Author Topic: First manned mission to Phobos  (Read 31000 times)

Offline alexterrell

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First manned mission to Phobos
« on: 09/19/2009 10:23 pm »
Following a lot of discussion about Phobos, a potential exploration  scenario might include:
1. Robotic precursor missions, including sample return (Phobos Grunt), and testing of technologies.
2. Short stay mission departing from LEO: 30 to 60 days for a crew of 4-6 on the surface of Phobos.
3. Long stay mission departing from HEO: Establish permanent base on Phobos using large scale inflatables (http://forum.nasaspaceflight.com/index.php?topic=18759.0)
This focuses on part 2.

The mission is assembled in Low Earth Orbit. The crew stay in a Bigelow BA 330 module for 6-9 months out, 30-60 day stay, and 6-9 months return. Water is recycled in the service module.
The mission is launched using cryogenics. If available, a Jupiter Upper Stage with 175 tons of fuel will launch the stack to a Mars Transfer Orbit. Before Mars arrival, dehydrated waste is jettisoned. The mission uses aerocapture around Mars, and then a quick burn to meet with Phobos. The mission settle as Phobos, where crew spend 30-60 days doing a number of tasks:
   Drilling in to Phobos and testing methods of regolith processing;
   Testing water extraction and electrolysis equipment
   Testing a storm shelter inflating a 5m balloon under the regolith
   Testing anchoring methods
   Making observations of Mars possible remote piloting surface vehicles

At the end of the stay, the crew leave behind the Phobos exploration module and return to Earth Transit (using storable propellants). The mission uses aerocapture around Earth to enter a highly elliptical orbit and then a high orbit. An Orion Capsule meets with the BA-330 to return the crew. The BA-330 and service module remains in orbit.

Total mass in LEO is just under 300 tons, of which 175 tons is cryogenic fuel. The storable fuel is 53 tons, and the payload 72 tons. So four Jupiter 232 launches or about 12 EELV launches, plus an Orion crew module (and another one to collect or can it stay in orbit for 18 months.

Key components are:
Components   Mass      Notes
BA-330 module   23   tons   Source: Wikipedia
Service Module   10   tons   Incl solar panels, life support, water recycling
Return supplies   4   tons   
Heat shield   3   tons   
Return rocket   5   tons   
Phobos scientific module   10   tons   
Outbound supplies   5   tons   
LEO transfer rocket   12   tons   Based on Jupiter Upper Stage


Mass and Delta-V estimates are attached.

Is this doable for the mass?
Any new developments needed that are not in development?
Does anyone know the layout of a BA-330 module - how many floors, orientation etc. The BA website has nothing.

It fits nicely with the Jupiter 246, given a 175 ton fuel capacity in the upper stage. But it would also work with the ULA EELV approach. There's no need for an Altair lander, but some novel ideas will be needed for testing.

Thoughts?
« Last Edit: 09/19/2009 10:26 pm by alexterrell »

Offline A_M_Swallow

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Re: First manned mission to Phobos
« Reply #1 on: 09/19/2009 11:59 pm »
Total mass in LEO is just under 300 tons, of which 175 tons is cryogenic fuel. The storable fuel is 53 tons, and the payload 72 tons. So four Jupiter 232 launches or about 12 EELV launches, plus an Orion crew module (and another one to collect or can it stay in orbit for 18 months.
{snip}

Any chance of launching this mission whilst Obama is still president, i.e. in the next 7 years?

Offline Eric Hedman

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Re: First manned mission to Phobos
« Reply #2 on: 09/20/2009 01:29 am »

Any chance of launching this mission whilst Obama is still president, i.e. in the next 7 years?


Not likely for two reasons.  The first is to get a political agreement to do it in time isn't likely.  The second and bigger reason is that there is no good solution to bone loss as of yet.  The demineralization numbers for long duration flight are just plain scary.  What good would it do to send a crew where some members just might not survive the return to Earth.

A third possible reason if you look at poll numbers is that it might only be another 3 years.  The right track wrong track numbers are usually the best indicator and a majority think we are on the wrong track.

Offline MATTBLAK

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Re: First manned mission to Phobos
« Reply #3 on: 09/20/2009 01:39 am »
In the next 7 years the best we could hope for would be visit to a NEO, L-2 or lunar orbit.
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Offline alexterrell

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Re: First manned mission to Phobos
« Reply #4 on: 09/20/2009 08:43 am »

Any chance of launching this mission whilst Obama is still president, i.e. in the next 7 years?


Not likely for two reasons.  The first is to get a political agreement to do it in time isn't likely.  The second and bigger reason is that there is no good solution to bone loss as of yet.  The demineralization numbers for long duration flight are just plain scary.  What good would it do to send a crew where some members just might not survive the return to Earth.

What's the shortest trip time to Mars and back, without using too much extra propellant. Is it about 18 months? (I would like to see an extra propellant / time saving trade-off chart - any idea?)

Russian(s?) have stayed in space for over a year and survived. Impact exercises help, so I assume the journeys out and back would be spent running around the Bigelow module.

The journey to Mars could use the JUS as a spin weight, but this only weighs 12 tons. If it were joined by the Phobos exploration module, there'd be reeling in issues at Mars arrival. If the JUS were spun at 1g, then the crew might get 1/9g - not sure what effect that has. No reason though why it can't be spun at 3g.

At 3g (for the JUS), you have 36 tons of force. Assume break stree of 100tons, or 1MN. At 2GPA (Spectra) that's 0.5E-3m3. Assume length is 200m, that's 100kgs of fibre, plus reeling mechanism. It means adding 80m/s to the JUS velocity and about 10m/s to the BA330 velocity.

Other than this issue, then the development requirements are:
- Jupiter launch vehicle; or the scheduling of 12 or so EELVs and the development of a capable Earth Departure Stage.
- BA-330 development
- Fun things to do on Phobos - Robotic Razor Clams etc.
- Unmanned precursor missions - it looks like Phobos Grunt won't get there till 2012.

