Yet another Mars architecture

RGClark · 2015-06-18 07:55:23

SpaceNut wrote:

The table would suggest that each craft would be in orbit at the same distance and speed before entering Mars to landing but that is not quite the case. We know that we can try to compansate for the differences in mass so that they do come in at the same rate of speed at aerocapture but when we see the entry results they still do not come out in the same orbiting distance. Even when we do take the time to use Aerobraking all that is for certain is that we will be lower and slower but it takes time.
I see that we have for a 21 m difference in diameter that we have a 9mt change and with just a 10 m diameter change that we have a 6mT from the 23 m diameter base line but when we use a parachute we will loss 3 mT of down mass starting point in fuel needs or are the columns starting mass switched.
http://en.wikipedia.org/wiki/Aerocapture
AEROCAPTURE DEMONSTRATION AND MARS MISSION APPLICATIONS
Trajectory Guidance for Mars Robotic Precursors: Aerocapture, Entry, Descent, and Landing
A Comparative Study of Aerocapture Missions with a Mars Destination
http://en.wikipedia.org/wiki/Aerobraking

Thanks for those links. I'm in favor of fast travel times to Mars. Rather than using propulsion to slow down, aerocapture would allow a smaller size vehicle to be used, and cheaper mission cost.

Bob Clark

RGClark · 2015-06-20 15:00:49

RGClark wrote:

RobS wrote:
Regarding the radiation issue, nuclear thermal doesn't help. If you go to Mars faster, you can't aerobrake; the atmosphere isn't thick enough (according to Zubrin) if transit times are less than 5 months. So if you go faster, you have to haul along the fuel to stop, then the fuel to return to Earth faster as well. It's simply not feasible, from everything I have read.
If you have unlimited propellant such as from lunar-derived propellant depots that's not a problem with either nuclear propulsion or chemical propulsion. I prefer chemical propulsion since it's already here.

After a calculation I was surprised to discover that with orbital propellant depots, manned interplanetary flights become scarcely more expensive than flights to LEO. That is, spaceflight to the Moon, Mars, Venus, asteroids could become as routine as flights to the ISS are now just by having propellant depots in place at departure and arrival points.

For instance rather than the 1,000 metric tons(mT) estimated needed to be launched to orbit for a manned Mars mission, a single empty Falcon 9 first stage at ca. 15 mT dry mass could do ALL the propulsion stages by itself, when you have propellant depots at Earth orbit and Mars orbit. No huge, and hugely expensive, Mars Colonial Transport, SLS, or even Falcon Heavy required.

And it's not just the Falcon 9 first stage. It would also work for the first stages for the Atlas V, the Delta IV, the Ariane 5, the Soyuz, etc., with the empty stages lofted to orbit and refueled in orbit at both departure and arrival points. This means every space faring nation could do Mars missions for little more than currently used to send flights to the ISS.

Here is the calculation the Falcon 9 first stage could to the round trip flight with orbital refueling:

The Coming SSTO's: Applications to interplanetary flight.
http://exoscientist.blogspot.com/2012/0 … ns-to.html

This was focusing on single-stage-to-orbit (SSTO) vehicles but this is not a requirement. Any currently in use medium size launcher's first stage would work. You would need low cost propellant delivered to orbit. Fully reusable launchers bringing the price to orbit down to ca. $100 per kilo would do it.

But it could also be done with the propellant obtained off-Earth. Some Mars advocates have been opposed to propellant depots since it was thought the propellant had to be obtained from the Moon, requiring giga-dollar expenditures. But it doesn't have to be from the Moon. For instance there are near Earth comets that experience outgassing, as has been observed by the Rosetta spacecraft:

Dust Whirls, Swirls and Twirls at Rosetta’s Comet.

by BOB KING on MARCH 9, 2015
http://www.universetoday.com/119296/dus … tas-comet/

In such a case, no landing or mining would be required. You would just collect the released H2O, and CO2, CO for hydrocarbon fuel, from orbit.

Bob Clark

Last edited by RGClark (2015-06-20 15:13:01)

SpaceNut · 2015-06-20 19:06:19

We actually had a topic with Depot's but it is so dependant on type of fuel that is being stored as to its usefulness...

