New Mars Forums

kbd512

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Registered: 2015-01-02

Posts: 7,857

Re: Deep Space Habitat

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.

Ok.

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.

I think it's just as likely that SLS is simply not affordable.

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.

Do you understand why I'm so insistent on using Falcon Heavy and SEP for everything but TMI and TEI?

The cost to fly SLS won't magically come down.  Falcon X or Vulcan or whatever may be more affordable to fly, but those are all paper rockets.  Falcon Heavy is finally launching this year.

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

If you're sending 4 astronauts to Mars then the food, water, and air weigh as much or more than what Falcon Heavy can push through TMI, even with Centaur.  Use a soft habitat if you want.  That's not going to change the mass of consumables.

You keep moving the goal post on this.  Lay out exactly what you want to send and head count.  "I want to send a MAV" is not detailed enough.  Specify how much tonnage the MAV has to deliver to orbit.  We can use standard weight for astronauts, but samples weight, the orbit the MAV has to hit, and how you want to deliver it to Mars are all variables.  Let's work out the mass of everything you want to send using both chemical propulsion and electric propulsion.  Then we can say what we can realistically send to Mars using different launch vehicles and propulsion technologies.

After we've done that, let's look at development costs, fixed costs, and marginal costs.  We already know what SLS costs.  Let's look at what Falcon Heavy development might cost.  Let's also try to align development with what SpaceX could reasonably do.  For example, they could reasonably use different payload fairings and add or remove the landing hardware.  Anything more involved is launch vehicle development and we want to avoid that if we can.

You're going to find that there are things we can do with orbital mechanics that can increase payload or widen launch windows, but pure chemical propulsion is expensive in terms of mass allocation and costs and that's all there is to it.

For the purposes of this thread, let's try to align our discussion with DSH/ITV/MTV mass and the various types of vehicles and various propulsion technologies required to send the DSH/ITV/MTV to Mars and back.  I think the JPL/NASA DSH is mass/volume inefficient.

kbd512

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Registered: 2015-01-02

Posts: 7,857

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....

The habitat doesn't need to way 70t, let alone 130t, for 12 to 14 months of occupancy.  Around the 40t weight class is where realistic Mars bound DSH's start at.  If there's 60t of lift capacity remaining, connect a SEP tug to the DSH and drag it to L1 so you can use storable chemical propellant kick stages to push the DSH to TMI.

The big problem here is that even with a 40t habitat, there's no rocket capable of delivering an upper stage that can push it through TMI from LEO using a Hohmann transfer.  That includes SLS Block II.  That means you need multiple flights to fly any DSH.  My solution is to start from a higher orbit than LEO.

I think the ISS-derived and Skylab II DSH solutions are both extremely expensive from the perspective of launch cost if NASA insists on sending it through TMI from LEO.

The DSH/MSH/MDV/Orion concepts may as well be science fiction.  You'd need several SLS flights just to lift the stages required to kick the stack to TMI.

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....

NASA has already figured out that they can't afford to fly SLS more than twice a year.

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.

I'm trying to stay on topic, but this DSH topic is such a flagrant display of impracticality that it's hard not to comment on why it won't work very well.

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.

Let's hope.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

Is there any reason why another company with the like of Bigelow or space x out there that could and should build what Nasa wants just like Space X has done with its cargo/crew taxis for ISS. Do we really want another bloated cost plus driven program for developement and use for the Deep space habitat?

Terraformer

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From: The Fortunate Isles

Registered: 2007-08-27

Posts: 3,906

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Re: Deep Space Habitat

Since you mention Zubrin... why not borrow from his GAIASHIELD mission plan, and use multiple stages for TMI? A few 50 tonne stages, mated on orbit, should allow you to throw a fair amount of tonnage to Mars.

Alternatively, you could connect the plumbing up on orbit and not throw anything away, with a couple of fuel tanks attached to one with engines. That would also give you a long baton that can be spun en route.

Or if you wished, you could launch the entire craft in one or two launches, and transfer the propellent on orbit.

There is absolutely no need for super-heavy lift launchers. At least, not if you're serious about manned exploration.

---

Use what is abundant and build to last

kbd512

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Registered: 2015-01-02

Posts: 7,857

Re: Deep Space Habitat

Is there any reason why another company with the like of Bigelow or space x out there that could and should build what Nasa wants just like Space X has done with its cargo/crew taxis for ISS. Do we really want another bloated cost plus driven program for developement and use for the Deep space habitat?

If the established aerospace companies (Lockhed-Martin, Boeing, Aerojet Rocketdyne) can't or won't provide affordable spacecraft and lift vehicles, then the startups (SpaceX, Bigelow Aerospace, and Blue Origin) should be NASA's new service providers.  After more than five decades of space flight, the design principles, technology, and technical knowledge required to build reliable rockets and spacecraft are fairly well-known and don't involve much engineering magic.

