Blue Origin Thread (merged)

[Northstar1989]

There are a number of ways SpaceX could improve the efficiency of their plan:

(1)  Use a dedicated, reusable lander instead of taking the ITS all the way from LEO to the surface of Mars, and back again, each mission.  This way the ITS won't need to carry enough fuel to both make it to Low Mars Orbit from the surface AND return to Earth in a single stage (the lander should carry crew down to the surface on each trip, and fuel back up to the ITS.  Possibly these two functions could be seperated into different specialized landers for each task to obtain greater efficiency.)  The lander or landers would transfer fuel to the ITS after each ascent, in a similar manner to the tanker refueling the ITS in LEO.

Aside from reducing the Delta-V the ITS needs to carry and allowing the ITS to avoid the need to carry as much heatshielding  (the presentation by Musk shows that the most difficult re-entry with the most maximum G's will actually be on Mars, not Earth) this also benefits from the fact that smaller vessels have lower ballistic coefficients due to the Square-Cube Law (so the lander should experience fewer maximum G's during Mars re-entry), and avoids the need to accelerate any empty tank-mass (originally used to hold the fuel for Mars ascent) from Low Mars Orbit back to Earth.

(2)  Send the cargo seperately from the crew.  This will allow them to to shrink the MCT and use a smaller booster instead of a 42-engine behemoth, thus increasing their launch-volume.  The closer you get to mass-producing your rockets and keeping your launchpads in constant use, the better your economics...

(3)  Send the cargo a transfer-window ahead of the crew, on a slower trajectory.

We know the ITS is already capable of a minimum of 5.4 km/s in order to finish its orbital insertion after booster separation, and most estimates put the transfer trajectory at about 6 km/s based on the 3-5 month table in Elon's presentation, plus they must have additional Delta-V for orbital circularization after aerocapture ,and landing...

So the determining factor on the size of the spacecraft fuel tanks is the Delta-V needed for Mars insertion, capture, and landing- not for initial LEO insertion...  This means that if you developed a cargo-only variant of the ITS you could increase its payload, and send it on a slower transfer (we already know the launch stage is capable of handling a heavier upper stage than the crewed ITS, since the tanker variant weighs about 25 tons more on the launchpad...) since you wouldn't need as much Delta-V for TMI.

The slowest Mars transfers possible take about 16-18 months and 3.1 km/s (minus gravity-assists from the Moon), so there's certainly room in the Delta-V budget for extra cargo, especially if you're willing to not return the cargo-only ITS to Earth for reloading until the NEXT transfer-window (transfer windows come every 26 months,  so otherwise you probably wouldn't want to take longer than about 7-8 months getting to Mars so you'd have plenty of time to unload cargo, head back to Earth a good bit past the transfer-window, and load more cargo before the next transfer window...)

Edited September 30, 2016 by Northstar1989

[tater]

@Northstar1989, It is not carrying any of the fuel (except some LH2) for the return trip at all, that relies on ISRU.

Dedicated landers requires that you bring them, for one thing, and it requires an orbital insertion at Mars. Since the orbital craft stays in orbit, it must bring its propellant from Earth (unless you are proposing a lander for 100 people that also functions as a fuel tanker to bring 100 people, plus enough fuel for the orbital craft to return to Earth as well).

Their solution is actually pretty sensible in that regard. Mars DRAs have small ascent vehicles, and only the MAV uses ISRU. The problem here is that they are talking an arbitrarily large number of people, plus a lot of cargo down, but for safety, you need that same number of people UP, even without the cargo.

Then there is EDL at Earth. It either needs to be able to insert into LEO, then have some other craft offload people, or you need to drag a capsule for 100 along for the ride.

Edited September 30, 2016 by tater

[Northstar1989]

36 minutes ago, tater said:

@Northstar1989, It is not carrying any of the fuel (except some LH2) for the return trip at all, that relies on ISRU.

Dedicated landers requires that you bring them, for one thing, and it requires an orbital insertion at Mars. Since the orbital craft stays in orbit, it must bring its propellant from Earth (unless you are proposing a lander for 100 people that also functions as a fuel tanker to bring 100 people, plus enough fuel for the orbital craft to return to Earth as well).

Their solution is actually pretty sensible in that regard. Mars DRAs have small ascent vehicles, and only the MAV uses ISRU. The problem here is that they are talking an arbitrarily large number of people, plus a lot of cargo down, but for safety, you need that same number of people UP, even without the cargo.