And risk. If you're on Phobos and you hve a propellant leak, not good. (Maybe store the Kerosene inside the BA-330. Oxygen could be replaced by the experimental electrolysis gear.)

So if Obama wanted to do a Kennedy, yes he could.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #5 on: 08/05/2010 08:25 pm »
Summer holidays in the rain are a good time to revisit this!

After looking at the VASIMR discussion in Advanced Concepts, and replaying the numbers (based on input above, which mostly increases mass), I thought Id revisit a Phobos mission.

The principle is to use electric propulsion to send as much as possible to Phobos on a three-year journey. The crew then travel on a normal Hohmann trajectory (with Oberth plus aerocapture) for a month long stay at Phobos.

The equipment required:
   An exploration ship something that can support a crew of six for a two-year mission into deep space. The exploration ship is also equipped with heat shields to allow aerocapture at Mars and Earth. Solar powered with water and air recycling. Assumed mass 60 tons.
   A 1MW VASIMR based tug. Empty mass is 10 tons and it take 20 tons of Argon fuel. Uses thin film solar cells for light weight and resistance to Van Allen radiation. Able to carry
     -   60-90 tons LEO to L1, in 12-18 months, using 10-15 tons of Argon (and return empty)
     -   60 tons LEO to Phobos, in 36 months, using 20 tons of Argon (with no return)
     -   A hypergolic rocket stage, empty mass 5 tons, and 35 tons of fuel with Isp of 325 seconds.

The exact scheduling depends on the capability of HLV available. The VASIMR tug carries 60 tons and masses 20-30 tons depending on fuel load.

Schedule
In the first year, three Solar Electric Tugs depart for Phobos. Each carries one hypergolic rocket stage, and 20 tons of exploration equipment and supplies.

In the second year, the Exploration Ship is launched with 15 tons of supplies (for the outbound journey). A Kerolox rocket stage is also launched, with 60 tons of Kerosene / Lox. These elements weigh 142 tons. These are taken by two Solar Electric tug missions to Earth-Moon L1.

In the third year, an Orion mission delivers the crew of 6 (assuming Orion can be equipped for 6) to L1. The crew depart for Phobos, using Mars aero capture (total delta V 1.8km/s). On arrival at Phobos, the crew have a month on the surface. Experiments will include ISRU experiments and tests on suitability of Phobos as a base.

Note:
1.   An extra Solar electric tug could bring supplies, and an artificial gravity environment, to allow a 2 year stay.
2.   An extra Solar tug could bring a Mars lander/ascent vehicle to allow the crew to spend a few weeks on the surface of Mars.

For the return, two of the hypergolic stages are used to propel the exploration ship (with 15 tons of new supplies)  back to Earth (delta V 1.9km/s). The third hypergolic stage is spare / left for future missions. The exploration ship is aerocaptured to enter a Highly Elliptical Earth Orbit.

An Orion mission docks with the Exploration Ship and brings the crew home. A small rocket stage parks the Exploration Ship at L1 for the next mission. (By this time a propellant depot is being created).

Launches required:
   5 HLV cargo of circa 70 tons to LEO
   5 Solar Electric Tugs of 20-30 tons (Falcon 9H?)
   Crew delivery mission (J130 or Falcon9 combination?)
   Crew collection mission (J130 or Falcon9 combination?) 

IMLEO ~ 550 tons.

The following mission to Phobos will start a permanent base with ISRU to support Mars landings.

Thoughts?

Offline Hop_David

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Re: First manned mission to Phobos
« Reply #6 on: 08/05/2010 10:45 pm »
The second and bigger reason is that there is no good solution to bone loss as of yet.  The demineralization numbers for long duration flight are just plain scary.

Valeri Polyakov didn't suffer crippling bone loss during his 14 month stint in freefall.

Googling  Valeri Polyakov I found this page:
http://www.naturalhealthway.com/noblerex-k1/noblerex-k1-platinum.html

At first glance, the page smells like get rich scammers preying on the very large market of gullible overweight people who want to look great without discomfort, time or effort.

But Polyakov did enjoy an unusual and noteworthy success. Have the Russians developed an exercise method that's effective? Wish I knew more about Whole Body Vibration System.


Offline Robotbeat

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Re: First manned mission to Phobos
« Reply #7 on: 08/05/2010 10:54 pm »
There are also drugs which can help counter-act bone loss, and we haven't done a lot with those in manned missions, even though we could. The drugs we have now are pretty phenomenal, at least for osteoporosis.
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Offline MickQ

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Re: First manned mission to Phobos
« Reply #8 on: 08/06/2010 01:55 am »
Alex.

Do we know anything certain about the resources available on Phobos for ISRU ?

Nick.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #9 on: 08/06/2010 07:10 am »
Alex.

Do we know anything certain about the resources available on Phobos for ISRU ?

Nick.
Nothing certain, I believe, until Phobos Grunt get's there. That was meant to launch this year but has been put back 2 years.

There was a great suggestion here to crash Mars Express into Phobos, observed by the NASA Mars orbiter, to get spectral composition.

We do know that the density of Phobos is about 2, which implies it's carbonaceous chondrite, with high water content. It may even have Kerogen - a source of carbon and Nitrogen. It could also be a "rubble pile". I would take this to mean assume zero tensile strength in the regolith. That presents problems, but also opportunities - you can bury a base for perfect shielding from cosmic rays and micro-meteorites.