There's still a place for the established aerospace companies in space exploration.  I see them as providers of solutions that no other company could provide due to the depth and breadth of technical knowledge required.  For example, I don't see a startup company designing an active radiation shielding device.  It's at the very edge of what's technically possible from a physics standpoint and only NASA or a company like Lockheed or Boeing would employ the mix of specialists who could design and implement such a device.  There's simply too much and too varied technical knowledge required for commodity providers like SpaceX or Blue Origin to design such a device.

If NASA wishes to conduct an affordable space exploration program, their administrators are going to have to stop issuing cost plus contracts.  There's just no incentive for the contractor to minimize cost.  No more blank checks for commodities.  Rockets and spacecraft have become commodities.  There may not be a slew of different providers, but there are enough.  Quite frankly, some things should also be done in-house.  NASA should develop CL-ECLSS and MCP suits in-house or with assistance from government-sponsored organizations like universities.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

For COTS to work there must be other buyers that should want to get this service and use of the commodity that is a launch vehicle. As you say we seem to have enough variety to them now where are the customers? Or is it that there are not alot of topics that required space access....

If a space port on the ISS is created how will it be managed, will the remaining parts of the station be off limits, how else can we drive these space services if there is no place to go to?

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

I am going to answer some of my question in how many different companies want space x services of a launch vehicle....

http://www.spacex.com/missions

A simple history of what has been done

https://en.wikipedia.org/wiki/List_of_Falcon_9_launches

This one has probable launchings out through 2019....with Falcon Heavy Demo in late 2016....

SpaceNut

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From: New Hampshire

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Posts: 29,433

Re: Deep Space Habitat

Reposting conversationas its drifting to far in the other topic:

Congress Scolds NASA, Underscoring How Far We Are From Mars

The main issue is that NASA doesn't have a solid, detailed plan for how it's going to get to the Red Planet, according to Tom Young, the former director of NASA's Goddard Space Flight Center. "We do not have a planned strategy or architecture with sufficient detail," Young told the committee.

http://images1.houstonpress.com/imager/ … _mars.jpeg

In December Congress voted to give NASA a budget of $19.3 billion for 2016, an increase from 2015 of more than $1 billion, and $750 million more than President Obama had even requested. Of course, this largesse came with some strings attached, as we've previously noted — Congress gave NASA a brisk timetable of about 700 days to get a deep space habitat prototype built, for example.

NASA has just three technologies it must develop to go to Mars and come back:

1. SEP Cargo Transfer Vehicle (SEP-CTV) - 30t to 50t class

2. Storable chemical propellant kick stages - This is very old and well understood technology that requires minimal additional technology development

3. Deep Space Habitat (DSH) - 40t class 500 day mission duration ISS-derived module(s)

Once we have that hardware set, we can reasonably take astronauts to and retrieve them from Mars and Venus.  SLS and Orion are not required for inner solar system exploration and thus far have consumed all available funding for what's minimally required for manned exploration of the inner solar system.

Whether physicists understand it or not, NASA needs to determine whether or not the so-called EM-Drive or Q-thruster actually works by building a test setup that has a power input level in the range that the SEP-CTV will operate at.  If it actually works, then it produces thrust levels in the range of existing ion engines and requires no propellant.  We only need to determine thruster life and incorporate appropriate power conversion hardware for the new Q-thrusters.  If it doesn't work, then continue on with traditional SEP.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

comtinuing repost:

NASA has just three technologies it must develop to go to Mars and come back:

Thats a good question as to what is R&D versus bloated cost plus construction....

1. SEP Cargo Transfer Vehicle (SEP-CTV) - 30t to 50t class

Solar panels with higher efficiency, ion thrusters with higher levels of push both come to mind.

2. Storable chemical propellant kick stages - This is very old and well understood technology that requires minimal additional technology development

This one while its straight forward is dependant on the final mass of what they will push versus what we can then launch it on that changes its shape and need for orbital assembly versus changing to a large launcher.

3. Deep Space Habitat (DSH) - 40t class 500 day mission duration ISS-derived module(s)

article

The main one is that NASA needs to spend $55 million of its budget to start building a deep space habitat that will house astronauts during the actual missions to Mars. And Congress isn't fooling around: NASA has to get to work on this thing now and must have a prototype to show Congress by 2018, just about 730 days from now, so NASA scientists have to move this thing along as quickly as they can.

How the shape will determine how many pieces of what we will design if ISS derived, power source mass (solar panels & batteries) versus nuclear, artifical gravity will change the shape and design as well as the piece and launch count to build. Making the 700 days questionable.....

As for new engine types until we build it and put it in the environemt of use we just have experiments and paper.

Thats a good question as to what is R&D versus bloated cost plus construction....

We don't need to R&D anything.  We need to start building hardware.  That's what Congress has directed NASA to do.

Solar panels with higher efficiency, ion thrusters with higher levels of push both come to mind.

