Author Topic: Larger than ITS - The next generation  (Read 8978 times)

Online TomH

  • Full Member
  • ****
  • Posts: 1972
  • CA
  • Liked: 652
  • Likes Given: 195
Re: Larger than ITS - The next generation
« Reply #20 on: 07/08/2017 11:28 PM »
I think a cruise ship has more similarities.

Ocean liner. Cruise ships and ocean liners have different designs. Cruise ships are mainly designed to putter around and have all kinds of recreational activities. Liners, so named because they travel mainly in a straight line, are designed to go from Point A to Point B. While they may have luxuries, the hull, keel, etc. are designed for higher speed, the ability to handle larger waves, and the ship is intended for constant long distance transport; cruise ships are not. Cruise ships are boxier while liners are narrower, sleeker, and have a stronger superstructure. Cruise ships now employ bow planes for stabilization whereas liners avoid them due to drag. QEII, QMII, and SS United States are liners; almost all other ocean going passenger ships are cruise ships.

ITS will be designed to go from Point A to Point B.

https://frugalfirstclasstravel.com/2015/05/29/cruise-ship-vs-ocean-liner-whats-difference/
« Last Edit: 07/09/2017 06:09 AM by TomH »

Online meekGee

  • Senior Member
  • *****
  • Posts: 7490
  • N. California
  • Liked: 3821
  • Likes Given: 803
Re: Larger than ITS - The next generation
« Reply #21 on: 07/08/2017 11:46 PM »
If you look at airplanes, they stopped getting larger in any significant way after the B747.  They actually shrunk, so it wasn't infrastructure that was driving it... and the A380 is limited mostly by market forces.

What did explode instead was the amount of traffic.  10,000 flights in the air over the US during daytime...  An unthinkable number 30 years earlier.

I don't see why we need anything larger than a B747 for Mars.  So maybe one iteration beyond ITS.

However, I do think we will see 100 launch pads (probably offshore), and thousands of rockets flying up and down like airplanes from an airport.

I don't see the equivalent of sea transport happening, because I don't think you'll ever have a solar system global economy in the way you have it on Earth, because of the time constants.  (no real time communication, or any kind of reasonable transport times)


The plane analogy stands up somewhat, but for a trip to mars, as far as the ideal setup, I think a cruise ship has more similarities. You can't ask people to sit on a plane or something like a plane for 9 months; they would go crazy. You need room for privacy, room for socializing, and for a 9 month period which if far longer than most cruises, you are going to need some form of entertainment. If there is a large demand for trips to mars in the not too distant future, people will want to go in the largest and the most comfortable if the price is not too high, and that would add demand for bigger ships. I think Elon does an amazing job in his companies in realizing that looking and feeling cool and inspiring will eventually drive the success of the endeavor. We see this in ITS and its description and I think it will continue to get bigger for this reason.

Yes and no...  Manned trips to Mars will be 3-monthish, and will be a one-in-a-life time thing.  Immigration, not commuting.

Even if you're only going for 2 years (minimum stay), that's still acceptable.

In that context, 3 months in a space that gives you a cot and communal areas - I think that's acceptable

Other than number of flights, I think we'll see faster ships.  I can see an advanced electric drive ship going back and forth (still once every two years) - but faster.

Actually, the ability to travel faster will reduce the need for larger ships.

So I'm sticking with "large airplane" size, and not "cruise ship"/"battlestar" size...

ABCD - Always Be Counting Down

Offline ChrisWilson68

  • Senior Member
  • *****
  • Posts: 3493
  • Sunnyvale, CA
  • Liked: 2042
  • Likes Given: 2378
Re: Larger than ITS - The next generation
« Reply #22 on: 07/09/2017 06:57 AM »
At some scale, it will make more sense to build a Lofstrom loop and assemble your mega-ship in orbit.
That -is- where the progression leads, but I suspect it's a generation or two beyond elon's superliner.

I don't agree.  Rockets really are more efficient than most people give them credit for.  Once they're completely reusable and scaled up, they can be more efficient than Lofstrom loops or space elevators or orbital rings or any other megastructures, no matter how much we're launching to space and no matter how far in the future we go.

The cost comparisons for these megastructures tend to compare costs against today's expendable rockets.  That's not the right comparison.  The right comparison is against the optimized reusable rockets of the future when we're carrying large volumes of cargo to and from space.

