Author Topic: First manned mission to Phobos  (Read 30992 times)

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #20 on: 08/07/2010 07:01 am »
Given a spinning hab, you couldn't bury it.

Perhaps some radiation shielding could be enjoyed by having it spin within Stickney crater (this gives shielding from Phobos as well as Mars). Perhaps regolith or water could be exported from Phobos to the spin hab to use for radiation protection.
Some research on Earth indicates many humans can handle 4rpm. Then a 25 m radius gives a = .4^2 x 25 = 4m/s, or Mars surface.

There's no reason why a 50m wide torus couldn't be inflated under the Phobos regolith (assuming very low tensile strength).

Within the torus, you have a "rat wheel" type structure, which fills out when rotated - see picture
« Last Edit: 08/07/2010 02:29 pm by alexterrell »

Offline HappyMartian

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Re: First manned mission to Phobos
« Reply #21 on: 08/07/2010 02:30 pm »
Given a spinning hab, you couldn't bury it.

Perhaps some radiation shielding could be enjoyed by having it spin within Stickney crater (this gives shielding from Phobos as well as Mars). Perhaps regolith or water could be exported from Phobos to the spin hab to use for radiation protection.
Some research on Earth indicates many humans can handle 4rpm. Then a 25 m radius gives a = .4^2 x 25 = 4m/s, or Mars surface.

There's no reason why a 50m wide torus couldn't be inflated under the Phobos regolith (assuming very low tensile strength).

I like the idea of putting the base within Stickney and burying almost everything under the regolith of Phobos. However, instead of a spinning hab, I'd think that an extremely lightweight electric train running around inside a torus would work.

A train can be engineered to be simple and reliable and fixable. The train's length can extend all the way around the torus, thus it wouldn't have a front or tail. Centrifugal force is what you want. How to get centrifugal force in a lightweight and reliable format is one of the interesting questions for a Phobos base and spaceships. I have looked at some pretty lightweight and simple trains and roller coasters...

I don't see any advantages to giving angular momentum to the structure that has to deal with the centripetal force. Thus the structure that resists the centrifugal force should not rotate. :)

Let the Phobos centrifugal force train roll on and on in an endless circle. Stops are scheduled every hour on the hour. Maintenance checks are done continuously and automatically.  8)


Cheers!

Edited.
« Last Edit: 08/07/2010 03:11 pm by HappyMartian »
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Offline alexterrell

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Re: First manned mission to Phobos
« Reply #22 on: 08/07/2010 04:02 pm »
@Happy Martian, a trian might work at some point, though access can be a problem if you don't have access to the axis.

However, for early day, the illustration above could be built on Earth, and launched by a single J246, and be transported to Phobos by VASIMR. The whole thing can be assembled with minimal human input. Humans might have to connect up some of the plumbing, pump in 20 tons of air, and insert a couple of sound proofing sheets, but that's it for 5,000m2 of living space.
 

Offline Hop_David

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Re: First manned mission to Phobos
« Reply #23 on: 08/07/2010 04:03 pm »
Given a spinning hab, you couldn't bury it.

Perhaps some radiation shielding could be enjoyed by having it spin within Stickney crater (this gives shielding from Phobos as well as Mars). Perhaps regolith or water could be exported from Phobos to the spin hab to use for radiation protection.
Some research on Earth indicates many humans can handle 4rpm. Then a 25 m radius gives a = .4^2 x 25 = 4m/s, or Mars surface.

There's no reason why a 50m wide torus couldn't be inflated under the Phobos regolith (assuming very low tensile strength).

I like the idea of putting the base within Stickney and burying almost everything under the regolith of Phobos. However, instead of a spinning hab, I'd think that an extremely lightweight electric train running around inside a torus would work.

A train can be engineered to be simple and reliable and fixable. The train's length can extend all the way around the torus, thus it wouldn't have a front or tail. Centrifugal force is what you want. How to get centrifugal force in a lightweight and reliable format is one of the interesting questions for a Phobos base and spaceships. I have looked at some pretty lightweight and simple trains and roller coasters...

