Moon mission today - Dragon & Mars hab

kbd512 · 2016-12-17 23:41:29

All,

I'm trying to figure out if there are a set of technologies that NASA can use to implement humans to Mars using the sort of technologies we already have or have a lot of experience using.

I'll try to explain some of my technology selections:

* Falcon Heavy and Vulcan Heavy - It should be obvious to someone who can do simple math that we can affordably and therefore sustainably deliver more tonnage for substantially less cost than with super heavy lift rockets like SLS; it's not that I wouldn't rather have a super heavy lift rocket, it's that the utility is so limited and the time / expense associated with development and implementation too great even for NASA's substantial budget

* 2 Crew Members per Habitat Module - Heavy lift rockets like Falcon Heavy and Vulcan Heavy are limited to throw tonnages that support a maximum of 2 crew members per habitat without orbital assembly; more crew members do not increase the odds of a successful mission- whether or not the astronauts live through the ordeal is a function of the proper design and reliability function of the mission hardware combined with human intelligence applied by the astronauts to their mission activities

* Inflatable habitat modules - Lightest mass for a given volume, greatest level of protection from puncture by space debris, and lessened secondary effects from radiation exposure in a high radiation environment

* NTO / MMH RCS, Mars Ascent, Earth Return Stages - This propellant combination, along with similar hypergolics, represent the propellants we have the most and most recent experience using for in-space propulsion; the dV increments that must be provided are well within the capability of NTO / MMH and existing rocket engines to deliver, so there is no need to develop entirely new systems using propellants and rocket engine technologies that we have far less experience actually using in space flight

* ADEPT + electric lift fans for Mars and Earth EDL - We need a set of comparatively low-cost and low-mass technologies that enable EDL on multiple planetary bodies with atmospheres and this is just the best combination I could come up with for the wildly varying atmospheres of Earth and Mars

* Non-Nuclear Power Sources - There is some debate about the ability to generate sufficient power on Mars using solar panels due to the dust storms there, but there should be little debate about the fact that solar panels are incredibly reliable and efficient power sources for low-power applications and keeping the lift support systems running for two people living in a stationary habitat module qualifies

* CAMRAS / IWP / MOXIE - We simply must have more reliable and lower power consumption systems for atmospheric and water recycling for human exploration of Mars; I realize that these are lower-TRL technologies, but the greater reliability and lower power consumption is not debatable at this point- these systems simply work better than legacy life support systems and are substantially lighter and more compact

* MCP Suits - Much like the new life support systems, even though this is a lower-TRL type of space suit, it is also another enabler for missions requiring frequent EVA's

* No Orbital Assembly - It's not that orbital assembly can't be done or is problematic, but much like super heavy lift rockets this is another mission cost and complexity factor that is unnecessary if we're just trying to get the job done

* Consumables Splits - For us to use a single type of heavy lift launch vehicle, avoid orbital assembly, and minimize launch requirements, we need a mission hardware architecture that splits the masses of delivered payloads into roughly equal parts; it seems sensible to me that if you can't ascend to orbit from Mars, then there is no requirement for consumables for Earth return- this feature of the mission architecture may kill astronauts faster if there's a problem with descent or ascent, but they're still dead either way, so there is no need to draw out the process on national television

elderflower · 2016-12-18 05:17:20

What are your objectives? What do you want the people to do whilst they are there?

SpaceNut · 2016-12-18 10:35:58

1 Falcon/ heavy plus others which could be versus SLS for launch vehicle: This is for SLS is costs plus generated contracting, governement red tape, levels of paperwork and an aging very expensive work for. The cost is only part of the issue but rather its the size of the chunks to be made versus what can be placed together to made a mission possible that would normally mean a heavy lift.

2 crew habitat versus inflateable: for journey out or for surface these inflatebles are not proven yet.

3 storeable fuels to insitu for surface: storeables are a garrantee while insitu needs to be landed and tested under mars conditions.