Here is yet another architecture... A Scenario for a Human Mission to Mars Orbit in the 2030s
Its from Hoppy Price*, John Baker*, and Firouz Naderi* with thoughts Toward an Executable Program Fitting Together Puzzle Pieces & Building Blocks, A Future In-Space Operations (FISO) Telecon May 20, 2015 by *Jet Propulsion Laboratory California Institute of Technology.

It is suggested that splitting the efforts into a 2 step plan of first going to Mars orbit for a cycle duration and then a short stay on the surface in a later mission that returns to orbiting base as set by the first mission finally followed by a long term stay on the surface is to there liking. pg7/8

Using what we have currently but since we have no long term habitat other than the ISS or a lander we do not have all the pieces yet for this concept for it to work with keeping costs inline with current budgetting that Nasa has or of its future sand chart graphs....

By going to the Mars moons first we side step the issue of large mass landing for mars, a return mav from the surface using ISPP and it allows that time for design to catch up to what we do need for doing so. It starts a base to continue going to Mars if only be leaving the landers base behind as a building block for landing vehicles for Mars some far off future times once refueled.

So a re-designed for room lunar lander is more than capable to land on the moons of Mars and provide the stay that we would want.

The only item remaining on the fear page is exposure to radiation types that cause health issues.

RobS · 2015-06-20 22:01:58

Thanks, RGClark, for the link. I have taken a similar approach, but I assumed a vehicle with a delta-v of about 5 to 5.5 km/sec is sufficient. It can't launch itself to LEO from the earth's surface, but can serve as a second stage. Once in LEO, if it refuels it can get to low lunar orbit or, with aerobraking, to the Martian surface. Refueled on the Martian surface, it can get to high Martian orbit. Refueled in lunar orbit or at L1, it can land on the moon; refueled there, it has plenty of delta-v to return to Earth. All that depends on fuel depots, though.

RobertDyck · 2015-06-21 15:16:25

We are running in circles. Great recent discovery! Aerocapture reduces launch mass! That was part of Mars Direct in late 1989 / early 1990. And propellant depots work, but only if you collect propellant from asteroids, not the Moon. But that raises the question: how much infrastructure and how much cost to set that up? Again, same old stuff from 1990. We're stuck running in circles, like a dog chasing its tail. Meanwhile Old Space contractors and certain individuals in NASA keep trying to do the "90 Day Report", despite the fact Congress rejected it in 1989.

Last edited by RobertDyck (2015-06-21 16:18:47)

SpaceNut · 2015-06-22 20:48:04

Of all the running around in circles; what do we not have besides funding to make a mission to Mars mission Happen or astronauts to civilians that want to go?

Launchers we have if we ignore the Man rating question...

1. transit vehicle / habitat in 0G ; only the ISS as a model of the pieces that it would contain

2. Mars lander and ascent capable of down mass for life to be sustain as well as return to orbit ; developemental work at best in space x first stage reuseability or Nasa's lunar developement and flying saucer
A. insitu useage to lesson down mass ; only ISPP developement demonstrated but not working so well on
the ISS

RobertDyck · 2015-06-22 22:47:28

I argue NASA has sufficient funding right now. Many on this forum argued that cancelling Shuttle would free sufficient funds for Mars. Well, it is cancelled, but still no Mars. NASA currently has enough funding for JPL to continue unmanned probes to explore the solar system, plus develop aircraft technology (NASA inherited the mandate of NACA), and operate ISS, everything it currently does. And go to Mars. Doing that with current funding means give up on the Moon or asteroids, focus on Mars. Redirect funding for Orion and SLS to Mars. That may mean using SLS for Mars, but definitely cancel Orion. America would still have Dragon v2, CST-100, and I argue to fund DreamChaser. That's 3 crew vehicles. Plus Dragon CRS and Cygnus for cargo. Plus international partners: ATV and HTV.

I've listed before specific technologies we need for Mars. But most importantly we just need the will. NASA doesn't need more funding, but definitely don't cut NASA's budget. Perhaps part of the problem is certain individuals keep trying to do the 90-Day-Report, together with its multi-hundred-billion dollar price tag. As long as Mars advocates ask for that much funding, it won't happen.

