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#26 2016-01-31 20:06:38

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,910

Re: Deep Space Habitat

I would like to keep the topic more focused on the  parts and means to get a deep space habitat to and from earth and less on the remaining mission concepts...

here is the topic for the mission concept
Kbd512's human mission design for Mars


I have not removed the discusion as there are some parts to making the deep space habitat work.

First is being how many parts will make it up as that gets back to the launch counts and costs for just the first mission to mars.

What we know about launch vehicles are the Space X, Nasa, Lockheed and Boeing have heavy lift on paper for the 50 mT level of launcher but Nasa is targetting 70mT plus for use but it comes with a huge prices tag when compared to the others.

With any thing that we need that will ride on these launch vehicles coming with another cost as we do not have them....

First the mass of the deep space habitat will need to be capable of on orbit assembly with the TMI and TEI stages, capable of artificial gravity, with probable solar but could be small nuclear powered, with docking port for crew taxi and mars lander even if it goes ahead of the crew to mars.

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#27 2016-01-31 22:08:12

RobertDyck
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From: Winnipeg, Canada
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Re: Deep Space Habitat

My mission architecture includes a reusable habitat. The in-space habitat is separate from the surface habitat. And both habitats have life support. This allows use of the surface habitat as backup. And allows the in-space habitat dedicated to in-space use.

I like Robert Zubrin's idea for artificial gravity. That's light, it doesn't involve a truss or pipe or other connection arm. It does require manueovring while rotating in tethered flight. That technology requires some work. An easy way is to time thrusters so they "pull" the module, providing tension on the tether. And to ensure the "pull" force is less than the acceleration due to centripetal effect (artificial gravity). That ensures no hard bounce.

I have argued for laundry. The laundry machine can be an RV style single appliance washer/dryer. This requires gravity to work. When washing, clothes fall into and are pulled out of soapy water. That moves soap and water through clothes. When drying, clothes fall from the drum as it rotates slowly. During zero-G, just don't use the laundry machine. If artificial gravity fails, you have to wear the same stinky clothes.

Use of artificial gravity requires a hab with a flat floor. It can be sideways like an ISS module.

I have argued for aerocapture to enter Mars orbit, or Earth orbit. If you use this for an asteroid, then aerocapture into Earth orbit from that too. Use a deployable and reusable heat shield, such as ADEPT.

One reason for making the propulsion separate is so it can be replaced. It can be chemical, or SEP, or NEP, or nuclear thermal, or even microwave/water. Whatever the latest technology is. The propulsion stage could be expendable; that makes the tether easy. As described in Mars Direct, don't recover the stage. Just cut the cable/rope/strap/chain and let the spent stage fly off into space. It will enter orbit around the Sun. The hab then has to de-spin to prepare for aerocapture. A reusable stage has to be reeled-in, which makes de-spin more challenging.

Life support can be based on the system currently on the American side of ISS. It will require a few additions. I listed additions several times, the latest is the previous page of this discussion.

A reusable habitat can rendezvous and dock with ISS. Then any spacecraft that can carry crew to ISS, can return crew from this habitat. However, in case of aerocapture failure, you need an emergency escape pod aka lifeboat. That means a capsule. As an emergency vehicle, you want that to be as low mass as possible. Options: Dragon, CST-100, Orion, Soyuz. Since this is in case of aerocapture failure only, you would want the capsule only, no service module or orbital/mission/resource module.
Dragon: 4.2 tonnes dry mass + 1.29 tonne propellant = 5.49 tonne. Crew 7. That's for the cargo resupply ship, but official statements from SpaceX claim Dragon v2 will have the same mass. I suspect it will mass more once you add launch escape system, life support, seats, control consoles.
CST-100 Starliner: 13 tonnes, but that includes service module. Crew 7.
Orion: 8.6 tonnes. Crew 6.
Soyuz: 2.95 tonnes. Crew 3.

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#28 2016-01-31 22:56:19

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,910

Re: Deep Space Habitat

Thanks for posting the capsule options as they are part of the deep space habitat that is going to mars that effects the size of the TMI stage and the TEI stage as well...

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#29 2016-02-01 13:22:32

kbd512
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Re: Deep Space Habitat

SpaceNut,

NASA thinks their ISS-derived 500 day DSH will mass 45t (ISS-derived lab hab, ISS MPLM, connecting tunnel / airlock, radiators, solar power) and support 4 crew members for that length of time.  That solution does not provide artificial gravity or active radiation shielding.  The Orion capsule weighs 26t.  IIRC, ISS-derived 60 day DSH will mass 28t (ISS-derived lab hab, connecting tunnel / airlock, radiators, solar power).

I say a 60 day DSH is nearly worthless, so remove the MPLM, reinforce and lengthen the barrel section of the lab hab and just build a 500 day DSH.  Whatever minor structural reinforcement is required is unlikely to push the mass differential above the 4t structural mass of the MPLM.  We need to remove every kilogram of structural mass we can to minimize the mass and overall length of the solution.  For the same reasons, perhaps an inflatable airlock is worth pursuing.

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#30 2016-02-01 21:02:46

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,910

Re: Deep Space Habitat

All three initial topic images are lacking artificial gravity, TMI stages,ect... and that is what would and will make it a deep space habitat....The second image by Nasa with the mplm iss core design is good enough if we were using it cycling to and from the moon but thats about it.

The first image I pointed out the the transfer stage is all wrong and with more analysis of no artificial gravity and other makes for even a poor first run flyby as well to mars let alone a landing on phobo....

Bigelow's inflatables need really world test which means occupied by man at least for a long period of time to prove out that the lower mass of being inflatable is worth it....

From what I recall of GW's artificial gravity the distance from the center of spin needs to be 56 m at 4 rpm to create AG but that is only just one factor to consider as we will need to be able to traverse safely from end to end going from near zero to full as we get closer to the ends.

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#31 2016-02-02 10:00:38

kbd512
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Re: Deep Space Habitat

SpaceNut wrote:

All three initial topic images are lacking artificial gravity, TMI stages,ect... and that is what would and will make it a deep space habitat....The second image by Nasa with the mplm iss core design is good enough if we were using it cycling to and from the moon but thats about it.

Even with NASA's minimal complexity ISS-derived DSH designs, moving 28t to 45t from LEO would require multiple smaller kick stages or a much larger kick stage that only SLS can lift.  I think a SEP tug that transfers the DSH to L1 is the most realistic way to use a single Falcon Heavy launch to accomplish the transfer.

The Falcon Heavy payload shroud would have to be lengthened by 2m to 4m to accommodate a lengthened ISS lab module habitat and SEP tug, but width would remain unchanged.  My comment about doing away with the structural mass of the MPLM and rigid airlock was directed at accommodating a SEP tug.  My thinking was that once the crew is ready to occupy the DSH, a Dragon 2 capsule would take them directly to L1.

SpaceNut wrote:

The first image I pointed out the the transfer stage is all wrong and with more analysis of no artificial gravity and other makes for even a poor first run flyby as well to mars let alone a landing on phobo....

We don't have any realistic way to transfer the DSH to any orbit above LEO.  We need SEP tugs and we need kick stages that can perform TMI from L1 and TEI from Phobos.  The dV requirement for TMI from LEO is too severe without a LOX/LH2 kick stage that only SLS can lift.  The SEP tugs are required to contend with the severe dV requirements.  A SEP tug needs to transfer the DSH and a chemical kick stage with storable propellants or ZBO LOX/LCH4 propellants to L1 and a TEI stage needs to be pre-positioned at Phobos for a realistic shot at a Phobos exploration mission.