Then there is EDL at Earth. It either needs to be able to insert into LEO, then have some other craft offload people, or you need to drag a capsule for 100 along for the ride.

Read what I wrote more carefully.  I explicitly said the lander should bring fuel "back up" to the ITS.  This was obviously so that it can refuel the ITS, and it doesn't need to bring its return-fuel from Earth, as it can use propellant produced from ISRU on the Martian surface...

I'm going to edit and clarify that point further, since I doubt you will be the last person to misread what I wrote about a lander...

You also don't need to be able to take all 100 people back up to Mars orbit at once.  The whole point of this is that you're establishing a permanent surface colony.  So you're clearly going to leave them behind on the surface- the only people you bring back up are those who want to return to Earth, and Musk himself has said the nominal return capacity to Earth is only about 20 tons- so clearly you couldn't bring all 100 back at once anyways...

Finally, what's this about dragging along an 100-man capsule?  And plrase don't use acronyms that aren't clearly obvious from the context and have been used before.  I don't know what you mean by "EDL".

Anyways, using a dedicated lander doesn't mean you eliminate the capability to conduct a propulsive-landing: the thrust for that is already more or less baked-in with the ITS having the TWR to be used as its own upper-stage on LEO ascent, and slapping on some landing legs and extea avionics isn't THAT big a deal.  Rather, the main benefit is reducing the maximum Delta-V gap the ITS is designed for, and the robustness of its structure and heatshielding (Mars re-entry would subject it to higher maximum G's than Earth re-entry).

 

Regards,

Northstar

Edited September 30, 2016 by Northstar1989

[tater]

33 minutes ago, Northstar1989 said:

Read what I wrote more carefully.  I explicitly said the lander should bring fuel "back up" to the ITS.  This was obviously so that it can refuel the ITS, and it doesn't need to bring its return-fuel from Earth, as it can use propellant produced from ISRU on the Martian surface...

I'm going to edit and clarify that point further, since I doubt you will be the last person to misread what I wrote about a lander...

You also don't need to be able to take all 100 people back up to Mars orbit at once.  The whole point of this is that you're establishing a permanent surface colony.  So you're clearly going to leave them behind on the surface- the only people you bring back up are those who want to return to Earth, and Musk himself has said the nominal return capacity to Earth is only about 20 tons- so clearly you couldn't bring all 100 back at once anyways...

I missed the 20 ton return, actually. That's.... scary.  

Still, the lander would need to have the tank capacity to drag enough fuel for return back up, and ISRU is slow. This also means multiple trips are not really a thing. Bring a few people and some fuel. Return lander. ISRU for a year, bring a few more people and more fuel?

Obviously in a more established settlement, then you start talking about dedicated craft for servicing LMO.

[Northstar1989]

19 minutes ago, tater said:

I missed the 20 ton return, actually. That's.... scary.  

Still, the lander would need to have the tank capacity to drag enough fuel for return back up, and ISRU is slow. This also means multiple trips are not really a thing. Bring a few people and some fuel. Return lander. ISRU for a year, bring a few more people and more fuel?

Obviously in a more established settlement, then you start talking about dedicated craft for servicing LMO.

Don't worry if you missed it- some of this (llike the 20 ton return capacity) I actually got from other comments Musk made to reporters about ITS following the presentation.

Even if the lander were designed to carry up all crew and fuel at once, you'd still save on heatshielding, structure (since the ITS would be subjected to fewer max G's), and if you used dedicated capsules to ferry crew to and from the ITS in LEO (leaving the ITS in LEO after return would also be a lot cheaper than re-launching it after every trip) landing legs- which aren't trivial for a ship this size.  Plus, you don't end up accelerating empty tankage used to attain LMO from the Martian surface back to Earth, the lander has a lower ballistic coefficient, and the lander should be much smaller and have a higher TWR since it doesn't need to carry large lavish crew quarters built for a seceral month voyage.

In short, you save mass in a lot of ways even *IF* you can't store up the propellant needed for several trips to ferry the crew to the ITS and use a smaller lander multiple times each transfer window.  But Musk explicitly stated the ITS would be re-used every 26 months (transfer window), so this implies that he must be planning on storing up propellant on the surface, as I doubt he intends to produce all the return fuel in the month or so you'd have to return to Earth after a 3-5 month voyage, before it became too far past the teansfer window and the Delta-V requiremwnts became too large... (that Musk is apparently planning on returning the ITS in the same teansfer window also makes me think he's planning on a longer, slower return voyage, since even 3-5 months will sunstantially increase the minimum Delta-V needed for a return...)