We already have ion engines and solar panels that produce the required output.  No more development.  Let's start building and testing flight hardware.  Whether we could have squeezed a few more kWe out of better panels or not or used more efficient engines is irrelevant.  Engines that have the required output and solar panels that provide the required input have already been ground tested.  Let's stop wasting time and money screwing around and just decide to start building flight hardware.

This one while its straight forward is dependant on the final mass of what they will push versus what we can then launch it on that changes its shape and need for orbital assembly versus changing to a large launcher.

If you push everything to Mars from L1, you get more than enough dV capability from a storable chemical propellant kick stage than is required to push the mass class payloads we need to push using just one standard Falcon Heavy rocket.

FH 1 - Storable Chemical Propellant Kick Stage mated to SEP-CTV

SEP-CTV departs from LEO for L1.

FH 2 - DSH Module 1, SEP-CTV

Payload sent to ISS.

FH 3 - DSH Module 2, Airlock

Payload sent to ISS.  DSH assembled at ISS.  DSH departs ISS for L1 using SEP-CTV.

FH 4 - Dragon 2

Sent directly to L1.  FH can send 13t to TMI, so it can easily send slightly more than half that mass to L1.

No super heavy lift rockets are necessary because SEP-CTV's eat through high dV maneuvering requirements (going from LEO to a higher orbit).

The main one is that NASA needs to spend $55 million of its budget to start building a deep space habitat that will house astronauts during the actual missions to Mars. And Congress isn't fooling around: NASA has to get to work on this thing now and must have a prototype to show Congress by 2018, just about 730 days from now, so NASA scientists have to move this thing along as quickly as they can.

NASA needs to build a DSH that fits on either SLS or Falcon Heavy.  Give SpaceX money to design and build a lengthened payload shroud.  Increasing the width of the payload shroud is not required, so this should not be a major problem.

How the shape will determine how many pieces of what we will design if ISS derived, power source mass (solar panels & batteries) versus nuclear, artifical gravity will change the shape and design as well as the piece and launch count to build. Making the 700 days questionable.....

The requirement is 500 days and we can figure out how well that works in the interim by flying an astronaut for 500 days on ISS.  The MTV doesn't need a nuclear energy source.  No technology development.  Build it, fly it, and discuss how much better it could be after we've done a manned Mars fly-by.

As for new engine types until we build it and put it in the environemt of use we just have experiments and paper.

New engines are not required.  New solar panels and other energy sources are not required.  No new nothing.  Build it and fly it.

Edit:

Fly DSH-1 in LEO in late 2017.

Fly DSH-2 at L1 in late 2018.

No more super heavy lift rockets.  No more super heavy capsules.  Go to Mars with what we have.  Forget about what we could have and focus on what we do have.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

It would appear that your definition of R&D is different than the one I have as it does not mean cutting edge as it does. If it does not use the same form, fit, function then you are make an engineering change that is to one of them but when you are alterning 2 or 3 of them you are no longer changing but doing R&D as it needs to go through all testing which is a pilot production or prototype of what is being redesigned.

That said if we are building the same modules and launching them into orbit to place them in the order that is needed then you are correct its not R&D.

The solar panels and ion thristers are still in the pilot phase and are not fully tested as of yet in as you say building with metal what we want.

We will see how Nasa does with step one which has a deadline to meet....hopefully the likes of the upstarts will bend a few arms into motivation mode to get the real deal made....

kbd512

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Registered: 2015-01-02

Posts: 7,857

Re: Deep Space Habitat

It would appear that your definition of R&D is different than the one I have as it does not mean cutting edge as it does. If it does not use the same form, fit, function then you are make an engineering change that is to one of them but when you are alterning 2 or 3 of them you are no longer changing but doing R&D as it needs to go through all testing which is a pilot production or prototype of what is being redesigned.

I don't want to R&D anything.  I want to connect two ISS modules to each other using CBM, skip the airlock if it's not absolutely required, attach the radiators directly to the habitat module so there's nothing to deploy but solar panels.

Build it, fly it, and discuss what could have been done better after the mission is completed.

Two years later a SEP-CTV will be mated to an identical vehicle and the SEP-CTV will drag the DSH to L1.

That said if we are building the same modules and launching them into orbit to place them in the order that is needed then you are correct its not R&D.

The time for R&D is past.  It's time to actually build something.  ISS was R&D.  Apart from the SEP-CTV, if it hasn't already been R'd and D'd, then we're not using it.

The SEP-CTV R&D will consist of taking engines we've already tested on the ground, attaching them to a barrel with the Xe tanks inside, scaling up the PPU to handle 150kWe, and then attaching solar panels that provide 150kWe.  This is a pure engineering task.  We're using whatever we have on hand that we know works.  ISS modules work.  CBM works.  ROSA and Megaflex work.  HET's work.

Build it, fly it, and discuss what could have been done better after the mission is completed.