SpaceNut wrote:

Bigelow's inflatables need really world test which means occupied by man at least for a long period of time to prove out that the lower mass of being inflatable is worth it....

I want to demonstrate repair of both aluminum alloy habitats and inflatable habitats in LEO.

SpaceNut wrote:

From what I recall of GW's artificial gravity the distance from the center of spin needs to be 56 m at 4 rpm to create AG but that is only just one factor to consider as we will need to be able to traverse safely from end to end going from near zero to full as we get closer to the ends.

NASA and others have studied the effects of spin gravity here on Earth and concluded that humans could adjust to rotational rates of 10 to 12 with minimal training.

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#32 2016-02-02 14:30:15

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,367
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Re: Deep Space Habitat

56 m radius at 4 rpm = 1 full gee.  Gee is proportional to radius^1 and spin rate^2,  so 8 rpm at 14 m radius is also 1 gee. 

There is a gee gradient effect:  not as much gee at your head as at your feet.  If the gradient is too steep,  there might be a risk of fainting or other circulatory problems.  At constant spin rate,  the gradient (gees per meter of radius) is spin rate^2.  I do not know how much is tolerable,  or if that issue has yet been explored for long-term exposure to spin gravity.

How much gee is another issue.  We evolved at 1 gee,  we know that works.  The studies to determine efficacy of partial gee have never been done,  so it is foolish to assume that 0.38 gee or any other partial-gee value is enough.  On the other hand,  we do not need full gee 24/7 around the clock.  There is no benefit of gee while prone asleep,  or the bed rest studies would not be in the least a surrogate for microgravity in those studies that we have done. 

I suggest that the daily work stations be located at full radius from the spin center,  for pretty much 1 full gee during your work shift.  I suspect that recreational facilities could be at a smaller radius with partial gee,  and do no harm.  You can put sleeping quarters at the spin center and zero gee,  if you like.  If your hab design has a gym room,  put it too far out,  and do your exercises at more than 1 gee. 

4 Bigelow B-330's linked together end-to-end and fitted with the appropriate internal equipment cores could be spun end-over-end at something near 8 rpm as such a partial-gee experiment lab,  right alongside the ISS.  We don't even need an SLS to fling them there. 

You could answer all the medical questions about partial gee and spin gravity,  and gain experience at designing and building for spin gravity,  in pretty much 2-3 years and well-under $0.5B,  maybe even a whole lot less than that.  Does anyone know whether a Falcon-9 can fling a B-330 to the ISS orbit?

Update: 

I found the answers to my own questions on Bigelow's website.  The B-330 is 9.45 m long and 20 (presumed metric) tons.  Looks to be around 7.5 to 8 m outside diameter deployed.  330 m^3 interior volume with 0.46 m wall thickness.  Two would fit atop a Falcon-Heavy,  but 1 is too heavy for a Falcon-9. 

Shoot 6 up there with three Falcon-Heavy launches.  That's stack 56.7 m long,  for just about a 28 m spin radius end-over-end on the inside of the pressure shell.  Spin it at 6 rpm,  and there's 1.1 gee at both extreme ends.  Needs cores with extendable floors to stand on,  that's the only real difference between these and a "stock" B-330. 

Best-guess launch cost is about $120M each shot for $360M.  (That's based upon 53 tons at $1000/lb for a full load to LEO on Falcon-Heavy.)  Add some for the core mods and for crew pay and scientist pay,  running the studies.  My $0.5B wasn't far off. 

The payoff:  in 2-3 years we'd know everything we'd need to know for artificial gravity in a real Mars transit hab,  or any other mission anywhere else in the inner solar system,  all the way out to the asteroid belt.  Maybe beyond.

GW

Last edited by GW Johnson (2016-02-02 14:52:06)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#33 2016-02-02 17:38:56

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,910

Re: Deep Space Habitat

Effects of gravity

artificial_gravity_and_the_architecture_of_orbital_habitats.2.gif

I hope this helps....

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#34 2016-02-03 00:49:32

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,501
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Re: Deep Space Habitat

I have a question. I've raised this point before, but I would like someone to give me a real answer. Could Falcon Heavy launch with a wider, non-standard fairing?

The reason I ask is simple. Could we replace the upper stage of Falcon Heavy with the Exploration Upper Stage (EUS) from SLS? That would require an interstage adapter. The core stage of Falcon 9 or Falcon Heavy is 3.66 metres (12 feet) diameter. The standard fairing is 5.2 metres (17 feet) diameter, and that fairing covers the upper portion of the upper stage. So it can accommodate a payload wider than the core stage. EUS is 8.4 metres (27 feet, 7 inches) diameter. The standard Falcon upper stage uses RP1/LOX, while EUS uses LH2/LOX. The standard Falcon upper stage has dry mass of 4,000kg plus 103,500kg propellant = 107,500kg total. EUS is expected to have dry mass of 26,133 pounds, plus LH2/LOX propellant, plus RCS propellant 1,432 pounds, total mass 262,752 pounds = 119,182.3 kg. So total mass is not much greater. The LOX tank is 5.5 metre diameter, with an open 'X' structure between tanks, so the intertank requires a fairing. A weight bearing interstage could support the LOX tank and cover the RL10 engines, then taper to 3.66 meter to interface to the Falcon core stage.

The same question applies to Falcon 9. The upper stage for Falcon 9 is 13.8 metres long instead of 14.3 metres, resulting in lower inert and propellant mass. But aerodynamic forces should be similar.

I post this in the thread for Deep Space Habitat because EUS is 8.4 metre diameter. The Mars Direct habitat was 8.4 metre outside diameter, 8.0 meter inside diameter. It was designed to have the same diameter as the upper stage of Ares, and SLS is based on Ares. So replacing the upper stage of Falcon Heavy with EUS gives us more delta-V, but more importantly payload diameter for a good habitat.

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#35 2016-02-03 08:37:45

kbd512
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Registered: 2015-01-02
Posts: 4,207

Re: Deep Space Habitat

RobertDyck wrote:

I have a question. I've raised this point before, but I would like someone to give me a real answer. Could Falcon Heavy launch with a wider, non-standard fairing?

This question has been hashed out over at NASA's spaceflight forum.  The consensus is that it's technically possible, but there are practical limitations such as how quickly and smoothly your engines can gimbal.  That might not actually be a problem for Merlin.  Somewhere between 6m and 7m is where you top out at unless you make the core stage wider or the payload fairing longer.  If the core stage is 5M in diameter, then yes.  You're talking about designing a new launch vehicle at that point.

RobertDyck wrote:

The reason I ask is simple. Could we replace the upper stage of Falcon Heavy with the Exploration Upper Stage (EUS) from SLS? That would require an interstage adapter. The core stage of Falcon 9 or Falcon Heavy is 3.66 metres (12 feet) diameter. The standard fairing is 5.2 metres (17 feet) diameter, and that fairing covers the upper portion of the upper stage. So it can accommodate a payload wider than the core stage. EUS is 8.4 metres (27 feet, 7 inches) diameter. The standard Falcon upper stage uses RP1/LOX, while EUS uses LH2/LOX. The standard Falcon upper stage has dry mass of 4,000kg plus 103,500kg propellant = 107,500kg total. EUS is expected to have dry mass of 26,133 pounds, plus LH2/LOX propellant, plus RCS propellant 1,432 pounds, total mass 262,752 pounds = 119,182.3 kg. So total mass is not much greater. The LOX tank is 5.5 metre diameter, with an open 'X' structure between tanks, so the intertank requires a fairing. A weight bearing interstage could support the LOX tank and cover the RL10 engines, then taper to 3.66 meter to interface to the Falcon core stage.

