Author Topic: Blue Dragon and the International Mars Research Station  (Read 5874 times)

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Hi guys

I just wanted to alert you to the work I've been doing on a humans-to-Mars mission architecture (called "Blue Dragon") and concept for an International Mars Research Station. This is a work in progress, but what I've done so far is documented at http://marsbase.org. You can also watch my TEDx talk describing the ideas. I'd love to hear any feedback. Although incomplete, I do believe this to be the foundation for a realistic, affordable and very good plan for establishing a human presence on Mars.

Thank you
Shaun

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #1 on: 07/01/2014 12:31 AM »
Welcome to NSF!

I'll start this off:
Quote
Launching the BA 330

The mass of a BA 330 is approximately 20-23 tonnes, and it has an estimated deflated diameter of about 3.5m and a length of 14m. The rocket currently under consideration by Bigelow Aerospace for launching these to orbit is the Atlas V. The fairing of the current version of the SpaceX Falcon Heavy is not long enough.

The Atlas V Heavy has a payload diameter of either 5.4m, a payload length of 16m, and can carry 29.4 tonnes to LEO, which would certainly do the job. However, the Atlas V is a flexible vehicle with a range of payload configurations, including diameters of 4m or 5.4m, and lengths ranging from 9m to 16m or even more. An alternative configuration may be developed specifically for the BA 330, for example, an Atlas V 452, which would have a 4m diameter fairing and be capable of carrying approximately 21 tonnes to LEO.
The Atlas V Heavy is an architecture that was never pursued.  The engineering work required to launch a 3-core Atlas is considerably greater than the engineering work required to build a longer payload fairing on the Falcon Heavy - I've read on NSF that this longer fairing is already in the works.  Even if it wasn't, a custom lengthened fairing is not a particularly difficult task.

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #2 on: 07/01/2014 12:41 AM »
Quote
Following these will be the much larger, super-heavy-lift Falcon X rockets. These are being designed for Mars, which is the goal of SpaceX, but will be equally useful for heavy lifting to Earth orbit or the lunar surface. The Falcon X Heavy will be capable of delivering an impressive 125 tonnes to LEO or about 20-30 tonnes to the surface of Mars. Considering this is approximately the minimum mass of a surface habitat, this rocket will be a key enabler of human Mars missions.
"Falcon X" and "Falcon X Heavy" date to a 2010 powerpoint presentation which has been discredited as an obsolete chalkboard sketch.  Instead, the latest indications are that SpaceX will spend the next few years setting up launchsites and getting Falcon 9 and Falcon Heavy launching with rapid cadence, and prepare for a scaled-up craft we're referring to as the 'BFR', or 'Falcon XX', which will have one 15m†† core of 9 Raptor methane engines, and generate 15Mlbf, and carry ~300 tons to LEO.

†They have certainly been jumping around a bit.  I think there was at least one recent comment from Shotwell, as well, about making something in the 150mT class, but this has not been corroborated.  I was convinced based on that comment of a 3-core 400-500mT architecture to launch the MCT vehicle until Musk himself came out with the 15Mlbf number... which is 2.5x as large as we thought a core would be a year ago - so things are still in flux.  We don't even know the official name of this rocket.

††Still conjecture, subject of much debate.
« Last Edit: 07/01/2014 01:35 AM by Burninate »

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Re: Blue Dragon and the International Mars Research Station
« Reply #3 on: 07/01/2014 01:27 AM »
Thanks for the reply  :)

The Wikipedia article for the BA 330 mentions "Bigelow has stated that the Atlas V 452 could launch the BA 330" which is what started me looking at the Atlas. However, now I think an SLS is probably a better choice. An FH might be able to launch it to LEO but not deliver it to the surface of Mars, I think, since a FH can only put 13t on Mars but the BA 330 weighs 20+t.

I know the FX/H is out of date now, I need to update those slides. The MCT is probably its replacement, or I could use the SLS in place of the FXH.


Offline Coastal Ron

  • Senior Member
  • *****
  • Posts: 3672
  • I live... along the coast
  • Liked: 2427
  • Likes Given: 3096
Re: Blue Dragon and the International Mars Research Station
« Reply #4 on: 07/01/2014 01:50 AM »
Thanks for the reply  :)

The Wikipedia article for the BA 330 mentions "Bigelow has stated that the Atlas V 452 could launch the BA 330" which is what started me looking at the Atlas. However, now I think an SLS is probably a better choice. An FH might be able to launch it to LEO but not deliver it to the surface of Mars, I think, since a FH can only put 13t on Mars but the BA 330 weighs 20+t.

