Deep Space Gateway; a bad joke by NASA?

Lake Matthew Team - Cole · 2017-11-29 08:28:13

elderflower wrote:

How good is liquid methane as a shield? Or even LOX. I'm thinking in terms of doughnut tanks with a shelter in the middle.

Methane's effective, yes, but there are many potential ignition sources in and around crew quarters. I haven't heard of a crew shield design that accepts that risk.

Last edited by Lake Matthew Team - Cole (2017-11-29 08:29:27)

RobertDyck · 2017-11-29 10:40:56

There's no oxygen in space. A liquid methane tank outside the pressurized hull would not have any chance of ignition.

Lake Matthew Team - Cole · 2017-11-29 11:44:32

RobertDyck wrote:

There's no oxygen in space. A liquid methane tank outside the pressurized hull would not have any chance of ignition.

Unless you plan on using your methane tank as an interplanetary heat shield, the methane adjoins crew quarters. You think either is a good idea?

elderflower · 2017-11-29 12:17:01

In this case the core of the tank contains only a shelter for crew members, so probably only sleeping quarters. Of course it would be isolated by double bulkheads and some insulation and liners and would have vents overboard.

GW Johnson · 2017-11-29 12:41:09

I would think that almost any sort of propellant tanks, or water/wastewater tanks, would make decent low molecular weight shielding. Maybe not quite as good as water, but close. If you cluster some tanks like that around the outside of some part of the pressurized habitat, they should make a pretty good solar flare shield. Being on the outside, any leaks go to space, not the pressurized habitat.

The idea of going with stuff like that for at least part of your shielding is to make stuff you already have to have for other reasons, serve another purpose as well. It is crucial that it is stuff you have to have "in the future", in that propellant tankage used in this way should be slated for the upcoming burn, so that during coast they are full and actually function well as a shield.

GW

Last edited by GW Johnson (2017-11-29 12:41:53)

Lake Matthew Team - Cole · 2017-11-29 13:04:47

GW Johnson wrote:

If you cluster some tanks like that around the outside of some part of the pressurized habitat, they should make a pretty good solar flare shield.

Sure, but only for DSG, which isn't in transit to Mars. Doesn't work for transit, because when it's time to return home from Mars... "Now where'd we put those external tanks?"

If mod wants to split this line of thought off to another thread, np. Just wanted to apply your shielding knowledge to the challenge of cutting the 130-ton ITS water-shield.

Last edited by Lake Matthew Team - Cole (2017-11-29 16:13:42)

Oldfart1939 · 2017-11-29 18:45:57

The main item overlooked is the source of energy for various electromagnetic shielding systems It becomes another TANSTAFL. There Ain't No Such Thing As A Free Lunch. This brings the choice of nuclear versus solar arrays into the picture again.

SpaceNut · 2017-11-29 20:01:44

Since Mars had a remnant magnetic shielding in areas why no use long bar magnets on the hull to start the process of a shield and then create a static magnetic shield via RF transmission, one could seed the bubble with ionic elements that would be supended in the shield field.

Lake Matthew Team - Cole · 2017-11-29 20:51:49

GW Johnson wrote:

I really, really doubt whether there are any usable water resources at either Phobos or Deimos. These resemble nothing so much as the small asteroids, which seem to be very dry. It is the much-larger asteroids that seem to be wet. Somehow, that should not be surprising, since it takes cover with some weight to it to keep ice from subliming away in vacuum.

Actually, we chose Deimos with reason: Low density of 1.5 g/cm3 is very hard to explain absent volatile component. 50 wt% is consistent with both density and magnetospheric evidence. Water-evolution modeling suggests volatiles 20-60 m below polar surfaces. CAVoR and coal gasification reactors frame ISRU methane, oxygen and water production, for breadboard benchmarking.

Refs:

Bell, J. F., Fanale, F., & Cruikshank, D. P. (1993). Chemical and physical properties of the Martian satellites. Resources of near-earth space, 887-901.

Berggren, M., & Zubrin, R. (2015). Carbonaceous Asteroid Volatile Recovery (CAVoR) system.