You want to redesign the rocket to carry a heavier second stage.

RobertDyck wrote:

The same question applies to Falcon 9. The upper stage for Falcon 9 is 13.8 metres long instead of 14.3 metres, resulting in lower inert and propellant mass. But aerodynamic forces should be similar.

I'm not so sure about that.  It's certainly worth a feasibility study, though.

RobertDyck wrote:

I post this in the thread for Deep Space Habitat because EUS is 8.4 metre diameter. The Mars Direct habitat was 8.4 metre outside diameter, 8.0 meter inside diameter. It was designed to have the same diameter as the upper stage of Ares, and SLS is based on Ares. So replacing the upper stage of Falcon Heavy with EUS gives us more delta-V, but more importantly payload diameter for a good habitat.

Again, you want to redesign the rocket.  Let's do a feasibility study.

Edit: Only one of the Merlin 1D's in the first stage can throttle, so far as I know.  That may pose a Max-Q problem for a fairing considerably larger than the fairing originally designed for the rocket.  Lengthening the fairing a few meters should not be a significant problem.

Last edited by kbd512 (2016-02-03 11:17:01)

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#36 2016-02-03 15:15:45

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,910

Re: Deep Space Habitat

From what I recall the capsules of space-x, cst-100 and orion were meant to be all 5 m diameter, so that they could be used across the board on any launcher which includes Atlas V and Delta IV as well. The interchanger for the EUS for SLS could be placed at the end of the falcon first stage and then the EUS could be placed on top of it....so minimal design needs to be done. Also the interchanger for Da Stick would also be along the same lines....

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#37 2016-02-03 17:04:47

RobertDyck
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From: Winnipeg, Canada
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Re: Deep Space Habitat

I keep coming back to old technology. Skylab was originally designed to launch wet. That means the Skylab workshop was designed to be the upper stage of a Saturn 1B rocket. The liquid hydrogen tank was filled with liquid hydrogen during launch, but once in orbit it was vented, warmed, then filled with air for astronauts. The liquid oxygen tank was used as garbage dumpster and septic tank. A micrometeoroid shield, sun shade, and solar arrays were installed before launch. The two large solar array wings were folded and covered by an expendable fairing for launch, just like the Dragon trunk does today. Saturn 1B could only lift the workshop, it would launch without the Apollo telescope mount, without the multiple docking adapter, and without the airlock. But they planned to the first crew mission would be an Apollo CSM on another Saturn 1B, and the space for the LM would carry the airlock instead. The CSM would turn around, dock to the airlock the same way it would with LM, and the CSM would carry the airlock to the Skylab workshop. So the airlock would be attached before astronauts entered. The second mission would do the same with the multiple docking adapter. At that point they hadn't planned the Apollo telescope mount at all.

I'm thinking of using the liquid hydrogen tank as a deep space habitat. I previously posted the idea of launching the habitat on Falcon 9 v1.2, but could we do it as "self launching"? This time I'm thinking the liquid oxygen tank, support struts between tanks, and RL-10 engines would be discarded before docking with ISS. Again, use ISS as construction shack for the Mars stack. It would require modern micrometeoroid shield and thermal blankets, using the same blankets as modules for ISS. And modern solar array wings, deployed the same way as Dragon. The Exploration Upper stage has domed top and bottom, if you made the cylinder larger and the domed ends shallower, it would give more usable space. Skylab used open mesh metal grid for the ceiling and floor of the aft deck. That metal grid let liquid hydrogen flow through during launch, and acted as anti-slosh and anti-vortex baffles. Do the same. This would give a two stage habitat with the same diameter as a Mars direct habitat. Floors, walls, and big stuff would be installed during launch. Yes, it would be immersed in liquid hydrogen. Anything damaged by freezing would have to be removed. And early 1970s vintage electronics could withstand freezing, couldn't operate until it warmed, but wasn't damaged. However, modern electronics could not withstand that. So put anything small that could come loose and get into the fuel pump into a cargo ship, as well as electronics and anything that can't handle freezing. Skylab had water tanks inside, so they were obviously designed to freeze solid. I'm sure we could do as well.

The Skylab workshop had a dry mass of 35,100kg. The S-IVB stage dry mass was 15,900kg. That means Skylab was 19,200kg heavier than just a stage. This habitat would be smaller: shorter, but wider. No film vault, we have digital stuff now. Standard Falcon 9 can lift 13,150kg payload to LEO, and a LH2/LOX upper stage has higher Isp so should increase that. Definitely enough to lift itself. The EUS includes RCS; could it rendezvous with ISS? Grabbed by the station arm to "berth" the same as Dragon?

I had envisioned the ITV as a single deck, but as wide as Mars Direct. So launching the ITV as cargo on a standard Falcon second stage would have the same aerodynamic issues. The LH2 tank from EUS would be two decks. That's one big deep space habitat. Too much?

Last edited by RobertDyck (2016-02-03 18:44:54)

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#38 2016-02-03 17:47:53

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,910

Re: Deep Space Habitat

Here is the Skylab II topic of which we are talking about the same topic of how do we make an affordable deep space habitat....

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#39 2016-02-03 22:01:26

kbd512
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Registered: 2015-01-02
Posts: 4,207

Re: Deep Space Habitat

RobertDyck wrote:

I keep coming back to old technology. Skylab was originally designed to launch wet. That means the Skylab workshop was designed to be the upper stage of a Saturn 1B rocket. The liquid hydrogen tank was filled with liquid hydrogen during launch, but once in orbit it was vented, warmed, then filled with air for astronauts. The liquid oxygen tank was used as garbage dumpster and septic tank. A micrometeoroid shield, sun shade, and solar arrays were installed before launch. The two large solar array wings were folded and covered by an expendable fairing for launch, just like the Dragon trunk does today. Saturn 1B could only lift the workshop, it would launch without the Apollo telescope mount, without the multiple docking adapter, and without the airlock. But they planned to the first crew mission would be an Apollo CSM on another Saturn 1B, and the space for the LM would carry the airlock instead. The CSM would turn around, dock to the airlock the same way it would with LM, and the CSM would carry the airlock to the Skylab workshop. So the airlock would be attached before astronauts entered. The second mission would do the same with the multiple docking adapter. At that point they hadn't planned the Apollo telescope mount at all.

Skylab was and is the best solution for long duration space missions, but launching it wet is not worth the effort.  With 2 SLS flights and 2 Falcon Heavy flights and you have an all-chemical solution for TMI, MOI, TEI, and EOI.  No SEP, aerobraking, or fancy orbital mechanics are required.