I don't see any advantages to giving angular momentum to the structure that has to deal with the centripetal force. Thus the structure that resists the centrifugal force should not rotate. :)

Let the Phobos centrifugal force train roll on and on in an endless circle. Stops are scheduled every hour on the hour. Maintenance checks are done continuously and automatically.  8)


Cheers!

Edited.

I like the train in the Bigelow torus.

A rat wheel would do the job, but am trying to imagine how the rat wheel and torus balloon would fit inside plausible fairings. If put inside plausible fairings, seems to me a lot of assembly would be required. Although train tracks around torus perimeter might be almost as hard as a rat wheel.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #24 on: 08/07/2010 05:57 pm »

A rat wheel would do the job, but am trying to imagine how the rat wheel and torus balloon would fit inside plausible fairings. If put inside plausible fairings, seems to me a lot of assembly would be required.
OK - see the diagram above, and note, because we're burying in regolith, we don't need Bigelow style armour - "3 ply Kevlar" will do the trick.

The central column is solid. In the payload fairing, it's about 20m long, and 10m diameter. In here are pre-built the motors, air exchange mechanisms, power and data links. The central core doesn't rotate - part of the core around this rotates, and the "rat wheel" is suspended from this.

The rat wheel consists of several thousand 8m rigid "planks". These are held parallel to the main axis. They are all connected by thin sheets of Spectra, as well as Spectra cables running through them. All the planks are pushed into the core for transit. Once the rat wheel starts to rotate, the planks extend to make floors. The effect on each of the several floors is like walking on a rope bridge, about 8m wide, suspended by flexible sheet walls, with cables running through the planks.

All the room walls are also present, as thin flexible sheets.

The "bridge", spread over seven floors is 650m long. If each plank is 2cm thick, that needs 13m2 of the payload fairing cross section. I.e, wrapped around the core, they're only occupying a ring 9m in diameter and 1/2m wide. So plenty of room for "rigging" and sheets.

So actually packing is easy. Testing the rat wheel before departure will be impossible so hope the CAD models are correct!

After initial installation:
It might be desirable to screw the planks together to give rigidity, or more likely insert short poles with the appropriate radius through the planks.

Thin sheets of foam (perhaps made from local materials) can be put onto the walls for sound insulation between cabins.

Air is sucked out for purification and cooling.

Waste water is manually removed in septic tanks on a daily basis. Fresh water is loaded in new tanks.

"Above" and "below" the rat wheel are zero-g areas.

Contrary to the diagram above, I think agricultural units would be seperate units, due to the amount of light (and hence heat) required.
« Last Edit: 08/07/2010 06:15 pm by alexterrell »

Offline Hop_David

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Re: First manned mission to Phobos
« Reply #25 on: 08/07/2010 06:08 pm »
The rat wheel consists of several thousand 8m rigid "planks". These are held parallel to the main axis. They are all connected by thin sheets of Spectra, as well as Spectra cables running through them. All the planks are pushed into the core for transit. Once the rat wheel starts to rotate, the planks extend to make floors. The effect on each of the several floors is like walking on a rope bridge, about 8m in diameter, suspended by flexible sheet walls, with cables running through the planks.

All the room walls are also present, as thin flexible sheets.

The "bridge", spread over seven floors is 650m long. If each plank is 2cm thick, that needs 13m2 of the payload fairing cross section. I.e, wrapped around the core, they're only occupying a ring 9m in diameter and 1/2m wide. So plenty of room for "rigging" and sheets.

So actually packing is easy. Testing the rat wheel before departure will be impossible so hope the CAD models are correct!

An origami rat wheel? Intriguing idea. If the idea's viable, I believe it could be tested in LEO.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #26 on: 08/07/2010 06:53 pm »
An origami rat wheel? Intriguing idea. If the idea's viable, I believe it could be tested in LEO.
I can't see any fundamental issues. Packing should be easier than a 1MW Solar Electric VASIMR.

Testing in LEO? You have a 2-3mm fibre pressure vessel. With a 2000m2 cross section, how long before a puncture? However, the stress is not great enough to tear the material, so I suppose a puncture repair kit could be used.

