Author Topic: Mars Aligned - Ions, Methane, and Exploration  (Read 23163 times)

Offline redliox

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Mars Aligned - Ions, Methane, and Exploration
« on: 05/16/2015 12:06 pm »
Condensing and refining all my 'Aligned ideas here and will focus on this thread.

Once again I express the need for being conservative in flying to Mars, but also tempered with enlightened goals like long term exploration and sustainability, not a mere flags-and-footprints or a technological-and-political quagmire like the STS or ISS.  Reading through the many ideas expressed here gives further enlightenment; many of the refinements I suggest here are a result of your suggestions.  What I've concluded is that most of the technologies suggested for Mars are all indispensable; the only true limitation beyond R&D is, frankly, when to deploy them and that is where being practical comes into play.

Speeches and formalities out of the way, down to business...

Let's look at what NASA has been thinking about:
1) Asteroids are falling out of favor, but the SEP behind ARM may yet survive.
2) Orbiting Mars before landing seems favored.
3) Deimos and Phobos slowly garnering attention, partly as better targets for an ARM-Mars path.
4) Congress wants to prioritize Mars versus programs like ARM or Earth Science, which in their eyes detracts from space exploration.

So NASA's getting nudged away from asteroids but not quite toward Moon;  Mars is the unified goal.  We have enough technology to get beyond LEO but few for directly landing on Mars.  Still, Curiosity and Mars 2020 show we are starting to land sizeable (but not crew-ready) payloads directly on Mars.  What could we do prior to humans on Mars?

Improvise with what we got.

If we look at what we have available (in propulsion in this example), we currently have:
-Cryogenic H2/O2 upper stages (Centaur, soon ICUS & EUS)
-Hypergollic upper stages & onboard propulsion
-Solar Electric Propulsion (DS2, Dawn, Boeing 702 sats)

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)

Of the needed tech, CH4 rocketry should be available soon (via Blue Origin and ULA, perhaps SpaceX).  Life support and rad shielding obvious to merit, but if the ISS serves its mission we'll be prepared by 2030.  Considering how Curiosity survived direct descent, in principle we could aerocapture at Mars with current means but human life shouldn't be gambled until perfected (along with EDL furthermore).  On top of that, without complete ISRU any mission, orbital or landed, will require a propellant parade; if cryogenic, we'd risk boiling off mass without (unproven) long-term cooling systems...which would turn a simple stage into an expensive spacecraft in development.

What elements we have to work with, currently and the near future, are SLS, Orion, commercial capsule (Dragon 2, ect.), the larger commercial rockets (Delta 4, Falcon Heavy [perhaps Ariane 5, Vulcan]), and then hypergolic and electric propulsion systems.  Not completely ideal, since we will be currently bound to supply from Earth, but I believe it is possible.

Before, and in tandem with, human flights, there should be cargo flights embarking directly to Mars.  These would do two functions: test the unproven tech needed and deliver (obviously) cargo (chiefly to the surface, but serviceable satellites another).  I will get to these in a second post tomorrow.

The first crewed flight could indeed be orbital, but without dragging either Orion (which is effectively useless beyond the Moon) or a 'propellant parade' of stages to be dropped.  A Deep Space Habitat and a SEP tug could do the job - considering there'll never be a  budget to launch literally a dozen SLSs (or two dozen smaller commercial rockets likewise) just to deliver fuel pods.

The breakdown of both delta-v and mass during such an orbital flight:

Earth Departure Operations
LEO to EML 1 -  4 km/s
TMI from EML 1 - 1.5 km/s

Mars Orbital Operations
MOI - 1.5 km/s
Deimos - 1.1 km/s
Reserve - 0.5 km/s
ETI - 1.9 km/s
Total: 5 km/s

Earth Return Operations
EML 1 Capture - 2 km/s
Earth return - 0.7 km/s
Total: 2.7 km/s

Needed Delta-v: 9 km/s


Exploration Upper Stage
Dry Mass: 12 metric tons
Wet Mass: 120 metric tons
Propellant: 108 (H2/O2 - ISP 450)
Delta-v: 10.1 km/s

Mars Transit Habitat
Hab-30 mt/Kick Stage (Dry) 6.3 mt
Propellant 9.6 metric tons (N204/MMH - ISP 336)
Total Mass: 45.9 metric tons
Delta-v: 0.7 km/s

Interplanetary Ion Tug ITIT
Total Dry Mass: 30 metric tons
Total Wet Mass: 80 metric tons
Total Propellant: 50 metric tons (Xenon - ISP 3000)
Delta-v: 28.8 km/s

MTH+ITIT+EUS
Dry Mass: 137.9
Total Wet Mass: 245.9
Propellant: 108 (H2/O2 - ISP 450)
Delta-V: 2.5 km/s


Orbital Flight w/ MTH/ITIT/EUS+Orion

1) MTH docks with ITIT/EUS in LEO
2) Transfer Orbit - Mass Before 245.9 mt / Mass After 137.9 mt
Propellant consumed: 108 mt (H2/O2 - ISP 450)
Delta-v: 2.5 km/s
3) EUS jettisoned
4) EML1 - Mass Before 125.9 mt / Mass After 119.5 mt
Propellant consumed: 6.4 mt (Xenon - ISP 3000)
Delta-v: 1.5 km/s
5) Orion dock with MTH to transfer crew at EML1
6) TMI - Mass Before 119.5 mt / Mass After 110 mt
Propellant consumed: 9.5 mt (Xenon - ISP 3000)
Delta-v: 2.4 km/s
7) MOI - Mass Before 110 mt / Mass After 104 mt
Propellant consumed: 6 mt (Xenon - ISP 3000)
Delta-v: 1.6 km/s
8) Deimos - Mass Before 104 mt / Mass After 100 mt
Propellant consumed: 4 mt (Xenon - ISP 3000)
Delta-v: 1.1 km/s
9) Reserve - Mass Before 100 mt / Mass After 98.1 mt
Propellant consumed: 1.9 mt (Xenon - ISP 3000)
Delta-v: 0.5 km/s
10) ETI - Mass Before 98.1 mt / Mass After 91 mt
Propellant consumed: 7.1 mt (Xenon - ISP 3000)
Delta-v: 2.2 km/s
11) EM1 Capture - Mass Before 91 mt / Mass After 83.5 mt
Propellant consumed: 7.5 mt (Xenon - ISP 3000)
Delta-v: 2.5 km/s
12) Orion docks with MTH to return crew to Earth


Bear in mind, I am not an advocate of electric propulsion (indeed the actual advocates here would note I've criticized it heavily).  However, I did the math using EUS and hypothetical methalox stages, the later carrying 100 tons of methalox apiece, and while a EUS+2 methalox stages could get a crew to Mars, there was no way it could get a crew and the return fuel there too.  Using current technology with minimal R&D, the most effective combination to expect is H2/O2 stage+SEP.  In 5 years we could add CH4/O2 stages, but not the ISRU to make it long-term effective.  Not advocating anything, just stating what we can improvise with.

An all SEP-setup I wouldn't recommend actually, but on the very first flight to Mars orbit (and Deimos) it may be what to expect, especially without a magical-ever-frozen-cryogenic stage.  Given a conjunction class mission that will be in the area of 1000 days...frankly time will be in abundance...and while in orbit waiting on the ion drive to shuffle between MOI, Deimos operations, synchronous orbit, and possibly Phobos, the crew will constantly be in view of Mars exactly like the ISS crew has of Earth on it's month-long visits.  Time enough to be busy with remote Martian science, astronomy, and PR interviews to classrooms on Earth.

