works) but massy and there were fire incidents with them on ISS.
      3. CO2 scrubbing like Apollo via 2LiOH(s) + CO2(g) -> Li2CO3(s) + H2O(g) - it makes water - that has to be useful.
      4. Kanau team has 1.584 kg/day H2O being respired / perspired, much of it generated by human metabolism (apparently our bodies manufacture water). Also there is some H2O generated by the LiOH reaction. This humidity has to be removed from cabin atmosphere and would be potable => only 0.5 kg/day of H2O needs to be launched.
    6. Food: standard freeze dried 'space food'. 0.8 kg/day
    7. Water: Since CO2 removal and human metabolism generates about 1.5 kg/day of H2O we only need to launch 0.5 kg / day - less than 350 kg in total. We need empty baggies for urine collection.
    8. 'Human Waste': I guess the pilot passenger has to poop in baggies also. Does the human waste need to be sterilized? how?
    9. Exercise: ISS solution is size and mass of a car. Something smaller and lighter is required.
    10. Living room: I don't know what the absolute minimum is here. The astronaut needs exercise space, enough room to stretch out, there might be info from shipwreck and prisons re how little space people can 'put up with if they have to'.
    11. Home alone: people can handle solitude for that period if they have something to do. Mission monitoring, self maintenance,  and self monitoring for medical 'experiment' purposes will be large activities. Likely communication back home can be easy and frequent. Solid state storage for books and movies is light.
    12. Thermal management
    13. Communications
    14. Astrogation
    15. Attitude control
    16. Power - solar
  3. The Vehicle: depends on the numbers above. Ideal craft would be existing or small derivation of existing, in descending desirability:
    1. a single launch for the whole stack with astronaut aboard
    2. two launches; with either a docking assembly or crew transfer
    3. docking assembly of the flyby vehicle with additional crew transfer flight
  4. Adding Back: Once the minimum survival requirements are met any space in the mass budget can be filled with 'optional' and hopefully 'high value' things
    1. Medical monitoring of the effect of the longest ever time in space.
    2. How to capture the experience for those back home? IMAX cameras? internal and external cameras etc.
    3. Increase the drama? EVA? a pet?
    4. cube sats, impactors, landers, ?

 

Edited by DBowman
and an NEA

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I like Mars Direct (and Semi-Direct even more), but its main criticism is that the masses of the components (such as the ERV) were thought to be underestimated, and a mission involving on-orbit assembly (simple docking of propulsion stages, no EVAs), on-orbit refueling, and/or high-Isp propulsion (e.g. nuclear thermal or solar electric) would have better mass margins as opposed to a direct HLV launch to Mars.

Edited by Pipcard

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'Human Waste': I guess the pilot passenger has to poop in baggies also. Does the human waste need to be sterilized? how?

It ferments to methane gas, CO2 and sulfides, intractables remain. You don't want it in the space craft. You can chemically oxidize it with a minimal amount of solid oxidant.

I think you are way low of water, unless you are going to recycle urine. you can place the feces in a dehydrater and extract the remaining water, then you can simply bag it as a coprolite ($#!t crackers)

LiOH + CO2 generates Li2CO2 but the reaction is drive by moisture in the air, and the water is salt hydration, you can get it out with heating or lypholization but then some of the CO2 will also evolve. Its better if you have liOH cartriges, once a month put the copros and cartriges in a bag and eject them into space . . . . .bye, bye.

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10 hours ago, PB666 said:

It ferments to methane gas, CO2 and sulfides, intractables remain. You don't want it in the space craft. You can chemically oxidize it with a minimal amount of solid oxidant.

I think you are way low of water, unless you are going to recycle urine. you can place the feces in a dehydrater and extract the remaining water, then you can simply bag it as a coprolite ($#!t crackers)

LiOH + CO2 generates Li2CO2 but the reaction is drive by moisture in the air, and the water is salt hydration, you can get it out with heating or lypholization but then some of the CO2 will also evolve. Its better if you have liOH cartriges, once a month put the copros and cartriges in a bag and eject them into space . . . . .bye, bye.