Offline IsaacKuo

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Re: First manned mission to Phobos
« Reply #27 on: 08/07/2010 07:11 pm »
If we can assume loose regolith, then it still makes more sense to do a spinning space station.  This would be a "dumb-bell" style station where loose regolith is packed into empty fuel tanks and/or external balloon bags for long term cosmic ray shielding and countermass.

The "dumb-bell" could be a 120m long beam between a lightweight crew module and a heavier service/supply module.  At 2rpm, this provides Mars gravity on the crew side and Lunar gravity on the heavier side.  (It can start off life in LEO as a spin gravity research station--one ATV derived MSS module on one side and two MSS modules on the other side.)

I'm wary of spin rates greater than 2rpm, so an 80m radius may be the minimum practical for Mars level gravity.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #28 on: 09/02/2010 12:47 pm »
If we can assume loose regolith, then it still makes more sense to do a spinning space station.  This would be a "dumb-bell" style station where loose regolith is packed into empty fuel tanks and/or external balloon bags for long term cosmic ray shielding and countermass.

The "dumb-bell" could be a 120m long beam between a lightweight crew module and a heavier service/supply module.  At 2rpm, this provides Mars gravity on the crew side and Lunar gravity on the heavier side.  (It can start off life in LEO as a spin gravity research station--one ATV derived MSS module on one side and two MSS modules on the other side.)

I'm wary of spin rates greater than 2rpm, so an 80m radius may be the minimum practical for Mars level gravity.
Though "fixing" several thousand tons of regolith to the habitat modules, and accelerating this to 20m/s and supporting it under .38g will be problematic.

Perhaps you could launch the modules with a void space ready for filling.

I'd rather wait for some spin rate research, and if possible, inflate the whole thing on deimos or phobos and then cover in regolith (or inflate in deimos or phobos).

Offline IsaacKuo

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Re: First manned mission to Phobos
« Reply #29 on: 09/02/2010 02:54 pm »
If we can assume loose regolith, then it still makes more sense to do a spinning space station.  This would be a "dumb-bell" style station where loose regolith is packed into empty fuel tanks and/or external balloon bags for long term cosmic ray shielding and countermass.

The "dumb-bell" could be a 120m long beam between a lightweight crew module and a heavier service/supply module.  At 2rpm, this provides Mars gravity on the crew side and Lunar gravity on the heavier side.  (It can start off life in LEO as a spin gravity research station--one ATV derived MSS module on one side and two MSS modules on the other side.)
Though "fixing" several thousand tons of regolith to the habitat modules, and accelerating this to 20m/s and supporting it under .38g will be problematic.

Perhaps you could launch the modules with a void space ready for filling.

As I noted above, the loose regolith (if there is indeed loose regolith available) could be filled into empty fuel tanks or balloon bags.  This could be essentially the void space you suggest, but the space could be used for a fuel tank first.

I'd rather wait for some spin rate research, and if possible, ...

As I noted above, the dumb-bell spacecraft could start off as a spin gravity research station in LEO.

... inflate the whole thing on deimos or phobos and then cover in regolith (or inflate in deimos or phobos).

This would either require giving up on spin gravity or creating a huge circular (or toroidal?) volume.

Offline HappyMartian

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Re: First manned mission to Phobos
« Reply #30 on: 09/05/2010 10:14 am »
In the next 7 years the best we could hope for would be visit to a NEO, L-2 or lunar orbit.

Phobos round trip is easier than the vast majority of NEO round trips.

The "vast majority" but not all NEOs. Do some "easy" small NEOs and gradually do more difficult ones and before you know it you'll have the capability to go to Phobos. Small steps work! Small steps can evolve into big steps. As Neil Armstrong noted, "That's one small step for a man, one giant leap for mankind."

See:

http://www.lockheedmartin.com/data/assets/ssc/Orion/Toolkit/OrionAsteroidMissionWhitePaperAug2010.pdf

Edited.
« Last Edit: 09/05/2010 10:27 am by HappyMartian »
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Offline Lampyridae

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Re: First manned mission to Phobos
« Reply #31 on: 09/07/2010 07:26 am »
If we can assume loose regolith, then it still makes more sense to do a spinning space station.  This would be a "dumb-bell" style station where loose regolith is packed into empty fuel tanks and/or external balloon bags for long term cosmic ray shielding and countermass.