If this is all proved, then I think it makes Phobos the most attractive destination for a base:
- Water
- Very low energy access - a single SDHLV launch with electric thrust can take c 60 tons to Phobos.
-  A large inflatable base complete with rotating gravity section could be buried (without the need for radiation and micro-meteorite protection, a SDHLV launched inflatable base could be huge - say a 50m diameter torus).
- Once ISRU is working, access on demand to the Mars surface
- In the longer term (after a decade or two) great possibilities with tethers

Anyway, this really needs a proof of concept mission - say the 200KW version of VASIMR (as planned for ISS) to take a 10 ton robotic cargo to Phobos to do some serious drilling.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #10 on: 08/06/2010 07:16 am »
The second and bigger reason is that there is no good solution to bone loss as of yet.  The demineralization numbers for long duration flight are just plain scary.

Valeri Polyakov didn't suffer crippling bone loss during his 14 month stint in freefall.

Googling  Valeri Polyakov I found this page:
http://www.naturalhealthway.com/noblerex-k1/noblerex-k1-platinum.html

At first glance, the page smells like get rich scammers preying on the very large market of gullible overweight people who want to look great without discomfort, time or effort.

But Polyakov did enjoy an unusual and noteworthy success. Have the Russians developed an exercise method that's effective? Wish I knew more about Whole Body Vibration System.


Along time ago I went to a lecture given by a Skylab astronaut / Doctor.

NASA research discovered that the bones and joints need impact to prevent / slow down demineralisation (exercise bikes can help with muscle). On Earth, we get this from walking and jogging (and playing squash:) ). The Doctor came up with a treadmill which holds you down. I suspect the vibration system is to give some impact to the joints - it sounds scary.

Given medicines and machines, I see two solutions:
1. Put up with it for a short stay mission, total time away about 18 months. Polyakov did 14 months.
2. Send a centrifuge and lots of other stuff to Phobos and have the crew spend 2 years there. 

Offline Proponent

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Re: First manned mission to Phobos
« Reply #11 on: 08/06/2010 07:24 am »
Wish I knew more about Whole Body Vibration System.

Something along these lines is not actually too unusual in gyms these days.  The claim is that your muscles are engaged all of the time to counteract the vibration.  I tried it out once; I think the gadget was called "VibraplatePowerPlate" or something like that.  It didn't leave me much impressed, certainly not impressed enough to pay to use it after the half-hour free trial session.  But my experience and negative gut reaction is hardly a scientific trial.

I've long thought that the zero-g exercise wheeze that might catch on would be the centrifuge: get a high-speed workout at high-g.
« Last Edit: 08/09/2010 01:28 am by Proponent »

Offline tankmodeler

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Re: First manned mission to Phobos
« Reply #12 on: 08/06/2010 02:28 pm »
9 month travel legs on 2+ year duration trips to anywhere are unlikely unless and until we have a proper solution for radiation effects on humans. Bone loss is bad, but, perhaps managable, but so far the radiation above the Van Allen belts is too nasty for people to survive long term without truely massive amounts of shielding. Not just bunkers for solar flares, but shielding for the whole ship that reduces background radiation levels to really, really low levels. Medical science over the past 30 years has been consistently lowering the radiation doses that are considered safe. They are currently at a small fractrion of levels that were considered OK in even the mid 80s.

For BEO missions, radiation is the elephant in the room and it gets precious little attention out of the specialist community.

Unless we have a truely stupendous upmass capability (think nuclear pulse Orion or Sea Dragon) radiation exposure will likely drive us to NERVA or nuke powered, high-thrust Ion type high/very high ISP propulsion systems so that the trip can be made boosting all/most of the way to get trip times down in the 2-3 month span and stays at the destination can be accomplished in one close approach period of 6-9 months as opposed to being spread out over 2 + years.

That sort of mission isn't going to happen any time soon and not at all unless NASA starts to put some serious money into nuke propulsion. Which they ain't. And it ain't on their radars, neither.  :)
« Last Edit: 08/06/2010 02:29 pm by tankmodeler »
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Offline alexterrell

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Re: First manned mission to Phobos
« Reply #13 on: 08/06/2010 02:40 pm »
Let's hope this works out:
http://forum.nasaspaceflight.com/index.php?topic=22414.0

It seems a fair amount of research got done on magnetic propulsion, but not much on the easier matter of shielding.

One of the advantages of Phobos is likely the ease of in-situ shielding.

Offline Robotbeat

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Re: First manned mission to Phobos
« Reply #14 on: 08/06/2010 04:12 pm »
Just because medical doses of radiation have declined doesn't mean it's really that dangerous. I'm not convinced that the cosmic radiation is dangerous enough to double the mission mass. I haven't seen a good case. I mean, yeah, if you can get good cosmic radiation shielding for low mass, then why not, but otherwise, it's worth the slightly increased risk of cancer. Considering the lowering of the life expectancy just by the LOC risk alone, the lowering of life expectancy from cosmic radiation is minimal, even on 2-year trips.

In fact, there's evidence that the body responds to low levels of non-acute radiation by increasing the mechanisms for radiation damage repair, which may actually help reduce the risk of acute radiation. There are also antioxidant cocktails which do a lot to reduce the cellular damage caused by radiation (most of the damage is related to oxidation stress, so addressing that can reduce the damage), perhaps by quite a bit.

There are people who live long, healthy lives in Ramsar, Iran at annual radiation levels (132 mSv annually) up to about 25% of what astronauts en route to Mars would experience. Some even claim that the low level of radiation actually makes them more healthy (the same way that the stress of exercise stimulates the repair mechanisms of the body), although either way, it's clear that that level of radiation isn't a significant risk compared to the other risks astronauts face.

The risk of cosmic radiation is based on extrapolation from very high radiation doses where the body doesn't have enough time to repair the damage. I am not convinced the risk is as high as some say it is when the body is given enough time to repair the damage.
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Offline Hop_David

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Re: First manned mission to Phobos
« Reply #15 on: 08/06/2010 04:33 pm »
...the radiation above the Van Allen belts is too nasty for people to survive long term without truely massive amounts of shielding.

That is one reason I beat the drums about mining ice at the lunar poles for export to EML1 or 2.