I know the FX/H is out of date now, I need to update those slides. The MCT is probably its replacement, or I could use the SLS in place of the FXH.

Bob Bigelow stated that the Falcon Heavy would be able to lift a BA2100, which is substantially bigger than the BA330, so I would imagine the Falcon Heavy can also lift the BA330.  As to the fairing length, the Falcon 9 user's guide from 2012 (i.e. Falcon 1.0) references the fairing as their standard fairing, and I thought I had also heard that they could do custom fairings.  Ask SpaceX about it - I don't think it will be an issue.

As to Atlas V, the last I looked into it ULA was quoting something like 2-3 years to get Atlas Heavy ready for launch, since it has already passed it's PDR.  Atlas V can also accommodate custom fairings, and I think one they have in their user guide references the potential to go up to 100 feet long.  Lots of possibilities with that.

In general though I would hope that you settle on a payload architecture that can be lifted by more than one launcher.

You mention the SLS, but that is fraught with many issues, including that you would be a private concern trying to buy a taxpayer funded service, and the potential that the SLS won't be available when you need it (besides the potential for cancellation, NASA gets first dibs on whatever Congress funds).

So from that standpoint, if you standardize your payloads to not exceed what the current fleet of EELV-heavy launchers can support (i.e. Atlas V, Delta IV Heavy, Ariane 5, Proton, H-IIB and soon Falcon Heavy), then your ability to mount a mission quickly is greatly enhanced.  And yes, this does mean that departure stages have to go up separately, and maybe even be fueled in space - these are capabilities that we'll need for going to Mars in any case, so the sooner you use them the better.

My $0.02
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #5 on: 07/01/2014 03:12 AM »
Thanks for the reply  :)

The Wikipedia article for the BA 330 mentions "Bigelow has stated that the Atlas V 452 could launch the BA 330" which is what started me looking at the Atlas. However, now I think an SLS is probably a better choice. An FH might be able to launch it to LEO but not deliver it to the surface of Mars, I think, since a FH can only put 13t on Mars but the BA 330 weighs 20+t.

I know the FX/H is out of date now, I need to update those slides. The MCT is probably its replacement, or I could use the SLS in place of the FXH.

Bob Bigelow stated that the Falcon Heavy would be able to lift a BA2100, which is substantially bigger than the BA330, so I would imagine the Falcon Heavy can also lift the BA330.
Where? The BA2100 concept is suggested to be 70-100 tons and require an SLS-sized fairing.  Fortunately, it's largely notional - little more developed than a 'BA-1200' (that I just made up) that maximizes Falcon Heavy's capabilities.  The BA-330 is what they're trying to push as a mainstream building block.

Quote
In general though I would hope that you settle on a payload architecture that can be lifted by more than one launcher.
This would be a fair point, but a 20-ton payload & 5 meter fairing is depressingly small in reference to a Mars mission architecture, and the set of 20-ton launchers are 1-4x as expensive per launch as Falcon Heavy promises, and there really isn't anything else in the same class at this time.  The Angara/Angara-Baikal 7-core implementations are a few years farther off than Falcon Heavy, but they're the only things that come closer than the Delta IV Heavy to this tier of launch vehicle.

20 ton payloads would be *great* for the smaller or fully divisible building blocks if it were comparable, but the whole class is 2-8 times as expensive as the Falcon Heavy per kilogram.
« Last Edit: 07/01/2014 04:47 AM by Burninate »

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #6 on: 07/01/2014 04:31 AM »
Quote
However, if the BA 330 is launched deflated it will be empty after being inflated on orbit. This may necessitate at least one additional launch to deliver a fit-out crew to load supplies and fit-out the inside of the ship, including floors, cupboards, desks, beds, gym, laboratory, computers and solar storm shelter (the bathroom is already part of the BA 330 core). It is almost certainly preferable, simpler and safer to inflate, fit-out and stock the BA 330 on Earth prior to launch. Although this will require a larger vehicle to launch the module, it will avoid the cost of launching a fit-out crew as well as the necessary tools, supplies and equipment, and the risk to those astronauts.