Offline RoboGoofers

  • Full Member
  • *
  • Posts: 183
  • NJ
  • Liked: 69
  • Likes Given: 144
Re: Larger than ITS - The next generation
« Reply #23 on: 07/11/2017 05:30 PM »
At some scale, it will make more sense to build a Lofstrom loop and assemble your mega-ship in orbit.
That -is- where the progression leads, but I suspect it's a generation or two beyond elon's superliner.

I don't agree.  Rockets really are more efficient than most people give them credit for.  Once they're completely reusable and scaled up, they can be more efficient than Lofstrom loops or space elevators or orbital rings or any other megastructures, no matter how much we're launching to space and no matter how far in the future we go.

The cost comparisons for these megastructures tend to compare costs against today's expendable rockets.  That's not the right comparison.  The right comparison is against the optimized reusable rockets of the future when we're carrying large volumes of cargo to and from space.

I don't know, that sounds like you're saying, by analogy, ferries can be cheaper than bridges. it depends on your metric. maybe the ferry ticket cost is cheaper than the bridge toll, but thinking of them as whole systems, the bridge is far cheaper/efficient.

Offline DnA915

  • Member
  • Posts: 48
  • United States
  • Liked: 23
  • Likes Given: 29
Re: Larger than ITS - The next generation
« Reply #24 on: 07/11/2017 06:10 PM »
I don't know, that sounds like you're saying, by analogy, ferries can be cheaper than bridges. it depends on your metric. maybe the ferry ticket cost is cheaper than the bridge toll, but thinking of them as whole systems, the bridge is far cheaper/efficient.

Not to start arguing way off topic, but saying the statement broadly "the bridge is far cheaper/efficient" is not true. If it were, we would never use boats on a regular basis and would simply always build bridges. Its all about distance, efficiency, cost and convenience. I think the previous commenters point was that he thinks it would no longer make economical sense, at least in the timeframes that governments paying would be able to swallow.

Offline oldAtlas_Eguy

  • Senior Member
  • *****
  • Posts: 2919
  • Florida
  • Liked: 1237
  • Likes Given: 85
Re: Larger than ITS - The next generation
« Reply #25 on: 07/13/2017 03:57 PM »
I believe with the advent of a in-space propellant ISRU infrastructure that the cruise ship vs airplane analogies for what each would be but that it delineates how such planetary in-space only vs the surface shuttles  to orbit would be designed. The shuttles would look similar but maybe larger than the ITS. They would be Airplane like in their packing the passengers in since they would have at most a 3 day trip. The in-space planetary craft would be massive comfortable travel space for passengers in the thousands or 10s of thousands. Imagine a torus colony like moving vehicle using Nuclear Thermal or such like 900+ ISP engines. The crew including their families would live simi-permanently on the vehicle almost like its own in-space city. 

The key here is that even just the original ITS sized craft when used as a orbital shuttle could transport over 400 people at at time if the duration of the trip is short as in a few days. My original estimate was a value of 4 to 1 for number of short duration (3+ days) passengers to the longer duration (3+ months) numbers. This was for a Earth to Moon surface passenger service evaluation using a customized ITS). If the number is 200 for long duration this would then give a shuttle to orbit number at 800. To load then this massive 10,000 passenger in-space cruise ship would take just 2 tankers and the one ITS passenger flight to get from Earth to L2 and on Mars it needs no Tankers at all to get to Deimos orbit. That then makes for the transport of 10,000 people from Earth to Mars requiring 12.5 ITS passenger flights and 25 Tankers for every 10,000 people. So at 100 ITS and 200 tankers that would then be in this scenario for one or several "cruise" ships the transport of 80,000 people between planets every synod without much change to the surface infrastructures (Pads required or even LVs designs). This would be vs the use of only ITS and no in-space ISRU propellant sources only 50 ITS transporting just 200 each for a total of 10,000 passengers. This is a 8 to 1 cost reduction in transport costs for this first part of the leg of the journey. The massive cruise ships could have lifetimes measured in decades where the number of persons tranport in just one direction at 10,000 at a time would be over 30 years 150,000. If each such vehicle cost $10B even to build than that is a per person cost of $67K. The operations costs would nearly equal that cost putting the tiket price to travel on these very comfortable vehicles at ~$100K. Now add the surface shuttles cost at $100K at Earth and $30K at Mars the total trip price would be $230K. This also give the prices for going anywhere in Cis-Lunar space even the Lunar surface at about $100K. This then makes going to Mars vs just the Moon is only 2X as much.