 

Regards,

Northstar

Edited September 30, 2016 by Northstar1989

[Nibb31]

1 hour ago, Exoscientist said:

 Actually, there is. In his presentation at about the 54 minute mark Musk discusses that the second stage in its tanker form or in its spaceship form will be able to reach orbit when used as a single stage. He states though the tanker will not be able to land, presumably because of insufficient reserve fuel. Then it could be an expendable SSTO.

No. He said it *might* be able to reach orbit, if you really really stripped it down, with no payload, and no return capability.

That is not in any way a useful SSTO capability. There are already plenty of rockets that can do that. Nobody does it, because it's pointless.

[tater]

The landers in that case still need to be put into orbit around Mars vs a direct entry (which would require them to also have more substantial heat shields than they would need for LMO to the surface. Also, they'd need substantial cargo capacity unless you are suggesting a more Mars DRA type profile (landing a cargo pod). Still, given landing precision requirements, you want a propulsive cargo lander I think.

It would be interesting to see a breakdown of the difference between the 2 modalities in terms of total mass to Mars looked at over maybe 10 synods.

[Northstar1989]

38 minutes ago, tater said:

The landers in that case still need to be put into orbit around Mars vs a direct entry (which would require them to also have more substantial heat shields than they would need for LMO to the surface. Also, they'd need substantial cargo capacity unless you are suggesting a more Mars DRA type profile (landing a cargo pod). Still, given landing precision requirements, you want a propulsive cargo lander I think.

It would be interesting to see a breakdown of the difference between the 2 modalities in terms of total mass to Mars looked at over maybe 10 synods.

DRA?

That the lander (and for that matter the ITS) would and should capture into LMO before Mars descent is patently obvious.  Though I will admit, the best place to store the lander between transfer-windows is probably on the ground, at the ISRU site.  This way the lander wouldn't need heavily-insulated propellant tanks and an active-cooling system to store the propellant needed for a Mars ascent or propulsive landing for the years between transfer-windows (note you could re-use the lander every transfer-window).

The lander would probably reach Mars in the first place using its own MethLOX propellant stores for an unmanned TMI, but capture into orbit using a combination of aerocapture and repeated aerobrakes, and a small hypergolic orbital maneuvering system that it would use to circularize after aerocapture, dock with the ITS, and would replenish from stores on the ITS (which uses a cold gas RCS system, but could certainly carry some tiny amount of hypergolics from Earth for the purposes of refueling the lander) between each trip to the surface...

Alternatively, a combination of cold-gas Methane-propelled thrusters and a small more heavily-insulated propellant tank only connected to the OMS and refueling lines would work (although with the required insulation and cooling, it would actually mass more), and allow for reliance on ISRU even for the RCS system.

 

Regards,

Northstar

Edited September 30, 2016 by Northstar1989

[Elthy]

Dont forget that SpaceX is going for maximum cost efficency, not mass efficency. A cycler or a special lander would need additional developement, has to be launched etc.

Im sure they thought this through better than anyone else (especially in this forum).

[Northstar1989]

1 minute ago, Elthy said:

Dont forget that SpaceX is going for maximum cost efficency, not mass efficency. A cycler or a special lander would need additional developement, has to be launched etc.

Im sure they thought this through better than anyone else (especially in this forum).

Mass efficiency strongly correlates with cost efficiency in this case.  They plan on sending literally thousands of ITS missions to Mars, so it would be far better to invest in the R&D for a system with lower marginal costs for each mission than one with minimal R&D but high ongoing costs (which us what SLS represents, basically- or would if Congress and NASA hadn't managed to turn it into a fiscal black hole despite mostly just re-using Shuttle-derived hardware in its design...)

[Elthy]

I dont think mass scales well with costs. Sure, you need more engines and more fuel, but later doesnt realy matter and mass producing engines is desirable. If you produce rocket engines like car engines you dont pay much for the materials, but for the machines.

And for the rest of the rocket, does it realy matter if its 10m or 12m in diameter? Both cant be transported by truck, both need special tools and both need about the same technology.