The challenge, however, is finding a suitably capable vehicle that can accommodate a 6.7m-diameter payload. The obvious candidate is the SLS currently under development by NASA, which has a payload fairing of 8.4m. The Block IA Cargo version is capable of lifting 105 tonnes to LEO, which is obviously massive overkill in terms of launch capability, but it may be possible to include part of the cruise stage in the payload.
This seems ridiculous.  Inflatables are designed primarily to defeat the restriction on fairing diameter and maximize module volume per launch dollar.  I suggest that launching a second, (and third, and fourth, and fifth) Falcon Heavy flight to fill the inflatable hab in orbit, will be cheaper than flying one with a few extra tons of payload on it from the SLS pre-inflated.  Pre-inflated, aluminum is a familiar, proven technology with a good degree of structural rigidity and the option to use side attachment points.  From the SLS, Skylab or BA-2100 are both feasible - an inflated BA-330 combines the disadvantages of the one with the disadvantages of the other.
« Last Edit: 07/01/2014 04:38 AM by Burninate »

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #7 on: 07/01/2014 09:21 AM »
Quote
The MTV is constructed on Earth orbit. It’s designed to support a crew of six in a µg (microgravity) environment for the trip from Earth to Mars and back. It will only be used in space, and will not land on, or launch from, any planetary surface.

...

The engines will need to perform four major burns:

Trans Mars Injection (TMI) at ~Day 0
Mars Orbit Insertion (MOI) at ~Day 180
Trans Earth Injection (TEI) at ~Day 720
Earth Orbit Insertion (EOI) at ~Day 900
Quote
No aerobraking/aerocapture

An important consideration in Mars mission design is the amount of fuel to be carried with the spacecraft. In order to reduce the launched mass, aerobraking or aerocapture is sometimes used at Mars to slow the spacecraft and insert it into a Mars orbit, rather than controlling the spacecraft velocity purely using engines.

Aerobraking can take a very long time, up to six months at Mars, which makes it impractical for crew delivery, although it may be possible for cargo delivery.

Aerocapture is quicker, but the large drag forces can damage solar panels, antennas and other exposed equipment. It also requires a heat shield, and for a spacecraft with a 6.7 metre diameter this would be large and heavy (although an inflatable heat shield may be an option). The would partially or wholly offset the mass of saved fuel.

Aerobraking and aerocapture are also more risky. If the spacecraft hits the atmosphere at a slightly wrong angle, it can skip out and fly right past the planet. Also, due to atmospheric turbulence, variations in temperature, composition, etc., it can be difficult to predict the effects of aerobraking. However, if engines are used to control the spacecraft the effect can be precisely known, and if there are any minor miscalculations, additional small burns can be made to place the spacecraft into the correct, safe orbit.

Therefore, by ensuring we have enough fuel for MOI, and avoiding aerobraking/aerocapture, we gain the following advantages:

No risk to damage to spacecraft components through interaction with the atmosphere.
No need for a heat shield.
Higher predictability of spacecraft motion.
Higher certainty that the spacecraft will achieve the desired orbit.
No need to endanger the crew by attempting a risky manoeuvre with them on board.
The trade-off is additional fuel and a therefore a larger cruise stage.
So for 1 use, we're looking at something in the general vicinity, eyeballing some charts, of 17km/s, to get the MTV from LEO to LMO to LEO without using any aerobraking or aerocapture.  At 380s isp, this represents a wet:dry mass ratio of around 100:1, if you're returning the same cargo as you sent.  That's some stage, for a reusable vehicle - a high share of dry mass is likely to be tank and infrastructure for the MTV.  A ~20 ton hab with ~30 tons of supplies attached to a ~50 ton tank / superstructure thus implies 10,000 tons of fuel, not counting the one-way capsule.  That's far more than you've budgeted launches for, in the diagram where you build the MTV.

You could save some dV with high orbits, but what you wrote about aerobraking taking too long and direct injections to simplify the phases of the mission seems to suggest you don't want them.  Also, your comments seem to indicate that the lander ISRU is aimed at just enough delta V to get into a low orbit - so it would have to rendezvous with the MTV in that orbit.