Fanale, F. P., & Salvail, J. R. (1990). Evolution of the water regime of Phobos. Icarus, 88(2), 380-395.

Murchie, S. L., Fraeman, A. A., Arvidson, R. E., Rivkin, A. S., & Morris, R. V. (2013). Internal characteristics of Phobos and Deimos from spectral properties and density: relationship to landforms and comparison with asteroids.

Nichols, C. R. (1993). Volatile products from carbonaceous asteroids. Resources of near-earth space, 543-568.

--

Hi.

We're the Lake Matthew Team.

We don't need the grade and we don't work here, so please don't expect us to play along with dismissive hand-waving.

Thanks!

Lake Matthew Team - Cole · 2017-11-29 21:23:02

SpaceNut wrote:

Since Mars had a remnant magnetic shielding in areas why no use long bar magnets on the hull to start the process of a shield and then create a static magnetic shield via RF transmission, one could seed the bubble with ionic elements that would be supended in the shield field.

I think that would also be subject to the M2P2 hotspot and breakage troubles Metzger was talking about. Flares play rough.

For an EM shielding approach that does not use plasma, we can note the EU's SR2S effort, which ended in 2015. That team innovated quite a lot, of necessity, but the work was not continued.

The pumpkin

Video: SR2S Project Outcomes

Istituto Nazionale di Fisica Nucleare wrote:

The Roadmap
While we have found a new approach to the active protection with respect to the existing literature, we do not consider MT4 as the ultimate, optimized result. A systematic exploration could be carried on various kinds of “not fully confined” magnetic field configurations and geometrical coil layouts, which could deliver a similar or better result. The fractional contribution to the dose reduction due to the magnetic field suggests that there are “gaps” in the magnetic coverage, therefore the number of pumpkin coils can be increased/optimized. The mass of the coils could be further reduced by refining the optimization of the coil geometries and by applying advanced structural materials, whose cryogenic properties are not yet known.
Further steps of technical and conceptual developments have been identified and collected in the following SR2S roadmap:
- Increasing the TRL of the conductor (the SR2S prototype production allowed identifying the main issues);
- Optimization of the Active Shield configuration;
- Improving the pumpkin configuration in terms of number, shape, dimension and total current of coils as well as of their distance from the habitat;
- Studying new and innovative “not fully confined” magnetic field configurations and geometrical coil layouts, which could deliver a similar or better result;
- Deepen the knowledge of light structural materials. Within SR2S we proposed the use of many advanced materials but the cryogenic properties of most of them are not well known;
- Further development of the magnet cryogenics including enhancing of PHP TRL;
- Explore new solutions for quench detection and protections (non-insulated winding);
- Study of ancillary equipments like power supply or flux pump;
- More detailed studies of the shield assembling in orbit.

Last edited by Lake Matthew Team - Cole (2017-11-29 21:28:39)

Lake Matthew Team - Cole · 2017-11-30 15:27:02

GW Johnson wrote:

I don't doubt that what you say is true. I don't doubt that you are quoting some actual experts. My point is that this is not the only explanation for a low density. There is also (1) a dry rubble pile assembled with vacuum-containing voids due to extreme low gravity, and (2) voids left behind when the water sublimed away long ago.
But those aren't "popular" because they're unfavorable for planning missions based on exploiting local resources. You don't need 50% water to achieve that low a density. Something like ~25% vacuum-filled voids also explains it. We've already seen other small bodies like that.
My other point is that you cannot know the buried (hidden) water content is really there until you actually go there and dig/drill for it.

"Popularity" isn't the driver here. We do evaluate. If you could be careful not to insinuate otherwise, that would be great.

--

Deimos' 1.5 g/cm3 is unlikely without volatiles. Even Phobos' 1.9 g/cm3 is hard to compose dry. Bell et al. note:

Bell et al. 1993 wrote:

To explain the observed [Phobos] density with pore space alone would require Phobos to consist of at least 50% empty space. The only rocks with this much porosity are some lunar breccias which are soil rewelded by impact. Thus an ice-free Phobos would have to be a rubble-pile consisting entirely of regolith. This appears unlikely in view of the existence of large topographic features such as the walls of Stickney crater...