The solar panels and ion thristers are still in the pilot phase and are not fully tested as of yet in as you say building with metal what we want.

Not really, but even if they are, we're going to pilot program them in space.

Build it, fly it, and discuss what could have been done better after the mission is completed.

We will see how Nasa does with step one which has a deadline to meet....hopefully the likes of the upstarts will bend a few arms into motivation mode to get the real deal made....

If Congress threatens to pull funding for the manned space program, the DSH will get built and flown in record time and within budget.  Excellence demanded, perfection not required.  Perfect is the enemy of good enough.

Build it, fly it, and discuss what could have been done better after the mission is completed.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

This is the Nasa plan: http://www.nasaspaceflight.com/2012/03/ … ploration/

The ISS building block model would use a ISS Destiny-derived lab module, with airlock/tunnel, for the basic 60 day mission variant with a Cryogenic Propulsion Stage (CPS) or what is the SLS upper stage. The Destiny-derived lab houses both the crew quarters and the ECLSS components (these are not part of destiny). While the a Multi-Purpose Logistics Module (MPLM), Utility tunnel/airlock, to be made from the Node 4 Structural Test Article setting on a Nasa floor. It would be 56 feet long, with a diameter of 16 feet, not including the CPS. This Deep Space Habitat (DSH) is a 2012 proposed NASA conceptual design to support a crew of 4 for exploration beyond Low Earth orbit.

Not one piece as currently built for ISS only one or two features from each....

More internal design layout possibility...
http://www.astrobio.net/topic/solar-sys … e-habitat/

Humans to Mars Summit 2015 Stepping Stones (II): ISS and Beyond
Basically after 5 years all we have are mockups.....

DEVELOPING A HABITAT FOR LONG DURATION, DEEP SPACE MISSIONS

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

http://www.nasaspaceflight.com/2015/11/ … ploration/

Here is another deep space design with what you will like as its looks just like the real modules that are used....orbital/ATK cygnus.....

kbd512

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Registered: 2015-01-02

Posts: 7,857

Re: Deep Space Habitat

I think NASA's 2 MPLM + 1 Node + 1 Airlock is the most realistic DSH concept I've seen.  Every piece of that DSH architecture can be flown on Atlas V or Falcon Heavy and adding capability for additional crew members basically means adding MPLM's.

NASA's Proposed Configuration:

[MPLM]-[Airlock]-[Node]-[MPLM]

* Assembly requires 3 Atlas V, 3 Falcon Heavy, or 1 SLS
* For subsequent DSH missions in deep space, you need 1 more Atlas V or Falcon Heavy for the SEP-CTV.
* Using Atlas V or Falcon Heavy, the SEP-CTV is mated to the DSH at ISS and the DSH is then spiraled out to L1.
* Using SLS, the DSH and SEP-CTV is orbited with 1 launch and then spiraled out to L1, with no assembly at ISS required.
* Using SLS costs more than Atlas V or Falcon Heavy, but requires no on-orbit assembly at ISS.
* Launch costs to NASA (DSH only):

$375M using Falcon Heavy
$675M using Atlas V
$500M to $700M using SLS ($3B fixed program costs not included)

* 3 launches to construct the DSH (on-orbit assembly limited to mating of modules using infrastructure provided by ISS)
* 1 launch for a SEP-CTV (to transfer the DSH to L1)
* 1 launch for a storable chemical propellant TMI kick stage and SEP-CTV (to transfer the DSH to TMI)
* 1 launch for a storable chemical propellant TEI kick stage and SEP-CTV (to transfer the kick stage to HMO)

Points to Ponder:

Is the operations simplification that SLS provides worth the $3B per year program cost?

What are the economics of assembly operations at ISS versus single launch?

From a cost standpoint, is it cheaper to purchase 3 BEAM modules instead of the additional MPLM used to store crew provisions?

It's possible to cut an Atlas V or Falcon Heavy flight from the launch schedule if we use BEAM.  I think two launches to deliver the DSH components for assembly at ISS is entirely reasonable and launch costs using either rocket are significantly below the cost of using SLS.  SLS demonstrates its utility when the DSH and SEP-CTV are delivered with a single launch.

I've seen no cost figures for the MPLM's, so I have no idea what the cost differential is.  Bigelow Aerospace was awarded $17M to develop BEAM to fly it on ISS.  How much of that is manufacturing versus development cost?  If these things only cost a few million to manufacture, does NASA get a discount if they purchase 12 of them (enough to outfit 3 DSH vehicles and 3 for ground testing)?

If you pack each BEAM module solid with provisions, you get substantial radiation shielding in the Node module to contend with SPE.  However, you lose the 31m3 of habitable volume that the additional MPLM provides.  Each MPLM provides 76m3 of pressurized volume and 31m3 of usable pressurized volume not occupied by crew provisions.  Structural mass between 3 BEAM and 1 MPLM is nearly identical.