By this time the demand for travel may be much more than this level of infrastructure can handle.

If you increase the sizes of the surface to orbit craft then that also would make the size or number of in-space cruise ships grow. Eventually with enough DV from high thrust high ISP engines the departures would no longer be limited to the synods.

Offline RoboGoofers

  • Full Member
  • *
  • Posts: 183
  • NJ
  • Liked: 69
  • Likes Given: 144
Re: Larger than ITS - The next generation
« Reply #26 on: 07/13/2017 06:41 PM »
I believe with the advent of a in-space propellant ISRU infrastructure that the cruise ship vs airplane analogies for what each would be but that it delineates how such planetary in-space only vs the surface shuttles  to orbit would be designed. The shuttles would look similar but maybe larger than the ITS. They would be Airplane like in their packing the passengers in since they would have at most a 3 day trip. The in-space planetary craft would be massive comfortable travel space for passengers in the thousands or 10s of thousands. Imagine a torus colony like moving vehicle using Nuclear Thermal or such like 900+ ISP engines. The crew including their families would live simi-permanently on the vehicle almost like its own in-space city. 

The key here is that even just the original ITS sized craft when used as a orbital shuttle could transport over 400 people at at time if the duration of the trip is short as in a few days. My original estimate was a value of 4 to 1 for number of short duration (3+ days) passengers to the longer duration (3+ months) numbers. This was for a Earth to Moon surface passenger service evaluation using a customized ITS). If the number is 200 for long duration this would then give a shuttle to orbit number at 800. To load then this massive 10,000 passenger in-space cruise ship would take just 2 tankers and the one ITS passenger flight to get from Earth to L2 and on Mars it needs no Tankers at all to get to Deimos orbit. That then makes for the transport of 10,000 people from Earth to Mars requiring 12.5 ITS passenger flights and 25 Tankers for every 10,000 people. So at 100 ITS and 200 tankers that would then be in this scenario for one or several "cruise" ships the transport of 80,000 people between planets every synod without much change to the surface infrastructures (Pads required or even LVs designs). This would be vs the use of only ITS and no in-space ISRU propellant sources only 50 ITS transporting just 200 each for a total of 10,000 passengers. This is a 8 to 1 cost reduction in transport costs for this first part of the leg of the journey. The massive cruise ships could have lifetimes measured in decades where the number of persons tranport in just one direction at 10,000 at a time would be over 30 years 150,000. If each such vehicle cost $10B even to build than that is a per person cost of $67K. The operations costs would nearly equal that cost putting the tiket price to travel on these very comfortable vehicles at ~$100K. Now add the surface shuttles cost at $100K at Earth and $30K at Mars the total trip price would be $230K. This also give the prices for going anywhere in Cis-Lunar space even the Lunar surface at about $100K. This then makes going to Mars vs just the Moon is only 2X as much.

By this time the demand for travel may be much more than this level of infrastructure can handle.

If you increase the sizes of the surface to orbit craft then that also would make the size or number of in-space cruise ships grow. Eventually with enough DV from high thrust high ISP engines the departures would no longer be limited to the synods.

If i'm following, you would jam pack an ITS shuttle with people? So are you accounting for the cargo flights required for supplies?

Also you seem to be assuming that a 10000 person ship would scale linearly. I think that's unlikely. 10k people is ~1.5 million pounds just in flesh and bones. Not to get crude and into any IAC-question territory, but you'd need a full sewage plant to deal with all those people, and that equipment alone wouldn't scale linearly.

 Such a large ship might be much slower and require more supplies and room for the passengers, even assuming Nuclear thermal since 1st generation engines are likely to be sub-optimal.

Offline original_mds

  • Member
  • Posts: 45
  • MN, USA
  • Liked: 20
  • Likes Given: 32
Re: Larger than ITS - The next generation
« Reply #27 on: 07/13/2017 11:25 PM »
If i'm following, you would jam pack an ITS shuttle with people? So are you accounting for the cargo flights required for supplies?