A ship filled at an EML1 propellent depots has a 2.4 km/sec advantage over LEO. A lower delta V budget enables a more massive trans-Mars vehicle. A vehicle which could include more radiation shielding.

Besides supplying EML1 depots with Lox and LH2, the lunar poles could also export water there. Water is very good radiation shielding as well as necessary for life support. Loft the trans-Mars vehicle from earth with hollow walls, this would be less massive. At EML1 the hollow walls could be filled with lunar water.

Offline Hop_David

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Re: First manned mission to Phobos
« Reply #16 on: 08/06/2010 04:41 pm »
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.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #17 on: 08/06/2010 07:06 pm »
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.
Certainly less delta V for a crewed mission, though not for the SEP missions which can't use aerobraking or Oberth effects.

Making repeated trips to an NEO will be very difficult. They're only near a small fraction of the time.

Offline Robotbeat

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Re: First manned mission to Phobos
« Reply #18 on: 08/06/2010 07:19 pm »
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.
Certainly less delta V for a crewed mission, though not for the SEP missions which can't use aerobraking or Oberth effects.

Making repeated trips to an NEO will be very difficult. They're only near a small fraction of the time.
SEP can use aerobraking, just not aggressive aerobraking or aerocapture.
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Offline Hop_David

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Re: First manned mission to Phobos
« Reply #19 on: 08/06/2010 07:35 pm »
3. ... Establish permanent base on Phobos using large scale inflatables (http://forum.nasaspaceflight.com/index.php?topic=18759.0)
This focuses on part 2.
...
   Testing a storm shelter inflating a 5m balloon under the regolith

This is perhaps doable.

...
2. Send a centrifuge and lots of other stuff to Phobos and have the crew spend 2 years there. 

Although a solution to bone loss & other health issues, this sounds substantially more difficult and expensive than the buried Bigelow balloons you mentioned earlier.

How much more expensive? I don't know.

Some unanswered questions are minimum gravity needed to stay healthy and maximum angular velocity humans could live comfortably in.

Given high angular velocity and low gravity, spin habs could be much smaller and less expensive.

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.

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").

Offline Robotbeat

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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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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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Offline Robotbeat

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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!  :)

Offline MickQ

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Re: First manned mission to Phobos
« Reply #40 on: 09/22/2010 06:48 am »
I have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things.  Imagine an asteroid striking the planet at what is now the Hellas Basin.  This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes.  Phobos and Diemos couold be ejecta fron this event.  This could also account for Mars elongated orbit.

Anyone ???

Mick.

Offline Lampyridae

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Re: First manned mission to Phobos
« Reply #41 on: 09/22/2010 09:32 am »
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").

There seem to be somewhat adverse effects with a 2m radius centrifuge. The various organs are subjected to a range of different pressures, so you get the heart operating at 0.3g (in a 1g centrifuge), the head at near zero and the feet getting 1g. Plus your body exerts about 1/3 of its weight on the feet and anti-gravity muscles! The exercise effect seems all right, although you need hypergravity (1.5g+) for any real benefit.

Studies with longer arm centrifuges (~4m) exist, but aren't so common. DiZio's work was in a 5m diameter room, but that showed adaptation was possible. There is the added problem of vectoring your body to stand with these ground based tests. With a 4m radius, you get the head at 40-50% ambient. The big problems come when you start to move around in short radii systems. At 6RPM, you get one G but tangential velocity is 2.5 m/s. Very easy to step onto, but you start lifting off the floor when you walk anti-spinward and your RPM effectively drops to zero. Then when you walk spinward (at 2.5 metres per second), your RPM increases to 12. Coriolis force also causes problems. At 10RPM however, the tangential rises to 5m/s and Coriolis is more manageable.

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Offline Lampyridae

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Re: First manned mission to Phobos
« Reply #42 on: 09/22/2010 01:02 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.

Current BA 330 design is too small to accommodate an internal centrifuge. It *could* be done, with 6RPM you are looking at 0.12g, with 8, 0.2g. I would suggest a 10m diameter hab as a minimum (2001 Discovery centrifuge size). At these sizes, too *low* an RPM causes problems with Coriolis forces and walking speeds. But perhaps these aren't as big problems as we think they are.

A couple of rings of fluid around the rotation axis should keep instabilities down.

Gasbarri P., Teofilatto P. (2009) Fluid ring dampers for artificial gravity spacecraft. Acta Astronautica (64), 1286-1292
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Offline tankmodeler

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Re: First manned mission to Phobos
« Reply #43 on: 09/23/2010 02:52 pm »
One wonders how a Bigelow-type module could be designed so that it was of larger diameter and shorter length. If you could get it to fit within EELV launch shrouds you could have a 15m+ diameter centrifuge but the entire thing is only 2-3m wide. It is then docked to a more standard BA330 where zero-G storage and specialised tasks are performed. A centrifuge that narrow might seem kinda confining, but at 2 m wide would provide 94+ sq m (>2500 sq ft) of floor space which would support an awful lot of activities for a nominal crew of, say, 6 or 8 on a long term voyage. You could also have a second floor at a lower gravity level to allow the crew to prep for Mars and then on the way back they would move the first floor to prep for Earth gravity. A lot of mass turning, to be sure, but the coriolis effects may be more manageable. Certainly the negative effects of vertical movement would be diminished.