If a MPLM is penetrated by debris and you can't repair it, then you lose that habitable volume and may lose what's stored inside.  In addition to radiation shielding, BEAM provides a form of debris shielding for the Node module, but the surface area of the Node module so protected is less than ideal due to the geometry of BEAM.

In the final analysis, is the reduction in DSH component launches from 3 to 2 worth the reduction in habitable volume and increase in Node module protection that comes from using BEAM?

Last edited by kbd512 (2016-02-07 15:03:03)

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

Something to note is that the MPLM and cygnus are manufactured by the same compamy and are basically empty cans until you create within them what you want them to do.

The ATV and Cygnus resupply craft as provided by orbital/ATK all trace their origins to the MPLMs.

http://www.spaceref.com/iss/elements/mplm.html

MPLMs are 21 feet long, 15 feet wide, and weigh 4.5 tons empty. When fully loaded they can carry up to 10 tons of cargo.

So target 14.5 tons of launch required for a full up capability which is inside all current launchers capability.

Has a list at the bottom of page of all ISS modules even cancelled and logistics modules
http://space.skyrocket.de/doc_sdat/mplm.htm

Here is the inside view of the Leonardo module a MPLM....

Here is the logistics module book
http://www.spaceref.com/iss/ops/6a.mplm.pdf

Now can we duplicate the modules as they are such as the node 1,2,3 otherwise called Unity, Harmony, Tranquility

unity

Harmony

Tranquility

Node 3 will contain advanced life support systems. These systems will recycle waste water for crew use and generate oxygen for the crew to breathe. In addition, Node 3 will contain an atmosphere revitalization system to remove contaminants from the atmosphere and monitor/control the atmosphere constituents of the ISS. Node 3 will also contain a Waste and Hygiene Compartment (toilet) for supporting the on-board crew.

Node 3 is also designed to provide berthing locations with power, data and commanding, thermal and environmental control, and crew access for more attached habitable volumes or for crew transportation vehicles or stowage, or an appropriate combination of all of these.

http://csis.org/images/stories/space/050628_multi.pdf

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

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Re: Deep Space Habitat

Congress ordered NASA to developed a Deep Space Habitat. I'm hoping someone there is reading this. Could I please make a serious suggestion? Starting with a quote from page 2 of this discussion thread...

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.

I had argued for Mars Direct, using 8.4 metre diameter outer diameter. That's just the diameter of SLS core stage. But the Mars Direct hab was designed to be the Mars surface habitat. Let's make this one dedicated for in-space operation. But I still want artificial gravity, and a heat shield for aerocapture and aerobraking. So...

Let's shrink it to 6.6 metre diameter. That's within the limits estimated for Falcon. And happens to be the same diameter as Skylab. So here are a couple floor plan examples. First Mars Direct, as first proposed: 8.4m outside diameter.

MDRS, same diameter. This one has 6 bunks instead of 4. One improvement is the use of bunk beds. But upper and lower bunks open onto opposite sides, a private room for each bunk.

Skylab aft compartment. This is 6.6 metre diameter. Only 3 sleeping compartments, and since this was designed for zero-G, bunks are vertical.

ISS life support equipment is known, but non-trivial...

Water Processor Assembly, and Urine Processor. Installed on US side of ISS, sized for 3 astronauts.

Oxygen Generation System, with space reserved for Sabatier

Carbon Dioxide Removal Assembly

Assuming this will have ADEPT for aerocapture and aerobraking. And assume a capsule of some sort must be attached as emergency escape pod during aerocapture manoeuvre. And assume it must dock with ISS for vehicle assembly and crew embarkation. How do you put it all together?

I suggest a central radiation shelter like Mars Direct. Configured to function as air lock, with APAS docking hatches in both ceiling and floor. Attach Dragon to the floor hatch, with ADEPT beneath that. Since ADEPT is fabric, metal attachments could poke through for attachment thrust points for propulsion stage. The stage could be jettisoned, and fabric flaps cover the attachment points. The top hatch would be used to dock with ISS. Of course I'm also thinking the top hatch could dock a Mars lander. But right now Congress wants a Deep Space Habitat, and Obama likes asteroids. So let's talk about that.

A tether would connect the top of the habitat to the propulsion stage, running around the side of the Hab, capsule, and heat shield. After injection into trans-asteroid trajectory, the propulsion stage could separate. The propulsion stage would then start spinning, providing tension on the cable. The habitat, capsule, heat shield stack with turn around, pulled by the cable. Then increase rotation rate, and reel-out the cable. Curiosity used Technora for its parachute cord, so I recommend we use the same for the tether.

If the capsule is intended for emergency escape only, then we can use a capsule without solar arrays. Instead transfer power from the DSH to capsule via docking hatch. That means Dragon without the trunk. Although Congress currently favours Orion, so perhaps design it to work with Orion without a service module. The solar arrays from the Dragon trunk could be transferred to the DSH during assembly at ISS, and the trunk jettisoned/de-orbited.