So a dry Deimos would need more than 50% empty space. Britt and Consolmagno 2001 hypothesizes, qualitatively, that a dry Phobos and Deimos could be possible given a very robust macroporous size-sorting mechanism, but that hypothesis hasn't been pursued quantitatively. And still, the magnetospheric data fits better with a volatile-rich origin than a dry origin.

Speaking of origin, the cometary possibility draws parallels with 3552 Don Quixote, a NEO cometary remnant having visible similarities to Deimos. Lee 2017 reasons from the parallel for a hypothetical Deimos water ice component to 55 vol%.

A Deimos sample mission would be needed to test everything, of course.

Anyway, there's reason to drive forward with ISRU research having Deimos as a proposed target. New results and new ideas for ISRU are of interest.

Refs:

Bell, J. F., Fanale, F., & Cruikshank, D. P. (1993). Chemical and physical properties of the Martian satellites. Resources of near-earth space, 887-901.

Britt, D. T., & SJ, G. C. (2001). Modeling the structure of high porosity asteroids. Icarus, 152(1), 134-139.

Lee, P. (2017, March). Phobos and Deimos: A Possible Comet Connection. In Lunar and Planetary Science Conference (Vol. 48).

GW Johnson · 2017-11-30 19:24:32

Don't get too hung up on the word "popular" that I used. Quite often what I have to say is "unpopular" with other participants on these forums. I'm an old retired engineer speaking from mostly a plain common sense perspective, further tempered with a whole lot of school-of-hard-knocks real-world experience. That sort of outlook tends to shoot holes in a lot of pet theories or pet designs. Just consider it "Devil's Advocate" stuff. It's well-intended; I have no agenda here.

As to void fraction effects on apparent density, consider these numbers. For a rather typical rock sp.gr of 2.5, a rock fraction of 0.6 yields an apparent sp.gr of 1.5. That rock fraction (by volume) is 0.4 void fraction (by volume). For a rather dense rock sp.gr of 3.5, a rock fraction of 0.429 yields an apparent sp.gr of 1.5, and corresponds to a void fraction of 0.571. For a modestly-unlikely rock sp.gr of 4.5, a rock fraction of 0.333 yields an apparent sp.gr of 1.5, and corresponds to a void fraction of 0.667. That brackets "50% void fraction".

All in all, a low sp.gr of 1.5 is entirely consistent with rather modest and realistic void fractions, for something assembled as a rubble pile under extreme low gravity circumstances from rocky particles of rather realistic density. How this might respond to a cratering event is problematical, as there is not enough gravity to enforce much of a collapse at all, at such a small mass.

That's not to say the water isn't there. It might really be. Or it might not be there (which was my first point in the earlier post). My second point in that earlier post was to counsel against betting a crews' lives that it's there without positive proof. That's all I tried to say.

My numbers were figured very directly and very crudely as volumetric rock fraction multiplied by rock sp.gr equals "apparent sp.gr". Void fraction is unity minus rock fraction. That's so utterly simple that no expert sources are needed. It's only first order, but it is "in the ballpark". How Deimos and Phobos were assembled is still entirely in question. Nobody really knows.

GW

Last edited by GW Johnson (2017-11-30 19:34:07)

elderflower · 2017-12-01 04:08:37

The bulk density of smallish particulates (relative to overall dimensions of the sample) is commonly around 0.5 to 0.6 times the true density of the particles. This depends on how closely they can be packed. Adding other stuff into the voids will increase the weight of the sample without increasing the volume so then the bulk density will increase.

Lake Matthew Team - Cole · 2017-12-01 10:35:35

We can say that "Deimos' 1.5 g/cm3 is unlikely without volatiles," if we keep the possible components in mind. For example, Rosenblatt 2011 lays out a range of conceivable porosity and water ice wt % values for several possible rocky components:

Duke et al. 2003 discusses lunar ISRU mining of 2 wt% water ice. If we take that as the minimum useful %, and allow only anhydrous, dense rocks, an impractically dry Deimos has composition and porosity somewhere in the overlaid magenta box, at upper left in the second figure.

