Author Topic: Mars Aligned - Ions, Methane, and Exploration  (Read 22887 times)

Offline KelvinZero

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #20 on: 05/20/2015 03:44 am »
Re depots, I did not mean to pull the thread off topic. I just meant IMO there is no reason to be afraid of including them in a mars plan if they happen to solve a particular problem for you. If they don't that is fine also.

There is a thread for propellent depots here. http://forum.nasaspaceflight.com/index.php?topic=12338.0

Offline Oli

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #21 on: 05/20/2015 04:19 am »
What we further need is:
-CH4/O2 rockets (Blue Origins' B-4 engine may remedy this in near future)
-ISRU of CH4/H2/O2 on Mars (MOXIE on 2020 may establish O2, but still need CH4 & perhaps H2)
-Aerocapture & General Improvement of EDL (bigger heatshields, some-kinda-flaps to extend said-shields, powered descent, and pintpoint landing)

I actually kind of disagree with that.

CH4/O2 storage is nice to have, but hypergolics can do the job if combined with SEP. For example, the kick stage in the Raftery concept merely provides around 450m/s, that's no problem with an ISP of ~320. For Mars ascent hypergolics are ok too, you just have to land it on the surface. In fact a ~25t ascent vehicle with hypergolics can probably do the job if you only ascent to low Mars orbit.

Agree with EDL though.

Btw., contrary to what I said in another thread, a 30t Habitat should be enough for a crew of 4 for 500 days.

« Last Edit: 05/20/2015 04:32 am by Oli »

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #22 on: 05/20/2015 08:52 am »
What we further need is:
-CH4/O2 rockets (Blue Origins' B-4 engine may remedy this in near future)
-ISRU of CH4/H2/O2 on Mars (MOXIE on 2020 may establish O2, but still need CH4 & perhaps H2)
-Aerocapture & General Improvement of EDL (bigger heatshields, some-kinda-flaps to extend said-shields, powered descent, and pintpoint landing)

I actually kind of disagree with that.

CH4/O2 storage is nice to have, but hypergolics can do the job if combined with SEP. For example, the kick stage in the Raftery concept merely provides around 450m/s, that's no problem with an ISP of ~320. For Mars ascent hypergolics are ok too, you just have to land it on the surface. In fact a ~25t ascent vehicle with hypergolics can probably do the job if you only ascent to low Mars orbit.

Agree with EDL though.

The biggest problem with relying on hypergolics too heavily is, if you plan to reduce mass and to encourage long-term reusability, those fuels are a little too complex to produce on Mars.  Not to mention they're A LOT more explosive than methane.

Another angle I'd suggest could be using hypergolics for the descent stage of a two-stage lander.  Considering we need some fuel to land with and, even with ISRU, we would need the descent's tanks loaded from Earth to accomplish this.  Leave the ascent stage empty and draw on ISRU for return.  Much of the lander's velocity from orbit could be reduced by aerobraking beforehand as well.

Otherwise I'd push for a SSTO Mars shuttle, but I know this would be a tough push.


Btw., contrary to what I said in another thread, a 30t Habitat should be enough for a crew of 4 for 500 days.

I'll spare you the 'told ya so' and just say that I was pretty confident when I saw that kind of mass range from Mars Direct, DSH, and the MTV plans.
« Last Edit: 05/20/2015 08:54 am by redliox »
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Offline RanulfC

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #23 on: 05/20/2015 04:50 pm »
The biggest problem with relying on hypergolics too heavily is, if you plan to reduce mass and to encourage long-term reusability, those fuels are a little too complex to produce on Mars.  Not to mention they're A LOT more explosive than methane.

Depends on the "hypergolic's" actually. Peroxides are present naturally on Mars so its possible you could produce H2O2 locally quite easily. If it's stored in a cool place, (5c/41f, which on Mars would "heated" I suppose) no decomposition occurs at all. (http://www.hydrogen-peroxide.us/history-US-General-Kinetics/AIAA-2005-4551_Long_Term_Storability_of_Hydrogen_Peroxide.pdf) And it can in fact be stored as "ice" in a frozen state with complete safety. What "fuel" you'd use with it greatly depends on local resources. (Not finding Bruce Dunn's "Alternate Propellant for SSTOs" article online anymore with a quick search but here's a tidbit from yarchive:
http://yarchive.net/space/rocket/fuels/fuel_table.html, IIRC Propargyl Alcohol, {C3H4O} works best with peroxide but there are others which give good results, http://yarchive.net/space/rocket/fuels/propargyl_alcohol.html)

Methane is like hydrogen rather insidious as a gas and has a pretty wide "explosive" range, though I doubt if handled properly either is going to be a "danger" on Mars given the environment.