NTRS 20140012883.pdf

RobertDyck wrote:

I'm thinking of using the liquid hydrogen tank as a deep space habitat. I previously posted the idea of launching the habitat on Falcon 9 v1.2, but could we do it as "self launching"? This time I'm thinking the liquid oxygen tank, support struts between tanks, and RL-10 engines would be discarded before docking with ISS. Again, use ISS as construction shack for the Mars stack. It would require modern micrometeoroid shield and thermal blankets, using the same blankets as modules for ISS. And modern solar array wings, deployed the same way as Dragon. The Exploration Upper stage has domed top and bottom, if you made the cylinder larger and the domed ends shallower, it would give more usable space. Skylab used open mesh metal grid for the ceiling and floor of the aft deck. That metal grid let liquid hydrogen flow through during launch, and acted as anti-slosh and anti-vortex baffles. Do the same. This would give a two stage habitat with the same diameter as a Mars direct habitat. Floors, walls, and big stuff would be installed during launch. Yes, it would be immersed in liquid hydrogen. Anything damaged by freezing would have to be removed. And early 1970s vintage electronics could withstand freezing, couldn't operate until it warmed, but wasn't damaged. However, modern electronics could not withstand that. So put anything small that could come loose and get into the fuel pump into a cargo ship, as well as electronics and anything that can't handle freezing. Skylab had water tanks inside, so they were obviously designed to freeze solid. I'm sure we could do as well.

I'm thinking we fly SLS two or three times per year since the marginal costs and annual cost is on par with STS.  Forget about on-orbit construction.  It's not worth the hassle.

RobertDyck wrote:

The Skylab workshop had a dry mass of 35,100kg. The S-IVB stage dry mass was 15,900kg. That means Skylab was 19,200kg heavier than just a stage. This habitat would be smaller: shorter, but wider. No film vault, we have digital stuff now. Standard Falcon 9 can lift 13,150kg payload to LEO, and a LH2/LOX upper stage has higher Isp so should increase that. Definitely enough to lift itself. The EUS includes RCS; could it rendezvous with ISS? Grabbed by the station arm to "berth" the same as Dragon?

Skylab II C-1 has a total mass of 22t.

Skylab II C-2 (full capability) has a total mass of 27t.

Skylab II C-3 (MTV) has a total mass of 41t.  That's provisions for 6 crew for 1000 days.

RobertDyck wrote:

I had envisioned the ITV as a single deck, but as wide as Mars Direct. So launching the ITV as cargo on a standard Falcon second stage would have the same aerodynamic issues. The LH2 tank from EUS would be two decks. That's one big deep space habitat. Too much?

You could always section a Skylab II barrel for a split Mars Surface Habitat and Mars Transfer Vehicle.  1/3 MSH and 2/3 MTV.

Incidentally, I was wrong about what LUS could throw to TMI.  It's not 41t, it's only 31t.

SLS Upper Stage Proposals

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#40 2016-02-04 00:37:04

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,501
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Re: Deep Space Habitat

The launch sequence I came up with was:
First mission:
- 1 SLS Block 2B for MAV (direct launch from KSC to Mars surface)
- 1 SLS Block 2B for lab & pressurized rover (direct launch)
- 1 Falcon 9 v1.2 for ITV
- 1 Falcon Heavy for TMI stage
- 1 Falcon 9 lander & unpressurized rover
- 1 Falcon 9 for Dragon

Subsequent missions:
- 1 SLS Block 2B for MAV
- 1 Falcon Heavy for TMI stage
- 1 Falcon 9 lander & unpressurized rover
- 1 Falcon 9 for Dragon

Your idea is intriguing: splitting a Skylab II barrel into Mars Surface Habitat and Interplanetary Transit Vehicle (aka Mars Transfer Vehicle). It would require substantial modification.

However, compare launches. Mars Direct has been marketted as 2 Ares launches per mission, but in reality it requires 3 for the first mission, plus 2 for each mission thereafter. I say that because the first mission starts with the ERV, then hab, then followed by a second ERV. The 1996 edition of the book "The Case for Mars" said the second ERV would use a 6-month transit, but I don't see why. Spirit and Opportunity used the "express trajectory" of 6 months, but Curiosity rover used 8.5 months because that maximized mass to Mars. The ERV would use an 8.5 month transit, while crew would use 6 month. That means if the second ERV is launched 2 weeks after crew, then it arrives at Mars 3 months after crew land. That gives them plenty of time to decide whether it's needed as a backup, or let it start the second mission. But the last mission would still need a backup ERV. That means the first mission has ERV + hab + ERV. Each later mission has hab + ERV. So using today's launch vehicles, that means 3 launches of SLS block 2B for the first mission, then 2 for each subsequent mission.

My mission architecture requires 2 SLS block 2B for the first mission, 3 Falcon 9, and 1 Falcon Heavy. Each subsequent mission requires 1 SLS block 2B, 2 Falcon 9, and 1 Falcon Heavy. And if you leave the Dragon attached to the ITV, using something else to return crew from ISS, then subsequent missions can replace 1 Falcon 9 with that other something. That could be CST-100 or DreamChaser, either launch on Atlas V.

My architecture requires a soft lab, so it can be moved to the surface hab. The surface hab could also be soft, but would be nice if it's hard. A hard hab (aluminum hull) has structural strength to allow piling sandbags full of Mars regolith on the roof for radiation protection.

How many launches does yours require?

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#41 2016-02-04 06:31:43

Antius
Member
From: Cumbria, UK
Registered: 2007-05-22
Posts: 1,003

Re: Deep Space Habitat

Regarding artificial gravity: I can remember a discussion on this board a while back about tolerable limits in terms of rotation rates and radius of rotation.  There were studies that indicated that high rotation rates induce nausia and disorientation in most people, but a high degree of adaptation was achieved over a period of hours and days.  This suggests to me that the 4rpm limit for 1g may be overly conservative.

I will see if I can dig out the references.  This is one area of research that could be investigated quite cheaply here of earth.  Build a rotating hab designed to simulate hypergravity through a combination of natural gravity and rotational gravity.  The hab floors will be angled such that they are perpendicular to the effective direction of gravity.  Keep groups of people in there for varying periods at varying g levels and record the results.  Sounds like a good Mars Society project.

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#42 2016-02-04 10:20:56

kbd512
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Re: Deep Space Habitat

RobertDyck wrote:

The launch sequence I came up with was:
First mission:
- 1 SLS Block 2B for MAV (direct launch from KSC to Mars surface)
- 1 SLS Block 2B for lab & pressurized rover (direct launch)
- 1 Falcon 9 v1.2 for ITV
- 1 Falcon Heavy for TMI stage
- 1 Falcon 9 lander & unpressurized rover
- 1 Falcon 9 for Dragon

Falcon 9 can't send any substantial payload to Mars.  Falcon Heavy can send 13t to Mars, IIRC.  You need another SLS launch, fancy orbital mechanics, or SEP.  The rest looks good.

RobertDyck wrote:

Subsequent missions:
- 1 SLS Block 2B for MAV
- 1 Falcon Heavy for TMI stage
- 1 Falcon 9 lander & unpressurized rover
- 1 Falcon 9 for Dragon

Send the unpressurized rover with the MAV.  There's plenty of tonnage left.  A realistic pressurized MAV for 4 astronauts weighs 15t using storable propellants.  Even if you want a fancy 20t MAV, you can still send the rover with the MAV.  Unpressurized rovers should be 4 seat battery operated go-carts.  Our battery tech has improved dramatically since the Apollo program.

RobertDyck wrote:

Your idea is intriguing: splitting a Skylab II barrel into Mars Surface Habitat and Interplanetary Transit Vehicle (aka Mars Transfer Vehicle). It would require substantial modification.

I certainly hope not.  I want a 2/3 barrel section length Skylab II.  In other words, Skylab II C-1 from NASA's documents.  I want a 1/3 barrel section length Skylab II for the Mars Surface Habitat.  In other words, chop Skylab II C-1 in half.  The bottom dome accommodates the ADEPT payload mount ring and the periphery accommodates the propellants required for propulsive landing.  The bottom dome would contain a fresh water tank mounted over a grey water tank.  That's a good configuration for ADEPT to use for CoG shifting required to generate lift during descent.