DSH will require RCS thrusters. It will also require toilet, sink, shower, and RV laundry. Exercise machine during transit, either treadmill or exercycle.

Notice an exercycle for zero-G exercise, and Skylab design shower that can be used in either zero-G or artificial gravity. The RV style washer/dryer combo would only work in artificial gravity, so if artificial gravity fails, no clean laundry.

Life support would require toilet that can recover moisture (either vacuum desiccation or electric oven), direct CO2 electrolysis. One great room could be lounge, exercise, and galley. A kitchenette would probably include hot water dispenser like Shuttle for rehydrating food. As well as hot plate and microwave oven. Would that be a warming plate like Shuttle, or an actual stove element for cooking? I'm suggesting no separate laboratory, because this won't be the surface habitat. And rather than a flight deck, just use laptop or tablet computers. With Wifi they can be moved anywhere.

Anyone care to draw a floor plan for that?

kbd512

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Registered: 2015-01-02

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Re: Deep Space Habitat

Rob,

How much is that habitat going to weigh?  The diameter of the habitat is less of a problem than the mass.  We keep going back to aluminum cans and aluminum cans that support 4 people for 500 days are in the 40t range.  The new ECLSS technologies NASA is working on might shave 2t off the ECLSS setup (IIRC, the ECLSS setup NASA wanted to use was between 4t and 5t), but the structural mass of ISS and Skylab solutions is still quite high.

Are the fabric habitats substantially lighter for a given volume?

The only thing I can think of that dramatically reduces the structural mass is wholesale use of composites.  The composite fuel tanks Boeing is working on have substantially lower mass than aluminum alloy fuel tanks.

Regarding ADEPT, I assume you still want to aerocapture the habitat at Mars.  If it the heat shield can't be reused for aerocapture at Earth, then you need two heat shields.  What's wrong with spiraling in to LMO using SEP?  Propellant requirements are minimal and you only lose 60 days of surface time using SEP.  You don't have to be "off" by much for aerocapture to fail.  Unless I'm unaware of something, ADEPT and HIAD work because the CG of the entire payload is shifted to provide aerodynamic control using actuators.  How much would the ADEPT setup weigh for a habitat module?

GW Johnson

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From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,801

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Re: Deep Space Habitat

Re:  spin gravity.  You get 1 gee with a 56 m spin radius at 4 rpm.  Untrained civilians can tolerate 3 to 4 rpm.  Trained and acclimatized crews might tolerate 10-12 rpm.  Certainly 8 rpm should be feasible.

At 8 rpm,  for 1 gee your spin radius is 14 m.  Twice that falls within typical combined lengths for many (if not most) kick stage and habitat module designs.

Dock your hab module to your kick stage,  and just spin the silly thing up to 8 rpm,  end-over-end.  You got 1 gee at the farthest deck,  less as you climb toward the spin center. 

So,  who needs the extra failure modes of cable-connected designs,  or the inert weight penalties of truss-connected designs? And no one needs to do "Battlestar Galactica",  either! 

As for the weight of "aluminum can" designs,  what's wrong with using Bigelow B-330-size modules with an internal equipment layout revised for spin gravity?  These are 13.7 m long and 20 metric tons,  about 6 m diameter,  330 cu.m internal available volume (some of which gets occupied with the equipment).  The 20 tons includes internal equipment for a space station application,  at least somewhat similar to what we would need out of a deep space habitat. 

For a 40 ton allowance,  you can have two those!  For some 660 cu.m to play with,  in your design.  Would you like a larger crew?  Use more modules,  accept the heavier thrown weight,  and spin even slower.  Except for the weight,  those are desirable things.

One B-330 fits a Atlas-5 heavy lifter to LEO.  Two can be flown to LEO on a Falcon-Heavy.  Versions of it should be ready for testing sometime in 2017,  according to what I found on Bigelow's website. 

Just some food for thought.  But out of a different box.  You must look outside the box you're in,  to see what's inside a different box. 

GW

Last edited by GW Johnson (2016-03-08 15:13:46)

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GW Johnson
McGregor,  Texas

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

kbd512

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Registered: 2015-01-02

Posts: 7,857

Re: Deep Space Habitat

Re:  spin gravity.  You get 1 gee with a 56 m spin radius at 4 rpm.  Untrained civilians can tolerate 3 to 4 rpm.  Trained and acclimatized crews might tolerate 10-12 rpm.  Certainly 8 rpm should be feasible.

At 8 rpm,  for 1 gee your spin radius is 14 m.  Twice that falls within typical combined lengths for many (if not most) kick stage and habitat module designs.

A Falcon 9 v1.1, and presumably Falcon Heavy, upper stage is 13.8m.  The payload shroud is 13.1M in length, although the "bottom" of the habitat module would likely be 8m from the base of the upper stage.  BTW, how would you spin this up and what's the gravity gradient like?