Just a thought.
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Offline Robotbeat

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Re: First manned mission to Phobos
« Reply #44 on: 09/23/2010 03:05 pm »
On a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.
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Offline tankmodeler

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Re: First manned mission to Phobos
« Reply #45 on: 09/24/2010 05:47 pm »
On a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.
For the foreseeable future this won't be an issue and certainly not with current rapid prototype materials. None of them have even a small fraction of the strength of standard aerospace materials so there are no parts that will be repaired by rapid prototypes using today's technologies. If we posit some magic that can rapid prototype out of flight-grade materials, then we may not have to worry about gravity. No sense even putting it on the radar as its a completely "magic" technology at this point

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Offline Robotbeat

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Re: First manned mission to Phobos
« Reply #46 on: 09/25/2010 06:40 am »
On a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.
For the foreseeable future this won't be an issue and certainly not with current rapid prototype materials. None of them have even a small fraction of the strength of standard aerospace materials so there are no parts that will be repaired by rapid prototypes using today's technologies. If we posit some magic that can rapid prototype out of flight-grade materials, then we may not have to worry about gravity. No sense even putting it on the radar as its a completely "magic" technology at this point

Paul
Perhaps "rapid prototyping" is the wrong word... There already exist "additive manufacturing" systems capable of making items out of flight-grade materials:
http://www.designnews.com/article/510610-3_D_Printers_versus_3_D_Production_Systems.php (shows a picture of landing gear for a Russian aircraft produced on a "3d production" system) There are many materials that are available now for additive manufacturing, including stainless steel. It's not magic. Do your research!

Get with the times. ;)

(However, a small lathe or multi-axis cnc machine may make more sense for some things... also could benefit from some gravity, although probably could be made to work without gravity)

But for the lower end machines, there are also aerospace-certified (using that term loosely) thermoplastics which can be used:
http://www.engineerlive.com/Design-Engineer/Materials_Processes/Fortus_900mc_3D_Production_System_gains_four_new_materials/22033/

EDIT:Here's a neat website where you can upload a 3d model and order the object fabricated on-demand in all sorts of materials, like plastic, glass, a temp-resistant ceramic, and (of course) stainless. Price is per-cubic-centimeter, and stainless is the most expensive at $10/cm^3 (others are more like $2/cm^3), and details to within about 0.2 mm (depending on material):
http://www.shapeways.com/materials/
(This is mostly an artistic shop, but other places are more aerospace-friendly... and probably with more of an aerospace price!)

Paul Breed of Unreasonable Rocket has started to use 3d printing for some of his rocket engines.
« Last Edit: 09/25/2010 07:01 am by Robotbeat »
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Offline SpacexULA

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Re: First manned mission to Phobos
« Reply #47 on: 09/25/2010 07:07 am »
On a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.

Actually the thermoplastic additive process does not require gravity to work properly.



I have actually replicated this test with my Makerbot, and it works just fine.

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Offline A_M_Swallow

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Re: First manned mission to Phobos
« Reply #48 on: 09/25/2010 07:35 pm »
Great video.

It is worth testing the equipment on its side just in case some pipes only work when vertical.

Offline orbitjunkie

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Re: First manned mission to Phobos
« Reply #49 on: 09/27/2010 02:22 am »
On a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.
For the foreseeable future this won't be an issue and certainly not with current rapid prototype materials. None of them have even a small fraction of the strength of standard aerospace materials so there are no parts that will be repaired by rapid prototypes using today's technologies. If we posit some magic that can rapid prototype out of flight-grade materials, then we may not have to worry about gravity. No sense even putting it on the radar as its a completely "magic" technology at this point

Paul

I must disagree. I recently mentioned the relatively new direct manufacturing technology Electron Beam Free Form Fabrication (EBF3). Works in vacuum and zero gee with aerospace materials such as Al and Ti. Not sure about Al-Li.
http://forum.nasaspaceflight.com/index.php?topic=22716.msg639117#msg639117

I spoke to an engineer at MSFC a few years ago who was working on more traditional rapid prototyping technology that worked with some powdered metals. I asked how the end product compared to something produced by traditional methods on the same material. The answer surprised me, in that they can be superior. That particular process, at least, produced more homogeneous material with more uniform structural and thermal properties. Combined with the ability to make unique shapes and finer scale structures (imagine a part made of tiny trusses through and through instead of solid metal) there could be big potential gains over traditional aerospace processes.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #50 on: 09/27/2010 12:22 pm »
On a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.
For the foreseeable future this won't be an issue and certainly not with current rapid prototype materials. None of them have even a small fraction of the strength of standard aerospace materials so there are no parts that will be repaired by rapid prototypes using today's technologies. If we posit some magic that can rapid prototype out of flight-grade materials, then we may not have to worry about gravity. No sense even putting it on the radar as its a completely "magic" technology at this point

Paul
Even if you're correct that rapid prototyping materials are weak (and the SLAs and SLSs I've received are flakey), many of the parts won't need to be flight-grade materials. Toilet lids, air-conditioning blades, the silly widget that holds the cables in place, the feeding tube that our lab rat nibbled through, the actuator on the air-con unit, the ventilation grill you broke with you head - all these will go wrong. In a low-g environment, the majority of parts don't even need Earth-g grade materials, let alone flight grade.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #51 on: 09/27/2010 12:27 pm »
I have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things.  Imagine an asteroid striking the planet at what is now the Hellas Basin.  This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes.  Phobos and Diemos couold be ejecta fron this event.  This could also account for Mars elongated orbit.

Anyone ???

Mick.
Given the decay in their orbits, one would surmise that the impact was fairly recent (~100 million yrs?) and not early solar system. To create the Tharsis bulge would have been like making Earth's moon.

If Phobos is from Mars, it may have less water and hydrocarbons. However, it could be a composite body - it really does a need a manned visit.


Offline MickQ

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Re: First manned mission to Phobos
« Reply #52 on: 09/28/2010 01:06 am »
I have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things.  Imagine an asteroid striking the planet at what is now the Hellas Basin.  This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes.  Phobos and Diemos couold be ejecta fron this event.  This could also account for Mars elongated orbit.

Anyone ???

Mick.
Given the decay in their orbits, one would surmise that the impact was fairly recent (~100 million yrs?) and not early solar system. To create the Tharsis bulge would have been like making Earth's moon.

If Phobos is from Mars, it may have less water and hydrocarbons. However, it could be a composite body - it really does a need a manned visit.