4 Adept, electric fan, other landing boosts to payloads: both are untested with adept being less in mass versus electric fan. Still unknown is the selection of surface hab type, mass numbers to surface with methods of crew return to orbit, number of payload chunks

5 solar/battery versus nulcear power: near nuclear(RTG as well) would be ok if it puts out the wattage other wise plan a preload of solar with batteries

6 life support: relies heavely on insitu water and other processes which are not light when totalled all together.

7 space suits and surface suits: the need for both suits still are needed asout or return trip can not use the MCP for a space walk.

8 no orbital versus some assembly: refurs back to number 1 in what can we afford, what size are the chunks...

9 food: relies on water source to which recycling, insitu make the amounts less, along with less will be any for of greenhouse plant growth methods as well as structure to do it in.

kbd512 · 2016-12-18 14:48:44

Elderflower,

I want to do three things:

1. Contain technology development to what is minimally required for astronauts to go to and from Mars and remain counted amongst the living. I want to send people in pairs because that is what heavy lift rockets can realistically deliver. It's not optimal, but nothing in real life ever is.

* All required consumables brought from Earth until recycling is proven to work for the entire mission duration

* Consumables splits equalize mission hardware component masses so the same launch vehicle and configuration delivers all hardware

* All atmospheric interface events use ADEPT and electric lift fans for reentry and soft landing because variants of that hardware can be made to work on Earth, Mars, and any other planetary body with an atmosphere

2. Minimize launch costs and maximize launch schedule flexibility. $300M in launch costs over three launches per pair of astronauts seems affordable and therefore reasonable for getting humans to and from Mars within NASA's current and projected budget.

* I want funding directed towards life support and EDL technology development and flight demonstrations, not launch vehicles

3. Minimize initial mission objectives to what is absolutely required for a surface exploration, which equates to landing, collection of core samples and water during a handful of carefully planned EVA's, and return to Earth.

* No rovers, greenhouses, bases, or other unnecessary complications to detract from the goal of simply going there and coming back alive

SpaceNut,

BEAM is the ultimate test of habitability. I seriously doubt we're going to have an unsuccessful test at this point since the two precursor demonstrators have been flying in space now for longer than a Mars mission would last. In another two years, we're going to know one way of the other. If a BEAM-sized inflatable survives the EDL test on Earth, it'll survive EDL on Mars.

Storables were selected because that is the propulsion technology we have right now. We're limiting ourselves by using hypergolics, but it adequately services dV requirements for Mars surface ascent and return to Earth.

ADEPT and electric lift fans are not proven technologies, but neither is any other technology that can land 10t+ on Mars. We don't have a 10t+ delivered tonnage capability specifically because the launch vehicle throw requirements for a rocket-propelled landing are so high that we can't affordably deliver 10t to Mars. If ADEPT and electric lift fans are at all feasible, then there is no advantage of any kind to a rocket-propelled landing. ADEPT and electric lift fans should be a lot less expensive to develop and test than rockets and both technologies can be tested here on Earth.

The solar power and battery power storage requirements fall within the limitations current technology and any mention of the word "nuclear" gets people worked up over it. I want to minimize objections from all the lunatics who are afraid of their own shadow. The "impossibility" of contamination from Mars reaching Earth already has these people going nuts and I don't want to add one more point of contention for the idiots to argue over.

My life support selections do not depend upon recycling or ISRU. All required consumables are split between habitation / ascent / return hardware. It's maximum mass, thus the splits, but still within the capability of 3 launches to deliver.

The space suit selection is debatable. The Space Activity Suit was designed for hard vacuum environments. Irrespective of what suits are selected, I want to minimize EVA's for the first mission cycle.

SpaceNut · 2016-12-18 17:15:43

http://www.space.com/32485-beam-bigelow … tures.html

Yes Beam is currently on orbit at ISS still awaiting habitation as it will allow investigators to gauge how well the module protects against solar radiation, space debris and contamination, paving the way for the future, much-larger inflatable space habitats. I am not in the know of any return of it as it requires repacking into a truck which does not have a safe return from orbit as its filled with garbage. But that would be worth the return to make it happen as to be able to inspect it.