Dock your hab module to your kick stage,  and just spin the silly thing up to 8 rpm,  end-over-end.  You got 1 gee at the farthest deck,  less as you climb toward the spin center.

That seems to be what NASA wanted to do to provide AG for the BNTR powered inflatable from DRM 5.0.

So,  who needs the extra failure modes of cable-connected designs,  or the inert weight penalties of truss-connected designs? And no one needs to do "Battlestar Galactica",  either!

What are the odds of the cable snapping?

As for the weight of "aluminum can" designs,  what's wrong with using Bigelow B-330-size modules with an internal equipment layout revised for spin gravity?  These are 13.7 m long and 20 metric tons,  about 6 m diameter,  330 cu.m internal available volume (some of which gets occupied with the equipment).  The 20 tons includes internal equipment for a space station application,  at least somewhat similar to what we would need out of a deep space habitat.

If we can get the weight down to 12t or so, presumably by giving up internal volume, nothing as far as I can tell.  BA-330 is just too heavy for Falcon Heavy to TMI it.  Chop it in half and that's pretty much what we need for two people.

For a 40 ton allowance,  you can have two those!  For some 660 cu.m to play with,  in your design.  Would you like a larger crew?  Use more modules,  accept the heavier thrown weight,  and spin even slower.  Except for the weight,  those are desirable things.

Send two 10t modules with two people each with the MDV (T Space CEV or Scaled Composites CXV?) attached.  Send as many DSH's as you want, but make sure the thing can be TMI'd by one Falcon Heavy or Vulcan rocket.  Use another Falcon Heavy or Vulcan to deliver Boeing's active radiation shielding device.  If it fits, it ships.

One B-330 fits a Atlas-5 heavy lifter to LEO.  Two can be flown to LEO on a Falcon-Heavy.  Versions of it should be ready for testing sometime in 2017,  according to what I found on Bigelow's website.

One DSH per rocket is all you get.  Something has to TMI it.  Keep it simple.

Just some food for thought.  But out of a different box.  You must look outside the box you're in,  to see what's inside a different box. 

GW

Yep.  But in the end, NASA will try to turn something simple into an impossible task.

GW Johnson

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From: McGregor, Texas USA

Registered: 2011-12-04

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Re: Deep Space Habitat

One of the many points I wanted to make is that if (1) you assemble in LEO instead of direct injection into a Mars trajectory,  and (2) if you "tank up" your propellant supply in LEO before you depart for Mars,  then you absolutely are NOT limited by the TMI payload for a launcher,  only the LEO payload.  At only a nominal $100M per launch,  why is this approach considered to be a problem?  Why is it that we MUST at all costs try to launch all the way to TMI speed?  This makes no sense to me.

The vehicle I am talking about is something you do not want to throw away.  You recover it in LEO upon return,  and use it again.  That would be however many B-330's we choose to dock together,  plus some sort of of a docking module at the cg spin center,  where you can have a capsule for either the normal 4 gee descent from LEO,  or the 12-15 gee emergency direct "bailout free return" if something goes wrong with return-to-LEO. 

If the core propulsion stage engine(s) is (are) restartable multiple times,  there is no reason not to scab-on stage-off propellant tanks to this cluster.  After the Earth departure burn,  stage off those empties.  After arrival in Mars orbit,  stage off those empties.  After Mars orbit departure,  stage off those empties.  The core stage itself need only cover return to LEO,  plus some reserves. 

My calculations say that it is only outbound to Mars where we could use additional radiation shielding,  during year one.  The not-yet-used tanks can help provide that shielding. 

But as you can see by these ideas,  I find the entire Mars Direct class of ideas far too limiting to a practical mission design.  Staging out of LEO makes all sorts of things a whole lot easier. 

GW

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GW Johnson
McGregor,  Texas

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

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Deep Space Habitat

From the reading about inflateables in general they are roughly 30% less in Mass for a given same volume as a tin can....

Adept heatshield fabric is a use once as far as I know....

AG, tethered and tumbled in how I feel is very dangerous and that a spiral or spin (think football pass) is preferable to either of the others.

kbd512

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Registered: 2015-01-02

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Re: Deep Space Habitat

One of the many points I wanted to make is that if (1) you assemble in LEO instead of direct injection into a Mars trajectory,  and (2) if you "tank up" your propellant supply in LEO before you depart for Mars,  then you absolutely are NOT limited by the TMI payload for a launcher,  only the LEO payload.  At only a nominal $100M per launch,  why is this approach considered to be a problem?  Why is it that we MUST at all costs try to launch all the way to TMI speed?  This makes no sense to me.