Quote
Since our intention is to capture the spacecraft into Earth orbit, an EOI burn is required. The additional fuel must be transported to Mars and back, and this will necessitate a larger propulsion stage, which will incur a non-trivial cost. Note that this additional fuel requirement is mitigated by the fact that, in Blue Dragon, Adeona does not have a capsule attached during the return trip, hence the fuel required for TEI is correspondingly lower.
Coming back without a capsule attached leaves you reliant on everything working perfectly for an uncomfortable amount of complexity.

Quote
For now it is assumed that, unlike in the DRA, there will be only one cruise, so that no engines are discarded. This means a larger, heavier cruise stage that will cost more to build and launch, as the amount of mass that travels to Mars and back will be greater, necessitating more fuel and larger tanks. However, ultimately this approach is cheaper because the vehicle can be used over and over. It avoids wasting perfectly good engines, thus saving money and producing less space debris, and makes it cheaper, quicker and easier to run the next mission. Imagine the price of the tickets if every airline flight required new engines!
This analogy only gets you and Elon Musk so far.  A 100:1 wet:dry mass ratio is part of the reason we discard engines and tanks we don't want any more;  You saw this with the capsule.

The plan is missing specific quantified elements like orbits, delta V & propellant consumed per burn, and mass numbers for every part of the mission, along a timeline from start to finish.  If some of those numbers are unreasonable, as I suspect, then the mission needs to be redesigned.
« Last Edit: 07/01/2014 10:12 AM by Burninate »

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #8 on: 07/01/2014 09:59 AM »
Quote
Blue Dragon is somewhat more ambitious in that none of the propellant is brought from Earth. H2 is obtained from locally-available water extracted from the surrounding regolith. This is one of the most important and ambitious differences in the architecture. Collected H2O is electrolysed into H2 and O2, with the H2 being reacted with CO2 to produce CH4 and O2, as in Mars Direct, and the O2 from the water kept as additional oxidiser.

Although obtaining water from the regolith is a technical challenge, it’s certainly an achievable one. Since the development of Mars Direct and the DRA, considerable research has been conducted into how water can be obtained from the Martian environment, at NASA and elsewhere. There are important benefits to this strategy:

If we don’t have to bring any H2 from Earth, the mass of the landed MAV is reduced by the mass of the H2 and the associated tankage, including the additional H2 and tankage necessary to compensate for boil-off. As discussed in the section on propulsion systems, there are a range of non-trivial problems associated with storing and transporting H2 in space.
Making methalox from brought H2 and local CO2 doesn’t produce quite enough O2 for optimal combustion. For this reason, in Mars Direct additional O2 is produced from CO2 using the RWGS reaction. However, by using local H2O instead of brought H2, electrolysis of the water produces plenty of surplus O2, which means there’s no need for a RWGS circuit.
There are two potential sources of water on Mars. Accessing it is discussed further in the section on ISWP.

The atmosphere contains a small amount of water vapour, which can be collected using WAVAR equipment. The quantity of water that could be obtained in this way would be insufficient for ISPP, but a WAVAR-type device is still useful for drying atmospheric CO2.
The regolith holds up to about 60% water, depending primarily on latitude, with the dirt becoming wetter with increasing latitude. As discussed in the section on Location, an approximate useful latitude to obtain sufficient water from the ground is around 45°N, where the concentration is about 10% water.
Research has shown that a useful fraction of the water frozen in the top layer of regolith may be liberated using microwave radiation. A mobile robot equipped with a SRG (Stirling Radioisotope Generator) could potentially explore the local area around the MAV and use both microwaves and heat to liberate water from the regolith, capture it via condensation onto a cold surface, and deliver it to the MAV. This idea has been named AWESOM (Autonomous Water Extraction from the Surface Of Mars) and is described further in the section on ISWP.
Regolith H2O extraction is indeed ambitious relative to pure atmospheric ISRU, and well-suited to a rover precursor mission (or numerous identical rover precursor missions) like Green Dragon & MARCO-POLO.  I like this part.  The solar panel blanket is admirably simple - I don't think we're exploring the design space of photovoltaic versus reactor adequately ~20 years out, and the default choice is simply tons of solar panels, rolled out on the ground.

Have you thought about still sending the hydrogen, in a separate launch, for 'backup' purposes?  Nobody wants their ISRU rover to break down, but sometimes shit happens.  Saving 1.8 tons usable doesn't seem like a big enough deal to jeopardize the mission for, even if developing water extraction is a central component. 