If you really want the Mars Direct tuna cans, you can still do that but then you have to modify the cans.  I wouldn't call that a substantial modification, but a test and integration cycle is still required.

RobertDyck wrote:

However, compare launches. Mars Direct has been marketted as 2 Ares launches per mission, but in reality it requires 3 for the first mission, plus 2 for each mission thereafter. I say that because the first mission starts with the ERV, then hab, then followed by a second ERV. The 1996 edition of the book "The Case for Mars" said the second ERV would use a 6-month transit, but I don't see why. Spirit and Opportunity used the "express trajectory" of 6 months, but Curiosity rover used 8.5 months because that maximized mass to Mars. The ERV would use an 8.5 month transit, while crew would use 6 month. That means if the second ERV is launched 2 weeks after crew, then it arrives at Mars 3 months after crew land. That gives them plenty of time to decide whether it's needed as a backup, or let it start the second mission. But the last mission would still need a backup ERV. That means the first mission has ERV + hab + ERV. Each later mission has hab + ERV. So using today's launch vehicles, that means 3 launches of SLS block 2B for the first mission, then 2 for each subsequent mission.

The SLS program costs $3B per year to maintain infrastructure, whether you launch or not.  The Orion program adds another $1B to $2B a year, whether you launch or not.  The rockets only cost $500M to $700M per flight.  Launching 3 SLS rockets per year is well within NASA's budget.  There's nothing to refurbish.

RobertDyck wrote:

My mission architecture requires 2 SLS block 2B for the first mission, 3 Falcon 9, and 1 Falcon Heavy. Each subsequent mission requires 1 SLS block 2B, 2 Falcon 9, and 1 Falcon Heavy. And if you leave the Dragon attached to the ITV, using something else to return crew from ISS, then subsequent missions can replace 1 Falcon 9 with that other something. That could be CST-100 or DreamChaser, either launch on Atlas V.

Your plan has a mass budget allocation problem for dV required for TMI from LEO.  The ITV is not going to TMI from LEO using a Falcon Heavy supplied TMI stage.  If you want to use Hohmann transfers from LEO, there's no tricks you can employ that make up for the substantial dV requirement.  You need SLS to send your ITV to TMI from LEO.  Your MOI, TEI, and EOI stages can be delivered to LEO using Falcon Heavy, but that's it.  Falcon 9 can deliver the astronauts to the ITV using Dragon 2.

Please accept that NASA's rocket scientists and the rocket scientists employed by their contractors have done the math on the dV requirements to ship payloads in the ITV's tonnage class from LEO to LMO and back, thus they know what types of upper stages and how much propellant is required for Hohmann transfers.  This isn't coming from me, it's coming from them.  I posted a link.

RobertDyck wrote:

My architecture requires a soft lab, so it can be moved to the surface hab. The surface hab could also be soft, but would be nice if it's hard. A hard hab (aluminum hull) has structural strength to allow piling sandbags full of Mars regolith on the roof for radiation protection.

Ok.  So you want sandbags or a lightweight HESCO barrier to be shipped with the MSH.  Pack that sucker.  EVA #1 will be moving all the crap out of the MSH.  Just like moving day here on Earth.

RobertDyck wrote:

How many launches does yours require?

SLS 1 - MAV and perhaps an unpressurized rover and additional supplies (ADEPT + RP) <- Launched 2 years ahead of the MTV/MDV stack

SLS 2 - MTV (Skylab II C-1) and MDV/MSH (1/2 Skylab II C-1 ADEPT + RP)

SLS 3 - TMI2, MOI, TEI, EOI stages (storable propellants)

SLS 4 - TMI1 stage (LOX/LH2 propellants)

F9 1 - 4 crew transfer to ITV

Note: The only time critical stage is TMI1.  After TMI1 has been mated, F9 needs to transfer the crew immediately and they need to be on their way.

Unlike Mars Direct, the MTV is not reused.  Everything is expendable.  Subsequent missions repeat the launch sequence.  It's simple, but expensive in terms of launch costs.  It's mostly the rocket development program that Congress wants versus the payload development program that I want.  Develop the rocket and develop the LUS.  Stop there.

I would much rather spend $4B-$5B a year on DSH/MSH/MAV development.  I would freeze SLS development at IOC because no further lift capability is required for a realistic Mars exploration program.  The funding required for SLS Block II capability is insane, relative to the minimally improved lift capability.

My program doesn't actually get us to Mars quicker, but it substantially improves our landed tonnage for the same or similar cost once we develop the required electric propulsion technology.  NASA's program will also work, but a substantial portion of the mass delivered to Mars is propellants.

NASA is going back to the Apollo Program model.  Maybe that's not a bad thing since that's what they know best, but it doesn't advance our space flight capabilities.  As you've stated many times, the basic technology required to go there and come back has existed since the 1970's.  I would like to improve upon what we can actually do once we get there and electric propulsion meaningfully improves our Mars exploration capabilities by meaningfully improving delivered tonnage.

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#43 2016-02-04 12:16:49

RobertDyck
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Re: Deep Space Habitat

kbd512 wrote:

Falcon 9 can't send any substantial payload to Mars.  Falcon Heavy can send 13t to Mars, IIRC.  You need another SLS launch, fancy orbital mechanics, or SEP.

I am tempted to say something rude. You know better than that. I already said several times that my plan assembles the spacecraft in Low Earth Orbit. I use ISS as construction shack and bus terminal. Actually, with the station arm it's more than a shack. This means all the Falcon launch vehicles (Falcon 9 and Falcon Heavy) launch their payload to ISS. Not to Mars, to ISS. Falcon 9 is rated to lift 13.15 metric tonnes to LEO, while Falcon Heavy is rated for 53 tonnes. Actually that's to 185km orbit, it's a bit less to ISS. I could calculate that for you, but the point is you DON'T launch everything directly to Mars.

You appear to be obsessed with SEP. Again, SEP means slow transit to Mars. Not fast. It has extreme Isp, very low thrust. I've already posted what the Russian mission plan looks like. The Russian plan was from 1988, but updated in 1999. It's huge, but still takes months. It's 700 metres wide from tip to tip. It takes 3 months to spiral out of Earth orbit, 8 months to Mars, 1 months spiral down in Mars orbit, 1 month on Mars surface, 1 month spiral out of Mars orbit, 7 month transit back to Earth, then 3 month spiral down in Earth orbit. That's 24 months total, of which only 1 month is spent on Mars. Mars Direct uses chemical propulsion, LH2/LOX, so 6 month transit from Earth to Mars. No spiral out of Earth orbit, no spiral down in Mars orbit. And it uses aerocapture to enter Mars orbit, so the only propellant is manoeuvring thrusters. Russian plan: 12 months from surface of Earth to surface of Mars. Mars Direct plan: 6 months. Then Mars Direct would stay on Mars 500 days. Then transit back to Earth in 6 months. Return with chemical propulsion: liquid methane / LOX. It would enter Earth atmosphere directly, not Earth orbit. Returning to Earth like Apollo. You can do that with a PICA heat shield. Dragon already uses PICA-X. So total time from Mars surface to Earth surface: 6 months.