1. If you don't assemble anything in LEO, then you don't pay for assembling anything in LEO.

2. If you launch payloads that one commodity rocket can deliver, you don't pay for extra launches.

The BA-330 costs $125M and the Falcon Heavy costs $125M.  That means delivery of two BA-165's (BA-330 chopped in half) through TMI is going to cost around $500M for the hardware.  We haven't talked about orbital insertion or TEI yet.  Delivery of two TEI stages is another $250M for launch costs.  The two 10t BA-165's have to be TEI'd from LMO.  Thankfully, dV is only 2.1km/s to 2.9km/s so I believe SuperDracos can get the job done.  Unless my math is wrong.

This mission isn't going to be cheap, but it doesn't have to be so expensive that we can't afford it.  We're at the price of two STS flights just to go there and come back.  The surface hardware costs what one STS flights costs and that's just launch costs.

The vehicle I am talking about is something you do not want to throw away.  You recover it in LEO upon return,  and use it again.  That would be however many B-330's we choose to dock together,  plus some sort of of a docking module at the cg spin center,  where you can have a capsule for either the normal 4 gee descent from LEO,  or the 12-15 gee emergency direct "bailout free return" if something goes wrong with return-to-LEO.

I agree about not "wanting" to throw anything away, but what you're talking about is an orbital inspection of the DSH and that can only be properly done with facilities and crew provided by ISS, assuming such a thing is even possible.  If something like the ECLSS requires replacement, I don't think a capsule is going to get that job done on-orbit.

If the core propulsion stage engine(s) is (are) restartable multiple times,  there is no reason not to scab-on stage-off propellant tanks to this cluster.  After the Earth departure burn,  stage off those empties.  After arrival in Mars orbit,  stage off those empties.  After Mars orbit departure,  stage off those empties.  The core stage itself need only cover return to LEO,  plus some reserves.

This is bound to be expensive and potentially dangerous.  Just deliver one payload of reasonable mass using one affordable rocket.  That's simple and easy to do.

My calculations say that it is only outbound to Mars where we could use additional radiation shielding,  during year one.  The not-yet-used tanks can help provide that shielding.

My calculations say there's no calculating when a SPE is going to hit your spacecraft.  Flying in formation behind the active radiation shielding device is about preventing snow days.  GCR protection = "go flight".  No GCR protection = "no flight".  Those are NASA rules, not mine.

But as you can see by these ideas,  I find the entire Mars Direct class of ideas far too limiting to a practical mission design.  Staging out of LEO makes all sorts of things a whole lot easier. 

GW

Agreed, but one payload of reasonable mass delivered by one affordable rocket makes things really easy.  If the payload is sane, the rocket is sane.  If the rocket is sane, launch costs are sane.  If costs are sane, then there's some tiny chance of actually doing the mission.

RobertDyck

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From: Winnipeg, Canada

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Re: Deep Space Habitat

Capture into planetary orbit is more difficult because the planet's gravity causes acceleration. Electric propulsion has very low thrust, but very high specific impulse. It works by applying thrust continuously over a long time, gradually accumulating speed. That doesn't work when you whip past the planet quickly. You need sharp deceleration to slow into orbit. Not sure how the Russians hoped to do it. Their Hall thrusters are electric. But they used massive solar panels to provide massive electric power to their engines, in order to get descent acceleration. Still, their plan requires spiralling in over 3 months.

kbd512

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Registered: 2015-01-02

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Re: Deep Space Habitat

Capture into planetary orbit is more difficult because the planet's gravity causes acceleration. Electric propulsion has very low thrust, but very high specific impulse. It works by applying thrust continuously over a long time, gradually accumulating speed. That doesn't work when you whip past the planet quickly. You need sharp deceleration to slow into orbit. Not sure how the Russians hoped to do it. Their Hall thrusters are electric. But they used massive solar panels to provide massive electric power to their engines, in order to get descent acceleration. Still, their plan requires spiralling in over 3 months.

On a graphic that you posted in another thread from Energia's web site, it showed that Russia's 600t Battlestar only took 30 days to spiral in.

Why would our 15t inflatable + MDV take more time?

If we can't account for the local atmospheric density and subsequently mess up aerocapture, the crew are no longer amongst the living.

I'm not concerned that ADEPT will fail to protect the vehicle.  It won't.  The question is whether or not you fall out of the sky like a meteor or slingshot off into space based on some transient local conditions that dramatically vary pressure.

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

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Re: Deep Space Habitat

So it did. Bad memory. It took 3 months to spiral in/out of Earth orbit. Only 1 month at Mars.

Perhaps a better answer is to avoid a 600t Battlestar. Notice the DSH on that ship is just one Zvezda module. And the Mars lander with ascent module is fairly compact. Plus an Earth return capsule. Solar arrays are thin film, with supporting truss structure on two sides of each large square. That's required to provide 15MW necessary to power a 300 Newton electric thruster system.

NASA's current work on a DSH (or is it Boeing's?) uses Orion and 2 ISS modules. The Russian plan has only one ISS module. So replacing the cryogenic propulsion stage with SEP would result in the same Battlestar.