Bigelow Expandable Activity Module (BEAM) - 11.22.16

The trouble I have with inflateable is they are empty devoid of hardware to make them work sure there is some electrical ect... but not to the extent that is needed to operate a science lab within it or to have a good kitchen....

So we could have a mars mission looping around moon earth system to wring out any design bugs including tests of landers on mars as well as the moon....as a bonus.

kbd512 · 2016-12-18 19:18:47

SpaceNut,

I want to send an inflatable to Mars pre-expanded in the payload shroud and appropriately equipped. I want something akin to a docking ring atop the habitat and a connector ring on the bottom of the habitat that connects the module to ADEPT. I want a hard internal hard airlock in the center surrounded by food and water. This is also the radiation shelter / sleeping quarters.

[top of shroud]
[solar][RCS][solar]
[e-fan][p-batt][e-fan]
[habitat top / dock]
[CAMRAS][r-batt][CAMRAS]
[avionics]
[astronauts living area]
[shower][l][galley]
[food][o][food]
[IWP][c][IWP]
[water][k][water]
[habitat bottom]
[landing gear]
[ADEPT]
[bottom of shroud]
[Falcon Heavy Upper Stage]

SpaceNut · 2016-12-18 20:57:22

I think the payload shroud would work even for a mars EDL as its already been tested on the way up on the launch just fine but normally its discarded as dead mass before Earth departure, so any mass savings from the inflatable is lost for fuel to leave earth normally and is only gotten back by using the ION drive since men are not onboard this surface unit. Since the shroud is still intact then maybe the inflatable can be made with less layers as the shroud will protect it from sand blasting dust storms....

Interesting layout using the batteries and water for shielding. The shroud I hope is not a small 5M size as that makes the unit quite small as there is an area between the shell and inflateable thats not useable. I have seen .6 meters for the 10 meter SLS shroud to its contents would make it smaller still for a 5 meter shroud.

SpaceNut · 2016-12-18 23:06:16

SpaceX Dragon Air Circulation System

Near Term Space Exploration with Commercial Launch Vehicles Plus Propellant Depot

kbd512 · 2016-12-19 04:50:28

SpaceNut,

The inflatable is quite small- only a slightly enlarged version of BEAM. It won't win any NHV studies awards. The small size of the habitat module makes it light enough to land with lift fans. The payload shroud dimensions I used are those of the current Falcon Heavy. Using the payload shroud as a heat shield is an interesting idea that's worthy of a feasibility study.

The lift fans and solar arrays fold upwards into the conic portion of the payload shroud. I expect life support and communications power requirements to be 2kWe or less and 4 UltraFlex or MegaFlex arrays will provide 2kWe each. That equates to ~53kg using the current UltraFlex arrays at .15W/kg or 40kg using the new MegaFlex arrays at .2kW/kg. The 8kW array is for redundancy due to the extended mission duration and the 50% lower solar irradiance at Mars.

In any event, this is all you get with a 13.6t TMI. If the upper stage had a higher Isp, throw might improve a bit. I would love to squeeze 16t out of the upper stage.

SpaceNut · 2016-12-19 22:08:06

Not sure if numbers have been posted but here are a couple sites with content for the rocket and payload shroud...
http://www.spacelaunchreport.com/falcon9.html

http://www.spacex.com/sites/spacex/file … ev_2.0.pdf

Page 36 has the flairing dimension

SpaceNut · 2016-12-19 22:30:04

Some links for Beam...
Then BEAM will be inflated from its packed dimensions of 5.7 feet long and just under 7.75 feet in diameter to its pressurized dimensions of 12 feet long and 10.5 feet in diameter—the size of a large closet. They also have a low weight-to-volume ratio. At 3,000 pounds and 560 cubic feet of pressurized volume, for instance, BEAM weighs only 5.35 pounds per cubic foot. The BEAM's skin is made up of multiple layers which include a layer of Vectran, a bulletproof fabric two times stronger than Kevlar. Vectran doesn't tear if punctured, and tests have shown that micrometeoroids that would penetrate the walls of ISS only got halfway through the BEAM's skin. Even if it is punctured, BEAM wouldn't burst like a balloon.