I have a few issues with Mars Direct. One is total time: 180 transit to Mars + 500 day surface stay + 180 day transit back to Earth = 860 days total. That's 28 months and 8 days. Earth and Mars align every 26 months, so that means the second mission departs before the first mission lands. Mission control has to support two missions at once for 2 months and a week. And the two crews don't get to meet, so can't pass on knowledge before the second crew departs. So I want to reduce surface stay to 425 says. That would take a bit more fuel because launch windows won't be optimal, but would be worth it. Crews get to meet. Mission control only supports one mission. And bean counters would be tempted to delay the second mission to the next launch window, so one mission every 52 months instead. That would create temptation to cancel the Mars program all together.

So no fancy orbital mechanics. No SEP. No "spiral". Just directly launch using LH2/LOX, enter Mars orbit with aerocapture, return with LCH4/LOX. My mission plan takes inspiration from Apollo. "Lunar Orbit Rendezvous" proved the best plan. The key feature is don't land your Earth return capsule on the Moon, instead leave it parked in Lunar orbit and use a light weight lunar lander. So Mars Orbit Rendezvous does the same thing. That allows a dedicated Deep Space Habitat for both transits (to Mars and back), and allows the Deep Space Habitat to be reused. To ensure it's reused, it has to enter Earth orbit. Learning from Mars Direct, use aerocapture. So the same heat shield for aerocapture at both planets.

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#44 2016-02-04 12:43:09

RobertDyck
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From: Winnipeg, Canada
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Re: Deep Space Habitat

kbd512 wrote:

Send the unpressurized rover with the MAV.  There's plenty of tonnage left.  A realistic pressurized MAV for 4 astronauts weighs 15t using storable propellants.  Even if you want a fancy 20t MAV, you can still send the rover with the MAV.  Unpressurized rovers should be 4 seat battery operated go-carts.  Our battery tech has improved dramatically since the Apollo program.

Mars Direct includes a rover in case the hab lands more than walking distance to the ERV. The rover includes 1,000km of fuel. If the hab lands more than that, then the ERV for second mission has to be landed beside the hab. I include a rover with the hab for the same reason. But an open rover can be very light-weight. I'm thinking more like this...
as17_147_22526.jpg images?q=tbn:ANd9GcQiedamRtts4jgdhXPoOLjZWn7QdM50cQJsIW9gQA0aw59ZwSJr
Obviously that's the Apollo lunar rover. A Mars rover would have a second row of seats to carry all 4 astronauts. And Robert Zubrin proposed an internal combustion engine using LCH4/LOX, so it could be refuelled by the ISPP device at the ERV. After all, ERV propellant tanks would be full before astronauts leave Earth, so the ISPP device would no longer operate. But a nuclear reactor has fuel for years. So you could operate the device to produce propellant for the rover while on Mars. Ok. That's a way to use nuclear power while not carrying the nuclear reactor.

A Mars rover would not have the big dish antenna. No need. It could communicate with the surface hab, use that to relay to Earth. And all Mars orbiters now include a Mars Relay Antenna: MGS, Odyssey, MRO, Mars Express. That can be used to store and forward digital messages to Earth. That could be recorded voice, video, or text. An antenna to compatible with that system is much smaller. So yea, go-cart for Mars.

One feature is to charge suit batteries from power provided by the rover. And allow suit radios and rover radios to act as relays for each other, to extend range from the hab.

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#45 2016-02-04 12:48:06

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: Deep Space Habitat

RobertDyck wrote:
kbd512 wrote:

Falcon 9 can't send any substantial payload to Mars.  Falcon Heavy can send 13t to Mars, IIRC.  You need another SLS launch, fancy orbital mechanics, or SEP.

I am tempted to say something rude. You know better than that. I already said several times that my plan assembles the spacecraft in Low Earth Orbit. I use ISS as construction shack and bus terminal. Actually, with the station arm it's more than a shack. This means all the Falcon launch vehicles (Falcon 9 and Falcon Heavy) launch their payload to ISS. Not to Mars, to ISS. Falcon 9 is rated to lift 13.15 metric tonnes to LEO, while Falcon Heavy is rated for 53 tonnes. Actually that's to 185km orbit, it's a bit less to ISS. I could calculate that for you, but the point is you DON'T launch everything directly to Mars.

You appear to be obsessed with SEP. Again, SEP means slow transit to Mars. Not fast. It has extreme Isp, very low thrust. I've already posted what the Russian mission plan looks like. The Russian plan was from 1988, but updated in 1999. It's huge, but still takes months. It's 700 metres wide from tip to tip. It takes 3 months to spiral out of Earth orbit, 8 months to Mars, 1 months spiral down in Mars orbit, 1 month on Mars surface, 1 month spiral out of Mars orbit, 7 month transit back to Earth, then 3 month spiral down in Earth orbit. That's 24 months total, of which only 1 month is spent on Mars. Mars Direct uses chemical propulsion, LH2/LOX, so 6 month transit from Earth to Mars. No spiral out of Earth orbit, no spiral down in Mars orbit. And it uses aerocapture to enter Mars orbit, so the only propellant is manoeuvring thrusters. Russian plan: 12 months from surface of Earth to surface of Mars. Mars Direct plan: 6 months. Then Mars Direct would stay on Mars 500 days. Then transit back to Earth in 6 months. Return with chemical propulsion: liquid methane / LOX. It would enter Earth atmosphere directly, not Earth orbit. Returning to Earth like Apollo. You can do that with a PICA heat shield. Dragon already uses PICA-X. So total time from Mars surface to Earth surface: 6 months.

I have a few issues with Mars Direct. One is total time: 180 transit to Mars + 500 day surface stay + 180 day transit back to Earth = 860 days total. That's 28 months and 8 days. Earth and Mars align every 26 months, so that means the second mission departs before the first mission lands. Mission control has to support two missions at once for 2 months and a week. And the two crews don't get to meet, so can't pass on knowledge before the second crew departs.

Sure they could! Ever hear of radio?

So I want to reduce surface stay to 425 says. That would take a bit more fuel because launch windows won't be optimal, but would be worth it. Crews get to meet. Mission control only supports one mission. And bean counters would be tempted to delay the second mission to the next launch window, so one mission every 52 months instead. That would create temptation to cancel the Mars program all together.

So how much does Mission Control cost compared to the construction of a spacecraft in low Earth orbit? Human labor on the ground is cheaper than human labor in space, don't you think? Mars Direct doesn't involve constructing anything in space, you launch a hab and an Earth Return Vehicle. The Earth return vehicle goes first, it lands and produces fuel for the return journey, then the Hab gets launched with the crew onboard. You are worried about Mission Control handling two manned missions at once? That is still cheaper than constructing an interplanetary spacecraft in orbit I think!

So no fancy orbital mechanics. No SEP. No "spiral". Just directly launch using LH2/LOX, enter Mars orbit with aerocapture, return with LCH4/LOX. My mission plan takes inspiration from Apollo. "Lunar Orbit Rendezvous" proved the best plan. The key feature is don't land your Earth return capsule on the Moon, instead leave it parked in Lunar orbit and use a light weight lunar lander. So Mars Orbit Rendezvous does the same thing. That allows a dedicated Deep Space Habitat for both transits (to Mars and back), and allows the Deep Space Habitat to be reused. To ensure it's reused, it has to enter Earth orbit. Learning from Mars Direct, use aerocapture. So the same heat shield for aerocapture at both planets.