Also you seem to be assuming that a 10000 person ship would scale linearly. I think that's unlikely. 10k people is ~1.5 million pounds just in flesh and bones. Not to get crude and into any IAC-question territory, but you'd need a full sewage plant to deal with all those people, and that equipment alone wouldn't scale linearly.
...

One person's garbage is another person's gold mine.  More biomass and fertilizer to support agriculture at the end point.

On the sewage plant note, are you implying there would be ELCSS economies of scale?

Offline oldAtlas_Eguy

  • Senior Member
  • *****
  • Posts: 2919
  • Florida
  • Liked: 1237
  • Likes Given: 85
Re: Larger than ITS - The next generation
« Reply #28 on: 07/13/2017 11:29 PM »
The idea is that even though these vehicles would be very large and complex they would also  be significantly self sufficient in recycling/food production (using on-board farm) such that the supplies to be on loaded are very minimal. Most of the cargo to be loaded would be the individuals personal cargo. This vehicle would in essence be a mobile in-space colony. You are correct in that the key to such huge craft is high ISP/ high thrust systems of which some sort of Nuclear implementation seems to be the answer at this point in time. The advantage of such huge spacecraft is the safety factor that size itself creates.

The negative is the increase in kg per person transported over that of a smaller less "roomy" transport. But the direction that the market will push is for these "luxury liner" transports over that of a "cattle car". Musk already has indicated that the ITS could take more people but would be counterproductive from enticing or getting people to ride in it. For the short 3+ day intervals people will tolerate crowding but not for 3 months.

Offline IRobot

  • Full Member
  • ****
  • Posts: 1151
  • Portugal & Germany
  • Liked: 204
  • Likes Given: 189
Re: Larger than ITS - The next generation
« Reply #29 on: 07/14/2017 08:10 AM »
Really huge ships are limited by infrastructure (depth of ports and seaways, width of Panama Canal etc). Therefore their sizes increase rather slowly - only in sync with infrastructure upgrades.

Current embryonic state of our civilization's space capabilities require, at max, 12-15m diameter launcher. Anything larger would require humongous (meaning very expensive) launch pads, and would provide lift capability way in excess of the needs.
On a typical vertical launch chemical rocket, don't we hit other limits before we ran out of money? What about acoustic and vibration issues with huge rockets? Can we make a pad that survives such a beast?

Offline rsdavis9

Re: Larger than ITS - The next generation
« Reply #30 on: 07/14/2017 12:17 PM »
As far as pad's and proximity to people/structures. I think we will see offshore platforms for the really big rockets.
bob

Offline Semmel

  • Full Member
  • ****
  • Posts: 1005
  • Germany
  • Liked: 697
  • Likes Given: 2068
Re: Larger than ITS - The next generation
« Reply #31 on: 07/14/2017 12:45 PM »
So instead of talking about a self sufficient city on Mars, you are now talking about a self sufficient space ship that brings people to Mars. Maybe you are overcooking it a bit?

Offline IRobot

  • Full Member
  • ****
  • Posts: 1151
  • Portugal & Germany
  • Liked: 204
  • Likes Given: 189
Re: Larger than ITS - The next generation
« Reply #32 on: 07/14/2017 03:13 PM »
As far as pad's and proximity to people/structures. I think we will see offshore platforms for the really big rockets.
I was talking about the pad itself. Can it resist such a big rocket launch?

Offline rsdavis9

Re: Larger than ITS - The next generation
« Reply #33 on: 07/14/2017 03:16 PM »
As far as pad's and proximity to people/structures. I think we will see offshore platforms for the really big rockets.
I was talking about the pad itself. Can it resist such a big rocket launch?

There has got to be something that can resist it.
Inconel water cooled!
After all the rocket engine itself is made of something...
bob

Offline original_mds

  • Member
  • Posts: 45
  • MN, USA
  • Liked: 20
  • Likes Given: 32
Re: Larger than ITS - The next generation
« Reply #34 on: 07/14/2017 03:59 PM »
As far as pad's and proximity to people/structures. I think we will see offshore platforms for the really big rockets.
I was talking about the pad itself. Can it resist such a big rocket launch?

There has got to be something that can resist it.
Inconel water cooled!
After all the rocket engine itself is made of something...