[CatastrophicFailure]

12 minutes ago, Elthy said:

Dont forget that SpaceX is going for maximum cost efficency, not mass efficency. A cycler or a special lander would need additional developement, has to be launched etc.

Im sure they thought this through better than anyone else (especially in this forum).

What I like about this system is its simplicity. It doesn't require half a dozen different vehicles doing half a dozen different things. It's designed from the get-go to make everything as routine as possible. In the long run that sort of simplicity adds a great deal to overall efficiency, and the long run is exactly what Musk is planning for. 

He's a smart guy. He's already accomplished some darned impressive things. (And if his business presentations are anything like his public presentations, that speaks LOADS to what he says, because how he says it is pretty painful to watch.  ) Because he's a smart guy, I assume he's surrounded himself with a bunch of other smart people, smarter people, who are on board with this whole thing and have said, "yeah, this really can be done."

Musk's companies have a pretty good track record of delivering on their promises. Eventually. 

[Technical Ben]

I assume they are going for efficiencies of scale. Once you hit such a large craft, there is little to be gained from dropping unused engines. So you can take them with you (and back ).

Though as many have said, having a smaller crew capacity (because who is going to want to cram 100 people on a 6 month trip to Mars, it's not like... oh wait we did that with boats, but lots of people did die in storms ). So make it safer, give it more "luxuries" and fit it with more "cargo" to make the trip/arrival nicer, and have 20 or so people, paying a higher premium.

Eeeks, now I'm looking like a nutter, actually coming up with ideas like I think this idea is even sane! But as many have already said, the idea has a few flaws that should probably be addressed in a similar fashion to the current launches. "Less is more" for example, is shown in how they have scaled back the idea of a second stage return for a while. Same will happen with the latest idea, scales will need to be cut back, other areas might even get better efficiencies instead.

Edited September 30, 2016 by Technical Ben

[CatastrophicFailure]

7 minutes ago, Technical Ben said:

Though as many have said, having a smaller crew capacity (because who is going to want to cram 100 people on a 6 month trip to Mars, it's not like... oh wait we did that with boats, but lots of people did die in storms

We regularly cram 100+ very dedicated people in a small space and forget about them for 6+ months at a time, and they do just fine. Ask any submariner. 

[DerekL1963]

38 minutes ago, CatastrophicFailure said:

What I like about this system is its simplicity. It doesn't require half a dozen different vehicles doing half a dozen different things. It's designed from the get-go to make everything as routine as possible. In the long run that sort of simplicity adds a great deal to overall efficiency, and the long run is exactly what Musk is planning for. 

Exactly.  In the long run Musk seems to aiming at reaching airline levels of performance in costs, reliability, and efficiency.  Having a bunch of different vehicles is precisely how you don't go about attaining that.  Having as many thoroughly debugged identical vehicles flying as often as possible and maximum use of a minimum amount of fixed infrastructure (overhead) is the most straightforward path to that goal.  The main problem with the Shuttle's per flight costs wasn't that it cost so much per flight but that it cost so much per annum (the two things are not the same) - basically it didn't fly enough to amortize out the enormous fixed costs.  Musk seems to aiming to avoid that trap.

He's doing two things that I've screaming my lungs out about for a couple of decades now.  First, rather than the "classical" model of individual vehicles and individual missions, he's looking at the system as a pipeline.  Continuous systems are almost always cheaper and more reliable than discontinuous ones.  Second, and in support of the first, he seems to have brought the bean counters into the fold, analyzing the system in terms of cost and cash flow rather than shiny engineering.  When you're serious about reaching those airline levels - counting beans is as important, if not more important, than sliding rules.

I still think he's a lunatic - but he's a very intelligent lunatic.
 

38 minutes ago, CatastrophicFailure said:

Musk's companies have a pretty good track record of delivering on their promises. Eventually. 

Eventually - yes.
 

1 minute ago, CatastrophicFailure said:

We regularly cram 100+ very dedicated people in a small space and forget about them for 6+ months at a time, and they do just fine. Ask any submariner. 

True, as far as it goes.  (Been there, done that - USN Submarine Service 1981-1991.)  But there is a key difference - submariners are crew, we're busy 24/7 keeping the lights on.  Most of 100+ onboard the ICT are passengers.

[Technical Ben]

But do they go on one for a holiday? Why is there 100 people there? Is it not so they can actually work and perform tasks?