What I do recommend is using an MTH to shuttle between EML and areosynchronous orbit with a kick from hydrolox from Earth (through EUS or its descendants) and methalox from Mars for the outbound.  Inbound to each planet, to quote Patrick Star (of all characters, yes), they "gently float back down."  In other words, chemical thrust for the outbound, ion thrust on arrival.  Given the choice between slow SEP, super-cool liquids failing to stay cool over a few months, or a fiery hell-ride of aerocapture...well you tell me which is practical.  As for "why aren't you using both systems simultaneously?" well mass is why; if we don't have a super-chiller fuel tank the next choice is hypergolic...and the only reason that is listed with the MTH specs is to allow for maneuvers at EML and Deimos ill-suited for slow SEP.  Hypergolic is dead weight from low isp whereas cryogenic 'spoils' too quickly.  Best to use the speed of chemical rockets near their fuel supply.

While I am chiefly explaining an initial Mars orbital mission, I will mention crew landers before closing this initial post.  Their function would be dependent on ISRU, whereas the MTH is independent (hence how it could be used well before ISRU setup).  Like cargo landers, they would be delivered by aerocapture but placed into orbit essentially empty, awaiting the MTH to dock.  On the surface, like any ISRU architecture, they refuel and return to orbit and the MTH.  They would be single stage, reusable vehicles that draw on Martian fuel.  There could be a disposable ascent vehicle used instead, but in the long term a SSTO reuseable lander would be optimal.  Furthermore, a large version could double as the methalox stage the MTH would use to leave Mars.

Quite a bit to post...but I have been thinking thoroughly on this architecture.  I expect a few debates, but I have tried to error on the heavier side with matters like delta-v to give margin...not to mention drawing on SEP gives more margin for the same propellant mass.  More details to come, especially on Martian elements.
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Offline KelvinZero

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #1 on: 05/16/2015 12:42 pm »
Pet peeve: long term propellant storage is often implied as difficult, like violation of thermodynamics difficult. I think this is an absurd meme spawned because propellant depots are politically inconvenient for SLS, even though any long term BEO plans assume significant propellant storage.

Even passive systems are meant to bring boiloff down to a few percent per year in a high orbit. Then you just add some active cooling. If you can't reliquify a very slow trickle of cold gas in an environment where oxygen lines freeze by accident then the notion of ISRU to aquire - then liquify and store - tons of hot gasses is absurd and the fact we have been doing this on earth for a century or so is absurd.
« Last Edit: 05/16/2015 01:15 pm by KelvinZero »

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #2 on: 05/16/2015 12:55 pm »
Pet peeve: long term propellant storage is often implied as difficult, like violation of thermodynamics difficult. I think this is an absurd meme spawned because propellant depots are politically inconvenient for SLS, even though any long term BEO plans assume significant propellant storage.

Even passive systems are meant to bring boiloff down to a few percent per year in a high orbit. Then you just add some active cooling. If you can't reliquify a very slow trickle of cold gas in an environment where oxygen lines freeze by accident then the notion of ISRU to aquire - then liquify and store - tons of hot gasses is absurd and the fact we have been doing this on earth for a century or so is absurd.

If it is possible then that means, during initial assembly, the MTH and the ITIT could each launch with an EUS.  The first EUS would be spent in a transfer orbit, but the second could be held onto up through EML (1 or 2), and once the crew boards they could be injected onto a swift transit (perhaps even as low as 5 months).

Even with passive systems, you are still talking multiple launches and dealing with the annoying mass problem prior to ISRU freeing up the system.  Furthermore, any SLS launch not involving Orion is best spent sending a large hab/cargo lander to Mars itself.  The chiller option would help, especially if ion tugs are employed between LEO and the Moon, but it shouldn't be treated as a crutch.
« Last Edit: 05/16/2015 01:03 pm by redliox »
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Offline gbaikie

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #3 on: 05/16/2015 01:38 pm »
I think NASA should mothball or some other option [other than crashing ISS into atmosphere] of no longer having the need of 3 billion per year cost of ISS, by 2025.
And think should start a major Mars exploration program by 2025.

In the time before 2025, NASA should develop operational use of depots in Orbit [LEO- KSC inclination].
And should start a major lunar exploration program which will be ended by 2025.
The lunar exploration start with robotic program [lander/orbitors] which intended to determine if and where there is minable water deposit in the lunar polar regions. And prior to 2025, have few manned mission
to lunar surface which will bring back well preserved lunar samples.
And major lunar program does not include building a lunar base, nor mining lunar water.
And the total cost should be about 40 billion and roughly 1/2 is manned and 1/2 is robotic or non manned.
Generally speaking the non crewed exploration will require more years than crewed missions. And crew missions will tend to explore the moon more thoroughly in a given location and in shorter period of time than compared to robotic missions.
So around 2025, in terms of human spaceflight, NASA will have 3 programs: ISS and lunar- which are ending, and Mars which is beginning.
And prior to 2025 one will continue the scheduled/planned Mars mission and add more robotic  mission in regards to Mars in preparation for crew going to Mars. And they should be related to landing sites selection for crewed mission to Mars.
As far as Mars moons, it seems we should send robotic mission to evaluate potential use of moons related to crew exploration of Mars. Not sure when, but of course before sending crew or making too many plans in terms of mars bases.
And at 2025, would have operational depot at LEO and/or at high earth orbit. And most likely not have commerical lunar water mining, though could have the beginning steps of such operation beginning as result positive results of lunar exploration. But waiting such things which may or may not occur is unrelated
to the mars exploration program. And perhaps something like the result of Mars moon's exploration could [though perhaps unlikely] could have more commercial mining potential. Or who knows what else might be possible by that point in time. But seems that if lunar exploration in beginning appears to being giving negative results, that NASA may need to re-evalate lunar exploration. And it's focus should related to exploration related to starting new markets in space. As that is sole purpose of exploring the Moon.
Mars is similar though probably a longer project- or it's purpose of determine if human settlement are viable option related to Mars. And is more possible if there is lunar markets which exist.
« Last Edit: 05/16/2015 01:49 pm by gbaikie »

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #4 on: 05/16/2015 11:43 pm »
As promised, I'll now elaborate on the cargo and robotic elements.

Compared to crews, that are effectively cradled, robots can be handled a little more forcefully directly.  While there will be a significant orbital element to crew delivery, the robotic elements will be primarily surface-based.  The whole focus will be to create a significant, self-sustaining base with the minimal number of flights as possible.  This will happen in two forms:

1) Pathfinders - 66% scale testbeds
2) Base Habs - Full scale habitats

The Pathfinders would consist of 2 types of payloads: a ISRU lander with rovers and a SEP satellite with docking and refueling capability; the landers would mass about 20 metric tons while the satellites around 30.  They would be optimized for launch aboard something other than SLS, namely Falcon Heavy into LEO.  From there, the SEP sats spiral the whole Pathfinder out to Mars.  Prior to arrival, lander and sat split - the sat spiraling down to synchronous orbit while the lander aerocaptures prior to landing.

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.

The Pathfinder satellite has two primary tasks with some long-term secondary functions.  First, it would loft itself and an accompanying lander from LEO to Mars, settling into a synchronous orbit above the future base site.  When it's tug task is complete, the same SEP is used for station-keeping.    Then it other primary task comes into play: communication relay, which is could do with both traditional radio and laser communication, the former acting as a backup in case the later fails (since lasers do eventually burn out).  It would be meant as a long-term comsat, largely thanks to the SEP; the visiting MHTs could deliver a ton of fuel to refuel the sats, enabling them to last as long as the Hubble (perhaps even upgrading them in similar fashion, if budgets are generous enough); I would presume to give the sats at least refueling capability if nothing more.  A final long-term function would be a docking node; not so much to make them space stations, but so any loitering spacecraft have an open garage to sit at; coupled with the SEP this would be useful.  One end of the satellite would have three passive ports while the sides and aft end dominated by solar arrays, com equipment, and the SEP thrusters.  Modest (but not small) package with multiple uses.