Cutaway view

kbd512 · 2016-12-20 04:12:23

SpaceNut,

Rambling here, but...

The variant I want to send is pre-inflated in the payload shroud, with an interior volume of 706ft^3 or 20m^3. I calculate the mass of the empty module as closer to 5.5lb/ft^3, or 1763kg. The equipped module (life support / batteries / avionics / solar panels / radiators) mass needs to be on the order of 2300kg or so. The lift fan system should weigh 700kg or so.

180 day outbound transit consumables: 1,811kg, assuming no recycling
Consumables for the first increment of the surface stay:2,515kg, assuming no recycling
Equipped module with consumables: ~7,326kg
ADEPT / Landing Gear / RCS: 6,274kg or less, because that's all we have to work with
Entry interface habitat module mass: 5,515kg, presuming the astronauts consume all of their consumables during the outbound transit and recycle nothing

How much propellant would the RCS require for attitude control and mid-course corrections?

5,700kg for the habitat module with empty RCS tanks, for sake of argument, or 2,166kg on Mars. The best info I can find on ADEPT seems to indicate a heat shield mass of approximately 50% of whatever the payload mass happens to be, so we're already at 10,176kg of Falcon Heavy's 13,600kg throw.

If we included all of the food in the habitat module for the transits and surface stay, assuming 360 days of transit and 500 days of surface stay, we'd have 3,045kg of food onboard. We can feasibly use the free return trajectory without running out of food.

We can't store all the water with no recycling, but we can store all the food. The equipped module now weighs 6,045kg with all the food and now we need some water recycling. If I have 1,500kg of water, how long can I make that last at 85% recycling efficiency and still maintain 5cm or more of water around the crew's sleeping quarters for radiation shielding at all times? If my heat shield really does weigh 50% of my payload and my habitat is only 637kg lighter at reentry, then my heat shield mass just grew to 3,454kg, presuming I retain 1500kg of water. Our payload mass is now 10,999kg, leaving only 2,000kg for the landing gear and RCS.

The heat shield mass seems really high. AVCOAT is only 39lb/ft^2. I must be mistaken about what ADEPT weighs. It's composites and carbon cloth.

Can someone provide info on what our RCS requirements are and how far off I must be on what ADEPT actually weighs? Orion's heat shield doesn't weigh nearly as much as this hypothetical ADEPT heat shield and ADEPT is supposed to be 25% lighter than AVCOAT. Good info would be greatly appreciated.

SpaceNut · 2016-12-20 22:48:34

I think the information I have for you will get you some numbers but what will add the most mass is not the fabric but the umbella structure....

Adaptive Deployable Entry system Project (ADEPT)

woven carbon fabric (which covers 90% of the deployed surface and is supported by semi-rigid ribs) is the primary drag-producing surface. Its flexibility also allows it to be stowable. The pure carbon fabric, with its high thermal conductivity, allows re-radiation from both the windward and leeward side of the fabric. This activity will include the detailed design and fabrication of a sub-scale prototype test article (approximately 2-m diameter) that will include as many flight-like and mission-traceable aspects as possible

https://solarsystem.nasa.gov/docs/Day%2 … rse_v4.pdf

NASA tests foldable cloth heat shield in Mars entry simulation

The ADEPT shield does most of the deceleration with less heating and forces of only 30 Gs, which in turn causes less stress, eliminates the need for a supersonic parachute, and means the probe can land at sites of any elevation. The current version of the concept shield can handle a 1,000 kg (453 lb) payload and is undergoing tests at Ames that include vibration, acoustic, and vacuum-thermal testing.