The "dumb-bell" could be a 120m long beam between a lightweight crew module and a heavier service/supply module.  At 2rpm, this provides Mars gravity on the crew side and Lunar gravity on the heavier side.  (It can start off life in LEO as a spin gravity research station--one ATV derived MSS module on one side and two MSS modules on the other side.)

I'm wary of spin rates greater than 2rpm, so an 80m radius may be the minimum practical for Mars level gravity.

DiZio's work on rotational adaptation has shown that 5RPM is feasible, possibly as high as 10RPM. If people get sick, don't send them. Skylab astros were happily running on the "race track" at rates greater than 5RPM. However, program managers really hate the idea of artificial gravity, so a short-arm centrifuge for exercise sessions is probably all that will be used.
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Offline alexterrell

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Re: First manned mission to Phobos
« Reply #32 on: 09/07/2010 08:05 am »

DiZio's work on rotational adaptation has shown that 5RPM is feasible, possibly as high as 10RPM. If people get sick, don't send them. Skylab astros were happily running on the "race track" at rates greater than 5RPM. However, program managers really hate the idea of artificial gravity, so a short-arm centrifuge for exercise sessions is probably all that will be used.
DiZio's work was with very small radii under 1g down load. Can it be extended to larger radii in zero-g? I don't see why not, but would like a reference case from research in zero-g.

I recall that higher rates are possible by screening people for susceptibility, and not moving quickly through the "vertical" plane. If Skylab astronauts had to run round an elliptical track they might have suffered.

Here's a gravity simulator with a 5m radius  http://www.psw-leisure.co.uk/roundup.htm. I estimate about 15-20rpm with a 5m radius? Next time I see one of these I might do some experiments.
« Last Edit: 09/08/2010 08:55 am by alexterrell »

Offline A_M_Swallow

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Re: First manned mission to Phobos
« Reply #33 on: 09/07/2010 08:19 pm »
A further factor is how much gravity difference can the human body take between the toes and the head?

We were designed to operate under a nearly fixed amount of gravity with some intermittent turning torque.
Human beings are about 2 metres high (6'6").

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Re: First manned mission to Phobos
« Reply #34 on: 09/07/2010 08:39 pm »
I agree that astronauts can probably adapt to ~5-10rpm, which should be good enough for Mars-level gravity in something like a Bigelow Sundancer module. Heck, you could just build it after you orbited the module, inside the module. You could have an artificial-gravity section of the module where sleeping, exercising, and perhaps other activities that could benefit from artificial gravity (like fixing or making something... most rapid manufacturing techniques rely on gravity). Also, if even idle activity in artificial gravity is found to be helpful, computers and desks could be placed in the artificial gravity section.

The ring wouldn't need to be sealed at all (in fact, it would best not be sealed), and should be able to be spun-down at any time. Any structural considerations should be handled by the structure of the ring.

Just an idea.

EDIT: Part of the benefit of this idea is that the whole artficial gravity mechanical system would be inside a pressurized environment, and thus could be fixed mid-flight using conventional hand tools without a difficult and risky EVA.
« Last Edit: 09/07/2010 09:02 pm by Robotbeat »
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Offline HappyMartian

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Re: First manned mission to Phobos
« Reply #35 on: 09/09/2010 02:36 pm »

The ring wouldn't need to be sealed at all (in fact, it would best not be sealed), and should be able to be spun-down at any time. Any structural considerations should be handled by the structure of the ring.

Just an idea.

EDIT: Part of the benefit of this idea is that the whole artficial gravity mechanical system would be inside a pressurized environment, and thus could be fixed mid-flight using conventional hand tools without a difficult and risky EVA.


Why not modify your design and make your ring into two trains? Trains are easily fixed systems. If you have four rails on your track, the central two could be for a very low cargo train with the same mass as the upper train but traveling in the opposite direction underneath the main train. This would reduce your your torque issues with starting and stopping the habitat train since the cargo train would also be slowed and accelerated at the same rate as your habitat train. The upper train would use the outer rails and would have extremely lightweight compartments. The lower cargo train would contain dense food items, water reserves, waste, compressed garbage, surface exploration equipment, and other heavy and dense supplies.