Alternately, send all the methane down and just ISRU the oxidizer - as a backup to the normal route, which can be used for additional sample return in the event it's not needed.
« Last Edit: 07/01/2014 11:07 AM by Burninate »

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Re: Blue Dragon and the International Mars Research Station
« Reply #9 on: 07/01/2014 11:10 AM »
This seems ridiculous.  Inflatables are designed primarily to defeat the restriction on fairing diameter and maximize module volume per launch dollar.  I suggest that launching a second, (and third, and fourth, and fifth) Falcon Heavy flight to fill the inflatable hab in orbit, will be cheaper than flying one with a few extra tons of payload on it from the SLS pre-inflated.  Pre-inflated, aluminum is a familiar, proven technology with a good degree of structural rigidity and the option to use side attachment points.  From the SLS, Skylab or BA-2100 are both feasible - an inflated BA-330 combines the disadvantages of the one with the disadvantages of the other.

Thanks, Burninate. I agree that it does somewhat defeat the point of launching an inflatable, although inflatables still have the advantage of comparatively low density. However, I feel that fitting out the interior of a BA 330 for trip to Mars and back is a major task, and, even if it costs more, it is probably preferable for the engineers and designers to be able to do this work on Earth, rather than assign astronauts to the task and attempt to do it in µg.

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Re: Blue Dragon and the International Mars Research Station
« Reply #10 on: 07/01/2014 11:21 AM »
So for 1 use, we're looking at something in the general vicinity, eyeballing some charts, of 17km/s, to get the MTV from LEO to LMO to LEO without using any aerobraking or aerocapture.  At 380s isp, this represents a wet:dry mass ratio of around 100:1, if you're returning the same cargo as you sent.  That's some stage, for a reusable vehicle - a high share of dry mass is likely to be tank and infrastructure for the MTV.  A ~20 ton hab with ~30 tons of supplies attached to a ~50 ton tank / superstructure thus implies 10,000 tons of fuel, not counting the one-way capsule.  That's far more than you've budgeted launches for, in the diagram where you build the MTV.

Thanks for your help here. I am new to the rocket equation. The propellant page http://marsbase.org/propellant is my first application of it, and I've yet to apply this calculation to the MTV. I understand than in the DRA the engines and tanks are discarded after each burn, but this just seems wasteful to me. I may be overly optimistic, but I think that, with state-of-the-art engineering and manufacturing 15 years from now, it should be possible to avoid this. Nanostructured materials in particular should contribute to significantly reduced superstructure mass.

Quote
You could save some dV with high orbits, but what you wrote about aerobraking taking too long and direct injections to simplify the phases of the mission seems to suggest you don't want them.  Also, your comments seem to indicate that the lander ISRU is aimed at just enough delta V to get into a low orbit - so it would have to rendezvous with the MTV in that orbit.

Yes, that is the case. Same as the DRA.

Quote
Coming back without a capsule attached leaves you reliant on everything working perfectly for an uncomfortable amount of complexity.

True, but you're reliant on everything working perfectly anyway. By capturing into Earth orbit (if possible), a capsule can be launched from Earth, and the crew can descend from orbit, which is much safer and gentler than direct entry.

Quote
The plan is missing specific quantified elements like orbits, delta V & propellant consumed per burn, and mass numbers for every part of the mission, along a timeline from start to finish.  If some of those numbers are unreasonable, as I suspect, then the mission needs to be redesigned.

It's a work in progress :) Thanks so much for the feedback, it helps a lot.

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #11 on: 07/01/2014 11:24 AM »
This seems ridiculous.  Inflatables are designed primarily to defeat the restriction on fairing diameter and maximize module volume per launch dollar.  I suggest that launching a second, (and third, and fourth, and fifth) Falcon Heavy flight to fill the inflatable hab in orbit, will be cheaper than flying one with a few extra tons of payload on it from the SLS pre-inflated.  Pre-inflated, aluminum is a familiar, proven technology with a good degree of structural rigidity and the option to use side attachment points.  From the SLS, Skylab or BA-2100 are both feasible - an inflated BA-330 combines the disadvantages of the one with the disadvantages of the other.