Last edited by RobertDyck (2015-06-23 00:02:30)

RGClark · 2015-06-24 07:03:55

SpaceNut wrote:

We actually had a topic with Depot's but it is so dependant on type of fuel that is being stored as to its usefulness...
Here is yet another architecture... A Scenario for a Human Mission to Mars Orbit in the 2030s
Its from Hoppy Price*, John Baker*, and Firouz Naderi* with thoughts Toward an Executable Program Fitting Together Puzzle Pieces & Building Blocks, A Future In-Space Operations (FISO) Telecon May 20, 2015 by *Jet Propulsion Laboratory California Institute of Technology.
It is suggested that splitting the efforts into a 2 step plan of first going to Mars orbit for a cycle duration and then a short stay on the surface in a later mission that returns to orbiting base as set by the first mission finally followed by a long term stay on the surface is to there liking. pg7/8

Don't know if the report discusses this but it has been suggested that Phobos has high amounts of subsurface water as Mars does. This conclusion comes from its surprisingly low density. Then it may be possible to set up propellant depots on Phobos and you could do the Mars landing on the first mission. Note also having a propellant depot on Phobos allows you to do a fully propulsive landing on Mars, solving the problem of landing large mass on Mars.

Bob Clark

Antius · 2015-06-24 21:55:45

RobertDyck wrote:

We are running in circles. Great recent discovery! Aerocapture reduces launch mass! That was part of Mars Direct in late 1989 / early 1990. And propellant depots work, but only if you collect propellant from asteroids, not the Moon. But that raises the question: how much infrastructure and how much cost to set that up? Again, same old stuff from 1990. We're stuck running in circles, like a dog chasing its tail. Meanwhile Old Space contractors and certain individuals in NASA keep trying to do the "90 Day Report", despite the fact Congress rejected it in 1989.

What about harvesting propellant from Earth's rarefied atmosphere in LEO? The ionosphere is about 50-50 mix of oxygen and nitrogen. That's most of the mass needed for an ammonia oxygen propellant.

kbd512 · 2015-06-27 18:51:45

SpaceNut wrote:

Of all the running around in circles; what do we not have besides funding to make a mission to Mars mission Happen or astronauts to civilians that want to go?
Launchers we have if we ignore the Man rating question...
1. transit vehicle / habitat in 0G ; only the ISS as a model of the pieces that it would contain

2. Mars lander and ascent capable of down mass for life to be sustain as well as return to orbit ; developemental work at best in space x first stage reuseability or Nasa's lunar developement and flying saucer
A. insitu useage to lesson down mass ; only ISPP developement demonstrated but not working so well on
the ISS

Development of a SEP tug, CL-ECLSS, active radiation shielding, artificial gravity, Dragon V2, and Falcon Heavy have not been completed. Once those development tasks have been completed and the hardware has been flown, everything required to get to/from Mars will be ready. Assuming development funding continues, SLS would permit NASA to use larger MTV's modeled after the Skylab II concept.

If the argument for continuation of Orion's development is national security, then the military can pay for it. Apart from that, it serves no other purpose in its current configuration for deep space exploration. If Orion's command module was redesigned for in-space operation only, as in the Orion Deep Space Vehicle concept, only then would Orion have marginal utility for cislunar missions.

There's currently no funding available for a lander of any kind because the combination of Orion and SLS is sucking the life out of the manned space program. In another ten years or so we'll have the technology to get there and back, but not land. Since the goals for NASA's manned space program clearly don't involve any actual space exploration, it doesn't matter.

RobS · 2015-06-28 08:31:28

Boom! So much for Falcon 9's perfect launch record.

GW Johnson · 2015-06-28 09:56:47

If I were them, I'd be looking real hard at propellant leaks in the second stage. Early at lower altitude I saw signs of propellant flash-burning erratically alongside the rear end of the first stage. Then I saw flashes of white "cloud" moving down the side of the vehicle coming from the interstage. The higher the altitude and thinner the air, the more of this leaking "something" I saw. When the explosion occurred, I saw "for sure" in the video that the first stage was still intact with all engines firing, for a finite amount of time.

That tells me that something reactive was leaking from the second stage into the interstage volume around that engine. They were approaching the staging point, and systems were firing up electrically to make that happen. Electricity and loose propellants are an explosive combination. It couldn't have been just kerosene, there's almost no air up there with which it could burn (you can see that by the first stage rocket plumes ballooning out in the nearly-zero backpressure). It had to be both kerosene and LOX that were leaking! Holes in both tanks cannot be ruled out, but seem most unlikely.