If Elon was asking for 100 people to run the ISR and maintenance and science, then great. 100 people "to buy tickets". He'd better hope he can fit a lot of batteries and all the VR gear he can get on that transfer craft! (Alternative is 100 iPhone 7s, but that may not be enough for everyone when the signal drops out after launch)

Edited September 30, 2016 by Technical Ben

[Northstar1989]

3 hours ago, Northstar1989 said:

There are a number of ways SpaceX could improve the efficiency of their plan:

(1)  Use a dedicated, reusable lander instead of taking the ITS all the way from LEO to the surface of Mars, and back again, each mission.  This way the ITS won't need to carry enough fuel to both make it to Low Mars Orbit from the surface AND return to Earth in a single stage (the lander should carry crew down to the surface on each trip, and fuel back up to the ITS.  Possibly these two functions could be seperated into different specialized landers for each task to obtain greater efficiency.)  The lander or landers would transfer fuel to the ITS after each ascent, in a similar manner to the tanker refueling the ITS in LEO.

Aside from reducing the Delta-V the ITS needs to carry and allowing the ITS to avoid the need to carry as much heatshielding  (the presentation by Musk shows that the most difficult re-entry with the most maximum G's will actually be on Mars, not Earth) this also benefits from the fact that smaller vessels have lower ballistic coefficients due to the Square-Cube Law (so the lander should experience fewer maximum G's during Mars re-entry), and avoids the need to accelerate any empty tank-mass (originally used to hold the fuel for Mars ascent) from Low Mars Orbit back to Earth.

(2)  Send the cargo seperately from the crew.  This will allow them to to shrink the MCT and use a smaller booster instead of a 42-engine behemoth, thus increasing their launch-volume.  The closer you get to mass-producing your rockets and keeping your launchpads in constant use, the better your economics...

(3)  Send the cargo a transfer-window ahead of the crew, on a slower trajectory.

We know the ITS is already capable of a minimum of 5.4 km/s in order to finish its orbital insertion after booster separation, and most estimates put the transfer trajectory at about 6 km/s based on the 3-5 month table in Elon's presentation, plus they must have additional Delta-V for orbital circularization after aerocapture ,and landing...

So the determining factor on the size of the spacecraft fuel tanks is the Delta-V needed for Mars insertion, capture, and landing- not for initial LEO insertion...  This means that if you developed a cargo-only variant of the ITS you could increase its payload, and send it on a slower transfer (we already know the launch stage is capable of handling a heavier upper stage than the crewed ITS, since the tanker variant weighs about 25 tons more on the launchpad...) since you wouldn't need as much Delta-V for TMI.

The slowest Mars transfers possible take about 16-18 months and 3.1 km/s (minus gravity-assists from the Moon), so there's certainly room in the Delta-V budget for extra cargo, especially if you're willing to not return the cargo-only ITS to Earth for reloading until the NEXT transfer-window (transfer windows come every 26 months,  so otherwise you probably wouldn't want to take longer than about 7-8 months getting to Mars so you'd have plenty of time to unload cargo, head back to Earth a good bit past the transfer-window, and load more cargo before the next transfer window...)

Re-quoting because this got buried under newer posts surprisingly quickly,  and my final list is actually to be about 5 or 6 items long.  Here's #4:

(4)  Instead of designing the ITS as a Mars transit vehicle that is responsible for supporting the crew all the way to the surface of Mars (or LMO if a dedicated lander were utilized instead of the plan Musk presented), design it as an interceptor-ship to meet up with an Aldrin Cycler Ship to Mars.

The design for a good interceptor is basically the same- a big spacecraft with a lot of Delta-V and a large crew capacity, which you can get to LEO by using it as its own upper-stage stage and refueling it in LEO before proceeding further.   But instead of carrying lots of living space for each crew member sufficient to last months, it should pack the crew in like sardines and only have enough life support for a few days.

When the Cycler ship swings by Earth, the interceptor ship would speed up to match velocity, and should easily be able to rendezvous within a few hours (although stretching that out to closer to 24 might reduce fuel consumption).

The crew would then transfer over to the Cycler Ship (which would be about the mass of the current ITS on the launchpad, but with slightly more of that mass dedicated to crew accommodations and life support, since it wouldn't need a heatshield or landing equipment, and it takes about the same mass to reach a Cycler Orbit as it does to make a 3-5 month transfer to Mars.  In fact, Musk may have selected the current trajectory-time for the ITS since it is almost exactly right to turn into a Cycler Orbit with a small course-correction and make a free return to Earth as a possible emergency abort-option...) and remain on the Cycler until shortly before passing by Mars.  At this point, they would board the interceptor again, and make a course-correction to aerocapture at Mars...