The most spectacular recent test used a blast of hot air from a 21-in (53 cm) diameter nozzle to simulate a bow shock wave in front of a 2-m (6.5 ft) wide ADEPT shield, which was attached to a water-cooled support arm. During the tests, temperatures on the shield reached 3,100º F (1,700º C) while bluish streaks streamed away as a special resin-infused protective coating ablated from the stitching.

http://www.sunspiral.org/vytas/cv/tense … Shield.pdf

kbd512 · 2016-12-21 04:22:56

SpaceNut,

Thanks for the info. Unless I missed something in the links provided, no masses for test articles or densities for the heat shield material were provided. ADEPT must still be very experimental. In contrast, I have quite a bit of info to work with regarding HIAD. Maybe an inflatable habitat should use an inflatable heat shield.

626775main_November_2011_Cheatwood.pdf

HEART FLIGHT TEST OVERVIEW

HEART is an 8.3m HIAD designed for an entry mass of 5,000kg and is expected to weigh 1,592kg. We need to deliver approximately 10,000kg, including the heat shield.

SpaceNut · 2016-12-21 22:28:43

Engineers at NASA Ames successfully completed the Bi-axially Loaded Aerothermal Mechanical (BLAM) Arcjet test series of the Adaptable Deployable Entry and Placement Technology (ADEPT) project element of DACC (Deployable Aeroshell Concepts and Conformal TPS).

The team, led by BLAM test PI, Keith Peterson, met all test objectives by performing ten individual runs of the
carbon fabric under varying aerothermal test conditions and tension loads of the fabric during the test.
The test conditions best approximate the expected heating conditions and mechanical (tension) loading the
material is expected to see on a Venus entry mission scenario.

Payload Separation Risk Mitigation for a Deployable Venus Heat Shield

page 8 table has a density value

Viability of 3 D Woven Carbon Cloth and Advanced Carbon-Carbon Ribs for Adaptive Deployable Entry Placement Technology (ADEPT) for Future NASA Missions

http://solarsystem.nasa.gov/docs/VENKATAP.pdf
http://solarsystem.nasa.gov/docs/1_Venk … yables.pdf

SpaceNut · 2016-12-22 20:02:22

The blanket material is simular to the products that are used in the welding industry which also employees cooling gels as well.

I think these products will be close
http://www.easycomposites.co.uk/#!/comp … -explained
http://www.eas-fiberglass.com/products/ … Fabric.htm
The blankets appear to be multi layer and they are looking to see how many layers are required....
http://www.hitco.com/HITCO%20Refrasil%20Silica.html
http://www.chicagoprotective.com/pdf/CarbonX.pdf

kbd512 · 2016-12-23 05:25:23

SpaceNut,

Thanks for the PDF's with the mass and density figures provided. I had the other PDF's you previously posted, but not the Venkat presentations.

I think we need an 11.75m diameter inflatable intended for a total vehicle mass of 10,000kg vs the 8.35m inflatable intended for a total vehicle mass of 5,000kg to maintain the same surface area to mass as HEART has.

HEART Element Max. Expected Mass (kg) for 5,000kg reentry mass
Structure - 504
Avionics, Data, & Thermal - 530
Inflation - 83
Inflatable Structure - 196
TPS - 279

HEART Dimensions for 5,000kg reentry mass:
55 degree conic
Each stacked inflatable torus is 14" in diameter and the shoulder torus is 8" in diameter
Smallest torus has an inner diameter of 64.326" and outer diameter of 92.326", so 78.326" center-to-center of the smallest torus
I think the height of the stacked tori is ~88", presuming the tori aren't compacted, which seems about right since the PCM is 3.9m long.