I'd be looking very, very seriously at propellant line stop valves to the turbopumps that opened prematurely somehow.

GW

RobertDyck · 2015-06-28 11:59:08

kbd512 wrote:

Development of a SEP tug, CL-ECLSS, active radiation shielding, artificial gravity, Dragon V2, and Falcon Heavy have not been completed. Once those development tasks have been completed and the hardware has been flown, everything required to get to/from Mars will be ready. Assuming development funding continues, SLS would permit NASA to use larger MTV's modeled after the Skylab II concept.

We don't need SEP for a human mission. It would be "nice to have" for the unmanned components, but too slow for crew, and we can use the SLS upper stage for TMI. Especially for crew. Minimagnetosphere is active radiation shielding. That would be *REALLY* nice to have, but the Mars Direct concept of a radiation shelter with 10cm of water or equivalent with food is good enough. Especially if transit is 6 months like Spirit or Opportunity, not 8.5 months like Curiosity. CL-ECLSS is absolutely necessary; I have argued for one based on the system on ISS, but with a few upgrades. Recent resupply failures demonstrate the need to install them on ISS. And I would like to operate ISS without resupply for the full duration of a Mars mission: Earth to Earth. Artificial gravity: absolutely! I have argued for a demonstration using Dragon V2 tethered to a Dragon CRS. It would use a cargo Dragon after all cargo has been delivered, and filled with garbage, destined to return to Earth or burn up in the atmosphere. That way the cargo Dragon is expendable. And demonstrate they can manoeuvre while rotating in artificial gravity. Falcon Heavy is scheduled for first test flight some time this year, with first payload in 2017. Let's hope that happens.

I have argued for an MTV (as you call it) based on the upper floor alone of Mars Direct, plus ADEPT for aerocapture, plus Dragon for an escape pod / lifeboat. That would have the same diameter as Skylab II, but much shorter. Keep it small to keep it affordable.

kbd512 wrote:

There's currently no funding available for a lander of any kind because the combination of Orion and SLS is sucking the life out of the manned space program. In another ten years or so we'll have the technology to get there and back, but not land. Since the goals for NASA's manned space program clearly don't involve any actual space exploration, it doesn't matter.

Corporate executives from all "Old Space" contractors, and some individuals at NASA, are still trying to do the "90 Day Report". People on this forum argued that cancelling Shuttle would free funds for Mars, but as soon as it was cancelled, all funds were directed to the "90 Day Report". That plan called for a space station as large as ISS, but ISS is built. The next step was a permanent human base on the Moon. Notice were Shuttle funding went: Constellation included the Altair lander that was to be a permanent human base on the Moon. Obama cancelled Constellation, but Congress brought it back. NASA is continuing to limp along in the direction of "90 Day Report". One NASA manager said "we have a plan, don't change change direction now". But the plan NASA is trying to follow is the one Congress rejected in 1989: the "90 Day Report". Orion has one purpose, and only one purpose: return to the Moon. But it can't even enter lunar orbit; it needs some other stage to do that. And would require the Orion 606 service module to depart lunar orbit, the ATV-based service module isn't quite good enough for that. So Orion can't do anything. It's just a cash cow. Time to redirect cash to actually accomplish something.

RobertDyck · 2015-06-28 13:03:46

RobS wrote:

Boom! So much for Falcon 9's perfect launch record.

(Sniffle) What more can I say?

RobS · 2015-06-28 16:07:04

Well, no one expected it to continue forever. It turns out, this was the first flight of the upgraded rocket, with extended fuel tanks and new, lighter, more powerful engines. Sounds like they didn't get everything tweaked right for the new version.

SpaceNut · 2015-06-28 16:47:15

With regards to "CL-ECLSS is absolutely necessary" I base the desicion on it only being a 8 month trip out or back as not needing a fully closed loop as the period of operation is not forever and even with the ISS we know that its system can do what we need it to do with the proper resupply quantities made readily available for when it does not have anything remaining to reprocess for the system.
Mars surface will also be one where with the proper location selection we will use the insitu resources to resupply our system in just the same way so it does not need to be a total closed loop system either.