{quote]Otherwise I'd push for a SSTO Mars shuttle, but I know this would be a tough push.[/quote]

Well much less tough than SSTO on Earth :)

Randy
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Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #24 on: 05/20/2015 09:15 pm »
Otherwise I'd push for a SSTO Mars shuttle, but I know this would be a tough push.

Well much less tough than SSTO on Earth :)

Exactly, thanks to Martian gravity.  A big difference though is the crew's Mars Transit Habitat loiters in areosynchronous orbit, not low Mars orbit.  This entails at least a 5 km/s effort; however, compared to Earth's over 9km/s to LEO alone, this is a modest hurdle.  The original Mars Direct schemes pushed for a complete escape, and reaching synchronous orbit is close to 70% of this - indeed it's a reason why I recommend it so escaping back to Earth is easy to accomplish with a low-thrust SEP orbiter.

So for SSTO ability on Mars the true hurdle is developing sturdy yet reusable heat shielding and structure.  I'm confident this is easier to accomplish at Mars than Earth, but it wouldn't be easy all the same.  I debate as to whether there should be a two stage lander initially, perhaps with the ascent stage recovered and stored, before ultimately sending a SSTO Mars shuttle.
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Offline Ionmars

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #25 on: 05/22/2015 01:01 am »
redliox, this is a snippet from your Reply #4, describing the cargo specifications of your architecture:
 
"Elaborating on the Pathfinder lander, it would chiefly be a fuel factory with two MER-sized ultility rovers.  The lander would produce methane and oxygen, the later both in Sabatier reactions and solid-oxide electrolysis; furthermore there could be water electrolysis to experiment with getting hydrogen out of Martian soil. The rovers would primarily plow the area around the lander to turn it into a landing field and eventually a base site.  Otherwise they would map the area optically supplemented by subsurface radar and neutron spectroscopy; shoving dirt around and taking pictures would be their sole job.  In the end, the lander's function would be to create a fuel supply and safe haven for a Mars base."

My pitch is to locate the landing site near a large source of water. Recent articles have shown that water is abundant in the form of dust-covered glaciers. This is not so critical for the initial explorations, but a build-up of equipment will make the site attractive for further exploration and then colonization. Rather than squeeze a few ml out of the regolith, let's go ahead with electrolysis to produce substantial quantities of H2 and O2 -- long term benefits.
« Last Edit: 05/22/2015 01:02 am by Ionmars »

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #26 on: 05/22/2015 06:40 am »
My pitch is to locate the landing site near a large source of water. Recent articles have shown that water is abundant in the form of dust-covered glaciers. This is not so critical for the initial explorations, but a build-up of equipment will make the site attractive for further exploration and then colonization. Rather than squeeze a few ml out of the regolith, let's go ahead with electrolysis to produce substantial quantities of H2 and O2 -- long term benefits.

Right, I've heard about the glaciers in the mid-latitudes.  Could become a very viable choice, just like the poles on Luna.  My main pitch toward equatorial sites centers on convenience, specifically towards synchronous orbit: straightforward descent, maximum comsats coverage, maximum sunlight.  All the same, a source of water and hydrogen is valuable.  The only source of protest may be from the same scientists that advocate for 'special areas' on Mars to avoid contamination from Earth.  I'm certain the committee to choose a dedicated base site would factor in both ice and hydrogen abundance to the choice.
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Offline KelvinZero

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #27 on: 05/22/2015 07:40 am »
This seems to show a spot with more water around the equator. Does anyone know what it is called and why it is higher in water? (The caption says something about hydrogen measured in the top meter of soil)

water in lower latitudes?

I also thought it would be interesting to start a thread purely on landing sites for HSF.

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #28 on: 05/22/2015 08:44 am »
This seems to show a spot with more water around the equator. Does anyone know what it is called and why it is higher in water? (The caption says something about hydrogen measured in the top meter of soil)

water in lower latitudes?

I also thought it would be interesting to start a thread purely on landing sites for HSF.