The Base Habs would be 30 mt landers that function as the core of a Mars base.  As their name implies, they'd primarily be a habitat, but solar arrays, at least an unpressurized crew rover, and oxygen ISRU would be included with this.  They would arrive in the same manner as the Pathfinders, by aerocapture then propulsive landing.  One advantage their landing would have is the landed Pathfinder could have a guiding beacon, and the space cleared by the utility rovers (even if only a square kilometer) would provide both a visual target and landing zone.

All together, I would suggest flying two sets of Pathfinders (2 landers+2 sats) and three Base Habs to a single site adjacent to a prominent equatorial region; this could include Valles Marineris or Meridiani Planum for examples.  I advocate focusing instead of numerous sites for several reasons:

1) Avoid spreading resources (and limited temperamental Congressional funding) too thinly
2) Build a solid base with more redundancy and sustainability
3) Thoroughly investigate one region deeply and not at a glance
4) By 2030 (if not already) the database from probes will allow selection of a worthwhile permanent base site

Long-range rovers would allow more than local science.  Even if only one base is ever made, if the base is placed expertly scientists could visit many varied sites.  Referring to V.M. and M.P. for instance, a rover from a base in the canyon's center could eventually drive to Noctis Labyrinthus in the West or the channels emptying into Chryse Planitia out East and for the Planum sampling the varying craters and small channel systems.

As for the Pathfinder comsats, while two might not suffice for a GPS network this could be bolstered by complementary cubesats.  Their orbital positions, just like satellites over Earth, could be adjusted to widen their range; this could reasonably be as much as 66% of the planet while keeping base contact - even a circum-Martian expedition would draw use from this.  Otherwise giving them the ability to dock and hold a crew lander between flights may be preferable to wasteful dumping or leaving them unattended and frozen on Mars.

At least hypothetically more could be done; this could range from adding more hab modules to ISRU from the Martian moons.  I would suggest a solid approach, establishing a capable base within reach yet interesting for both science and PR.  I will further add, much of this scheme is open; the Pathfinders are intentionally smaller than the Mars Habs or MTH so that commercial or international partners could assist, and likewise a crew lander could take many forms more creative than I could conceive.  I would like to think what I've laid out here would amount to a solid bridgehead for bigger plans.
« Last Edit: 05/17/2015 01:16 am by redliox »
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Offline KelvinZero

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #5 on: 05/17/2015 02:57 am »
About asteroids are falling out of favor.. The nearest I can see are hints of a DSH in high lunar orbit with international cooperation, which would be silly not to do if we take the asteroid route anyway. It just needs more money so is likely to happen second.

So Im thinking this MTH should also be this DSH. All these pieces won't emerge at once so it is just as interesting to think about what we do in the meantime. I think we can gain excellent confidence for a mars orbit mission just sitting in high lunar orbit, but without attention to our politicians we could end up with a lunar DSH that somehow proves irrelevant to Mars ambitions which would be a great pity.

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #6 on: 05/17/2015 03:25 am »
So Im thinking this MTH should also be this DSH. All these pieces won't emerge at once so it is just as interesting to think about what we do in the meantime. I think we can gain excellent confidence for a mars orbit mission just sitting in high lunar orbit, but without attention to our politicians we could end up with a lunar DSH that somehow proves irrelevant to Mars ambitions which would be a great pity.

Unsure if you imply support or discontent for a DSH.

The reason I support a DSH/MTH is two-fold:
1) NASA seems convinced significant breathing room is needed for Mars flights; considering these will be month/year-long endeavors there is a point.
2) An orbital Mars mission will need something better than Orion to do the job, both in habitat volume and propulsive capability; we all know Orion's really a cheap Moon ship.
« Last Edit: 05/17/2015 03:32 am by redliox »
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Offline spacenut

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #7 on: 05/17/2015 10:39 pm »
I agree with using Falcon H to do a lot of Mars preparation work. 

1) Reusable large SEP tugs, that can be refueled by say a Falcon 9 or compatible rocket in LEO for round trip to Mars. 

2) Disposable landers which carry and land:

a) Landing area preparation equipment
b) Fuel manufacturing equipment.
c) Robotic electric powered graders, excavators, dump trucks for ISRU work.
d) Solar power equipment.
e) Habitats
f) A Mars GPS and satellite communication system in orbit prior to colonization.
 
50 ton total payloads of this equipment with disposable landers can be delivered by Falcon Heavies to each returning SEP tug along with a Falcon 9 refueling on the tug. 

This could keep Falcon Heavies busy launching and if other nations or other companies wish to participate, they either refuel the tug, or launch something for the Tugs to take to Mars.  That could insure them a ride to Mars when the MCT's are built. 

I personally believe the BFR and MCT should not exceed pad 39a and 39b's capability (12 million lbs thrust) so as to be able to not only use Kennedy, but also the Texas site.  Even if it means say 75 tons to Mars instead of 100 tons for a practical more robust reusable system.  However, Falcon Heavies could do a lot of prep work on Mars 4-8 years prior to MCT's coming on line. 

Offline KelvinZero

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #8 on: 05/17/2015 11:08 pm »
Im a big supporter of a DSH. :)
I was just noting it should be thought of as independent of the propulsion. The DSH is an excellent component to build early and start accruing confidence in for multiyear missions, long before heading for Mars.


Offline spacenut

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #9 on: 05/18/2015 12:00 am »
What does DSH and MTH?  Can't figure out what they mean?  Thanks.

Offline Pipcard

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #10 on: 05/18/2015 02:26 am »
Deep Space Habitat and Mars Transit Habitat.

Offline Darkseraph

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #11 on: 05/18/2015 02:43 am »
Pet peeve: long term propellant storage is often implied as difficult, like violation of thermodynamics difficult. I think this is an absurd meme spawned because propellant depots are politically inconvenient for SLS, even though any long term BEO plans assume significant propellant storage.

Even passive systems are meant to bring boiloff down to a few percent per year in a high orbit. Then you just add some active cooling. If you can't reliquify a very slow trickle of cold gas in an environment where oxygen lines freeze by accident then the notion of ISRU to aquire - then liquify and store - tons of hot gasses is absurd and the fact we have been doing this on earth for a century or so is absurd.

I don't think they are impossible...I do think we don't have them off-the-shelf, so putting them on the critical path makes programs around them much more expensive and easier to cancel. I absolutely support their development and I believe in the long run that they are necessary, that the mega-rocket cargo cult has to go away to make human expansion into space viable, even when there are lulls in government support.

 My pet peeve is people counting their MCT's before they hatch. I believe mega rockets will return to being relevant when we're sending thousands of people to space every year...but we're not doing that for a long time and even multiples of current flight rates can be supported with systems that lift no more than 50 tons to LEO. I was personally amazed that those who slung mud at Ares/SLS for years completely changed tune with SpaceX saying about doing a rocket in that class, even though most of the arguments against the former system equally apply to any system SpaceX would field. I could be wrong about this and there are details to the MCT that make it a scalable system that has other commercial uses, but I've heard nothing of that nature yet. For expected near terms missions to Mars and the Moon, I overall think it makes more sense to do a single core reusable methane rocket that lifts about the same payload as Falcon Heavy, can support wider payloads; that can be later scaled up as demand increases. But hey, it's not my company!
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." R.P.Feynman

Offline spacenut

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #12 on: 05/18/2015 04:21 am »
At least SpaceX is shooting for completely reusable systems.  SLS is not.  It could have been.  It was suggested way back then that it should have fly back liquid boosters.  The core should have used the old J2 plug nozzle technology with about 4 of this making a ring to return the core.  Then you could have a completely reusable system at say 70-75 tons to LEO.  Then add a possible single J2 plug nozzle 3rd stage and you have your 120 tons or so to LEO and completely reusable system.  As much money as they have thrown around, that was possible. 