Alex.  I agree.  Phobos should be a priority target.  I think it was Kkattula who recently posted that it is essentially a NEO with a great view.  A perfect place for an outpost to conduct teleoperated research of Mars as well.

Mick.

Offline Lars_J

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Re: First manned mission to Phobos
« Reply #53 on: 09/28/2010 01:11 am »
Is Phobos tidally locked with Mars, or does it spin?

Offline orbitjunkie

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Re: First manned mission to Phobos
« Reply #54 on: 09/28/2010 02:17 am »
Is Phobos tidally locked with Mars, or does it spin?

It is tidally locked, though it is not in a synchronous orbit so Mars spins beneath it.
« Last Edit: 09/28/2010 02:18 am by orbitjunkie »

Offline MickQ

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Re: First manned mission to Phobos
« Reply #55 on: 09/28/2010 05:16 am »
Is Phobos tidally locked with Mars, or does it spin?

It is tidally locked, though it is not in a synchronous orbit so Mars spins beneath it.

If I recall correctly, Phobos is above the Mars horizon for something like 4 hours at a time, twice a day, for any location on the surface in a broadly equatorial region.  From a base on the Mars facing end of Phobos multiple surface units could be teleoperated in succession during each orbit for hours at a time.

Mick

Online John Santos

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Re: First manned mission to Phobos
« Reply #56 on: 09/28/2010 06:09 am »
Is Phobos tidally locked with Mars, or does it spin?

It is tidally locked, though it is not in a synchronous orbit so Mars spins beneath it.

If I recall correctly, Phobos is above the Mars horizon for something like 4 hours at a time, twice a day, for any location on the surface in a broadly equatorial region.  From a base on the Mars facing end of Phobos multiple surface units could be teleoperated in succession during each orbit for hours at a time.

Mick


Relaying through a few low-orbit comsats, it could be close to 24x7.  I think the rovers already use Mars Odyssey and MRO to relay to Earth and Phoenix used Mars Express.  It might be harder to track a spacecraft at Phobos because it's moving faster than Earth (angular speed, not absolute velocity!), but it should be doable.

Offline kkattula

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Re: First manned mission to Phobos
« Reply #57 on: 09/28/2010 08:09 am »
Relaying through a few low-orbit comsats, it could be close to 24x7.  I think the rovers already use Mars Odyssey and MRO to relay to Earth and Phoenix used Mars Express.  It might be harder to track a spacecraft at Phobos because it's moving faster than Earth (angular speed, not absolute velocity!), but it should be doable.

IMO, a priority and prerequisite for Mars exploration should be the establishment of a constellation of small Com Relay/GPS sats.

They don't need to be anything like the capacity or accuracy of the Earth's. They just need to provide basic support for the first couple of decades of exploration.

Maybe six in areostationary orbit (17,000 km) at 60 deg intervals.  Might need a few more for accurate GPS.

Offline Hop_David

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Re: First manned mission to Phobos
« Reply #58 on: 09/28/2010 08:25 am »
I have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things.  Imagine an asteroid striking the planet at what is now the Hellas Basin.  This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes.  Phobos and Diemos couold be ejecta fron this event.  This could also account for Mars elongated orbit.

Anyone ???

Mick.
Given the decay in their orbits, one would surmise that the impact was fairly recent (~100 million yrs?) and not early solar system. To create the Tharsis bulge would have been like making Earth's moon.

If Phobos is from Mars, it may have less water and hydrocarbons. However, it could be a composite body - it really does a need a manned visit.



Around 6 or 7 months ago, Mars Express did some close fly bys of Phobos. Evidently some of the data from those encounters is now being released. For example This BBC article on Phobos

A few paragraphs from that article:
Quote
Recent observations as thermal infrared wavelengths using the Planetary Fourier Spectrometer (PFS) instrument on Mars Express show a poor match between the rocks on Phobos and any class of chondritic meteorite known from Earth.

These would seem to support the "re-accretion" models for the formation of Phobos, in which rocks from the surface of the Red Planet are blasted into Martian orbit to later clump and form Phobos.

"We detected for the first time a type of mineral called phyllosilicates on the surface of Phobos, particularly in the areas northeast of Stickney, its largest impact crater," said co-author Dr Marco Giuranna, from the Italian National Institute for Astrophysics in Rome.

These phyllosilicate rocks are thought to form in the presence of water, and have been found previously on Mars.

"This is very intriguing as it implies the interaction of silicate materials with liquid water on the parent body prior to incorporation into Phobos," said Dr Giuranna.

"Alternatively, phyllosilicates may have formed in situ, but this would mean that Phobos required sufficient internal heating to enable liquid water to remain stable."

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #59 on: 09/28/2010 08:32 am »
I have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things.  Imagine an asteroid striking the planet at what is now the Hellas Basin.  This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes.  Phobos and Diemos couold be ejecta fron this event.  This could also account for Mars elongated orbit.

Anyone ???

Mick.
Given the decay in their orbits, one would surmise that the impact was fairly recent (~100 million yrs?) and not early solar system. To create the Tharsis bulge would have been like making Earth's moon.

If Phobos is from Mars, it may have less water and hydrocarbons. However, it could be a composite body - it really does a need a manned visit.



Alex.  I agree.  Phobos should be a priority target.  I think it was Kkattula who recently posted that it is essentially a NEO with a great view.  A perfect place for an outpost to conduct teleoperated research of Mars as well.

Mick.
And:
- It can be reached every 2.2 years. NEOs with low delta V will have infrequent access opportunities.
- With Mars / Earth aero capture, delta V requirements are low - about 1.2km/s from Earth Moon L1
- A SDHLV (e.g. Jupiter 246) with SEP transfer stage can put 50 tons on Phobos.