Good info thanks. I'll look at dehydrators and oxidizers. Shame about the LiOH water not being recoverable. Do you think 2 kg/day water is un-survivable? or that inevitably one needs some hygiene/other water also? the respired/perspired H2O in Kanau report surprised me, I'm going to cross check that.

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This paper is pretty old (1969! http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0698118) but seems to imply that LiOH needs to be hydrated for the reaction to Li2CO2 to occur but that in the end it liberates the H20. This one from Reaction Engines (the Skylon folks) http://www.reactionengines.co.uk/tech_docs/mars_troy.pdf budgets the water produced from CO2 scrubbing as usable water.

For a 589 day trip with Kanau essential water ration, respire/perspire H2O capture, O2 used at 2 hours max and 22 hours normal we'd need 708 kg of LiOH which would liberate 497 kg of H2O 245 kg excess water - I mean the trip would start with a couple liters only and finish with 245 left over! Here the 'CO2 removal part' of the 708 kg is 211 kg (the part that does not become water) - guess what the ISS  Carbon Dioxide Removal System mass is? 201 kg! (http://salotti.pagesperso-orange.fr/lifesupport3.pdf) but it's rated for 6. Space Shuttle one was 147 kg (http://ston.jsc.nasa.gov/collections/trs/_techrep/CR-2004-208941.pdf). 

I guess one could make / have made a smaller CDRA and save between 100 - 600 kg depending on the actual usability of LiOH water. If it was bespoke we'd have to insert 3 years for development, unit testing and soak testing. The ISS one still isn't quite working right.

My current estimates for this trip are approx: 740 kg for O2+tankage, 448 kg food+packaging, and between 0 and 1,370 kg of H2O. (obviously a lot of items left out)

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I decided to evaluate current space craft against this mission profile - maybe it's possible 'anytime now'.

The only re-entry vehicle that is currently available is the Soyuz:

  • good: the orbital module provides an airlock - EVA potential!
  • close: the thermal protection is not up to the 14 km/s of Inspiration Mars, but the Soviet Luna plans had designed a derivative with a thicker & heaver heat shield for the 11 km/s ex-Luna re-entry. 700 day Mars flybys with 12.2 km/s reentry speeds are common. So it seems doable. One time the Orbital Module didn't separate properly and so they entered OM first, it burnt off and the rest of reentry went 'normally' - not sure one should plan on using the OM as supplemental TP - Jeb might.
  • bad: it's kinda heavy 7,200 kg vs 4,200 kg Dragon
  • bad: it's kinda small 8.5 m^3 vs 10 m^3 Dragon
  • red flag: it's 'rated' for 215 days in orbit - not sure why, maybe it's just a certification thing, maybe it's some consumables, hopefully not something breaking down...

I think 2,800 kg consumables would cover a 704 day Mars flyby (704MFB) - so evaluate current launchers for a 10,000 kg payload. The only real existing contenders are Proton and Delta IV Heavy. Inspiration Mars trajectories are 4.9 km/s and up (I haven't managed to find good numbers for Plan B Venus & Mars flyby), http://trajbrowser.arc.nasa.gov/traj_browser.php 704 day is 4.61 km/s

Proton:

The numbers say it would be possible with multiple launches and docking assembly. The final stage Briz-M version has non cryo-propellant and 8 restarts, so multiple launches and assembly are possible. One would have to make a version of the Briz-M that could 'stack' by docking, it's got control and avionics but probably not attitude control etc. http://www.astronautix.com/lvs/probrizm.htm says Proton will put 21,000 kg into LEO. Launches: 

  1. Soyuz + Consumables is 10,000 kg => 1.687 km/s 'residual' DeltaV

  2. A slightly under-fueled final stage as payload => another 1.868 km/s

  3. another => another 1.117 km/s

that's 4.67 km/s for about 315 M USD

Delta IV Heavy:

The numbers say it's not obviously impossible - it might be possible with a Dragon. Delta Heavy is all cryo-stages. From http://www.wikipedia.com for LEO 28,790 kg and TMI 8,000 kg 'rating' and http://www.astronautix.com/lvs/delheavy.htm (shows an extra ton to LEO) for extra info on stages masses, using 4.3 km/s as TMI DeltaV I calculate it should throw 7,000 kg on the 704MFB. That's almost exactly a Dragon + consumables. One caveat is that the trajbrowser trajectory has 0.14 km/s correction burn, one cannot use the Delta final stage for that, maybe the trajectory can be optimized to eliminate the correction, maybe Dragon can handle the correction, maybe it needs a little 'CSM' (one has to wait for the Dragon ...). Also the Delta is not 'man rated'.

That's about 324 M USD

 

It looks like the Russians could do this soon if they felt like spending 400 M USD. It should be very comfortably doable with a Falcon Heavy (when it arrives) with mass budget left over for EVA and 'extras'.

Edited by DBowman

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You'd need to test the life support gear on earth with about 10 extra copies of the capsule, built on earth, and tested by volunteer astronauts, right?

For the entire trip.  Uggh.  And then launch a couple who get to camp in orbit and not actually go to Mars, right? These test missions, the capsule would be tethered to the ISS, separated by some closed hatches from the normal station.  So if anything goes wrong you could open the hatches and have the astronauts move back to the ISS.

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SomeGuy123 - I'm trying to avoid that time and $$ cost by minimizing the life support complexity - so far a dehumidifier and Apollo style LiOH CO2 scrubbers - very old school tried and true tech. Otherwise as you say you front load the mission with years and hundreds of millions of development and testing costs. So far the ISS closed cycle life support has things going wrong with it all the time - and that's the best we have.

Edited by DBowman

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Did you calculate how much LiOH you need for such a long trip? Also i dont see you mentioning a landing. A pure manned flyby is worthless from a scientific standpoint, only a few days of real time control for rover could help with exploration, but for that the costs/risks are way to high.

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The idea of using trash as extra propellant is... Novel I suppose ? No more costly mid-course corrections (with engines and propellant)... Imagine not needing to have any RCS on the craft... Reentry might be a bit rough though, but Soyuz does them nicely even if deliberately disrupted. Maybe launching the trashes with some springs would help !

For those who wonder "where's lander ?" the OP have stated it will only be a flyby for "tourists" or so. I mean... We did flyby first for Moon no ? So why not on Mars ?

 

Edited by YNM

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The flyby of the moon was to test the equipment for a landing, i dont see such reasons for this flyby mission.

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9 hours ago, Elthy said:

Did you calculate how much LiOH you need for such a long trip? Also i dont see you mentioning a landing. A pure manned flyby is worthless from a scientific standpoint, only a few days of real time control for rover could help with exploration, but for that the costs/risks are way to high.

Yep - 850 kg, and the scrubbing process might liberate 593 kg of H2O.

8 hours ago, Elthy said:

The flyby of the moon was to test the equipment for a landing, i dont see such reasons for this flyby mission.

It's almost a pure glory and trail-blazing mission. The only legit science is the medical data on 700 days weightless. They could do it on ISS but they are working up to it gradually so this mission would provide true novel data. 

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Disappointing; https://en.wikipedia.org/wiki/Crew_Return_Vehicle "the TMA [Soyuz] has a lifespan of about 200 days before it has to be rotated out, due to the degradation of the hydrogen peroxide used for its reaction control system" - One couldn't use an 'off the shelf' Soyuz, effort / risk / cost to customize reaction control would have to be done.