I think I need 16.75 of the 14" tori for an 11.75m HIAD versus HEART's 11 14" tori, unless I did the math wrong, which wouldn't surprise me. I know I have enough information to figure this out, but it's been over a decade since I've done any this. All the information required to determine what the volume is, and therefore what the mass / volume ratio would be for the TPS and inflatables, is present in the figures presented in "HEART FLIGHT TEST OVERVIEW". I'll figure it out later.

kbd512 · 2016-12-23 20:34:16

SpaceNut,

The rough HIAD inflatable structure mass multiplier, using the maximum expected mass figure of 392kg for the inflatable structure and not taking the shoulder torus or tri-torus into account, is 4.235kg. I need to refine that figure by incorporating the tri-torus and shoulder torus in the mass distribution calculation, which is slightly more complicated but still relatively easy to do.

The first torus of the HEART HIAD weighs approximately 14.46kg and we can EDIT: add 4.235kg to the mass of each successive torus by approximately, not multiply. This presumes the torus diameters of an inflatable that could deliver 10,000kg is the same as the torus diameters for an inflatable that can deliver 5,000kg, which is almost certainly not the case for a piece of functional hardware.

If the tori could be the same diameter HEART uses and we needed to double the surface area to double the entered mass, then the inflatable structure would weigh a little more than 900kg, including the tri-torus and shoulder torus.

Mass Estimates for a 17 torus (EDIT: mass includes the third torus in the tri-torus, so 18 tori total) HIAD to enter a 10,000kg mass at Mars:

Structure - ???
Avionics, Data, & Thermal - 530
Inflation - 174 (approximately 210% increase in volume)
Inflatable Structure: 900kg
TPS 558kg

If the mass of the structure stayed the same, which would not be the case, then HIAD would weigh ~2,666kg to enter a mass of 10,000kg. I'll ballpark it at this point and say that HIAD mass to enter 10,000kg at Mars is approximately 3,000kg. Curiously, there were figures posted for a slightly smaller 8m diameter HIAD that was supposed to be able to enter a 5,600kg mass at Mars. Irrespective of whether or not HIAD is capable of greater peak heating and dynamic pressure performance than what HEART is intended to demonstrate, I think ~3,000kg is a reasonable mass estimate for the heat shield.

More importantly, HIAD is intended to reach subsonic speeds at an altitude between 5km to 10km. GW said that he thought it would be necessary to start the lift fans at supersonic speeds or use retro-rockets to reduce speed to subsonic velocities. This does not appear to be the case, although I still think the lift devices need to work in a supersonic flow to produce enough lift to make them feasible.

EDIT: I need to determine what the mass of ADEPT would be to enter 10t and then select the lightest technology. In this mass-constrained mission architecture, we must get rid of every superfluous kg we can to obtain sufficient margin to account for the varying dV requirements associated with the synodic cycles. Mr. Musk undoubtedly baked some margin into that 13.6t figure, but I don't know much.

An upper stage with improved Isp, perhaps a variant of the 1/3 scale LOX/LCH4 Raptor, would be a most welcome development. However, we can't count on that.

Last edited by kbd512 (2016-12-23 22:42:55)

SpaceNut · 2016-12-24 18:23:49

What I see so far the difference of the HIAD and the ADEPT systems are not so much the temperature of a fabric but when can it be deployed. The tube within a tube cone structure adds a section to couple the decelerator to the payload which is landing while the Adept just adds some composite or metal ribbing with control to unfold the umbrella like structure.

Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Nasa Fact sheet

Thring tube approach starts with an under pressure fill but the heat causes the gas inside to expand which will force the shape but at some point that expansion will cause the fabric to vent from the pressurization.

Some how we will need to isolate the tubes more from the heat with something simular to the space shuttle blanket material that isolated the tiles from the hull....

Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Technology Development Overview

The place to use the system if it can not be temperature isolated is some where after peak heating and long be for a parachute could be used as inflating these would be the parachute higher up in the atmosphere....

SpaceNut · 2017-02-05 09:34:13

It is funny how quickly our topics get burried....

kbd512 · 2017-02-05 18:40:21

There is no reason why we can't go back to the moon and on to Mars using the rockets and technology we already have. There are no budgetary or scientific benefits to making missions more complicated and costly than is absolutely necessary. Dr. Zubrin is right about that point, every day of the week.