If that figure were printed and used as a dartboard, the small magenta box would be very hard to hit -- assuming blindfolded throws, of course.

Refs:

Duke, M. B., Blair, B. R., & Diaz, J. (2003). Lunar resource utilization: Implications for commerce and exploration. Advances in Space Research, 31(11), 2413-2419.

Rosenblatt, P. (2011). The origin of the Martian moons revisited. Astronomy and Astrophysics Review, 19(1), 1-26. (Presentation 2012)

Last edited by Lake Matthew Team - Cole (2017-12-01 10:45:16)

Oldfart1939 · 2017-12-02 10:58:43

Using an electromagnetic shield would have to be pretty extensive in order to deflect these charged particles, since they are moving very fast. What argues against this approach is the power requirement. If the vehicle in transit is going to rely on PV cells, it just doesn't add up. It would require a major nuclear reactor installation. I'm in favor of a passive approach as suggested by Zubrin in the Mars Direct architecture. Which, incidentally, is a LOT cheaper to incorporate into the financial planning.

SpaceNut · 2017-12-02 17:44:16

Lake Matthew Team - Cole wrote:

GW Johnson wrote:
It's fine (and fun) to dream up all these ways of doing things better, utilizing resources predicted to be there at these various destinations. The point I have tried to make in multiple threads on these forums is: "you inherently do not know that those resources really are there, until you actually go there and dig or drill". Applies to Mars, its moons, asteroids, comets, and any other planet or moon.
The feedback I keep getting is nothing but arguments-from-authority: this or that paper or prestigious name says the buried resource stuff is there. It's all based on remote sensing in one form or another, precisely because no human has ever actually been there and dug or drilled...
Lumping us in with less informed [straw-man?] posters is inappropriate. Rejected. We do understand the literature, warts and all, and we apply it, even in our own novel designs. As for Deimos: We quantified the Deimos possibilities in forum, not you. E.g. post 1, post 2. That's not fallacious argument from authority, that's knowing more than you.
Anyone taking your own posts at face value would have been badly misinformed on that topic. So before posting again, read our refs, and read something more; maybe then you'll have some information or self-correction for the thread.
And do keep it on-topic. This is the thread for the new Omaha Shield proposal, specifically; not for rehashes of old and irrelevant text.

The origin of the Martian moons revisited by Pascal Rosenblatt Royal Observatory of Belgium 46th ESLAB Symposium: Formation and evolution of moons Session 5 – Observational constraints June 27th 2012 – ESTEC, Noordwijk, the Netherlands.

Like your above references these are all spectral for its color guess work via wavelength and other such optical, while they are probable and from other on the ground tests performed on Mars can be taken with a near acuracy for this data be used. Why as we used these same tools for mars before going and putting the rovers on the surface which has been comfirmation.

Abstract On the formation of the martian moons from a circum-martian accretion disk by Pascal Rosenblatt, Sébastien Charnoz

GW Johnson · 2017-12-02 19:35:17

Thank you, Spacenut. You just proved my point made in this thread and the other one.

The scientists still obviously disagree about both the formation mechanisms for Phobos and Deimos, and what the low apparent densities really mean.

What that really means is that the pore ice might, or might not, really be there, on either moon. This is something that a robot lander with a drill rig of some sort might determine. This is not something to bet lives on. Not yet.

GW

Lake Matthew Team - Cole · 2017-12-07 20:41:11

SpaceNut wrote:

Lake Matthew Team - Cole wrote:
GW Johnson wrote:
It's fine (and fun) to dream up all these ways of doing things better, utilizing resources predicted to be there at these various destinations. The point I have tried to make in multiple threads on these forums is: "you inherently do not know that those resources really are there, until you actually go there and dig or drill". Applies to Mars, its moons, asteroids, comets, and any other planet or moon.
The feedback I keep getting is nothing but arguments-from-authority: this or that paper or prestigious name says the buried resource stuff is there. It's all based on remote sensing in one form or another, precisely because no human has ever actually been there and dug or drilled...
Lumping us in with less informed [straw-man?] posters is inappropriate. Rejected. We do understand the literature, warts and all, and we apply it, even in our own novel designs. As for Deimos: We quantified the Deimos possibilities in forum, not you. E.g. post 1, post 2. That's not fallacious argument from authority, that's knowing more than you.
Anyone taking your own posts at face value would have been badly misinformed on that topic. So before posting again, read our refs, and read something more; maybe then you'll have some information or self-correction for the thread.
And do keep it on-topic. This is the thread for the new Omaha Shield proposal, specifically; not for rehashes of old and irrelevant text.
The origin of the Martian moons revisited by Pascal Rosenblatt Royal Observatory of Belgium 46th ESLAB Symposium: Formation and evolution of moons Session 5 – Observational constraints June 27th 2012 – ESTEC, Noordwijk, the Netherlands.
Like your above references these are all spectral for its color guess work via wavelength and other such optical, while they are probable and from other on the ground tests performed on Mars can be taken with a near acuracy for this data be used. Why as we used these same tools for mars before going and putting the rovers on the surface which has been comfirmation.
Abstract On the formation of the martian moons from a circum-martian accretion disk by Pascal Rosenblatt, Sébastien Charnoz

Rosenblatt et al. 2016 interprets previous work as setting an upper limit on the porosity of accreted moons:

Rosenblatt et al. 2016 wrote:

"up to 30% of the volume"

This max porosity is far below the 50%+ required of a dry Deimos.

If a plausible mechanism is not found for 50%+ porosity, the magenta box will be not merely hard to hit, but edging off the dartboard.

Refs:

Rosenblatt, P., Charnoz, S., Dunseath, K. M., Terao-Dunseath, M., Trinh, A., Hyodo, R., ... & Toupin, S. (2016). Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons. Nature Geoscience, 9(8), 581-583.

Last edited by Lake Matthew Team - Cole (2017-12-07 20:44:21)

Oldfart1939 · 2017-12-08 10:54:19

Arguments based on indirect observations and theoretical calculations aren't good enough for undertaking a mission based on the availability of any necessary resource. Water, being that resource in this case. Perhaps this approach could become useful and integrated in later missions to Mars once an actual drilling team finds water on Deimos, but not early-on.

I always hate to respond negatively, but it's simply the inner voice of caution calling out for a measured approach based on facts and not hypothecation.

RobertDyck · 2017-12-08 12:58:25

Oldfart1939: I think we all agree. There's enough indirect evidence to justify looking, but you can't rely on anything or make your mission plan dependant on it until you send a probe to verify it exists. And not just exists, but now much, how easy it can be accessed, how pure, etc.

Notice I've argued for a human base at the frozen pack ice in Elysium Planetia, based on published data from ESA. However, I also argue to start by sending an unmanned rover with a drill rig to verify the ice is there.

Last edited by RobertDyck (2017-12-08 21:44:30)

SpaceNut · 2017-12-08 21:03:19

Found some more news on the direction that Nasa is taking with the SLS EM3 mission plans and the Deep space station.

NASA evaluates EM-2 launch options for Deep Space Gateway Power Propulsion Element (PPE)

NASA recently awarded multiple contracts to industry to do a detailed study of the PPE that would be the first proposed piece of the Deep Space Gateway operating in cislunar space. A total amount of approximately $2.4 million was divided up in awards to Boeing, Lockheed Martin, Orbital ATK, Sierra Nevada Corporation, and Space Systems/Loral.
The kickoff meetings start the contract work for the 120-day study. Each of the awardees will provide an initial 45-day status briefing to NASA, which is planned for the January time-frame. That would be followed by draft study results at the 90-day point, and the final study results at 120 days.

Well space x is not in the list....

The combination of the cancelled asteriod mission and first moon mission for the unit seems to be still wanting to use Solar Electric Propulsion (SEP).

What I found interesting was on this image

Previous studies have been for SEP

Analysis of a notional launch, deployment, and insertion of the PPE into cislunar space was recently detailed in a paper prepared for presentation in an American Astronautical Society (AAS) meeting titled “Low Thrust Cis-Lunar Transfers Using a 40 kW-Class Solar Electric Propulsion Spacecraft.”

No surprise that the archetecture for the moon is looking to the past..