[edit: I later learned that in current Soyuz MS the H2O2 is only used in the descent module for attitude control while re-entering (it can generate lift if oriented correctly) and they have failure contingency flight plans - i.e you don't need it. In fact with the high entry speed you'd want a steep descent to decelerate asap to minimize heat, so you wouldn't use it even if you had it, so don't take any and save 30-70 kg.]

Edited by DBowman
info update

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12 hours ago, DBowman said:

Disappointing; https://en.wikipedia.org/wiki/Crew_Return_Vehicle "the TMA [Soyuz] has a lifespan of about 200 days before it has to be rotated out, due to the degradation of the hydrogen peroxide used for its reaction control system" - One couldn't use an 'off the shelf' Soyuz, effort / risk / cost to customize reaction control would have to be done.

I think that was exploited in Gravity or so...

Anyway, maybe we can use trash-launcher as a replacement of RCS ?

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On 12/10/2015, 10:43:23, YNM said:

Anyway, maybe we can use trash-launcher as a replacement of RCS ?

I'm aiming to stick to tried and true systems with flight heritage. Also trying to minimise trash; urine, faeces, & Li2CO2 are the major ones and I think they will be needed as shielding 

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Delta IV Heavy + Soyuz TMA can do a 500 day Venus then Mars flyby with 1,600 kg available for life support and any other modifications.

Mission Opportunities for Human Exploration of Nearby Planetary Bodies - Cyrus Foster & Matthew Daniels has a 2023 departure 500 day Earth, Venus, Mars, Earth trajectory. It needs 4.31 km/s initial deltaV and 0.07 km/s adjustment burns. It reenters at 14.1 km/s, faster than I'd like but doable.

Delta IV Heavy can throw 8,000 kg to Mars, nominally that's 4.3 km/s. Soyuz TMA masses 7,200 kg and has 900 kg of fuel for 390 m/s deltaV, 700 kg of that fuel is excess and the mass can be used for life support. That gives a life support mass budget of 1,500 kg.

If one could use an ISS style Carbon Dioxide Removal Assembly (half size say) the consumables would mass 1,300 kg.

You'd certainly be able to remove a docking port from the Soyuz to strip more mass, so maybe there are 300 - 400 kg 'left over' for contingency deltaV and 'customization' that might be necessary; more solar cells, parasol, non peroxide RCS, ???, and more thermal protection for reentry.

Am I missing something? Can this be shown to be not do-able without looking into the fine details?

Edited by DBowman
oops

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mmm urine ... 1.9 kg/day - too good to throw away?

This looks pretty promising as a simple, low mass, no maintenance, no energy, few failure point way to recover H2O from urine. HTIWater.com

  1. A semi permeable membrane bag inside a 'waste water' bag
  2. The 'clean water bag' is primed with a concentrated solution of electrolytes and glucose (from food mass budget)
  3. The waste water is placed in the enclosing bag
  4. Wait hours and osmosis draws H2O into the clean bag to dilute the priming solution
  5. Dispose of the now concentrated waste
  6. Drink the clean solution
  7. Repeat 

I'm not sure how flexible the priming solution can be, soup? coffee? hopefully the astronaut won't be forced to use 'gatorade' as a significant part of their calorie intake. The website's details are a little sketchy re mass ratios etc. However they mention a single use disaster relief product where 50 lb of pouches replaces 660 lb of plastic bottled water. For now I'll estimate 1/13 required water as urine recovery consumables, these will reduce the food mass also, but I'm not sure by how much. Single use has some advantage in minimising multiple handling of urine and urine concentrate.

For 500 days the water budget could be:

  • NASA kg/day: 4 consumption  - 1.584 vapor sweat respire recovery = 2.416 kg/day => 1,208 kg
  • Kanau kg/day: 2 consumption - 1.584 vapor sweat respire recovery = 0.416 kg/day => 208 kg
  • NASA with HTIWater => 93 kg - makes a huge difference.

Anyone have alternate urine processing ideas? ideas / details for potential delicious & nutritious priming solutions?