It's a bit east of Opportinuty's area.  The giant crater closest to the center was Schiaparelli Crater: http://en.wikipedia.org/wiki/Schiaparelli_%28Martian_crater%29.  I actually looked over that same map while gaguing what regions of Mars would have decent hydrogen (i.e. water) rich regolith.  That crater has some layered terrain and is one of the larger craters outside of Argye and Hellas.  I'd be tempted to suggest that for a base site but aside from the layering and hydrogen-richness I'm honestly unsure how it ranks.  Anything that would be green or better should be targeted for resources, and fortunately that looks like about half the planet, even excluding the poles.

Definitely make a thread up!  Labeling these regions is wise.
« Last Edit: 05/22/2015 08:48 am by redliox »
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Offline sanman

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #29 on: 05/25/2015 04:32 am »
Here's the latest article in the New Yorker on Mars colonization:

http://www.newyorker.com/magazine/2015/06/01/project-exodus-critic-at-large-kolbert

Offline gbaikie

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #30 on: 05/25/2015 05:53 am »
Here's the latest article in the New Yorker on Mars colonization:

http://www.newyorker.com/magazine/2015/06/01/project-exodus-critic-at-large-kolbert

A lot of the same old same old.
I like the Musk quote:
"Musk recently told the online magazine Aeon. “And it could be that there are a whole lot of dead, one-planet civilisations.” Of course, a galaxy that contains “a whole lot of dead, one-planet civilisations” may also contain a lot of dead, two-planet ones."

And that's why we don't want two-planet ones. But I would disagree. First it's unlikely to have "two-planet ones". Assumption of having just Earth and Mars is based upon the delusion that Mars is like Earth. Mars is closer to being like Mercury. Or Earth is just as similar to Mercury as it is to Mars.
Mars atmosphere in terms living things is vacuum.
And if want an atmosphere and gravity like Earth, then Venus provides earth atmospheric pressure which only slightly warmer than hottest day on Earth.
And obviously provide less atmospheric pressure than Earth sea level pressure which can as cool as Earth is at higher pressure sea level**. The thick atmosphere also provides almost as much pressure as is available in Earth's oceanic depths.
Now, Earthlings have failed to become sky dwellers- and is only in that sense that Venus not like Earth. Or Earthlings are overly attached to the ground and have instinctual fear of heights.

Anyways if whole purpose of exploring Mars was to simply live on another planet then does not seem like it's very worthwhile thing to spend money on. The significant purpose of exploring Mars is to open the Space frontier- increase access to our solar system [and eventually perhaps the galaxy and beyond].

When we have much more access to space, then we harvest solar energy from Space. Which means limitless supply of electrical energy which translates into global wealth. Or everyone on Earth can have same standard of living as the US [or more likely far higher standard of living than US has had]. And of course there lots of fun things one do in space.
If I had pick which was more important commercial suborbital travel or NASA mars exploration, I would have to pick suborbital travel. Because it's a faster way to open the frontier. And is a more certain way of doing this. But I don't have to pick. And certainly don't ant NASA "doing" commercial suborbital travel.
So NASA should get on with exploring the moon, and spend much more time exploring mars. So less than 10 year exploring moon- finished in 2025, and at least couple decades exploring Mars, so might be finished by say, 2050. But we might have suborbital travel from US to Europe by 2025 or 30. So suborbital could be much faster path to get greater access to space.
Now discoveries from lunar exploration might lead to lunar water mining by 2030. But what help lunar water mining would mars settlement and what helps Mars settlements is lunar water mining. And lunar water mining leads to other lunar mining, and lunar bases, lunar tourist, Lunar telescopes and etc. And eventually to SPS for Earth.
So can't have Mars settlement without lunar activity and lunar activity is closely related to economic well being of people living on Earth.

**Edit Earth atmoshere cools at 6.5 C per 1000 meters in elevation. And so 5000 meters up cools by 32.5 C and considering earth average temperature is 15 C. On average it's pretty cold at 5000 meter.
And Venus likewise cools has one goes higher. So 5000 meters higher that 1 atm pressure on Venus would cooler the Earth average temperature. Or one can pick whatever average temperature one wants on Venus- and without spacesuit breathe.
« Last Edit: 05/25/2015 06:09 am by gbaikie »

Offline R7

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #31 on: 05/25/2015 06:19 am »
Here's the latest article in the New Yorker on Mars colonization:

http://www.newyorker.com/magazine/2015/06/01/project-exodus-critic-at-large-kolbert

Project FUD logical fallacies at large :P

I demand time wasted reading the fluff refunded.
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Offline A_M_Swallow

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #32 on: 05/26/2015 03:56 pm »
Argon is a much cheaper SEP propellant than Xenon and is a waste product from the production of LOX. Currently most is just thrown away.