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #13 on: 05/18/2015 10:26 am »
There could be a possibility for reuseable vehicles, depending on their function.

For starters, the more passive the vehicle's function, the better its odds for longevity.  The MTH and Pathfinder sats, after launch and basic deployment (solar arrays, radio dishes) would be quiet vehicles.  They would fire either maneuvering or ion thrusters, but no major moving parts, fried super engines and heat shields,  or exposure to events like reentry or debris strikes in LEO (moreso since MTH would only return to EML-1/2 from Mars and never closer).  Indeed, I would expect the MTH to be reused numerous times with modest refuels.  In the case of the sats, the least that should be done for them is to refuel their xenon tanks every few years, at best treat them like a com-themed Hubble; indeed for some of Hubble's earliest missions they actually succeeded in replacing parts that hadn't been intended to be replaceable.

The crewed lander, acting as a Martian shuttle, could be the next avenue of reuseability.  Except when the lander doubles as a permanent surface hab, even modern schemes still dump the vehicle.  However, as the space shuttle itself and the failed X-33 remind us, they're not easy.  How much easier this would be at Mars is further debatable.  However, if we are to reuse it and store it somewhere, Mars orbit would be better to avoid cold damage from the red planet.  I would heavily recommend some kind of SSTO lander/shuttle, but I could only guess how it could be developed - but this could be an avenue taken up by ESA or commercial entities in place of NASA to lessen issues.  The Orion capsule/cabin may have use, but its weight may fit like a box in a round hole here...which is why the Orion's only role in my plans is crew delivery and retrieval from near the Moon.

Inevitably there will be some disposable components.  However, I believe this could be limited strictly to launch vehicles and booster stages.  Anything that carries crew should be reused, but I wouldn't give as much priority to reuseable Mars boosters as opposed to something like ISRU...which would supply the 90% of mass that fills the rocket to begin with.  Two exceptions I'll make to this: a future Mars tanker shuttle and a reusable first stage on Earth.  SpaceX will eventually perfect landing the stages back, and that alone will help considerably (so long as the engines and tanks remain intact).  The Mars tanker could come in two forms: a shuttle that carries fuel from Mars to a stage or pod in orbit, or carries the fuel and is the booster stage that sends crew back to Earth.  I favor the later, since it would be easier just to transfer the entire load once, on Mars, rather than multiple trips and worrying about a leaky fuel line in orbit.  I would prioritize just getting the crew up to synchronous orbit with ISRU for a start, but in the long run getting chemical propulsion on both ends of a Mars trip.  Whether or not the booster stages should be reused is trivial during base construction and initial footsteps (~10 years) but after a Mars base that can supply fuel is established, THEN advocate total reusability.
« Last Edit: 05/18/2015 10:30 am by redliox »
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Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #14 on: 05/18/2015 11:53 am »
At least SpaceX is shooting for completely reusable systems.  SLS is not.  It could have been. 

Not much point in crying over spilt milk, but because it will be a one-shot HLV, here's my policy on using it for Mars: save it for the big stuff.

Here's the breakdown on my schemes' vehicles and masses:

Pathfinder Satellite
Total Dry Mass: 20 metric tons
Total Wet Mass: 30 metric tons
Propellant: 10 metric tons (Xenon - ISP 3000)
Delta-v: 32.3 km/s

Pathfinder Lander
Total Dry Mass: 17 metric tons
Total Wet Mass: 20 metric tons
Propellant: 3 metric tons (N204/MMH - ISP 336)
Delta-v: 0.5 km/s

Mars Transit Habitat - MTH
Hab-30 mt/Kick Stage (Dry) 6.3 mt
Propellant 9.6 metric tons (N204/MMH - ISP 336)
Total Mass: 45.9 metric tons
Delta-v: 0.7 km/s

Interplanetary Ion Tug - ITIT
Total Dry Mass: 30 metric tons
Total Wet Mass: 80 metric tons
Total Propellant: 50 metric tons (Xenon - ISP 3000)
Delta-v: 28.8 km/s

Mars Surface Habitat - MSH
Total Dry Mass: 42 metric tons
Total Wet Mass: 50 metric tons
Total Propellant: 8 metric tons (CH4/O2 - ISP 380)
Delta-v: 0.6 km/s


For better or worse, we will have to expect an Orion/SLS flight twice for one Martian mission - first to deliver and the second to retrieve the crew from the MTH.  That puts the number at once a year at least.

As can be seen though, most of my vehicles are sized for 50 tons, with only ITIT above this (and its mass is a gross estimate; it could possibly be lighter and retain its performance).  Both types of habitats, surface and transit, are within the threshold for a FH, as is the combined Pathfinder package.  The Pathfinders would definitely fly by FH, using SEP from LEO to Mars all the way.  For the habs and ITIT there are two routes to take:

Falcon Path:
1 MTH
3 MSH
2 ITIT
6 FH

SLS Path:
1 MTH
3 MSH
1 ITIT
4 SLS

On the Falcon path, it would be assumed the ITIT is downsized to match ~51 mt, with the difference being a reduction in xenon.  Two ITITs, one for the MTH (with the humans aboard) and the second for the MSH.  The lessened propellant would be inconsequential to the MSH - the ITIT's job is boosting to Hoffman orbit speed and returning to Earth while the MSH aerocapture at Mars.  For the MTH, the ITIT would first boost the pair all the way to EML from LEO (not a small chore); the same Orion that delivers the crew might need to bring some xenon with it - but given the capacity of the SLS (especially with the Block 1B's EUS) this may be minor.  More time is needed for all the habitats to reach Mars, but feasible with some TLC to the crew's ITIT specifically.

The SLS would send the MSHs on a Mars Direct-style course; even at the heavier 50 mt (versus 'Direct's ~25 mt) they would be flying on reasonably swift paths at over 4 km/s out of LEO (the Hoffman minimum is 2.2 from LEO), no ITIT required.  A MTH+ITIT could fit together on SLS, but would only receive a boost slightly better than a Geostationary Transfer Orbit.  The ITIT could easily shove the MTH the rest of the way, and indeed is nominally configured this way.  The only refuel needed for ITIT would be after the returning crew link with the 2nd Orion at EML.

So, in short, we could choose between a 2 SLS/6 FH combo or a 6 SLS.  These flights would be distributed over the course of 6 years, and exclude the Pathfinders' launches; 3 surface habs delivered to fully form the base and an orbital mission conducted.

A crewed surface mission would face a similar selection, with a crew lander & ITIT with 2 FHs or a single SLS flying the crew lander alone; in both cases the lander aerocaptures into orbit.  The crew fly totally independently in the previous MTH-ITIT to rendezvous in synchronous Mars orbit.

I slightly favor the SLS for fewer flights, but the FH I would press for use all the same whenever possible.  Otherwise the true decider is radiation tolerance of the Van Allen belts - the MTH-ITIT will have to endure moderate exposure even on an SLS path, but the EUS boost would hasten the trip.  No humans would be aboard during this moment, only for the EML rendezvous via Orion.
« Last Edit: 05/18/2015 11:57 am by redliox »
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Offline spacenut

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #15 on: 05/18/2015 01:51 pm »
I would prefer argon for SEP tugs vs xenon.  Argon is in earths atmosphere and is far more abundant.  It is also about 4-5% of Mars atmosphere.  It could be extracted from Mars and launched up to fuel a SEP tug for it's trip back to earth, at least eventually.  Xenon is very rare and with all the moving around between earth and Mars, to me it makes sense in the long run to use argon. 