As for Space x changes in design creep always will do this if not enough testing is done...just glad no people were onboard for this acident... just saying

RobertDyck · 2015-06-28 17:49:14

A Canadian news network interviewed a Canadian astronaut re today's failure. Chris Hadfield said ISS recycles 92% of its water. That's pretty good. In the book "The Case for Mars", Robert Zubrin said NASA wanted 95% water and O2 recycling before they would go to Mars. I suggested a toilet that can recover moisture from feces. I suggested a contest: NASA build one based on the one JSC built for the Advanced Life Support Project, and Russia just install the one they already designed for Zvezda. And a clothes washer; they could launder wash cloths to recover moisture. Add the sink and shower designed for the US Hab module. The water processing assembly can already handle wash water. All that should push water recycling to the 95% that NASA wanted for Mars.

For oxygen recycling, I said also tweak the system on ISS. Add a direct CO2 electrolysis system, based on the ISPP Precursor built for the Mars 2001 Lander. That lander was not launched after failure of Mars Polar Lander. It was later reconfigured to become Mars Pheonix. The ISPP Precursor and radiation sensor were removed to add more science instruments. Curiosity has a radiation sensor, so that function is covered. But the ISPP Precursor would have produced oxygen by direct CO2 electrolysis. Currently ISS routes half the CO2 removed from cabin air into the Sabatier, but what the Sabatier cannot use is dumped in space. I suggest the CO2 that would otherwise be dumped, instead directed to the direct CO2 electrolysis system. It would only convert 80% of CO2 into CO and O2, so that means only recover 40% of O2 contained in that CO2. But 40% is better than zero percent. That would consume significant electrical power, about 3 times as much per kg of O2 vs the current system. But it would help replenish recycling losses.

And SpaceNut (I think) posted a link about a device to use pyrolysis to recover hydrogen from methane. The Sabatier produces methane, currently dumped in space. Pyrolysis will recover some of the hydrogen, to be recycled back to the Sabatier. More hydrogen means the Sabatier can process more CO2. Which is more efficient? CO2 electrolysis or methane pyrolysis? Test on ISS.

Remember, Mars Direct is 6 months to Mars, 500 days on the surface, then 6 months back. That's 28.5 months round trip. The trip back is in the ERV, but that's still 22.5 months in the Hab. We need a good life support system, and I could go on about backup modes, but these specific updates to the system on ISS would make us ready for Mars.

RobertDyck · 2015-06-28 19:25:47

Perhaps I should mention backup modes. If life support partially fails, but water electrolysis still works, then melt some Mars permafrost, filter, and run through electrolysis for water. Direct CO2 electrolysis is needed for ISPP, so the ERV will have it. If everything else fails, that can be used to harvest CO2 from Mars atmosphere and produce oxygen for cabin air. Stored, pressurized O2. Oxygen "candles" like those on ISS. And the suits have a certain amount of life support. The greenhouse should have a connection to the Hab, so it can be used as a backup for O2. And humidity will condense on cold walls of the greenhouse, dripping into troughs. That water can be fed back into greenhouse soil trays, but can also be used as a backup for water recycling. Biosphere 2 demonstrated a greenhouse cannot be relied upon exclusively for O2, but it's the only backup to generate O2 that doesn't require power. Plants use sunlight.

The point is both electrolysis systems are needed.

kbd512 · 2015-06-29 04:04:44

RobertDyck wrote:

We don't need SEP for a human mission. It would be "nice to have" for the unmanned components, but too slow for crew, and we can use the SLS upper stage for TMI. Especially for crew. Minimagnetosphere is active radiation shielding. That would be *REALLY* nice to have, but the Mars Direct concept of a radiation shelter with 10cm of water or equivalent with food is good enough. Especially if transit is 6 months like Spirit or Opportunity, not 8.5 months like Curiosity. CL-ECLSS is absolutely necessary; I have argued for one based on the system on ISS, but with a few upgrades. Recent resupply failures demonstrate the need to install them on ISS. And I would like to operate ISS without resupply for the full duration of a Mars mission: Earth to Earth. Artificial gravity: absolutely! I have argued for a demonstration using Dragon V2 tethered to a Dragon CRS. It would use a cargo Dragon after all cargo has been delivered, and filled with garbage, destined to return to Earth or burn up in the atmosphere. That way the cargo Dragon is expendable. And demonstrate they can manoeuvre while rotating in artificial gravity. Falcon Heavy is scheduled for first test flight some time this year, with first payload in 2017. Let's hope that happens.
I have argued for an MTV (as you call it) based on the upper floor alone of Mars Direct, plus ADEPT for aerocapture, plus Dragon for an escape pod / lifeboat. That would have the same diameter as Skylab II, but much shorter. Keep it small to keep it affordable.