Mars Orbit Rendezvous has two failure modes instead of one.
Either the lander fails to get the crew off of Mars, and the orbiting Earth Return Vehicle is of no use to them, or the lander gets them into low Mars orbit, and then the Earth Return vehicle fails to get them back to Earth, a partial failure in either part is a total failure, as you need both to get the crew back to Earth. If you were an astronaut, would you rather be stranded on Mars or in space?

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#46 2016-02-04 13:03:26

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,501
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Re: Deep Space Habitat

kbd512 wrote:

Please accept that NASA's rocket scientists and the rocket scientists employed by their contractors have done the math on the dV requirements to ship payloads in the ITV's tonnage class from LEO to LMO and back, thus they know what types of upper stages and how much propellant is required for Hohmann transfers.  This isn't coming from me, it's coming from them.

My experience has been that whenever anyone says "trust me", that's when you have to question everything. As soon as you hear "trust me" that's when you trust nothing. If you blindly trust, you get screwed. "Trust me" is the mantra of criminals and scams.

And compare Mars Direct to NASA Design Reference Mission. Two launches of the equivalent SLS block 2 or 2B. DRM requires several. Major cost difference.

I first came up with my plan in 1999 through 2002. When Boris Yeltsin was president of Russia, and members of the Mars Society wanted to use Russia's Energia launch vehicle. The idea originally came from Robert Zubrin's book "The Case for Mars". My plan would have used Energia to launch the TMI stage. Without its upper stage, it can lift 88 metric tonnes to 200km orbit. That's a lot more than Falcon Heavy. We have to be very careful with mass to fit it on Falcon Heavy. The alternative is SLS block 1, or two Falcon Heavy launches. Two launches would mean splitting the TMI stage into two pieces. But this means working out detail mass of everything. I've re-done it many times, but keep getting people argue over mission architecture. We can't get details as long as we're arguing over the architecture.

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#47 2016-02-04 15:09:35

kbd512
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Registered: 2015-01-02
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Re: Deep Space Habitat

RobertDyck wrote:

I am tempted to say something rude. You know better than that. I already said several times that my plan assembles the spacecraft in Low Earth Orbit. I use ISS as construction shack and bus terminal. Actually, with the station arm it's more than a shack. This means all the Falcon launch vehicles (Falcon 9 and Falcon Heavy) launch their payload to ISS. Not to Mars, to ISS. Falcon 9 is rated to lift 13.15 metric tonnes to LEO, while Falcon Heavy is rated for 53 tonnes. Actually that's to 185km orbit, it's a bit less to ISS. I could calculate that for you, but the point is you DON'T launch everything directly to Mars.

Falcon Heavy can not lift a TMI stage heavy enough to send any realistic ITV to TMI using a Hohmann transfer from LEO.  Not even with a LOX/LH2 second stage.  The wet mass of the Merlin-equipped second stage is around 92t and it can carry a 53t payload to LEO.  Even if Falcon Heavy's only payload was the second stage, it still can't produce enough dV to throw more than 12t to 13t of payload to TMI.  Your 145t upper stage / payload has to make it to orbit, which means it's going to burn through quite a bit of its propellant to accelerate to orbital velocity.  Mars Semi-Direct says with LOX/LH2 upper stage (basically a Centaur), you could realistically send about 17t to TMI using Falcon Heavy.

LUS weighs 119t and can send 31t to TMI from LEO.  Some of that propellant is expended to make it to orbit, IIRC.  However, you can still throw 31t to TMI.

What's the combined mass of everything that's not related to propulsion that you want to send to TMI?

RobertDyck wrote:

You appear to be obsessed with SEP. Again, SEP means slow transit to Mars. Not fast. It has extreme Isp, very low thrust. I've already posted what the Russian mission plan looks like. The Russian plan was from 1988, but updated in 1999. It's huge, but still takes months. It's 700 metres wide from tip to tip. It takes 3 months to spiral out of Earth orbit, 8 months to Mars, 1 months spiral down in Mars orbit, 1 month on Mars surface, 1 month spiral out of Mars orbit, 7 month transit back to Earth, then 3 month spiral down in Earth orbit. That's 24 months total, of which only 1 month is spent on Mars. Mars Direct uses chemical propulsion, LH2/LOX, so 6 month transit from Earth to Mars. No spiral out of Earth orbit, no spiral down in Mars orbit. And it uses aerocapture to enter Mars orbit, so the only propellant is manoeuvring thrusters. Russian plan: 12 months from surface of Earth to surface of Mars. Mars Direct plan: 6 months. Then Mars Direct would stay on Mars 500 days. Then transit back to Earth in 6 months. Return with chemical propulsion: liquid methane / LOX. It would enter Earth atmosphere directly, not Earth orbit. Returning to Earth like Apollo. You can do that with a PICA heat shield. Dragon already uses PICA-X. So total time from Mars surface to Earth surface: 6 months.

I'm obsessed with tonnage, Rob.  I think payload development and tonnage matters most and launch vehicle capability is a distant second when reasonably capable launch vehicles like Falcon Heavy are available.

I already posted why my mission is not the Russian mission that you keep bringing that up.  Make a pertinent argument against something I've actually proposed doing.

I want to use a SEP tug to deliver the TEI stage to HMO from LEO

I want to use a SEP tug to deliver the ITV/MTV to L1 from LEO

I want to use a SEP tug to deliver the TMI stage to L1 from LEO

I want to use a Dragon 2 to deliver the crew of 4 to L1

ITV/MTV coming and going is accomplished using chemical propellants and Hohmann transfer.  Capturing is done by spiraling in.  You lose 2 months spiraling in, 1 month spiraling in to LMO and 1 month spiraling in to L1.  So what?  Is there something magical that a 500 day surface stay accomplishes that a 440 day surface stay can not?

Do you want to spend $3B per year to use SLS, at a cost of $500M to $700M per rocket, or do you want to spend that $3B per year on payload development?  Falcon Heavy development is nearly paid for.  That 119t LUS that we want to use with SLS hasn't even been developed or funded for development yet.  SLS hasn't even flown yet, for that matter.  How much funding for launch vehicle development is enough before you pull back and start devoting some funding to payload development?

RobertDyck wrote:

I have a few issues with Mars Direct. One is total time: 180 transit to Mars + 500 day surface stay + 180 day transit back to Earth = 860 days total. That's 28 months and 8 days. Earth and Mars align every 26 months, so that means the second mission departs before the first mission lands. Mission control has to support two missions at once for 2 months and a week. And the two crews don't get to meet, so can't pass on knowledge before the second crew departs. So I want to reduce surface stay to 425 says. That would take a bit more fuel because launch windows won't be optimal, but would be worth it. Crews get to meet. Mission control only supports one mission. And bean counters would be tempted to delay the second mission to the next launch window, so one mission every 52 months instead. That would create temptation to cancel the Mars program all together.

NASA will either decide to do this or not.  Conjunction class mission duration is what it is.  Fancy orbital mechanics can widen your launch windows or decrease propellant mass, but that's it.

RobertDyck wrote:

So no fancy orbital mechanics. No SEP. No "spiral". Just directly launch using LH2/LOX, enter Mars orbit with aerocapture, return with LCH4/LOX. My mission plan takes inspiration from Apollo. "Lunar Orbit Rendezvous" proved the best plan. The key feature is don't land your Earth return capsule on the Moon, instead leave it parked in Lunar orbit and use a light weight lunar lander. So Mars Orbit Rendezvous does the same thing. That allows a dedicated Deep Space Habitat for both transits (to Mars and back), and allows the Deep Space Habitat to be reused. To ensure it's reused, it has to enter Earth orbit. Learning from Mars Direct, use aerocapture. So the same heat shield for aerocapture at both planets.