Thanks, Burninate. I agree that it does somewhat defeat the point of launching an inflatable, although inflatables still have the advantage of comparatively low density. However, I feel that fitting out the interior of a BA 330 for trip to Mars and back is a major task, and, even if it costs more, it is probably preferable for the engineers and designers to be able to do this work on Earth, rather than assign astronauts to the task and attempt to do it in µg.
On the contrary, moving around multi-ton furnishings is *the easy part* of being in microgravity.  Velcro here, velcro there, carabiner here, cargo net there...  The limiting factor tends to be the diameter and availability of the portals between modules.

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #12 on: 07/01/2014 11:27 AM »
Quote
The MTV is constructed on Earth orbit. It’s designed to support a crew of six in a µg (microgravity) environment for the trip from Earth to Mars and back. It will only be used in space, and will not land on, or launch from, any planetary surface.

...

The engines will need to perform four major burns:

Trans Mars Injection (TMI) at ~Day 0
Mars Orbit Insertion (MOI) at ~Day 180
Trans Earth Injection (TEI) at ~Day 720
Earth Orbit Insertion (EOI) at ~Day 900
Quote
No aerobraking/aerocapture

An important consideration in Mars mission design is the amount of fuel to be carried with the spacecraft. In order to reduce the launched mass, aerobraking or aerocapture is sometimes used at Mars to slow the spacecraft and insert it into a Mars orbit, rather than controlling the spacecraft velocity purely using engines.

Aerobraking can take a very long time, up to six months at Mars, which makes it impractical for crew delivery, although it may be possible for cargo delivery.

Aerocapture is quicker, but the large drag forces can damage solar panels, antennas and other exposed equipment. It also requires a heat shield, and for a spacecraft with a 6.7 metre diameter this would be large and heavy (although an inflatable heat shield may be an option). The would partially or wholly offset the mass of saved fuel.

Aerobraking and aerocapture are also more risky. If the spacecraft hits the atmosphere at a slightly wrong angle, it can skip out and fly right past the planet. Also, due to atmospheric turbulence, variations in temperature, composition, etc., it can be difficult to predict the effects of aerobraking. However, if engines are used to control the spacecraft the effect can be precisely known, and if there are any minor miscalculations, additional small burns can be made to place the spacecraft into the correct, safe orbit.

Therefore, by ensuring we have enough fuel for MOI, and avoiding aerobraking/aerocapture, we gain the following advantages:

No risk to damage to spacecraft components through interaction with the atmosphere.
No need for a heat shield.
Higher predictability of spacecraft motion.
Higher certainty that the spacecraft will achieve the desired orbit.
No need to endanger the crew by attempting a risky manoeuvre with them on board.
The trade-off is additional fuel and a therefore a larger cruise stage.
So for 1 use, we're looking at something in the general vicinity, eyeballing some charts, of 17km/s, to get the MTV from LEO to LMO to LEO without using any aerobraking or aerocapture.  At 380s isp, this represents a wet:dry mass ratio of around 100:1, if you're returning the same cargo as you sent.  That's some stage, for a reusable vehicle - a high share of dry mass is likely to be tank and infrastructure for the MTV.  A ~20 ton hab with ~30 tons of supplies attached to a ~50 ton tank / superstructure thus implies 10,000 tons of fuel, not counting the one-way capsule.  That's far more than you've budgeted launches for, in the diagram where you build the MTV.

You could save some dV with high orbits, but what you wrote about aerobraking taking too long and direct injections to simplify the phases of the mission seems to suggest you don't want them.  Also, your comments seem to indicate that the lander ISRU is aimed at just enough delta V to get into a low orbit - so it would have to rendezvous with the MTV in that orbit.
Aerocapture is a very useful thing for interplanetary orbits, even Hohmann-transferred ones.  A nearly "free" solution seems to be the MSNW Magnetoshell AeroCapture system that Jon Goff is refining.  Its utility for a mission with parameters like this, where you want to re-use everything, is extreme.

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Re: Blue Dragon and the International Mars Research Station
« Reply #13 on: 07/01/2014 11:30 AM »
Regolith H2O extraction is indeed ambitious relative to pure atmospheric ISRU, and well-suited to a rover precursor mission (or numerous identical rover precursor missions) like Green Dragon & MARCO-POLO.  I like this part.  The solar panel blanket is admirably simple - I don't think we're exploring the design space of photovoltaic versus reactor adequately ~20 years out, and the default choice is simply tons of solar panels, rolled out on the ground.