My opinion, and NASA's apparently, is that we do need SEP for a human mission to Mars. Any mission that provides adequate consumables and spares to account for losses requires a lot of cargo delivered to the surface of Mars. The chemical alternative requires an excessive amount of mass to be devoted to propulsion.

WRT a more reliable ECLSS than current ISS hardware, NASA's still some five to seven years away from flying it aboard ISS.

As far as radiation shielding is concerned, I think an active + passive solution is the way to go. It's layered defense against the radiation environment. Radiation is not a showstopper, but I want our explorers afforded reasonable protection from the lethal environment they must traverse to get to Mars and I think this is reasonable.

I wanted something like Skylab II developed because it has the requisite internal volume for comfortable long duration habitation, propellant storage for electric propulsion, and active radiation shielding in a package requiring fewer assembly operations. I think a manned Mars Transfer Vehicle rates flagship mission status and justifies the expense of a SLS flight.

As far as the capsule systems are concerned, I don't see Dragon V2 or Orion as realistic lifeboats for missions so far from Earth. I think adding a capsule of either type is dragging unnecessary mass to Mars and back. The crew can't live aboard either capsule for more than a few days and any exigent circumstance that requires the crew to abandon the MTV is not likely to be a temporary condition.

RobertDyck wrote:

Corporate executives from all "Old Space" contractors, and some individuals at NASA, are still trying to do the "90 Day Report". People on this forum argued that cancelling Shuttle would free funds for Mars, but as soon as it was cancelled, all funds were directed to the "90 Day Report". That plan called for a space station as large as ISS, but ISS is built. The next step was a permanent human base on the Moon. Notice were Shuttle funding went: Constellation included the Altair lander that was to be a permanent human base on the Moon. Obama cancelled Constellation, but Congress brought it back. NASA is continuing to limp along in the direction of "90 Day Report". One NASA manager said "we have a plan, don't change change direction now". But the plan NASA is trying to follow is the one Congress rejected in 1989: the "90 Day Report". Orion has one purpose, and only one purpose: return to the Moon. But it can't even enter lunar orbit; it needs some other stage to do that. And would require the Orion 606 service module to depart lunar orbit, the ATV-based service module isn't quite good enough for that. So Orion can't do anything. It's just a cash cow. Time to redirect cash to actually accomplish something.

You're preaching to the choir, rev.

RobS · 2015-06-29 06:46:22

Regarding artificial gravity, here a link to a paper that says 6 rpm is probably not a problem and that even 10 rpm may be adaptable:

http://space.alglobus.net/papers/RotationPaper.pdf

--RobS

RobertDyck · 2015-06-29 10:51:44

kbd512 wrote:

My opinion, and NASA's apparently, is that we do need SEP for a human mission to Mars.

More obstacles = more delays. And more excuses to not go.

kbd512 wrote:

WRT a more reliable ECLSS than current ISS hardware, NASA's still some five to seven years away from flying it aboard ISS.

Not sure what "WRT" is. There have been a few proposals for life support, not of which are anywhere near ready for space. The system on ISS has proven itself. It works.

kbd512 wrote:

As far as radiation shielding is concerned, I think an active + passive solution is the way to go.

Again, more obstacles = more delays. And more excuses to not go.

kbd512 wrote:

I wanted something like Skylab II developed because it has the requisite internal volume for comfortable long duration habitation, propellant storage for electric propulsion, and active radiation shielding in a package requiring fewer assembly operations. I think a manned Mars Transfer Vehicle rates flagship mission status and justifies the expense of a SLS flight.