So you want to spend $3B a year on SLS before launch costs are factored in to gain a measly 60 days of surface stay?  A 440 day surface stay isn't enough?

Annual costs not included, you can fly 4 Falcon Heavy's for every 1 SLS.  You can deliver 31t with 1 SLS and 1 FH using chemical propulsion or you could deliver as much as 80t with 4 FH using 2 SEP-CTV's, with 60t being more likely to keep transit times reasonable.  That's double the payload for the same launch costs.  Unless you think 2 SEP-CTV's will cost substantially more than the annual cost of the SLS program, there's simply no comparison in delivered tonnage.

There's not even any funding left for payload development because SLS development costs so much.  That was the entire problem with STS and the reason ISS assembly took so long.

Your options are using really efficient propulsion to deliver cargo to where you intend to go or use really inefficient propulsion to deliver propellant to where you intend to go.  Payload fraction with chemical propellants is just awful.  Earth to LEO is bad enough.  There's no reason to compound the problem using chemical propulsion all the way to Mars.  There is no NTR and there is no NEP.  SEP is what we do have and it's good enough for cargo delivery and orbital insertions for manned vehicles.  Therefore I would like to use it for what it can do since, like SLS, we're paying for it anyway.

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#48 2016-02-04 15:49:45

kbd512
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Registered: 2015-01-02
Posts: 4,207

Re: Deep Space Habitat

RobertDyck wrote:

My experience has been that whenever anyone says "trust me", that's when you have to question everything. As soon as you hear "trust me" that's when you trust nothing. If you blindly trust, you get screwed. "Trust me" is the mantra of criminals and scams.

I'm not asking you to trust me or Dr. Zubrin or NASA or Boeing.  I'm asking you to plug your numbers into the formulas to see what you get.  I guarantee you that that's exactly what Dr. Zubrin did and he says a Centaur equipped Falcon Heavy delivers 17t to TMI.

RobertDyck wrote:

And compare Mars Direct to NASA Design Reference Mission. Two launches of the equivalent SLS block 2 or 2B. DRM requires several. Major cost difference.

Compare Mars Direct with which DRM?  NASA's DRM probably requires more launches than Dr. Zubrin's DRM because they've calculated out exactly what everything weighs using current technology and have given themselves margin for unexpected weight increases.

The major cost of the SLS program is development and fixed costs.  You have to launch 6 rockets per year for marginal costs to equate to fixed costs, assuming each rocket costs $500M.  In other words, a SLS flight costs about as much as a STS flight.

That's $10B from start of program to first flight, including the rocket.  You have to launch 20 rockets before launch costs exceed development costs and even after the first flight, the rocket is still in development.  Is launching an extra rocket or two, every two years, a big deal in light of fixed costs and development costs?

RobertDyck wrote:

I first came up with my plan in 1999 through 2002. When Boris Yeltsin was president of Russia, and members of the Mars Society wanted to use Russia's Energia launch vehicle. The idea originally came from Robert Zubrin's book "The Case for Mars". My plan would have used Energia to launch the TMI stage. Without its upper stage, it can lift 88 metric tonnes to 200km orbit. That's a lot more than Falcon Heavy. We have to be very careful with mass to fit it on Falcon Heavy. The alternative is SLS block 1, or two Falcon Heavy launches. Two launches would mean splitting the TMI stage into two pieces. But this means working out detail mass of everything. I've re-done it many times, but keep getting people argue over mission architecture. We can't get details as long as we're arguing over the architecture.

Your plan needs to reconcile mass delivered with the math involved in actually delivering it.  Your plan doesn't bump up against the limit of the capabilities of the rockets you want to use, it grossly exceeds those capabilities.  A TMI stage lofted using a single Falcon Heavy can't even come close to pushing any realistic ITV through TMI, let alone the mass of the ITV and MSH/MDV.

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#49 2016-02-04 18:57:06

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,501
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Re: Deep Space Habitat

kbd512 wrote:

Compare Mars Direct with which DRM?  NASA's DRM probably requires more launches than Dr. Zubrin's DRM because they've calculated out exactly what everything weighs using current technology and have given themselves margin for unexpected weight increases.

They took Zubrin's ideas, and completely redid it. Just to say they did it. But they increase crew from 4 to 6, although NASA always talked about a Mars mission having 4 before that. And didn't use ISPP for return to Earth, but did use ISPP for the MAV. So a lot of things that increase mass. Zubrin estimated his plan would cost $20 billion for the first mission plus $2 billion per mission thereafter, or $30 billion for 7 missions if they commit up-front to that many. NASA DRM was estimated at $55 billion for 7 missions. So they doubled the cost. At a time Congress was ansi about cost after they asked for $450 billion. Congress saw the price increase without anything built yet, and say No.

It's amazing current Congress is supporting anything. But they'll cancel everything unless costs gets under control.

kbd512 wrote:

The major cost of the SLS program is development and fixed costs.  You have to launch 6 rockets per year for marginal costs to equate to fixed costs, assuming each rocket costs $500M.  In other words, a SLS flight costs about as much as a STS flight.

I'm sure corporate executives at ULA is trying to ensure SLS does cost as much as STS. They want the money, and actively fight against anything that slashes cost.

We need a launch vehicle the size of SLS. But cost has to come down. I'm hoping competition will force ULA to be reasonable. The alternative is SpaceX builds Falcon X, X Heavy, or XX. They haven't yet, and Congress supports SLS for now, so ULA has a great opportunity. Looks like they'll blow it. They could get EM-1 and EM-2, then nothing.

kbd512 wrote:

Your plan needs to reconcile mass delivered with the math involved in actually delivering it.  Your plan doesn't bump up against the limit of the capabilities of the rockets you want to use, it grossly exceeds those capabilities.  A TMI stage lofted using a single Falcon Heavy can't even come close to pushing any realistic ITV through TMI, let alone the mass of the ITV and MSH/MDV.

That's one reason I talked of all soft habitats. But you keep saying this without working out detailed mass for my mission plan.

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#50 2016-02-04 19:49:06

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,910

Re: Deep Space Habitat

Thanks kbd512 for the NASA "Habitat Concepts for Deep Space Exploration" as it does make me wonder how long nasa is going to take to make a deep space habitat when it has already taken an enhance version of the shuttle derived launch vehicle. Why only 45 mT for the deep space habitat designs when the block I is capable of 70mT payload to orbit and a Block II is in the 130 mT. I find there is lots of data points missing from the designs if we are only lofting a little over half of the payload capability, which means bare minimum of utilization of the launch vehicle.
I am still reading thou....

I would love to see the 3 or more launchs as shuttle did in a year but the imagination of what the SLS is capable does not seem to be coming out in its moon to mars plans as they are again 1 to 2 at most in a year and for some year none....

kbd512 and RobertDyck I have enjoyed the mission launch profiles for what we could to as a means to keep costs down and maximize what we use for launchers to create what Nasa seems to be lacking in for imagination. That said though there is other topics that mission profile can be brought up in as I setup earlier for that purpose.

The altered lunar rover concept for a light mars vehicle should be a must for Nasa to develope as it should not cost all that much to include for first missions until we can go RV'ing around mars. This would give a mission more surface that could be covered for real science and exploration for the possible Mars colony location.

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