An interceptor-ship version of the ITS would obviously be a lot lighter than the current ITS due to its much more draconian crew accommodations.  The extra mass freed up that the booster is capable of lifting could be used in a variety of ways, but the most useful to me would seem to be launching with full, somewhat larger fuel tanks (in its current form, the ITS launches with only a partial fuel-load, since it would be too heavy for the booster if it launched fully-fueled).

This would mean the ITS would reach orbit with fuel to spare, and reduce the number of tanker launches necessary to fully refuel it for its Mars injection- thus saving money.  I would advocate shrinking the booster and fuel tanks and sticking with the current strategy of partially-loading and completely refueling instead, but the booster ought to be kept its current size to allow for the Cycler Ship to launch atop it the same way the ITS would (as the Cycler Ship would require about the same booster nominal capacity as the current ITS, though the redesigned ITS would have a lower dry mass...)

The transit-time to Mars on a Cycler Orbit is 146 days- almost *exactly* the same voyage and Delta-V as the 3-5 month journey the ITS is designed for.  In fact, when the Earth-Mars distance is such that the current ITS would make a 5-month journey, the only real difference between the current ITS trajectory and that of a Cycler Ship is that you intentionally miss Mars by a bit, so that its gravity doesn't change your orbital period too much...

Similarly, a Cycler Ship only needs to support crew for 5 months (the short leg of its orbit).  So the necessary crew accommodations would be almost identical to the current ITS- except that not needing a heatshield or to carry any fuel aboard for a Mars capture or surface landing would give you a bit more mass to play around with for things like better radiation-shielding, a small greenhouse to reduce the demands on the life-support system and provide fresh food to improve crew morale, solar sails to reduce fuel consumption needed for station-keeping and small course-corrections, and even MORE crew living-space than you find in Musk's current ITS design.

 

 

Realizing that the Delta-V needed to establish a Cycler Orbit, and the Delta-V needed for a 5 month Mars journey like in Musk's current plan are almost IDENTICAL kind of struck me dumb.  It's like finding a Christmas gift you missed opening- in June.

It basically means that if Elon Musk wanted to switch to a Cycler Ship type mission-plan, he wouldn't even have to throw out the ITS design he is presumably already working on at SpaceX.  The company could just use THAT design, with its luxurious crew accommodations, as the Cycler Ship (ideally they'd still shrink the fuel tanks a bit, remove the heatshield, lughten the structural reinforcement needed for re-entry and landing, and rededicate that mass to other things- but they wouldn't have to), and design another version of the ITS as an interceptor-ship with greatly reduced crew accommodations and slightly larger fuel tanks.

Both could launch atop the current behemoth booster design, and the only real change to their launch cycle would be an extra launch in the second transfer-window for the Cycler Ship (the current launch schedule calls for the launch of a cargo-only ITS a window ahead ofvthe first frewed mission to land the ISRU and test the design for safety/reliability).  The first time around they send crew to Mars they could even dock the interceptor and cycler-ship together BEFORE their Mars injection in order to save fuel vs. a rendezvous is solar orbit... (they'd even be able to fire their engines together with a bit of differential throttling between the two, since they'd have very similar masses and probably even shapes when both fully-fueled).

 

Regards,

Northstar

Edited September 30, 2016 by Northstar1989

[Technical Ben]

Hopefully these little things will be done as steps. The last thing I want to see is the "we sent the first mission, it was 100 people to mars" because something may go wrong. But if they do the "cycler" idea... well, it gives them steps to learn and succeed (by failing ).

So send an empty crew ship. But don't land at Mars. Instead just swing by, and now your empty ship is a cycler, and you proved you can get it there. Now send the ISR and dock it with the cycler. You have proven you can meet up with the cycler. Now you can land the ISR, and prove you can land on Mars. Then you can look at sending people.

Though I guess the other option just swaps out the cycler. That is probably a good idea. We don't want it going Space Station 13 when it's time to go back into the landing craft... keeping it all in one lowers the emotional and physiological risk (no choice given for chickening out).