Boiling point of Argon 87.302 K ​(−185.848 °C, ​−302.526 °F)
Boiling point of Oxygen 90.188 K ​(−182.962 °C, ​−297.332 °F)

Offline RanulfC

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #33 on: 05/26/2015 05:47 pm »
Argon is a much cheaper SEP propellant than Xenon and is a waste product from the production of LOX. Currently most is just thrown away.

Boiling point of Argon 87.302 K ​(−185.848 °C, ​−302.526 °F)
Boiling point of Oxygen 90.188 K ​(−182.962 °C, ​−297.332 °F)

It's "thrown-away" from LOX production because we produce much more than there is a market for currently. There IS an argon gas market (the military is a big user) and SEP use would probably not increase that market significantly but there is also an xenon market so the difference may actually be a "wash" for SEP.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
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Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #34 on: 05/31/2015 06:06 pm »
My apologies for picking on this thread but it seemed the closest to what I was thinking and I didn't feel it needed a new thread. As some would be aware I have been working on an architecture and every so often I find the time to think about it. To briefly recap it involves the following.

A minimal lander/ascent vehicle. When I originally started this was specified as being around 1.5 tonnes in mass (dry). That was pretty minimal and it really had very limited life support capability and no pressurised environment. I since refined that concept and came up with a lander/ascent vehicle that can provide up to 2 weeks of life support in a pressurised environment but is still fairly light weight for what it does - about 3 tonnes. Some will argue that this is to light but I hasten to add that materials and manufacturing have improved a lot since the days of the lunar lander and this is not designed for aerodynamic braking stresses. Its designed to land fully propulsively on Mars and as such is also quite capable of ascent from mars. It has a notional delta-V capability of 5Km/s. That means fully fueled it carries 2 tonnes of methane and 7 tonnes of oxygen.

A transit vehicle. This vehicle is designed entirely to live in space. It doesn't land. It doesn't ascend. It just goes from Earth orbit to Mars orbit and back again. It can carry notionally about 30 tonnes of fuel but that can be added to with strap on tanks. It has all the necessary life support, storage crew space etc for half a crew and if necessary can support a full crew in cramped conditions. Two of these vehicles are used for the months long journey to Mars and likewise two of these vehicles are used for the months long journey back to Earth. They can be coupled to form one vehicle with shared space and specialisation of galley, sleeping etc. And in a coupled form they can be spun to provide a low level of gravity.

Ok that's the brief recap. What's new here is I was thinking about flexible missions involve the moons of Mars and wondering how the vehicles above could be best used for that purpose. And I'm inviting ideas.

On approach to Mars, one transit vehicle will take on as much movable mass as possible (water, fuel etc) and this vehicle will aerocapture. The other vehicle containing the crew will propulsively capture. Originally I had these vehicles performing a slow series of aerobraking passes down to low orbit. At one point I suggested that the moons of Mars could be visited on the way down.

Prior to all of this, a fully fueled transit vehicle is pre-positioned in high Mars orbit. Also the lander/ascent vehicle would be pre-positioned either in low Mars orbit or left attached to the waiting transit vehicle. Now if it were the latter it could travel with the crewed transit vehicle on its descent to lower orbits.

I have to wonder. What if the lander/ascent vehicle were instead to spend its time waiting for the crewed mission stationed on one of the moons? This would be a somewhat more protected environment. It also occurred to me that the 50 tonne class transit vehicle could actually attempt a landing on at least the smaller of the two moons. Its mass would amount to something like 50Kg of Earth weight there. Its just a thought anyway.

Ok, what would you do then? Well on the descent to low Mars orbit you could visit either or both of the moons, using the lander/ascent vehicle. If you felt one lander wasn't enough you could have two. In fact you could have part of your crew check out the moons whilst the other part of the crew landed on Mars. Followed a week or so later by the rest of the crew. You'd now have two landers just in case one wasn't enough.

Its for this reason that I decided to give the pre-positioned return vehicle extra strap on tanks to provide more fuel for the landers. One option is for the landers themselves to carry the fuel and for refrigeration (liquid nitrogen) to be transferred rather than the fuel. There would be extra insulation that the crew might have to remove prior to use.