Thanks. I must add to this section that Mars One are planning a precursor mission to experiment with water extraction from the regolith.

Re the solar blanket, how I imagine it will work is that, once the MAV has landed, a door will open up in the base and rotate forwards to form a ramp, down which will roll the AWESOM robot, connected to the end of the solar blanket, which it will unroll behind it. Once it has fully unrolled, the rover disconnects from it. For this to work the blanket must be resistant to sharp rocks, which may be a non-trivial challenge. The rover must also be able to work in the area around the MAV while avoiding the blanket.

Quote
Have you thought about still sending the hydrogen, in a separate launch, for 'backup' purposes?  Nobody wants their ISRU rover to break down, but sometimes shit happens.  Saving 1.8 tons usable doesn't seem like a big enough deal to jeopardize the mission for, even if developing water extraction is a central component.

This is a great idea! A Dragon capsule can deliver 2 tonnes of PL, which is enough for the H2 although tank mass is a consideration. Perhaps the whole capsule could be made into an H2 tank. The problem still remains how to get it to the MAV for ISPP.

Quote
Alternately, send all the methane down and just ISRU the oxidizer - as a backup to the normal route, which can be used for additional sample return in the event it's not needed.

This is the conclusion of the DRA trade study. It does make sense, I just feel we are capable of the greater challenge. It has been some time since DRA 5 and much has been learned.

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Re: Blue Dragon and the International Mars Research Station
« Reply #14 on: 07/01/2014 11:33 AM »
On the contrary, moving around multi-ton furnishings is *the easy part* of being in microgravity.  Velcro here, velcro there, carabiner here, cargo net there...  The limiting factor tends to be the diameter and availability of the portals between modules.

:) This made me laugh. Ok I'll concede the point. What they would do is build a mock-up on Earth anyway, and the astronauts could study it before going up to do the fit out.

Offline Burninate

  • Full Member
  • ****
  • Posts: 1130
  • Liked: 346
  • Likes Given: 72
Re: Blue Dragon and the International Mars Research Station
« Reply #15 on: 07/01/2014 11:47 AM »
This is the conclusion of the DRA trade study. It does make sense, I just feel we are capable of the greater challenge. It has been some time since DRA 5 and much has been learned.

So for 1 use, we're looking at something in the general vicinity, eyeballing some charts, of 17km/s, to get the MTV from LEO to LMO to LEO without using any aerobraking or aerocapture.  At 380s isp, this represents a wet:dry mass ratio of around 100:1, if you're returning the same cargo as you sent.  That's some stage, for a reusable vehicle - a high share of dry mass is likely to be tank and infrastructure for the MTV.  A ~20 ton hab with ~30 tons of supplies attached to a ~50 ton tank / superstructure thus implies 10,000 tons of fuel, not counting the one-way capsule.  That's far more than you've budgeted launches for, in the diagram where you build the MTV.

Thanks for your help here. I am new to the rocket equation. The propellant page http://marsbase.org/propellant is my first application of it, and I've yet to apply this calculation to the MTV. I understand than in the DRA the engines and tanks are discarded after each burn, but this just seems wasteful to me. I may be overly optimistic, but I think that, with state-of-the-art engineering and manufacturing 15 years from now, it should be possible to avoid this. Nanostructured materials in particular should contribute to significantly reduced superstructure mass.

The DRA 5 isn't the only mission architecture out there.  We probably have a list somewhere, though I can't find it atm.  The most common term used in descriptions of the Tsiolkovsky Rocket Equation is 'bitch', or in more polite company, 'tyranny'.  A purely chemical mission (no SEP, no nuclear thermal, no ISRU) is certainly brute-forceable using a propellant depot, but every little bit helps logarithmically, and the difficulty is per-landed-mass.