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With some further research I find NASA had tested HTI's forward osmosis of urine in orbit ( though without drinking it! ):

  • 1 L urine + 60 ml of driver solution = 0.9 L sports drink
  • you have to pre filter urine through an activated carbon filter first

1.9 L urine per day => can recover 1.596 L H2O per day, for a 500 day trip:

  • 950 kg urine available
  • 798 kg H2O recoverable
  • 62 kg of consumables required to recover it, 57 kg is 'driver solution'
  • ?? kg of activated carbon filters
  • to match NASA 4 kg/day you need 410 kg of water to start with, some of that is 'driver solution water' - so say 360 kg pure H2O to start with

Some sources say 3 kg/day is enough, but the data I have on vapor and urine matches the 4 kg/day consumption. I assume if you reduced consumption that would also reduce vapor and urine (though some H2O is generated from metabolism) hmm NASAs numbers have 3.484 kg/day being emitted by the body (poop is some more, maybe 0.1 kg) - say 3.6 and some of that is metabolically generated so no way you need to drink 4 kg even by their numbers.

Anyway something like 160 kg to 360 kg of water required at launch.

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Solar Storm Shelter - a water 'sleeping bag' (sarcophagus?, coffin? ). Climbers and hikers routinely spend days in their sleeping bags weathering storms, though usually not fully zipped in 24 hours a day...

How much water shielding is required:

Bag design:

  • A 1.9m tall oval prism 'sleeping bag' 'cut fairly loose' and hitting ESAs more stringent numbers would need 800 kg of water. 320 kg for NASA numbers
  • By tapering the legs, but still sleeping bag like, you could cut it to 700 kg. 280 kg for NASA

Worst case the vehicle would launch 120 kg short of the water required to hit NASAs easy numbers. I could not yet find good data on using dehydrated food as shielding, it's not water but there is 380 kg of it. 300 ml/day urine brine accumulates + 100 ml in poop, it would take 300 days to accumulate the missing 120 kg - so food better be a good substitute for water.

Also worth noting that gonads, gut, & brain are the big three targets for protection and that tissue itself serves as a shield. Your legs will handle a higher dose than your gut. If the 'sleeping bag' were knee length the tissue of your thighs would shield the much more delicate gut etc.

It seems like the vehicle could launch providing NASA level whole body protection, but maybe not ESA level. Maybe someone has already done the simulations for something like this, maybe not - they are usually assuming much more resources to work with.

If there is 'free mass' on the final budget taking 'excess' water would have a couple of advantages:

  • improve the solar storm shielding level
  • provide some holiday / buffer / flush days to not recover water from urine
  • sponge bath? woot!

The mission still seems near the border line of doable / not doable.

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Soyuz facts: good: 15 M USD, bad: the main engine turbo-pumps use hydrogen peroxide - so the main engine has the ~200 day duration limit => you'd have to 'customise' the main engines to use it in a 500 day flyby - a big problem. [edit: oops I later learned this is wrong. The launch vehicle has H2O2 driven turbos, the spacecraft is pure hypergolic.]

RCS you could imagine getting by with a dock-able 'flyby module' attached to the OrbitModule at assembly stage. The flyby module could provide attitude control since it only needs to point the right direction for the 70 m/s flyby adjustment burn. But if the main engines cannot last until final Earth approach and reentry tuning then simple attitude control is not enough. 

Edited by DBowman
info update

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This kind of kraken will never happen due to tiny margins and high risk. Doing it in many launches also increases complexity, shown by the ISS.

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18 hours ago, fredinno said:

This kind of kraken will never happen due to tiny margins and high risk. Doing it in many launches also increases complexity, shown by the ISS.