I proposed the upper floor alone of the Mars Direct habitat. That has as much floor area as a 60-foot class A motorhome with slide-outs. That's so large that government regulations do not permit it in many states of the US. It's categorized as mobile home, not a motorhome. It's only available in states that categorize it as a motorhome. Class A motorhome is one that looks like a highway bus, such as a Greyhound bus. The largest on the Winnebago website is 42' 10" long, and that has dual rear axles. You claim that isn't enough? With my mission plan, the vehicle would include the ITV habitat (you call it MTV), expendable propulsion stage, Dragon capsule as lifeboat, ADEPT heat shield for aerocapture, and Mars lander. The ITV with ADEPT could be launched on a single SLS block 1, the Dragon capsule on Falcon 9, and propulsion stage on another SLS block 1. I had originally said launch the ITV on Delta IV Heavy or Falcon Heavy, but there is concern over fairing diameter. The lander with unpressurized rover should fit on Falcon 9. But if you use SLS block 1 to launch ITV with ADEPT, then it has so much additional launch mass that it could lift the Mars lander with unpressurized rover as well. That eliminates one launch and assembly step.

kbd512 wrote:

As far as the capsule systems are concerned, I don't see Dragon V2 or Orion as realistic lifeboats for missions so far from Earth. ... The crew can't live aboard either capsule for more than a few days and any exigent circumstance that requires the crew to abandon the MTV is not likely to be a temporary condition.

Dragon V2 total launch weight is 8.0 metric tonnes, including full propellant tanks and LAS. Orion launch weight is 28.0 metric tonnes. So no, we can't use Orion. But astronauts can live in Dragon. With addition of a life support module docked to the nose, they could travel all the way from Mars to Earth, but that means 6 months in zero-G. But that isn't why my plan includes it. My plan uses aerocapture at Earth, to enter Earth orbit. Then aerobraking down to the orbit of ISS. The reusable ITV would then dock with ISS, using the ISS as both construction shack and bus terminal. But design of any spacecraft must include contingencies in case something goes wrong. During the interview on NASA TV yesterday, Gwynne Shotwell said if Dragon V2 were on top of Falcon 9 when yesterday's incident happened, the Launch Abort System would have been able to pull astronauts to safety. She said it's designed for more energetic contingencies that the one that happened. So contingencies are necessary. So what happens if aerocapture fails? ADEPT is not designed to protect a Mars Direct habitat for direct entry in Earth's atmosphere on return from Mars. If aerocapture dips too deeply into Earth's atmosphere, then they can "bail out" in Dragon. That means they'll only be in Dragon for about half an hour. Then either splash down, or enter Earth orbit for a slow series of aerobraking to drop down to ISS orbit.

kbd512 wrote:

You're preaching to the choir, rev.

Everybody say: "Hallelujah!"

Last edited by RobertDyck (2015-06-29 10:52:10)

RobS · 2015-06-29 10:58:56

We don't need SEP if propellant in LEO is cheap enough, and by the time we are ready to launch to Mars, launches to orbit may be as low as a million dollars per tonne. As I noted before, xenon is incredibly expensive. The latest NASA plan uses it because SLS is incredibly expensive to LEO.

kbd512 · 2015-06-29 14:07:14

RobertDyck wrote:

More obstacles = more delays. And more excuses to not go.

If NASA has to pay for chemical propulsion, it's a guaranteed that we're not going. Launch costs are insane.

RobertDyck wrote:

Not sure what "WRT" is. There have been a few proposals for life support, not of which are anywhere near ready for space. The system on ISS has proven itself. It works.

WRT = With Respect To

NASA has had a replacement in development to replace the current ECLSS flying aboard ISS for some time. Development has tracked as expected thus far. These things take time.

RobertDyck wrote:

Again, more obstacles = more delays. And more excuses to not go.

NASA won't go without it because of all the hay they've made regarding a problem that our astronauts already contend with. It's a boogie monster meant to scare the children, I mean astronauts, with.

RobertDyck wrote:

I proposed the upper floor alone of the Mars Direct habitat. That has as much floor area as a 60-foot class A motorhome with slide-outs. That's so large that government regulations do not permit it in many states of the US. It's categorized as mobile home, not a motorhome. It's only available in states that categorize it as a motorhome. Class A motorhome is one that looks like a highway bus, such as a Greyhound bus. The largest on the Winnebago website is 42' 10" long, and that has dual rear axles. You claim that isn't enough? With my mission plan, the vehicle would include the ITV habitat (you call it MTV), expendable propulsion stage, Dragon capsule as lifeboat, ADEPT heat shield for aerocapture, and Mars lander. The ITV with ADEPT could be launched on a single SLS block 1, the Dragon capsule on Falcon 9, and propulsion stage on another SLS block 1. I had originally said launch the ITV on Delta IV Heavy or Falcon Heavy, but there is concern over fairing diameter. The lander with unpressurized rover should fit on Falcon 9. But if you use SLS block 1 to launch ITV with ADEPT, then it has so much additional launch mass that it could lift the Mars lander with unpressurized rover as well. That eliminates one launch and assembly step.