[CatastrophicFailure]

14 minutes ago, DerekL1963 said:

True, as far as it goes.  (Been there, done that - USN Submarine Service 1981-1991.)  But there is a key difference - submariners are crew, we're busy 24/7 keeping the lights on.  Most of 100+ onboard the ICT are passengers.

And here is where your ship analogy really comes in. They may be passengers, but they're effectively emigrating to start a new life and build a new world, much like settlers and colonists of 17th-19th centuries. They, too, generally had to pay their own way. 

Most of those first brave souls heading to Mars won't be going on vacation. And like Musk said, there'll be no shortage of jobs. 

[Aethon]

 

 

NASA has some big tanks too.

Weld complete on the core stage hydrogen SLS tank.

 

http://www.nasa.gov/exploration/systems/sls/multimedia/welding-complete-on-fuel-tank-for-sls-rocket

[Technical Ben]

Sorry, no. In no way are they "colonists". Any more than the trips to the poles were. This is a trip to the poles/up mount Everest type stuff. The slight difference is it is in an Ice Breaker/Helicopter (depending on scale of craft and length of stay).

There is no air. It is extremely cold. These are not small things.

[DerekL1963]

21 minutes ago, CatastrophicFailure said:

Most of those first brave souls heading to Mars won't be going on vacation. And like Musk said, there'll be no shortage of jobs. 

No shortage of jobs once they get there...  the real trick is keeping the knives away from them in transit.

[Technical Ben]

What jobs? What are they taking? They will have tasks. Like refuelling, food production (how?), some basic repair etc. As said, like on a ship, or a trip to the poles.

[Northstar1989]

I'm still really amazed to hit upon the fact that the Delta-V requirements of taking the ITS to Mars, and using it as a Cycler Ship, are basically identical.  This is actually really important, because it means that even without re-designing the Interplanetary Transport Ship at all, in any way whatsoever, SpaceX could easily use this to build consumer confidence.  Just launch one ITS unmanned, intentionally missing Mars by a little, with the same Delta-V burn it would take to reach Mars, and it enters a Cycler Orbit.  Use some of the fuel you normally would have used for capture and landing for course-corrections, and save the rest for a backup/emergency reserve.

When the ITS swings by Earth again in its Cycler Orbit, having already made a distant flyby of Mars, you'll have plenty of volunteers to board an identical ITS and rendezvous with it, such as to have extra living-space for the journey  (TWO luxurious spaceships instead if one!).  If for some reason you failed to rendezvous and dock, the crew would have the assurance of knowing their ITS is perfectly capable of reaching Mars on its own.  Meanwhile, you can be working on an interceptor version of the ITS that trades crew accommodations for extra fuel tankage on launch (so it requires less orbital refueling) and make use of it the NEXT transfer-window, or the one after that.

You could even bring back the very first ITS after a couple cycle orbits to Earth and refurbish it for more traditional use again, but not start development of the interceptor-version and an ITS actually specialized for use as a Cycler Ship (meaning you reduce the fuel tankage, strip the heatshield/landing-legs, and add stuff like extra radiation-shielding and a greenhouse) until you've already landed an ITS on Mars- and fund its development in part with profit from the more traditional missions, incorporating design improvements from lessons learned flying the first ITS designs along the way...

 

Seriously, I think this is a really good idea.  Is there anybody here who is good at formal/business/technical writing who would be willing to double-check the assumptions here a bit, and kindly write to SpaceX to inform them that the version of Interplanetary Transport Ship that Elon Musk presented on this month actually meets all the technical requirements  (Delta-V budget, crew accommodations, navigational systems, refueling ability, etc.) for use as a Cycler Ship- with the sole exception that when it docks with another ship it needs to have the capability to transfer over crew and basic supplies as well as fuel?

 

Regards,

Northstar

Edited September 30, 2016 by Northstar1989

[tater]

DRA is Design Reference Architecture. Before it was "Design Reference Mission" (DRM).

The current versions for a while have been heavily informed by Mars Direct. Sort of "Mars semi-Direct" as NASA is pretty risk averse. Multiple flights, send stuff ahead unmanned.

The trouble with the tall spacecraft landing vertically from a cargo standpoint is that, well, it's tall. Musk apparently said something about multiple cargo missions per crew mission for a while since they obviously need a destination to go to in the first place (which must be constructed). If it was actually a serious thing, I'd think that you'd send some squat landers (land the biconic horizontally?) designed to be covered in soil and used as habs.