The other nice thing about having a lander/ascent vehicle with a crew cabin is that it would allow you the time and flexibility to hop around the moon and explore. The real question is whether it would be worth spending the fuel to get the transit vehicle into orbit around the moon, or simply keep the transit vehicle in a transfer orbit. The former is probably safer but it would definitely cost more fuel.

Ok enough rambling for now. And if you've got any good ideas I might start a new thread for this. If not you can always call me names :)

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #35 on: 06/06/2015 02:48 am »
A minimal lander/ascent vehicle. When I originally started this was specified as being around 1.5 tonnes in mass (dry). That was pretty minimal and it really had very limited life support capability and no pressurised environment. I since refined that concept and came up with a lander/ascent vehicle that can provide up to 2 weeks of life support in a pressurised environment but is still fairly light weight for what it does - about 3 tonnes. Some will argue that this is to light but I hasten to add that materials and manufacturing have improved a lot since the days of the lunar lander and this is not designed for aerodynamic braking stresses. Its designed to land fully propulsively on Mars and as such is also quite capable of ascent from mars. It has a notional delta-V capability of 5Km/s. That means fully fueled it carries 2 tonnes of methane and 7 tonnes of oxygen.

What you suggest sounds a bit light, but I do take to heart the possibility that a Mars lander (at least the crew variety) could be made into a smaller vehicle than usually assumed.  I think there could be a chance something derived from a commercial capsule into a SSTO Martian vehicle may come into play.  More than likely someone will come up with a simple design for a Mars lander/shuttle.

A transit vehicle. This vehicle is designed entirely to live in space. It doesn't land. It doesn't ascend. It just goes from Earth orbit to Mars orbit and back again. It can carry notionally about 30 tonnes of fuel but that can be added to with strap on tanks. It has all the necessary life support, storage crew space etc for half a crew and if necessary can support a full crew in cramped conditions. Two of these vehicles are used for the months long journey to Mars and likewise two of these vehicles are used for the months long journey back to Earth. They can be coupled to form one vehicle with shared space and specialisation of galley, sleeping etc. And in a coupled form they can be spun to provide a low level of gravity.

You pretty much summarized what Buzz Aldrin was trying to sell in his latest idea, although I think his idea is basically a larger version of yours with SEP, inflatables, among other things.  As far as artificial gravity, I fear NASA dislikes the idea of spinning a spacecraft entirely.  Mars Direct had a nice idea of using an empty stage on a rope to do the trick, but I can sort-of-understand why NASA is phobic about spinning...unless it's aligned right a spacecraft spinning in the wrong way can be a recipe for disaster.  For better or worse I'm guessing astronauts will be stuck with treadmills and calcium pills.

Prior to all of this, a fully fueled transit vehicle is pre-positioned in high Mars orbit. Also the lander/ascent vehicle would be pre-positioned either in low Mars orbit or left attached to the waiting transit vehicle. Now if it were the latter it could travel with the crewed transit vehicle on its descent to lower orbits.

You do realize you just reiterated the Mars Semi-Direct scheme there...

I have to wonder. What if the lander/ascent vehicle were instead to spend its time waiting for the crewed mission stationed on one of the moons? This would be a somewhat more protected environment. It also occurred to me that the 50 tonne class transit vehicle could actually attempt a landing on at least the smaller of the two moons. Its mass would amount to something like 50Kg of Earth weight there. Its just a thought anyway.

I don't think your idea of a super-simplified-bare-bones Mars lander would be the best fit for exploring the Mars moons; your kind of vehicle's priority is getting back to the mothership asap, otherwise you're consuming the safety margin of fuel.  Since you're talking 50 tonne vehicles though, I do agree it would be child's play for the mothership to directly visit the moons itself.  With the nonexistent gravity, the various small free flying 'toys' (CEVs I think is their acronym) might not even be necessary  as opposed to just giving the crew an updated version of the MMU and have them fly over to objects like the Phobos monolith to investigate.