In the 1960's and 1970's, NASA was only interested in a logical and sensible progression to their activities:

Put a living organism in orbit with similar physiology to a human without killing it. - Check
Put a human into orbit without killing him or her. - Check
Put two humans into orbit without killing them. - Check
Perform complex orbital maneuvers like docking and undocking. - Check
Perform an EVA or spacewalk. - Check
Send humans around the moon and return them to Earth without killing them. - Check
Land humans on the surface of the moon, return them to orbit, and then return them to Earth without killing them. - Check
Build a space station to study the long term health effects of living and working in space. - Check
Launch probes to characterize and study the next target of interest for human space exploration, Mars. - Check

This is what we NASA is up to now:

Send a sample return rocket all the way to the surface of Mars to rendezvous with a robotic rover on Mars so it can load the sample capsules, launch the samples into orbit, have a SEP-powered spacecraft waiting in Mars orbit rendezvous with the sample capsule, return the sample capsule to L1, then send Orion to L1 to retrieve the sample capsule and study it there using a tiny fraction of the analysis equipment available on Earth, on the off-chance that something in the capsule is alive and could somehow survive in the totally alien environment of Earth and wipe out life as we know it.

Someone at NASA has an unhealthy fascination with Rube Goldberg experiments. It's technically possible to do what was proposed above, but at what expense and at what risk of failure due to the unnecessarily complicated mission activities? If we're returning the astronauts to Earth, is there not still some possibility of cross-contamination? If the possibility for contamination still exists, then what is all this nonsense about?

Alternatively, with the two billion or so that we'd save by not attempting that stunt, we could practice lunar landings on the moon using Falcon Heavy, Dragon, and Cygnus. After NASA proves it can still put the check in that block, the agency can then formulate the best method to do that on Mars.

Dragon Rider requires no special and egregiously expensive super heavy lift rocket to take a crew of two to four people to the moon. Cygnus is the closest thing we have to a lander module that can land on another planet. Falcon Heavy is the closes thing we have to an affordable heavy lift launch vehicle. There's no reason to glorify man-on-Roman-candle with a massive ascent stage. The result of any failure to attain orbit is no different in an Apollo-style ascent stage than it would be with a rocket strapped to your back. Further, putting more engines on Cygnus to handle an engine-out scenario during descent is no worse a plan than having two stages requiring a super heavy lift rocket, as was the case for the LEM.

Will we ever get humans off of this rock again in our lifetimes? Let's quit talking about doing it, cowboy up, and git r dun!

SpaceNut · 2017-02-05 19:22:22

What we are saying is that Boeing, Lockheed, Bigelow, Orbital/ATK, Space x, plus any others need to launch there own respective missions to LEO, Moon and to Mars for there own profit systems and stop waiting for nasa to fund them or to give a contract to build or launch something for them....
Only if I had a spare billion I would be self funding such a mission to the moon and back.
The twin study has a check off box for the long term stay in space in 0g and its a genetic cell change....

GW Johnson · 2017-02-05 21:03:18

We have known fundamentally what it takes to keep people healthy in the hostile space environment since about 1995. These are the key issues: microgravity disease, radiation exposure, living space, and until recently, food that would last long enough.

The various studies on zero-gee living done on ISS merely confirm what we already knew: over a year's exposure to zero gee will do serious damage, it is inevitable. We just keep finding more and more unexpected ways that it does damage. We have found nothing that would stave this off long enough. (Except what we have contemplated since about 1950: artificial gravity by spin.)

The way to avoid that issue entirely is just to plan on providing artificial spin gravity during those months of travel coasting through space. Period. End of issue. It's not a technical problem to do that, it is just a technical inconvenience, because it takes a bigger craft to do that safely and reliably, than most folks want to contemplate. Too bad, so sad! So, contemplate it! This is more than 20 years overdue!

We'll find out how healthy reduced gee will keep us when we go. Because we never ran the reduced-gee experiments in the spinning space station we never built. I do recommend transit with one full gee, so as to be fully-fit by journey's end for whatever gee and physical challenges await. Thar's one full gee at work station for a full shift. Sleep can be at zero gee, and recreation at partial gee.