A couple of months ago I became a fan of "Phobos Direct". Ignore Mars and set up a permanent, substantial base on Phobos. Four SEP cargo flights per year deliver 200 tons of supplies every year. Once the base is up, with ISRU and fuel production, exploring, and then settling Mars is "relatively" easy.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #60 on: 09/30/2010 09:32 am »
I finally found the HEFT study everyone is referring to. Not sure if it's in nasaspaceflight but I found it here in case I'm not the last to read it:
http://www.scribd.com/doc/37170377/NASA-future-missions-study-Heft-2

I think it could be adapted to Phobos. The issue I have with NEO missions is they are unique, visit once affairs. That makes them pretty much flags and footprints.

Phobos or Deimos is a destination that can be visited every 2.2 years, so long duration infrastructure can be built up with SEP delivered modules.

Offline MickQ

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Re: First manned mission to Phobos
« Reply #61 on: 10/07/2010 05:34 am »
I have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things.  Imagine an asteroid striking the planet at what is now the Hellas Basin.  This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes.  Phobos and Diemos couold be ejecta fron this event.  This could also account for Mars elongated orbit.

Anyone ???

Mick.
Given the decay in their orbits, one would surmise that the impact was fairly recent (~100 million yrs?) and not early solar system. To create the Tharsis bulge would have been like making Earth's moon.

If Phobos is from Mars, it may have less water and hydrocarbons. However, it could be a composite body - it really does a need a manned visit.



Alex.  I agree.  Phobos should be a priority target.  I think it was Kkattula who recently posted that it is essentially a NEO with a great view.  A perfect place for an outpost to conduct teleoperated research of Mars as well.

Mick.
And:
- It can be reached every 2.2 years. NEOs with low delta V will have infrequent access opportunities.
- With Mars / Earth aero capture, delta V requirements are low - about 1.2km/s from Earth Moon L1
- A SDHLV (e.g. Jupiter 246) with SEP transfer stage can put 50 tons on Phobos.

A couple of months ago I became a fan of "Phobos Direct". Ignore Mars and set up a permanent, substantial base on Phobos. Four SEP cargo flights per year deliver 200 tons of supplies every year. Once the base is up, with ISRU and fuel production, exploring, and then settling Mars is "relatively" easy.

Is "Phobos Direct" an actual mission study/proposal or just an idea ?

Mick.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #62 on: 10/07/2010 09:56 am »

Is "Phobos Direct" an actual mission study/proposal or just an idea ?

Mick.
Sadly just an idea - unless I consider my notes and spreadsheets a mission study :)

Offline MickQ

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Re: First manned mission to Phobos
« Reply #63 on: 10/08/2010 07:30 am »

Is "Phobos Direct" an actual mission study/proposal or just an idea ?

Mick.
Sadly just an idea - unless I consider my notes and spreadsheets a mission study :)


You have to start somewhere.  Care to share what you've done ???

Mick.

Offline Warren Platts

Re: First manned mission to Phobos
« Reply #64 on: 10/08/2010 07:47 am »
I finally found the HEFT study everyone is referring to. Not sure if it's in nasaspaceflight but I found it here in case I'm not the last to read it:
http://www.scribd.com/doc/37170377/NASA-future-missions-study-Heft-2

Thank you for actually posting the link!

Quote
I think it could be adapted to Phobos. The issue I have with NEO missions is they are unique, visit once affairs. That makes them pretty much flags and footprints.

Phobos or Deimos is a destination that can be visited every 2.2 years, so long duration infrastructure can be built up with SEP delivered modules.

Yeah, but the preferred mode these days seems to be the neverending pursuit of "firsts".... Thus NEO's are perfect for this, they only come around once a decade, so they're "cheap", and there's no denying that each new one is a new first....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline alexw

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Re: First manned mission to Phobos
« Reply #65 on: 10/08/2010 08:15 am »
I finally found the HEFT study everyone is referring to. Not sure if it's in nasaspaceflight but I found it here in case I'm not the last to read it:
http://www.scribd.com/doc/37170377/NASA-future-missions-study-Heft-2
Thank you for actually posting the link!
pdf at:
http://nasawatch.com/archives/2010/09/human-explorati.html
    -Alex

Offline Lampyridae

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Re: First manned mission to Phobos
« Reply #66 on: 10/08/2010 08:21 am »
I finally found the HEFT study everyone is referring to. Not sure if it's in nasaspaceflight but I found it here in case I'm not the last to read it:
http://www.scribd.com/doc/37170377/NASA-future-missions-study-Heft-2
Thank you for actually posting the link!
pdf at:
http://nasawatch.com/archives/2010/09/human-explorati.html
    -Alex


Thank you. scribd.com was taking its sweet time!
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Offline alexterrell

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Re: First manned mission to Phobos
« Reply #67 on: 10/08/2010 03:24 pm »

Is "Phobos Direct" an actual mission study/proposal or just an idea ?

Mick.
Sadly just an idea - unless I consider my notes and spreadsheets a mission study :)


You have to start somewhere.  Care to share what you've done ???

Mick.
It's all in Excel, rather than Word, but the numbers are attached.

The main premise is a 1MW VASIMR based upper stage with that means an SLS launch can deliver 50 tons to Phobos.

The sheet "Schedule" shows arrivals (Column C) at Phobos, by Quarter. This assumes a quarterly launch, but I haven't yet accounted for bunching - e.g Hohmann transfer is every 2.25 years (9 quarters) but I think the SEP tugs will arrive out of phase with this.

Every 1MW VASIMR arriving joins a solar tower (at the pole) to provide 400KW of power)

So in quarter 12, the first crew arrive (on ESS1). By then there is a significant base (550 tons) capable of ISRU and fuel production. (They also have emergency return boosters, in case they can't get rocket production going).

The ISRU fuel plant converts Kerogen and Water into LOX and Kerosene (or methane if easier). Then crew ships (and later Mars ships) are fueled up on Phobos. Crew ships then go from Mars to Earth Moon L1 and back on this fuel load.