I know what you mean

  • I was surprised that the margins were not very negative for current tech, but I think that means that there will be plenty of margin for a tiny/minimal mission with next gen launchers - 14 tons to Mars ... 'luxury'.
  • There is not much point doing a detailed quantitate risk assessment until there are sufficiently positive margins. However there doesn't seem to be any real reason it should have more extrinsic risk than any other planned mission. The background radiation seems within lifetime limits, the solar event risk seems manageable to ESA standards. The strategy is to minimise equipment risk by minimising the use of equipment and using long proven equipment where possible, simple is safe & proven is safe. There is not much one can do about the risk from doing it solo - but I saw today someone rowed across the pacific solo - so there are people who are content/eager to accept that kind of risk.
  • I agree so much re the multiple launches.
    • cost itself is a risk
    • you'd have to develop hardware to 'dock stack' stages - development risk and cost 
    • the stages would have to be able to loiter - which means lower ISP - which means more stages - more risk
    • it all snowballs away from you
  • taking on the 'solo' risk greatly reduces the 'funding risk'

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1967 Apollo Applications Manned Venus flyby paper - I came across this today ( the paper from nasaspaceflight.com ).

mvfcutaway.jpg

Even if you know the mission profile ( Apollo CSM + ESM (Environmental Support Module) + Saturn IVB/UI spent stage 'wet hab' thrown around Venus with one Saturn V launch ) it's interesting to read. Actually very much in line with what I was thinking above:

  • Only simple recover/cycle closing for life support; condensed cabin vapor, evaporate urine from wicks and condense (we have forward osmosis now)
  • LiOH was too massive, go with thermal swing molecular sieve - like ISS CDRA (CO2 removal assembly)
  • Cryo O2 (I was thinking pressure stored for 'less to go wrong', but it is heavier...)
  • passive heat management; 'paint' different sides of the craft with different absorptive/emissive surface treatment and orient the craft relative to Sol to balance insolation and radiation, supplement with heaters and radiators when orientation effect has maxed out.

Unexpected bonus info:

  • The solar wind expected to exert 0.001 lb force, they have estimates of how much RCS fuel they have to use to 'un-soak' the flywheels (few hundred pounds) from correcting for COM vs CODrag to maintain orientation.
  • 56kbs Earth to vehicle data transmission rate - welcome to the 1990s + killer latency
  • using the solar arrays as the  micro-meteorite shielding - although 99% chance nothing would hit you
Edited by DBowman
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9 hours ago, DBowman said:

1967 Apollo Applications Manned Venus flyby paper - I came across this today ( the paper from nasaspaceflight.com ).

index.php?action=dlattach;topic=34776.0;

Even if you know the mission profile ( Apollo CSM + ESM (Environmental Support Module) + Saturn IVB/UI spent stage 'wet hab' thrown around Venus with one Saturn V launch ) it's interesting to read. Actually very much in line with what I was thinking above:

  • Only simple recover/cycle closing for life support; condensed cabin vapor, evaporate urine from wicks and condense (we have forward osmosis now)
  • LiOH was too massive, go with thermal swing molecular sieve - like ISS CDRA (CO2 removal assembly)
  • Cryo O2 (I was thinking pressure stored for 'less to go wrong', but it is heavier...)
  • passive heat management; 'paint' different sides of the craft with different absorptive/emissive surface treatment and orient the craft relative to Sol to balance insolation and radiation, supplement with heaters and radiators when orientation effect has maxed out.

Unexpected bonus info:

  • The solar wind expected to exert 0.001 lb force, they have estimates of how much RCS fuel they have to use to 'un-soak' the flywheels (few hundred pounds) from correcting for COM vs CODrag to maintain orientation.
  • 56kbs Earth to vehicle data transmission rate - welcome to the 1990s + killer latency
  • using the solar arrays as the  micro-meteorite shielding - although 99% chance nothing would hit you

I'm fairly certain that this would never have happened even if they had the money- making wet workshops during transit is really a recipe for disaster. What happens if you accidentally damage something during construction?

I think wet workshops are something we should look into, but it could just end up being only marginally better than inflatables.

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