I have been gravitating more towards your idea of a small lander Russel, but even at its smallest making it an intact capsule with at least a week's worth of life-support should be the baseline.  You talk to any engineer, NASA or otherwise, and while they might agree your ultra-lite-style AV may work there should be some safety margin added.  Some seeds for thought, but basically give your ship a sturdier frame.
« Last Edit: 06/06/2015 02:50 am by redliox »
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Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #36 on: 06/10/2015 08:17 am »
Courtesy of Tea Monster, here is the first visual example of vehicles in my architecture.  This would be an example of the primary crew vehicles for orbital operation.  From left-to-right they are: ITIT, MTH, and Orion.  Obviously the Orion is rendezvousing with the MTH-ITIT at either mission's start or end, as the crew would travel between Lunar Lagrange and Mars synchronous orbit nominally.  Also, I've made a written document of Mars Aligned summing it up.  I've made a thread about submitting Mars Aligned to Innocentive as well, do look into if you think you can help: http://forum.nasaspaceflight.com/index.php?topic=37780.0
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Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #37 on: 06/22/2015 11:17 am »
A minimal lander/ascent vehicle. When I originally started this was specified as being around 1.5 tonnes in mass (dry). That was pretty minimal and it really had very limited life support capability and no pressurised environment. I since refined that concept and came up with a lander/ascent vehicle that can provide up to 2 weeks of life support in a pressurised environment but is still fairly light weight for what it does - about 3 tonnes. Some will argue that this is to light but I hasten to add that materials and manufacturing have improved a lot since the days of the lunar lander and this is not designed for aerodynamic braking stresses. Its designed to land fully propulsively on Mars and as such is also quite capable of ascent from mars. It has a notional delta-V capability of 5Km/s. That means fully fueled it carries 2 tonnes of methane and 7 tonnes of oxygen.

What you suggest sounds a bit light, but I do take to heart the possibility that a Mars lander (at least the crew variety) could be made into a smaller vehicle than usually assumed.  I think there could be a chance something derived from a commercial capsule into a SSTO Martian vehicle may come into play.  More than likely someone will come up with a simple design for a Mars lander/shuttle.

A transit vehicle. This vehicle is designed entirely to live in space. It doesn't land. It doesn't ascend. It just goes from Earth orbit to Mars orbit and back again. It can carry notionally about 30 tonnes of fuel but that can be added to with strap on tanks. It has all the necessary life support, storage crew space etc for half a crew and if necessary can support a full crew in cramped conditions. Two of these vehicles are used for the months long journey to Mars and likewise two of these vehicles are used for the months long journey back to Earth. They can be coupled to form one vehicle with shared space and specialisation of galley, sleeping etc. And in a coupled form they can be spun to provide a low level of gravity.

You pretty much summarized what Buzz Aldrin was trying to sell in his latest idea, although I think his idea is basically a larger version of yours with SEP, inflatables, among other things.  As far as artificial gravity, I fear NASA dislikes the idea of spinning a spacecraft entirely.  Mars Direct had a nice idea of using an empty stage on a rope to do the trick, but I can sort-of-understand why NASA is phobic about spinning...unless it's aligned right a spacecraft spinning in the wrong way can be a recipe for disaster.  For better or worse I'm guessing astronauts will be stuck with treadmills and calcium pills.

Prior to all of this, a fully fueled transit vehicle is pre-positioned in high Mars orbit. Also the lander/ascent vehicle would be pre-positioned either in low Mars orbit or left attached to the waiting transit vehicle. Now if it were the latter it could travel with the crewed transit vehicle on its descent to lower orbits.

You do realize you just reiterated the Mars Semi-Direct scheme there...

I have to wonder. What if the lander/ascent vehicle were instead to spend its time waiting for the crewed mission stationed on one of the moons? This would be a somewhat more protected environment. It also occurred to me that the 50 tonne class transit vehicle could actually attempt a landing on at least the smaller of the two moons. Its mass would amount to something like 50Kg of Earth weight there. Its just a thought anyway.

I don't think your idea of a super-simplified-bare-bones Mars lander would be the best fit for exploring the Mars moons; your kind of vehicle's priority is getting back to the mothership asap, otherwise you're consuming the safety margin of fuel.  Since you're talking 50 tonne vehicles though, I do agree it would be child's play for the mothership to directly visit the moons itself.  With the nonexistent gravity, the various small free flying 'toys' (CEVs I think is their acronym) might not even be necessary  as opposed to just giving the crew an updated version of the MMU and have them fly over to objects like the Phobos monolith to investigate.

I have been gravitating more towards your idea of a small lander Russel, but even at its smallest making it an intact capsule with at least a week's worth of life-support should be the baseline.  You talk to any engineer, NASA or otherwise, and while they might agree your ultra-lite-style AV may work there should be some safety margin added.  Some seeds for thought, but basically give your ship a sturdier frame.

Sorry for not getting back sooner but real life and all that..