Then there is radiation. I keep seeing bullshit scare stories about unexpected damage, but the sound of it is no worse than the damage done by microgravity. There's not a lot we can yet do about galactic cosmic radiation, except to use relatively-thin, hydrogen-rich shielding, so as not to create more problems with secondary showers. So, bite the damned bullet and just get on with it!

As for the erratic risk of lethal solar flares, we ignored it for convenience during Apollo, because over a week or two trip, the odds were with us. For 6-to-8 months one-way to Mars, and again during the return, the odds are not with us. Chances are pretty good a dangerous storm would strike. But, we already know that 15-20 cm water is a good enough shield.

If you have people on board, you have life support equipment that deals in both water and wastewater. Put those tanks and pipes, and a few small propellant tanks, around your designated shelter and sleeping quarters. That'll do the job of shielding. So, belly up to the damned bar and get on with it! If that's bigger and heavier than you wanted to build, that's just tough shit! Deal with it.

Food can be solved. There's commercial camp food good for 5 years plus, now. And there's frozen food, for which the ice in it is a radiation shielding item, by the way. If you have a garden on board, that's even better. But it does not fit a space capsule. What you build is very much larger than that. Plus, if it spins for gravity, you can do free-surface cooking with real food, too.

And then there's space in which to live. Even a crew of 4 will go insane and kill each other cramped inside a Dragon or an Orion for 6 months going to Mars. We knew that from Gemini 7 in the mid-1960's (which flight demonstrated 2 weeks max in cramped conditions, not the 3 they hoped for).

It's simply going to take a much larger vehicle in which they can ride and stay sane. It is unavoidable. The gross volume allowance per person should exceed that of Skylab, perhaps even that of ISS. You don't get that from something the size of an RV, not even from something the size of a school bus. Plus, it needs to be arranged such that there are places to be alone as well as to congregate. That is already apparent on ISS.

These disparate factors: microgravity disease, radiation protection, and space in which to live sanely, all are driving us in the same direction: somewhere between 100 to 200 cubic meters of space for each and every person on board. Not to be filled up with supplies and equipment, real space in which to live. (Musk got that at least partly right with his giant ship design.) It's way past time to face up to these facts.

You build things like this by docking modules together in LEO, modules small enough to launch with the rockets you got. There's no reason at all not to do it this way, because any large ship going to Mars (or even the moon) will stop in orbit, so as to make the departure burn window independent of any launch considerations. No one is going to shoot anything direct to Mars from launch, except small one-way probes.

GW

Last edited by GW Johnson (2017-02-05 21:21:47)

Oldfart1939 · 2017-02-05 22:28:14

GW-

I am in agreement with most if not all of your analysis of the hazards involved. The lack of gravitation is indeed a major problem, and even the early Wernher von Braun publications included the big bicycle wheel space station for producing artificial gravity through centripetal acceleration. The Cosmic Ray hazard is greatly overblown, and the problem attenuates > 50% once on the Martian planetary surface. The psychological issues aren't easily solved for the amount of living space required for sanity; the Navy screens the crews for duty on submarines pretty rigorously because of this problem. I seriously doubt that a nonstop pinochle or bridge tournament will suffice! As you mentioned, there needs to be some private/personal space for each crew member in addition to the community activities and communal living areas. Having artificial gravity will really help the crew members by allowing normal food preparation. God help us if some genius wants to feed the crews MRE rations the entire journey! As you pointed out--frozen foods are the ticket, but would more likely supplement the more concentrated rations. I could go on and on about this, but we are basically on the same wavelength.

Last edited by Oldfart1939 (2017-02-05 22:31:03)

elderflower · 2017-02-06 06:37:17

I dont suppose that anyone is going to design a space craft to operate at one bar, so free surface cooking wont work due to boiling point depression. They will have to cook in pressure equipment.

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