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #16 on: 05/18/2015 03:56 pm »
I would prefer argon for SEP tugs vs xenon.  Argon is in earths atmosphere and is far more abundant.  It is also about 4-5% of Mars atmosphere.  It could be extracted from Mars and launched up to fuel a SEP tug for it's trip back to earth, at least eventually.  Xenon is very rare and with all the moving around between earth and Mars, to me it makes sense in the long run to use argon.

I've actually heard xenon is a common byproduct of oxygen liquidation here on Earth.  Argon probably would work just as well, but xenon is the heaviest and a lot of the other choices for electric propulsion can be toxic metals, like mercury for one.  Given the low consumption rate of EP fuel to begin with there might not be much demand to refuel it at Mars, but then again that could be added to the long term goals alongside complete reusability.
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Offline spacenut

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #17 on: 05/18/2015 09:20 pm »
I was just thinking with the high concentration of argon on Mars, while we are cracking CO2 and making fuel, argon could be separated and pressurized to fly back up to be able to refuel a SEP tug system.  Wouldn't take a large rocket to take off in the 40% gravity well to dock and pressurize a tug.  This might be a long term solution since SEP tugs might be carrying cargo to Mars on a regular basis after a colony is established and growing.  Even dry food not grown on Mars would be a cheap bulk item to be carried to Mars such as wheat, corn, soybeans, sugar, or rice, which take more acreage to grow than just vegetables.  Argon, being plentiful on Mars might be cheaper to extract from Mars atmosphere launched into Mars orbit, than launched into earth orbit, or to an L2 gateway. 

Offline RanulfC

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #18 on: 05/19/2015 05:48 pm »
I don't think they are impossible...I do think we don't have them off-the-shelf, so putting them on the critical path makes programs around them much more expensive and easier to cancel. I absolutely support their development and I believe in the long run that they are necessary, that the mega-rocket cargo cult has to go away to make human expansion into space viable, even when there are lulls in government support.

The problem is that argument is circular in that because they are not "off-the-shelf" (and if you refer to the ACES/Depot studies it nearly is) we should not put them on the "critical path" yet at the same time nothing that is NOT on the "critical path" is being funded so they will by default, never be "off-the-shelf" so they should never be on the critical path...

This is exactly why we're here now. We choose a "goal" for which we develop a "critical path" but then specifically do not engage in any infrastructure or equipment development outside of that path but a lot of development within that path to achieve the goal. And pretty much ONLY the goal. This process has proved a failure at sustainment ever single time it has been followed, yet we continue to do the same thing over and over again and expect a different result. (This is the definition of crazy I will note)

Quote
My pet peeve is people counting their MCT's before they hatch. I believe mega rockets will return to being relevant when we're sending thousands of people to space every year...but we're not doing that for a long time and even multiples of current flight rates can be supported with systems that lift no more than 50 tons to LEO. I was personally amazed that those who slung mud at Ares/SLS for years completely changed tune with SpaceX saying about doing a rocket in that class, even though most of the arguments against the former system equally apply to any system SpaceX would field. I could be wrong about this and there are details to the MCT that make it a scalable system that has other commercial uses, but I've heard nothing of that nature yet. For expected near terms missions to Mars and the Moon, I overall think it makes more sense to do a single core reusable methane rocket that lifts about the same payload as Falcon Heavy, can support wider payloads; that can be later scaled up as demand increases. But hey, it's not my company!

Being honest Ares/SLS is what it is; A government launcher built to government specifications, not "exactly" a mouse/elephant relationship but dang close. MCT has at least suggested changes to the normal BFR paradigm with on-orbit refueling and some other suggestions which were all "rejected" (not off-the-shelf so not on the critical path and really NOT considered because they actively or were inferred to interfere with said "critical path" specifications) by the government. But to be fully honest you have to be aware of and consider the goals of each vehicle. BFR/MCT is aimed at putting a specific amount of payload (be it people or equipment) on the surface of Mars. SLS is aimed at putting 130 tons into LEO and that's it for the "official" reason for existence.

FH and an FH-class LV simply won't meet the requirements of either, though personally I think your closer to right, the point would be that it can't meet any of the targets presented as is. My personal belief is that we need higher flight rates to LEO and on-orbit infrastructure with dedicated space-to-space transfer vehicles using efficient in-space propulsion systems rather than launching huge missions on one-shot expendable launchers or surface to surface reusable vehicles. But the people with the actual money and control think differently and will have their way it seems.

Randy
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Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #19 on: 05/19/2015 06:41 pm »
I don't think they are impossible...I do think we don't have them off-the-shelf, so putting them on the critical path makes programs around them much more expensive and easier to cancel. I absolutely support their development and I believe in the long run that they are necessary, that the mega-rocket cargo cult has to go away to make human expansion into space viable, even when there are lulls in government support.

The problem is that argument is circular in that because they are not "off-the-shelf" (and if you refer to the ACES/Depot studies it nearly is) we should not put them on the "critical path" yet at the same time nothing that is NOT on the "critical path" is being funded so they will by default, never be "off-the-shelf" so they should never be on the critical path...

This is exactly why we're here now. We choose a "goal" for which we develop a "critical path" but then specifically do not engage in any infrastructure or equipment development outside of that path but a lot of development within that path to achieve the goal. And pretty much ONLY the goal. This process has proved a failure at sustainment ever single time it has been followed, yet we continue to do the same thing over and over again and expect a different result. (This is the definition of crazy I will note)

Regarding fuel depots, unless you count storage tanks attached to the ISRU on Mars (or Luna and perhaps Deimos/Phobos) I don't think they're honestly necessary.  I say that on the ground of cutting out the middleman.  Send down a lander, fill it up, put it back in orbit, and use it like a booster stage to push the vehicle back home.  You end up doing a similar pattern with a depot spread out over a dozen flights.  Follow something like a Mars Direct-Semi-Direct path and keep it simple.

The only orbital infrastructure I suggest under 'Aligned is a couple comsats that double as a parking space.  Otherwise with a fuel efficient system like EP (or future high-isp drives or EM drives) there's less need for fuel in deep space.  The gas station doesn't need to be in orbit itself.  If you're going to put up infrastructure, put it near the source of fuel.  This is another reason concentrating on a single strong base initially helps.
« Last Edit: 05/19/2015 06:46 pm by redliox »
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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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British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

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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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)

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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.

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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 :)

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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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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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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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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.

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #40 on: 06/28/2015 09:05 pm »
This is a visual example of the initial robotic elements I dubbed the PCP (Pathfinder Combined Payload).  You can see how the PathSat and PathLander would be linked during transit and how they separate on approach to Mars. 

I had Tea Monster render the PathLander with a ribbed deployable heatshield, kind of like an umbrella.  I suspect an inflatable decelerator would be lighter but also a one-shot deal; I wouldn't expect them to last more than an hour or two after inflation.  Because the PathLander would actually make two entries into the atmosphere, a hybrid shield that's a little more 'firmer' might be better, but then again if an inflatable can be made stable enough to last say 12 hours or so that seems viable.

The PathSat is easier to understand - a big satellite with ion engines.  Cygnus was made a reference because there'd be an option to dock landers for safekeeping to it; a combination of ion drive and gyroscopes would make it a stable platform.
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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #41 on: 06/28/2015 11:03 pm »
I know this has been asked before but how close is the Deimos or Phobs L1 point to the surface and how stable?

I'm thinking about giving the transit vehicle a small amount of ion drive.

Edit: I looked into this. Its about 4 to 5Km. Could even do that with an anchor.
« Last Edit: 06/29/2015 12:05 am by Russel »

Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #42 on: 06/29/2015 12:08 am »
What is Tea Monster?

Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #43 on: 06/29/2015 04:01 pm »
Again, forgive me for being somewhat tangential but I don't feel like starting a whole new thread just yet. I don't quite have the energy right now to write up my architecture in every detail. However I would like to mention where I'm at in case you're interested.

I had a couple of issues with my architecture that amounted to two things. One was to do with having enough fuel on the Mars end of things. And at some point I scaled up the ascent vehicle and that put the squeeze on doing stuff like visiting the moons. The other was that I wasn't particularly happy with the use of SEP, largely for economic reasons, but I hadn't fully defined where it would/could make sense.

I have issues with SEP because of the economics of having massive and expensive vehicles which engage in long mission cycles and the longer the mission cycles the fewer times the investment can be recovered by reuse. This is why I have serious issues with using SEP to get all the way to Mars, and I still do.

However SEP in Earth space, in an environment with higher solar flux and faster mission cycles may make sense and I've hinted at that before. It still depends on cost. If a SEP tug can save 50 tonnes lofted to Low Earth Orbit, then the saving is perhaps going to be under $100M. That's the cost of the launch vehicle plus the cost of the booster that I may have otherwise used. A suitable SEP tug in the order of 500KW to 1MW isn't going to cost $100M. Its going to cost many times more. And the development isn't going to be cheap either. But I think the technology can be gotten to the point where assembly is largely automated. So its in the right ballpark. And we're talking in the order of 6 months or so to raise a 50 tonne payload from Low Earth Orbit to High Earth Orbit. So reuse 20 times is a possibility.

This is not the case for SEP to Mars involving years-long cycles will never see the investment returned. Ok so much for prelude.

What I want to do with my architecture is I'm going to keep the same basic concepts. A transit vehicle that we pair up for long flights and a lander/ascent vehicle. To this add a Xenon/Krypton storage on the transit vehicle and a very limited amount of native ion thrust capability that matches its solar arrays.

There are basically two types of flight. Unmanned and manned. The unmanned flights begin with a transit vehicle (typically loaded with fuel and/or supplies) being put into Low Earth Orbit. The transit vehicle is also the vessel that transfers ion propellant to the waiting SEP tug. The tug now moves the transit vehicle into a high Earth orbit. The final pass close to Earth sees the vehicle use its own thrust (methalox) and then its own internal ion drive capabilities add to the overall delta-V plus course corrections. This should ensure a high percentage of the initial fuel is delivered to Mars. The trajectory chosen is what has been described as a ballistic capture. Which is essentially to minimise the relative velocity at intersection with Mars. A modest level of aerocapture completes the picture. Again this is the unmanned side of things.

Previous this was done with hydrolox boosters. The Earth side SEP tug is simply a device to increase the payload delivered to mars space. That extra payload allows me more freedom to have a more capable ascent vehicle and other luxuries like trips to and from moons. Plus I'm leaving more reserve in low Mars orbit.

Now the manned side of things still happens more conventionally. Two transit vehicles are delivered to Low Earth Orbit. The the crew are sent and the entire system is checked out in Low Earth Orbit. Then two hydrolox boosters are simultaneously delivered and these couple with the transit vehicles and the kick out of Earth space is done by chemical means. Yes I know I could also insert some assistance from the waiting SEP tugs, but time is of the essence here, plus safety of the crew. Once en-route the vehicles will have some ion thrust capability of their own which again contributes to the overall delta-v and provides flexibility and backup.

I won't go into the Mars side of things just now but you get the picture. I'm conceding to SEP for the Earth side boost of all the heavy unmanned stuff. And on the proviso that its possible to build a SEP tug for the purpose for a notional billion or so.

Hope you like :)

Offline kch

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #44 on: 06/29/2015 04:11 pm »
What is Tea Monster?

Not so much what as who -- one of our fellow posters.  :)

Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #45 on: 06/29/2015 04:45 pm »
What is Tea Monster?

Not so much what as who -- one of our fellow posters.  :)

Ah ok cool. I'm wondering if anyone has any tips on how I could do some simple renders without having to spend the next month learning autocad?

Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #46 on: 07/03/2015 11:06 am »
The crowning moment in Mars orbit would be visiting the moons.  In this case, being in the higher orbit proximal to synchronous orbit, Deimos would be the prime target of my 'Aligned orbital mission.  Considering the mico-gravity of either moon, landing could be optional for the MTH-ITIT the crew would travel in.  Although they might not "hover" this close to the Martian surface, modest thruster bursts could easily keep the vehicle suspended not to mention relocate to another landing site. 

Most of the exploration would be done by the crew themselves.  While NASA's done a lot of great research into Crew Exploration Vehicles, which essentially mimic the pods from Clarke's 2001: A Space Odyssey, frankly you could just fly the crew with updated Manned Maneuvering Units and use a robotic arm on the 'mothership' to grapple boulders (which might itself be another way to anchor to Deimos/Phobos).

Also this was my favorite of the images Tea Monster drew up for me. :)
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Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #47 on: 07/03/2015 04:36 pm »
As I think I said before, I don't think you can get away with hovering that close. Even with the micro gravity that would require quite a number of Kg (equivalent) of thrust continually.

What would be nice is being close to an L point and dropping an anchor. Of course if you had the crew fly down with an MMU they could take a few Km of tether and attach it to something.

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #48 on: 07/03/2015 10:25 pm »
As I think I said before, I don't think you can get away with hovering that close. Even with the micro gravity that would require quite a number of Kg (equivalent) of thrust continually.

What would be nice is being close to an L point and dropping an anchor. Of course if you had the crew fly down with an MMU they could take a few Km of tether and attach it to something.

Correct on the L point being an option, although for lumpy bodies like the Mars moons I doubt they would be particularly stable.  If there has to be a landing it may not be too difficult to arrange.
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Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #49 on: 07/05/2015 02:51 pm »
Given its gravitationally locked I think the correct wording is the L point is more unstable than a "normal" L point for spherical bodies, but I suspect its highly predictable.

Other nice thing about Phobos is that Mars itself occupies a large fraction of the sky so at the L point you get additional protection from GCR. Not perfect, but better than out in space.

Its also a great place for stuff like GPS (I guess Deimos would help too) and comms.

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #50 on: 07/08/2015 09:52 pm »
This would show how many of the various 'Aligned elements interact in preparation for a Mars landing.  My architecture's crewed components are largely orbital, but the Mars Excursion Vehicle (MEV as you can guess) is decidedly meant for Mars.  As you can further guess, I based it off SpaceX's Dragon 2 although there could be variations including a two-stage setup; personally I opt for a single stage reusable lander.

The MEV would be launched uncrewed and aerobrake into synchronous orbit.  Between flights, it furthermore is nominally docked with the previously launched PathSats in  synchronous orbit for storage.  The robotic arm attached to the MTH, as with the shuttle and ISS arms for vehicles, would grapple MEV and dock it to itself to transfer crew into it.

This shows how there could be a union between orbital and surface vehicles that takes advantage of experience in LEO.  The key is not to overdo orbital architecture heavily, just enough to where it assists what happens on Mars itself.
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Offline Ionmars

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #51 on: 07/09/2015 12:15 pm »
...
...
I have issues with SEP because of the economics of having massive and expensive vehicles which engage in long mission cycles and the longer the mission cycles the fewer times the investment can be recovered by reuse. This is why I have serious issues with using SEP to get all the way to Mars, and I still do.

 A suitable SEP tug in the order of 500KW to 1MW isn't going to cost $100M. Its going to cost many times more. And the development isn't going to be cheap either. But I think the technology can be gotten to the point where assembly is largely automated. So its in the right ballpark. And we're talking in the order of 6 months or so to raise a 50 tonne payload from Low Earth Orbit to High Earth Orbit. So reuse 20 times is a possibility.