I don't claim that a repurposed ISS module isn't "enough space" for the astronauts. It's entirely dependent upon the attitude of our explorers and whatever goes on upstairs in the designers heads. Some at NASA don't think ISS modules provide enough habitation space for the astronauts.

RobertDyck wrote:

Dragon V2 total launch weight is 8.0 metric tonnes, including full propellant tanks and LAS. Orion launch weight is 28.0 metric tonnes. So no, we can't use Orion. But astronauts can live in Dragon. With addition of a life support module docked to the nose, they could travel all the way from Mars to Earth, but that means 6 months in zero-G. But that isn't why my plan includes it. My plan uses aerocapture at Earth, to enter Earth orbit. Then aerobraking down to the orbit of ISS. The reusable ITV would then dock with ISS, using the ISS as both construction shack and bus terminal. But design of any spacecraft must include contingencies in case something goes wrong. During the interview on NASA TV yesterday, Gwynne Shotwell said if Dragon V2 were on top of Falcon 9 when yesterday's incident happened, the Launch Abort System would have been able to pull astronauts to safety. She said it's designed for more energetic contingencies that the one that happened. So contingencies are necessary. So what happens if aerocapture fails? ADEPT is not designed to protect a Mars Direct habitat for direct entry in Earth's atmosphere on return from Mars. If aerocapture dips too deeply into Earth's atmosphere, then they can "bail out" in Dragon. That means they'll only be in Dragon for about half an hour. Then either splash down, or enter Earth orbit for a slow series of aerobraking to drop down to ISS orbit.

Here you are talking about inserting more delays, more testing, and more launches into the mission, but delays for CL-ECLSS and active radiation shielding are unreasonable? Why? What magic do these tiny, but massive, capsules provide on deep space missions? If you don't do dangerous stunts like aerobraking, then you don't need them. Dragon V2, like Orion, isn't going to land anywhere but Earth in its present configuration. My argument is that the consumables and spares (repair kit for the MTV) is more valuable to the crew than a capsule that they can't live in for the duration of the mission.

RobertDyck · 2015-06-29 14:20:22

kbd512 wrote:

Dragon V2, like Orion, isn't going to land anywhere but Earth in its present configuration.

I said Dragon. Gwynn Shotwell talked about using Dragon V2 to transport crew to ISS. I would prefer the current Dragon for Mars. Dragon Rider was a design that never flew; a full-size mockup was built, but no flight vehicle. It was the current Dragon (Cargo Resupply Ship), but with launch abort rockets on the side, an APAS hatch instead of CBM hatch, seat / controls / life support. I don't think any form of LAS is needed for a life boat. Thrusters built into Dragon CRS are enough for my proposal. Of course if you deliver crew to the Mars vehicle from Earth with the same Dragon that you use as life boat, then you need LAS. Just for launch from Earth. But that means I'm not arguing for Dragon V2. If SpaceX says the only version of Dragon is V2, and it's the same mass as Dragon Rider, then fine. Use that. But SpaceX is adding complexity, not me.

RobertDyck · 2015-06-29 15:12:01

RobS wrote:

SLS is incredibly expensive

Congress wants SLS. Remember president Obama cancelled Constellation, and Ares I & V along with it. The Senate brought back Ares V as SLS. If we fight against that, we're unlikely go gain Congressional approval. Congress wants jobs in their districts. They want to justify JSC, and operating ISS without Shuttle cannot justify JSC. And they keep talking about decommissioning ISS. That would require closing JSC. So SLS is there to justify it's full staff and keep it open. Now that Shuttle ET is not longer made, Michoud not longer has any purpose at all. So the SLS core stage is based on ET, just to keep Michoud open. Stennis and Marshall need something to justify their staff level. So it's make-work.

If you remember, the first version of my plan didn't include SLS at all. I came up with a few options, using different launch vehicles. But using what Congress is trying to justify may have the greatest chance of approval.

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