Using two trains inside a pressurized inflatable torus means you don't need to rotate your spacecraft or the structure that supports the artificial g habitat. The inflatable torus might have the profile of a large bicycle tire.

Minimal rotating mass is a design objective. An equivalent and useful counter-rotating mass minimizes torque effects and is another useful design feature. Capability for repeated starts and stops of the artificial g system without the need to use valuable propellant is another aspect of this two train design.

Cheers!
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Offline HappyMartian

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Re: First manned mission to Phobos
« Reply #36 on: 09/21/2010 02:05 pm »
Are there any possible ramifications of this research for the early manned and robotic missions to Phobos?

Martian Moon Phobos May Have Been Formed by Catastrophic Blast

At: http://www.spaceref.com/news/viewpr.html?pid=31665

Cheers!
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Re: First manned mission to Phobos
« Reply #37 on: 09/21/2010 04:28 pm »
Are there any possible ramifications of this research for the early manned and robotic missions to Phobos?

Martian Moon Phobos May Have Been Formed by Catastrophic Blast

At: http://www.spaceref.com/news/viewpr.html?pid=31665

Cheers!
Kind of makes it halfway a Mars surface mission! At least, the remains of an older Mars. It makes it quite likely that fossilized life may be present, if there was such fossilized life on Mars in the distant past.

Depending on when life arose and when the catastrophic collision happened, of course.

It may mean there are fewer hydrocarbons there, though, which is too bad.
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Offline HappyMartian

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Re: First manned mission to Phobos
« Reply #38 on: 09/22/2010 05:12 am »
Are there any possible ramifications of this research for the early manned and robotic missions to Phobos?

Martian Moon Phobos May Have Been Formed by Catastrophic Blast

At: http://www.spaceref.com/news/viewpr.html?pid=31665

Cheers!
Kind of makes it halfway a Mars surface mission! At least, the remains of an older Mars. It makes it quite likely that fossilized life may be present, if there was such fossilized life on Mars in the distant past.

Depending on when life arose and when the catastrophic collision happened, of course.

It may mean there are fewer hydrocarbons there, though, which is too bad.


I wonder about that Robotbeat.

Martian Moon Phobos May Have Been Formed by Catastrophic Blast
At: http://www.spaceref.com/news/viewpr.html?pid=31665

The article notes, "High porosity is required in order to absorb the energy of the large impact that generated Stickney crater..."

Other comments in the article also imply the possibility that Phobos could be good at catching comets and meteoroids. The interior of Phobos could be a treasure house of useful material, including hydrocarbons and H2O. Maybe we could envision Phobos as being somewhat like a large scale gel object. I seem to remember that gels have been used to catch micrometeroids...

Anyway, this research may make a Phobos mission even more attractive for an early robotic explorer.

Cheers!

See: http://en.wikipedia.org/wiki/Comet

See: http://en.wikipedia.org/wiki/Fobos-Grunt


Edited.

Edited again to add Fobos-Grunt Wiki reference.
« Last Edit: 09/22/2010 08:33 am by HappyMartian »
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Offline Sparky

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Re: First manned mission to Phobos
« Reply #39 on: 09/22/2010 05:33 am »

I wonder about that Robotbeat.

Martian Moon Phobos May Have Been Formed by Catastrophic Blast
At: http://www.spaceref.com/news/viewpr.html?pid=31665

The article notes, "High porosity is required in order to absorb the energy of the large impact that generated Stickney crater..."

Other comments in the article also imply the possibility that Phobos could be good at catching comets and meteoroids. The interior of Phobos could be a treasure house of useful material, including hydrocarbons and H2O. Maybe we could envision Phobos as being somewhat like a large scale gel object. I seem to remember that gels have been used to catch micrometeroids...

Anyway, this research may make a Phobos mission even more attractive for an early robotic explorer.

Cheers!

See: http://en.wikipedia.org/wiki/Comet

Edited.
Makes it harder and harder to wait for Phobos Grunt!  :)

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