I'm reticent to suggest taking a standard capsule and turning it into a SSTO vehicle because given the need to engineer this thing to be light and still robust means designing it from the ground up. Strangely my idea does look a bit like Morpheus but with a capsule on top. Its certainly not your standard blunted cone. I am looking for someone who can draw better than I can.

I can't comment on what Buzz Aldrin is up to lately. I should investigate. Spinning around a used stage and with cables could work but it doesn't feel right. Spinning two identically shaped vehicles around a common docking point has to be more robust, even if the compromise is lower gravity. I think low gravity (somewhere around Mars gravity) is going to see more controllable bone loss than pure zero g. The treadmills and calcium pills will still be there, but the crew will be in better shape. You know one of the things that still bugs me about a lot of missions is the combination of zero-g conditions followed by high-g aerobraking.

Mars semi direct if I recall correctly wanted to return directly from low Mars orbit to Earth in one step. Which involves sinking a lot more mass deeper into the Mars gravity well. If I'm wrong and they intend to put their vehicle into high Mars orbit, other problems apply.

What I'm doing is a two step process. I'm splitting the return vehicle and catching up with the much heavier part (the one with all the return fuel) in high orbit. So it adds complexity in order to solve some of its problems.

Taking the mothership directly to the moons is something I'm seriously considering. Its not without its own risks mind you and even with tiny gravity, the mothership still exerts a force equivalent to the weight of a human (or thereabouts) and it still needs a controlled landing, some kind of landing "feet" and attention to the usual landing problems like debris. The lander/ascent vehicle is still quite capable though with a weeks life support at minimum. And you probably wouldn't want the mothership to go hopping. Indeed you'd probably invent some other local transport. Main reason I'm attracted to landing the mothership is giving it a relatively protected base and freeing it from station keeping.

I should also add that since I wrote all of this up as an exercise in showing how we can get to Mars with relative style and simplicity and still not have to loft a thousand tonnes or more of fuel into orbit, I've been struck by how close SpaceX really are to success with reusability. That really is a game changer in terms of bucks per Kg of fuel. With that in mind, future versions of my mission will have more redundancy (especially with the landers) and more margins all round. For instance there will an extra couple of landers from mission one, both for redundancy/safety and for flexibility of mission. I'm also leaning towards outfitting one of my transit vehicles as a fuel tanker with some of what would have been crew space taken up by extra tankage. Life support will still be a feature of the vehicle though.


Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #38 on: 06/23/2015 08:12 am »
You know one of the things that still bugs me about a lot of missions is the combination of zero-g conditions followed by high-g aerobraking.

I've come to agree, which is why I evolved Mars Aligned to take aerocapture away from the crewed element but focus it for the cargo half (or mainly anything that won't arrive with live crew at first).  Aerocapture is the most straightforward way to brake around Mars without fuel, so it should be applied wholesale to cargo.  The crew would brake into high orbit, but the crew lander could aerobrake and still lessen the need for fuel.

Taking the mothership directly to the moons is something I'm seriously considering. Its not without its own risks mind you and even with tiny gravity, the mothership still exerts a force equivalent to the weight of a human (or thereabouts) and it still needs a controlled landing, some kind of landing "feet" and attention to the usual landing problems like debris. The lander/ascent vehicle is still quite capable though with a weeks life support at minimum. And you probably wouldn't want the mothership to go hopping. Indeed you'd probably invent some other local transport. Main reason I'm attracted to landing the mothership is giving it a relatively protected base and freeing it from station keeping.

Considering how feeble the gravity is...I'm honestly thinking parking the mothership (in my case the MTH-ITIT) 50 meters above the satellite would suffice.  RCS thrusters could easily halt the extreme-slow-motion fall toward the moon and keep it near-perpetually suspended.  If a landing is required, it could just sit on a single modest pad the crew could stick to a docking port.  However I'm thinking just keeping it "hovering" might be wiser to minimize dust on the ship.  Just give the crews a newer version of a Manned Maneuvering Unit and let them roam the immediate surroundings.

I should also add that since I wrote all of this up as an exercise in showing how we can get to Mars with relative style and simplicity and still not have to loft a thousand tonnes or more of fuel into orbit, I've been struck by how close SpaceX really are to success with reusability. That really is a game changer in terms of bucks per Kg of fuel. With that in mind, future versions of my mission will have more redundancy (especially with the landers) and more margins all round. For instance there will an extra couple of landers from mission one, both for redundancy/safety and for flexibility of mission. I'm also leaning towards outfitting one of my transit vehicles as a fuel tanker with some of what would have been crew space taken up by extra tankage. Life support will still be a feature of the vehicle though.