This is not the case for SEP to Mars involving years-long cycles will never see the investment returned.
...
...
I recently posted on the MCT speculation thread the idea that SpaceX, who are considering SEP in their for their architecture, are also considering an all-propellant option. IMHO the reason for a non-SEP option would be to avoid the high development cost for SEP that you have pointed out.  Have you ever considered an all-propellant option?

One way that SpaceX could avoid SEP is by having the MCT cargo/tanker do double duty. In this scenario BFR is a stage one booster and  MCT (both passenger or cargo versions) would be a second stage to reach LEO using their own propulsion units. A propellant depot in LEO would receive MCT tankers to accumulate fuel and oxidizer in the depot storage tanks.

My idea was that one of the tankers could serve double-duty as a booster for a Mars-bound MCT. A fully-fuelred MCT would attach to a fully-fueled MCT-tanker at the LEO depot. The MCT-tanker would boost both units from LEO to HEO. After separation the Mars-bound MCT would then initiate the TMI burn for a fast transit to Mars and the tanker would return to depot or to Earth for propellant refill.

Are there instances where vehicles in your architecture could serve double-duty in a non-SEP  option?

Offline Russel

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #52 on: 07/09/2015 04:43 pm »
...
...
I have issues with SEP because of the economics of having massive and expensive vehicles which engage in long mission cycles and the longer the mission cycles the fewer times the investment can be recovered by reuse. This is why I have serious issues with using SEP to get all the way to Mars, and I still do.

 A suitable SEP tug in the order of 500KW to 1MW isn't going to cost $100M. Its going to cost many times more. And the development isn't going to be cheap either. But I think the technology can be gotten to the point where assembly is largely automated. So its in the right ballpark. And we're talking in the order of 6 months or so to raise a 50 tonne payload from Low Earth Orbit to High Earth Orbit. So reuse 20 times is a possibility.

This is not the case for SEP to Mars involving years-long cycles will never see the investment returned.
...
...
I recently posted on the MCT speculation thread the idea that SpaceX, who are considering SEP in their for their architecture, are also considering an all-propellant option. IMHO the reason for a non-SEP option would be to avoid the high development cost for SEP that you have pointed out.  Have you ever considered an all-propellant option?

One way that SpaceX could avoid SEP is by having the MCT cargo/tanker do double duty. In this scenario BFR is a stage one booster and  MCT (both passenger or cargo versions) would be a second stage to reach LEO using their own propulsion units. A propellant depot in LEO would receive MCT tankers to accumulate fuel and oxidizer in the depot storage tanks.

My idea was that one of the tankers could serve double-duty as a booster for a Mars-bound MCT. A fully-fuelred MCT would attach to a fully-fueled MCT-tanker at the LEO depot. The MCT-tanker would boost both units from LEO to HEO. After separation the Mars-bound MCT would then initiate the TMI burn for a fast transit to Mars and the tanker would return to depot or to Earth for propellant refill.

Are there instances where vehicles in your architecture could serve double-duty in a non-SEP  option?

Yes, I have considered an all-propellant option :)

Keep the ascent vehicle low mass.
Keep as much mass as possible in high Mars orbit.
Use aerocapture for non-crewed vehicles.

I also have the advantage that my space habitat is actually two separate vehicles that are docked together. Together they provide enough space and comfort for a crew on a long journey. That allows you to separate the vehicles transferring mass to one vehicle and the crew to the other. Meaning the lighter vehicle does the propulsive capture and the non piloted vehicle does the aerocapture.

I also catch up with the return capture back in Earth orbit.

Together these tools save a lot of mass.

Now regarding SEP. My main objection is economic. If you can't reuse the same SEP vehicle many times its probably not worth it. That pretty much rules out sending a large SEP vehicle to Mars, because it takes years to bring back and reuse. There's also the issue that you get less power out near Mars mean an SEP vehicle is less effective for a given size/cost.

I'm not ruling out using SEP as a tug in Earth space on missions measured in months. Such a vehicle has other uses anyhow including managing old satellites, dealing with space junk, etc. So the development work will happen, Mars or not.

Where I see SEP being most useful is in providing the initial lift into near escape orbit and for cargo and fuel.

My mission's workhorse is a "transit vehicle". Its a vehicle, with propulsion, navigation, life support and all the stuff you'd usually expect. It has a fair amount of tankage since its expected to be able to return from high Mars orbit. We're talking tens of tonnes of propellant here. Take such a vehicle, and send it without a crew and you have a tanker.

It also needs some electrical power systems and its own solar array. And in previous iterations I was considering that ion thrusters would be essential for efficient course correction, attitude control, deliberate spinning etc. its only a small jump in logic to have a vehicle that is capable of a modest amount of thrust (we're talking up to 50KW in Earth space).

Given a native SEP capability (with modest extra mass) what you could then do is load the vehicle up with extra tanks, get it up to near escape with a much larger SEP vehicle, and then let it do its own thrusting to complete the task. This wouldn't be suitable for crew (it'd take a couple of years) but for pre-positioning fuel and supplies it might make sense. With each vehicle you could have a "fuel depot" capable of storing around 50 tonnes of fuel.

I actually came at this because I figured it would be nice to actually have a lot of spare capability, so you can do stuff like refuel the lander/ascent vehicle multiple times, have spare lander/ascent vehicles in orbit, be able to do multiple trips to the moons etc.

I still need a different vehicle to do cargo landing on the surface. That vehicle might look rather like what's being proposed in that "minimal mission" by JPL. Just a scaled up MSL heat shield and go direct to retro. Use hypergolics, etc. It might be possible to simply launch one of those landers conventionally with a big chemical booster and expendable upper stage. But it might also be possible to do SEP to high orbit and then build an expendable version of the transit vehicle (methalox fuel, cryogenic storage capability) but without any extraneous mass like life support etc. Just get it up to high orbit then use methalox fuel to boost to Mars. You'd get a high leverage doing it that way. Might even get two or three cargo landers bundled together and pushed with the same vehicle. Beyond that you could go for expendable SEP but be prepared for multiple year transits.


Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #53 on: 07/10/2015 10:39 am »
...
...
I have issues with SEP because of the economics of having massive and expensive vehicles which engage in long mission cycles and the longer the mission cycles the fewer times the investment can be recovered by reuse. This is why I have serious issues with using SEP to get all the way to Mars, and I still do.

 A suitable SEP tug in the order of 500KW to 1MW isn't going to cost $100M. Its going to cost many times more. And the development isn't going to be cheap either. But I think the technology can be gotten to the point where assembly is largely automated. So its in the right ballpark. And we're talking in the order of 6 months or so to raise a 50 tonne payload from Low Earth Orbit to High Earth Orbit. So reuse 20 times is a possibility.

This is not the case for SEP to Mars involving years-long cycles will never see the investment returned.
...
...
I recently posted on the MCT speculation thread the idea that SpaceX, who are considering SEP in their for their architecture, are also considering an all-propellant option. IMHO the reason for a non-SEP option would be to avoid the high development cost for SEP that you have pointed out.  Have you ever considered an all-propellant option?

One way that SpaceX could avoid SEP is by having the MCT cargo/tanker do double duty. In this scenario BFR is a stage one booster and  MCT (both passenger or cargo versions) would be a second stage to reach LEO using their own propulsion units. A propellant depot in LEO would receive MCT tankers to accumulate fuel and oxidizer in the depot storage tanks.

My idea was that one of the tankers could serve double-duty as a booster for a Mars-bound MCT. A fully-fuelred MCT would attach to a fully-fueled MCT-tanker at the LEO depot. The MCT-tanker would boost both units from LEO to HEO. After separation the Mars-bound MCT would then initiate the TMI burn for a fast transit to Mars and the tanker would return to depot or to Earth for propellant refill.