I am of the opinion that we need as many tricks as possible.  Of the innovations specific to thinking about Mars exploration programs, quite a number of them are needed in concert for any hope of practicality.  SEP or nuclear thermal (or nuclear electric) promise higher specific impulse, which helps more and more as the delta V requirement goes up.  ISRU is also 'free' reaction mass, deep into the mission, and the more you can use it the better off you are, in terms of mission mass requirements - that's why some others have tried to turn the Mars Ascent Vehicle into the entire return.  In my view the weakness of this strategy is *not* the propulsion, but the 6 months of coffin-like conditions without a habitat.

http://www.strout.net/info/science/delta-v/intro.html and http://en.wikipedia.org/wiki/Delta-v_budget#Budget have been quite useful to me.

Here's a pure SEP lander mission using SLS launches: http://spirit.as.utexas.edu/~fiso/telecon/Raftery_5-14-14/
Here's a nuclear thermal Phobos mission, which aims for low-ping telerobotic exploration of Mars using Falcon Heavy launches: http://spirit.as.utexas.edu/~fiso/telecon/Kabbaligere-Pica_6-11-14/
« Last Edit: 07/01/2014 12:03 PM by Burninate »

Online JasonAW3

  • Senior Member
  • *****
  • Posts: 2438
  • Claremore, Ok.
  • Liked: 395
  • Likes Given: 11
Re: Blue Dragon and the International Mars Research Station
« Reply #16 on: 07/01/2014 02:14 PM »
Quote
Following these will be the much larger, super-heavy-lift Falcon X rockets. These are being designed for Mars, which is the goal of SpaceX, but will be equally useful for heavy lifting to Earth orbit or the lunar surface. The Falcon X Heavy will be capable of delivering an impressive 125 tonnes to LEO or about 20-30 tonnes to the surface of Mars. Considering this is approximately the minimum mass of a surface habitat, this rocket will be a key enabler of human Mars missions.
"Falcon X" and "Falcon X Heavy" date to a 2010 powerpoint presentation which has been discredited as an obsolete chalkboard sketch.  Instead, the latest indications are that SpaceX will spend the next few years setting up launchsites and getting Falcon 9 and Falcon Heavy launching with rapid cadence, and prepare for a scaled-up craft we're referring to as the 'BFR', or 'Falcon XX', which will have one 15m†† core of 9 Raptor methane engines, and generate 15Mlbf, and carry ~300 tons to LEO.

†They have certainly been jumping around a bit.  I think there was at least one recent comment from Shotwell, as well, about making something in the 150mT class, but this has not been corroborated.  I was convinced based on that comment of a 3-core 400-500mT architecture to launch the MCT vehicle until Musk himself came out with the 15Mlbf number... which is 2.5x as large as we thought a core would be a year ago - so things are still in flux.  We don't even know the official name of this rocket.

††Still conjecture, subject of much debate.

WOAH!

     With a 15 meter diameter and 300 tons to LEO, they copuld launch six BA330's docking adapters and structural components for a space station all in one launch.
My God!  It's full of universes!

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Re: Blue Dragon and the International Mars Research Station
« Reply #17 on: 07/02/2014 07:33 PM »
With a 15 meter diameter and 300 tons to LEO, they copuld launch six BA330's docking adapters and structural components for a space station all in one launch.

I believe their plan is to land a hab that can also refuel and launch from Mars. The 15m diameter may be required to accommodate a heat shield for a 10m-diameter hab.

Online Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 9928
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 6733
  • Likes Given: 4523
Re: Blue Dragon and the International Mars Research Station
« Reply #18 on: 07/02/2014 07:53 PM »
I confess I'm at a loss as to why this proposal is titled  either "blue" (Mars is red) or "dragon" .. .didn't see any Dragons in it when I skimmed the proposal.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline mossy2100

  • Member
  • Posts: 14
  • Liked: 1
  • Likes Given: 3
Re: Blue Dragon and the International Mars Research Station
« Reply #19 on: 07/02/2014 09:07 PM »
I confess I'm at a loss as to why this proposal is titled  either "blue" (Mars is red) or "dragon" .. .didn't see any Dragons in it when I skimmed the proposal.

Thanks :) It's explained in the introduction:

Quote
The mission is named “Blue Dragon” because it makes use of Dragon capsules from SpaceX for transporting crew and cargo to and from Mars. The name is inspired by the "Red Dragon" landing system currently being developed for landing payloads on Mars using Dragon capsules. It’s “blue” because the blue planet is linking with the red planet, and because we're bringing water and oxygen to Mars.

It also acknowledges the blue dragon in the Dragon capsule logo.

Tags: Mars HSF