I keep an eye on SpaceX; they seem the most genuinely ambitious regarding Martian goals and game-changing spacecraft.  I readily see the Falcon Heavy or "lite" heavy-lifters akin to it as an immediate "plan B" to SLS; whatever the giant NASA rocket doesn't have room to launch should immediately be shuttled to an alternative.  Also, this is a direct reason I'm sizing many of my elements around 30-50 tonnes so the FH (with its 52 mt capacity) can loft them at least to LEO.
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Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #39 on: 06/23/2015 11:33 am »
You know one of the things that still bugs me about a lot of missions is the combination of zero-g conditions followed by high-g aerobraking.

I've come to agree, which is why I evolved Mars Aligned to take aerocapture away from the crewed element but focus it for the cargo half (or mainly anything that won't arrive with live crew at first).  Aerocapture is the most straightforward way to brake around Mars without fuel, so it should be applied wholesale to cargo.  The crew would brake into high orbit, but the crew lander could aerobrake and still lessen the need for fuel.

Taking the mothership directly to the moons is something I'm seriously considering. Its not without its own risks mind you and even with tiny gravity, the mothership still exerts a force equivalent to the weight of a human (or thereabouts) and it still needs a controlled landing, some kind of landing "feet" and attention to the usual landing problems like debris. The lander/ascent vehicle is still quite capable though with a weeks life support at minimum. And you probably wouldn't want the mothership to go hopping. Indeed you'd probably invent some other local transport. Main reason I'm attracted to landing the mothership is giving it a relatively protected base and freeing it from station keeping.

Considering how feeble the gravity is...I'm honestly thinking parking the mothership (in my case the MTH-ITIT) 50 meters above the satellite would suffice.  RCS thrusters could easily halt the extreme-slow-motion fall toward the moon and keep it near-perpetually suspended.  If a landing is required, it could just sit on a single modest pad the crew could stick to a docking port.  However I'm thinking just keeping it "hovering" might be wiser to minimize dust on the ship.  Just give the crews a newer version of a Manned Maneuvering Unit and let them roam the immediate surroundings.

I should also add that since I wrote all of this up as an exercise in showing how we can get to Mars with relative style and simplicity and still not have to loft a thousand tonnes or more of fuel into orbit, I've been struck by how close SpaceX really are to success with reusability. That really is a game changer in terms of bucks per Kg of fuel. With that in mind, future versions of my mission will have more redundancy (especially with the landers) and more margins all round. For instance there will an extra couple of landers from mission one, both for redundancy/safety and for flexibility of mission. I'm also leaning towards outfitting one of my transit vehicles as a fuel tanker with some of what would have been crew space taken up by extra tankage. Life support will still be a feature of the vehicle though.

I keep an eye on SpaceX; they seem the most genuinely ambitious regarding Martian goals and game-changing spacecraft.  I readily see the Falcon Heavy or "lite" heavy-lifters akin to it as an immediate "plan B" to SLS; whatever the giant NASA rocket doesn't have room to launch should immediately be shuttled to an alternative.  Also, this is a direct reason I'm sizing many of my elements around 30-50 tonnes so the FH (with its 52 mt capacity) can loft them at least to LEO.

However, I've gone one step further and made the crewed landings fully propulsive. You're going to get higher g forces with an aerodynamic landing and even higher still if you land the crew with heavy cargo.

Phobos and Deimos gravity are at .0057 and .003 m/s/s so a 50 tonne mothership would "weigh" 29Kg and 15Kg respectively. So not a huge problem for landing, but permanent hovering would chew up too much fuel.

As clever as Elon is, I'm not going to worship him. I don't agree with the "imperative" to colonise Mars. However the world needs crazy people and I'm sure he'll do a lot of good in the process. What I'd really love to see is the reusability technology succeed to the point where Elon goes out and builds his own SLS killer. The hard part is the engine development but manufacturing technology plus Elon's ego might just get it there.

By the way, how do you feel about one of my transit vehicles being adapted to carry more fuel? Ok, its already a fuel tanker by design but I mean taking over some of the crew volume for extra tankage. You'd still have a "life boat" function but you could up the fuel stored and it might just do the trick for carrying fuel for more landers.

Again, one of the key points of my architecture is having two basic designs (the transit vehicle and the lander) that do most of the work. Keep the development simple thus get the development right.

 

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