Are there instances where vehicles in your architecture could serve double-duty in a non-SEP  option?

I believe in the long term there would be outgoing flights sent chemically while incoming flights would arrive via SEP (specifically for crew) or aerocapture (more often for cargo).  If you mean double-duty in a booster acting as a tanker, that makes perfect sense to me since an orbiting, outgoing vehicle would benefit from a swift departure thanks to Martian-made methalox. 

I only argue that such a setup would be for the long-term, not near-term.  NASA is damnably phobic about either aerocapture or ISRU...and that leaves SEP.  SEP's best application would be breaking the crew into orbit, since it would be gentler than aerocapture while still being mass-efficient (albeit requiring sizable solar arrays).  Otherwise locations as far out of gravity wells as possible should be targets, namely EML and areosynchronous orbit, so that SEP doesn't have to fight as hard when it has to be employed on outbound flights.

Most other applications I agree could be done by chemical boosters better (such as utilizing the Oberth effect for Lunar gravity assists); they just tend to be messy in both launch mathematics and space junk.  While SpaceX is making good advances in booster reuse, it's going to be a while yet before we can expect that at Mars.  An injection stage for Earth Departure and Mars Departure are good ideas, but we should limit the number of launchers needed (more specifically for SLS) to get the stuff into orbit as well as minimizing orbital debris piling up at Mars.

Here would be examples of tweaking to 'Aligned to include more chemical boosters within reason:
1) Sending a hypergollic Earth return stage to Mars orbit ahead of the crew
2) Setting up a booster/tanker that fuels on ISRU methalox from Mars, delivers it to orbiting crew vehicles, and speeds them to Earth (much faster than SEP [yes I'd definitely agree there])
3) Utilizing smaller non-SLS launchers to deliver stages more cheaply

I'd remain adamant on keeping the MTH-ITIT in high/synchronous Mars orbit to ensure an easier escape route; also bear in mind the calculated weight I gave to MTH actually includes the equivalent of an Orion SM kick stage; this is meant chiefly for minor course corrections and Deimos maneuvers but likewise it could assist in Phobos operations.  In short, with or without surface methalox the MTH brings some chemical propulsion.  If more is needed, I'd limit it to escaping Earth and Mars respectively.
"Let the trails lead where they may, I will follow."
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Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #54 on: 10/11/2015 10:19 pm »
In light of the recent NASA Flight to Mars and the Planetary Society's Humans Orbiting Mars, I am going to make a further revision in Mars Aligned that would use 4 SLS launches and 4 FH launches for the initial phases prior to Mars landing.  Reading into both their plans, I felt stupefied that they would think a single mission to Mars would require an average of 12 SLS flights just to orbit the planet and visit Phobos.  I firmly believe the same could be done with fewer rockets (specifically the SLS), and that the same goals could still be met.

The one alteration I am going to make for an orbital 'Aligned mission: inclusion of a hypergolic stage for Phobos/Earth Return.  Coupled with an ITIT tug, I believe it is reasonable to include one such stage to compensate for any shortcomings SEP may have in Mars orbit, enhance the mission to include a Phobos mission, and ensure a departure to Earth from Phobos.

Will be posting the mission plan shortly.
"Let the trails lead where they may, I will follow."
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Offline redliox

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Re: Mars Aligned - Ions, Methane, and Exploration
« Reply #55 on: 10/12/2015 11:19 am »
I'll elaborate on how a chemical stage could be integrated into a orbital-Mars-moons mission.  As every rocket engineer and enthusiast here knows, fuel weight is the key and anchor.  I will start this revival of 'Aligned with a few assumptions that I try to keep within reason:

1) The current plans to reach Martian orbit (The Planetary Society's version http://hom.planetary.org/, NASA's [as posted by our Chris Bergin] http://forum.nasaspaceflight.com/index.php?topic=38417.0 ), which require on average close to a dozen SLS flights per each Mars missions, may have a strong chance to be ruled unwieldy and impractical by policymakers in its current form.  Like all flavors of government pork, a way to trim is likely in order.
2) The logistics of needing so many SLS flights may outstrip production capability; 2 SLS flights yearly should be the most to expect; as such, whenever possible, a crew vehicle that requires SLS lift should be reused and not disposed.
3) If more mass than 2 SLS' can carry is needed, commercial launchers (i.e. Falcon Heavy, perhaps Vulcan) should carry the load, using SEP like ITIT to slowboat to Mars.
3) Landing on Mars is the true priority.  Orbiting Mars is a short stop beforehand.  Bearing this in mind, all orbital (including Phobos) efforts should be consolidated into one reusable vehicle to minimize expense and focus on its use as a Earth Return Vehicle for the Martian landings. (the Phobos habitat isn't planned for much use once the Long-term Mars missions get underway).
4) SEP should carry as much of the propulsive burden as possible, specifically for breaking into high orbit (over both Earth/Mars).  Chemical propulsion is most useful for escaping orbit, especially at Mars, but to fully rely on it (while still tied to Earth) rapidly leads to huge burdens.

I'll introduce the new element to Mars Aligned: MASS - MArs System Stage.  As the name implies, it is a single large booster stage (although not as massive as a fueled SLS upper stage).  General specs:

Mars System Stage - MASS
Dry Mass: 8 metric tons
Wet Mass: 80 metric tons
Propellant: 72 metric tons (N204/MMH - ISP 336)


MASS would launch onboard SLS, dock with an ITIT launched via Falcon Heavy, and the duo slowboat to Mars synchronous orbit.  After putting the hefty MASS in place, the ITIT would return to Earth for potential reuse while MASS remains in orbit, passively maintained by a hull-mounted solar panel and radiator with its hypergolic supply able to sit indefinitely.  Alternatively, MASS could carry methane/oxygen and have an ISP around 360, but the delta-v gain would be less than 200 m/s from such a fuel switch...so for the initial orbital mission hypergolic is the way to go to ensure a fueled rocket.

MASS could serve one of two roles, although not both simultaneously, using a budget of around 1.7 km/s:
A) A complete expedition to Phobos, including altering orbits and returning to synchronous or Deimos orbit.
B) Escape from Mars; while the 1.7 km/s would not instantly put a crewed MTH on an Earth return, this would give a large immediate push toward a more sunward path where the strength of SEP increases and puts the MTH-ITIT on Earth return.

A third potential role, one I normally didn't endorse (as I did for solar electric to begin with), could emerge from the Phobos option: fuel depot.  A spent MASS could be docked to one of the PathSats that would be placed earlier.  They could be stored and refueled either to replay their Phobos role, perform a Mars escape, or remain in place to hold fuel for other functions.

For an orbital mission, this is what I believe is required to launch MASS, MTH, two ITITs, the crewless elements on and orbiting Mars, and the crew themselves:
4 Falcon Heavies
4 Space Launch Systems
In sequence:
Launch Window 1: 2 FH, each carrying a PCP that host the crewless elements for Mars.
Launch Window 2: 2 FH, each carrying an ITIT.  2 SLS, one carrying MASS, one carrying MTH.  MASS-ITIT go to Mars orbit while MTH-ITIT go to EML.
Launch Window 3: 1 SLS, carrying Orion and crew.  After Orion transfers crew to MTH, MTH-ITIT go to Mars orbit.
Launch Window 4: 1 SLS, carrying Orion (with minimal crew if none).  Orion retrieves the returning crew from the MTH-ITIT in EML.

While not a complete solution for the mass problem posed by orbiting Mars, I do believe positioning at least one chemical stage could enhance a predominantly solar-powered-and-propulsed mission.  Moreso, I believe there has to be a far more affordable median between Mars Direct and a NASA Battlestar Galactica redeux.
« Last Edit: 10/12/2015 11:20 am by redliox »
"Let the trails lead where they may, I will follow."
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