SLS EM-1 & -2 launch dates realign; EM-3 gains notional mission outline

Screen-Shot-2017-09-22-at-12.03.55-350x213.png

SpaceNut · 2017-12-09 11:10:44

What I saw in my post #75 was that the block 1 sls was only using 40T or so of the 70T payload capability for the 3 launches of parts to build a Deep Space Gateway or mini station. That is with the capability of a Falcon 9 Heavy launch and would be a huge savings for Nasa to make more of these for other uses. This would drive down the costs of the modules as that is production and not just cost plus contracting....

Oldfart1939 · 2017-12-09 11:47:07

All I will be doing here is restating Robert Zubrin's analysis of the SLS and the DSG: it's to create a mission for the SLS that it's capable of (maybe) accomplishing. If we're going to Mars, build a rocket capable of undertaking that mission.

SLS = WORKFARE for Lockheed Martin and Boeing. DSG = more of the same WORKFARE for the same contractors.

elderflower · 2017-12-09 15:29:25

I would not be surprised if old space were not to attempt to put Mars off limits to Spacex and any others of like mind. It might be done by withdrawal of licences or by designation of the entire planet as a reserve for native life or by booking the entire output of the company then suddenly withdrawing leaving it with no income, or breaking a few arms in the banking community, or maybe introducing some new legislation which would have the "incidental and unfortunate effect" of making life impossible for private explorers or rocket launchers, or maybe just good oldfashioned personal blackmail.

SpaceNut · 2017-12-09 22:09:25

So the question is how do we get old space to change its ways and how do we accelerate the progress of Space X?

New Mars Forums

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#26 2017-11-29 08:28:13

Re: Deep Space Gateway; a bad joke by NASA?

#27 2017-11-29 10:40:56

Re: Deep Space Gateway; a bad joke by NASA?

#28 2017-11-29 11:44:32

Re: Deep Space Gateway; a bad joke by NASA?

#29 2017-11-29 12:17:01

Re: Deep Space Gateway; a bad joke by NASA?

#30 2017-11-29 12:41:09

Re: Deep Space Gateway; a bad joke by NASA?

#31 2017-11-29 13:04:47

Re: Deep Space Gateway; a bad joke by NASA?

#32 2017-11-29 18:45:57

Re: Deep Space Gateway; a bad joke by NASA?

#33 2017-11-29 20:01:44

Re: Deep Space Gateway; a bad joke by NASA?

#34 2017-11-29 20:51:49

Re: Deep Space Gateway; a bad joke by NASA?

#35 2017-11-29 21:23:02

Re: Deep Space Gateway; a bad joke by NASA?

#36 2017-11-30 15:27:02

Re: Deep Space Gateway; a bad joke by NASA?

#37 2017-11-30 19:24:32

Re: Deep Space Gateway; a bad joke by NASA?

#38 2017-12-01 04:08:37

Re: Deep Space Gateway; a bad joke by NASA?

#39 2017-12-01 10:35:35

Re: Deep Space Gateway; a bad joke by NASA?

#40 2017-12-02 10:58:43

Re: Deep Space Gateway; a bad joke by NASA?

#41 2017-12-02 17:44:16

Re: Deep Space Gateway; a bad joke by NASA?

#42 2017-12-02 19:35:17

Re: Deep Space Gateway; a bad joke by NASA?

#43 2017-12-07 20:41:11

Re: Deep Space Gateway; a bad joke by NASA?

#44 2017-12-08 10:54:19

Re: Deep Space Gateway; a bad joke by NASA?

#45 2017-12-08 12:58:25

Re: Deep Space Gateway; a bad joke by NASA?

#46 2017-12-08 21:03:19

Re: Deep Space Gateway; a bad joke by NASA?

#47 2017-12-09 11:10:44

Re: Deep Space Gateway; a bad joke by NASA?

#48 2017-12-09 11:47:07

Re: Deep Space Gateway; a bad joke by NASA?

#49 2017-12-09 15:29:25

Re: Deep Space Gateway; a bad joke by NASA?

#50 2017-12-09 22:09:25

Re: Deep Space Gateway; a bad joke by NASA?

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