Mars exploration starts in Q31 (pretty late).  Reusable cargo ships are refuelled on Mars, and send supplies down and return with Argon (which is used to send VASIMRs back to Earth with Water (for a L1 fuel depot).

Habitats are made of inflatables and covered with regolith (or inflated in the regolith). This provides the heavy shielding, so you can get a lot of volume for not much Earth mass.

From Q40, larger transport ships (100 passengers, ESS11 - 20) are substantially built at Phobos, using manufacturing equipment, moulds, CNC etc brought from Earth.

The sheets Missions and Mars Access are delta v calcs which need a bit more explanation.

Offline Patchouli

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Re: First manned mission to Phobos
« Reply #68 on: 10/08/2010 03:44 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.

Current BA 330 design is too small to accommodate an internal centrifuge. It *could* be done, with 6RPM you are looking at 0.12g, with 8, 0.2g. I would suggest a 10m diameter hab as a minimum (2001 Discovery centrifuge size). At these sizes, too *low* an RPM causes problems with Coriolis forces and walking speeds. But perhaps these aren't as big problems as we think they are.

A couple of rings of fluid around the rotation axis should keep instabilities down.

Gasbarri P., Teofilatto P. (2009) Fluid ring dampers for artificial gravity spacecraft. Acta Astronautica (64), 1286-1292

With a vehicle like SLS you can lift the type of solutions proposed for the Saturn V.
I think the Rigid Station 2 would be the perfect hab for a Phobos mission.
Use Bigelow's or LLC Dover's inflatable technology the hexagonal rim can be replaced with for a more desirable circular one.
http://www.astronautix.com/craft/selation.htm
« Last Edit: 10/08/2010 03:47 pm by Patchouli »

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #69 on: 10/08/2010 05:20 pm »
The stations from the 60s such as Rigid Station 2 don't really provide enough radiation protection - they were designed for LEO. The Bigelow devices are designed to provide protection, but weigh too much to get anything with artificial gravity.

On Phobos, with loose regolith, you can inflate BIG devices, and cover them in regolith. But the outer pressure vessel can't rotate.

You could of course inflate Rigid Station 2 inside a lightly pressurised balloon (0.01 bar would do it), which would hold the regolith off.

Or go for the design I showed in Reply #20. That can fit in Jupiter 246.

Offline Cinder

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Re: First manned mission to Phobos
« Reply #70 on: 10/09/2010 01:19 am »
Bigelow have said they've got designs in the works much larger than BA-330.
Warning - while you were reading 86 new replies have been posted. You may wish to review your post.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #71 on: 10/09/2010 07:51 am »
Good to hear that - I'm sure they have plans for something in the 70 ton class.

However, Bigelow always has to worry about shielding. So even 70 tons is probably limited to about a BA-1000 (i.e 1,000m3 - still bigger than ISS).

If you can use regolith as shielding, then 70 tons limits you to about 500,000m3 (with current materials).

Offline douglas100

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Re: First manned mission to Phobos
« Reply #72 on: 10/09/2010 10:03 am »
From alexterrell:

Quote
The ISRU fuel plant converts Kerogen and Water into LOX and Kerosene (or methane if easier). Then crew ships (and later Mars ships) are fueled up on Phobos. Crew ships then go from Mars to Earth Moon L1 and back on this fuel load.

It might be unwise to make this an important part of your architecture until we have a better idea of what Phobos is actually made of.
Douglas Clark

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #73 on: 10/09/2010 12:07 pm »
From alexterrell:

Quote
The ISRU fuel plant converts Kerogen and Water into LOX and Kerosene (or methane if easier). Then crew ships (and later Mars ships) are fueled up on Phobos. Crew ships then go from Mars to Earth Moon L1 and back on this fuel load.

It might be unwise to make this an important part of your architecture until we have a better idea of what Phobos is actually made of.

That would be true if I (or NASA) were going to spend serious money on this. Phobos is probably a highly desirable location, which is all the more reason to send some probes there.

If Kerogen is not present, but water is, then then ISRU needs to focus on water and LOX/LH2 propellent.

Kerogen would be nice to manufacture carbon fibres and various plastics. If it's not there, then metal working will need to move up the agenda (though CC asteroids are poor in Al, rich in Fe).

One scenario is that Phobos is resource rich, but buried by 100s of metres in dessicated carbon free dust.

Offline A_M_Swallow

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Re: First manned mission to Phobos
« Reply #74 on: 10/09/2010 11:51 pm »
One scenario is that Phobos is resource rich, but buried by 100s of metres in dessicated carbon free dust.

Then we would need to know what the dust is.  With a bit of thought practically anything that burns can be turned into rocket fuel, although the Isp may be low.  If the material can be converted into a solid say by pressure or melting then it can be used for construction purposes.  Phobos is in a shallow gravity well so even non-reactivate asbestos could be used as say a heat shield on the Mars landers.

Offline HappyMartian

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Re: First manned mission to Phobos
« Reply #75 on: 10/10/2010 05:19 am »
One scenario is that Phobos is resource rich, but buried by 100s of metres in dessicated carbon free dust.

Then we would need to know what the dust is.  With a bit of thought practically anything that burns can be turned into rocket fuel, although the Isp may be low.  If the material can be converted into a solid say by pressure or melting then it can be used for construction purposes.  Phobos is in a shallow gravity well so even non-reactivate asbestos could be used as say a heat shield on the Mars landers.


A_M_Swallow, I like it. If Phobos can supply lots of propellant, and you have a big reusable space tug, you might consider gluing or sintering the Phobos dust together into a very large heat sheild. Doing that would be an early high priority ISRU activity. The tug puts the payload and built on Phobos very large heat shield into a interception orbit with the atmoshere of Mars. Then the tug returns to Phobos for refueling and a new payload and very large heat shield... It sounds good.

Cheers!
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