Water launch it.  http://www.astronautix.com/s/seadragon.html

Even if salt corrosion is an issue at sea, there are enough fresh water bodies, both natural and unnatural, that it should be feasible (although I suspect environmentalist concerns about aquatic life will push it towards artificial bodies of water).

Online DAZ

  • Full Member
  • *
  • Posts: 111
  • Everett WA
  • Liked: 74
  • Likes Given: 1
Re: Larger than ITS - The next generation
« Reply #35 on: 07/15/2017 12:47 AM »
Would something like this https://www.nextbigfuture.com/2017/07/air-enhanced-nuclear-thermal-rocket-by-x-spacex-engineer.html lead to the next generation or the generation after the next?

Offline Eerie

  • Member
  • Full Member
  • ****
  • Posts: 742
  • Liked: 104
  • Likes Given: 6
Re: Larger than ITS - The next generation
« Reply #36 on: 07/15/2017 01:06 PM »
Would something like this https://www.nextbigfuture.com/2017/07/air-enhanced-nuclear-thermal-rocket-by-x-spacex-engineer.html lead to the next generation or the generation after the next?

I am willing to bet that the first operational nuclear rocket (of any kind) will be built outside of Earth and operate far away from Earth.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26602
  • Minnesota
  • Liked: 6476
  • Likes Given: 4700
Re: Larger than ITS - The next generation
« Reply #37 on: 07/15/2017 02:06 PM »
It will be built on Earth but operated only in space.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Eerie

  • Member
  • Full Member
  • ****
  • Posts: 742
  • Liked: 104
  • Likes Given: 6
Re: Larger than ITS - The next generation
« Reply #38 on: 07/15/2017 03:20 PM »
It will be built on Earth but operated only in space.

Well, this is pure sci-fi speculation, but I just don't see it happen like this. People won't want to test the nuclear rocket on Earth. People won't want to launch nuclear fuel from Earth either. And when you have the capability to mine and produce nuclear fuel in space, you are not that far from being able to build the rocket in space, too. And this is a point where you have an extensive space economy, which we have no idea how it would look like.

None of this is even remotely close, of course, so who knows. Personally, I don't believe SpaceX will land people on Mars before 2030 or having the Internet constellation operate before 2025 (sure would love to be mistaken on both accounts). And both of these things are achievable with chemical rockets.

Online DAZ

  • Full Member
  • *
  • Posts: 111
  • Everett WA
  • Liked: 74
  • Likes Given: 1
Re: Larger than ITS - The next generation
« Reply #39 on: 07/15/2017 10:07 PM »
It will be built on Earth but operated only in space.

Well, this is pure sci-fi speculation, but I just don't see it happen like this. People won't want to test the nuclear rocket on Earth. People won't want to launch nuclear fuel from Earth either. And when you have the capability to mine and produce nuclear fuel in space, you are not that far from being able to build the rocket in space, too. And this is a point where you have an extensive space economy, which we have no idea how it would look like.

None of this is even remotely close, of course, so who knows. Personally, I don't believe SpaceX will land people on Mars before 2030 or having the Internet constellation operate before 2025 (sure would love to be mistaken on both accounts). And both of these things are achievable with chemical rockets.

The comments say more about the sorry state of society then as to the technical merits of the concept.  Admittedly, we are approaching the point of total paralysis on just about every conceivable front.  In the 80s, when the anti-nuclear front was hitting its stride, it was being quietly backed by the petroleum industry.  Such backing with the advent of the Internet (see the book twitter and tear gas) is becoming totally unnecessary.  Smaller, less organized, less educated, minimally funded, ad hoc organizations are now swinging way above their apparent size.  It is now taking 2 to 3 times longer and 2 to 3 times more money to accomplish a project that the majority of the public agrees with but because of the influence of these microscopic groups and their tactics, almost nothing is getting accomplished.  A bridge across the waterway that should’ve taken 5 to 10 years is now taking 15 to 30 years.  A simple sewage treatment plant can now take decades to build and is almost unaffordable.  I personally do not believe we will actually reach total paralysis.  Other forces will come into play to counteract the forces attempting to reach paralysis for no other reason than simple day-to-day survival will dictate this.  Exactly how these counter forces will emerge and play out I do not know but I do know history teaches us that these things will eventually change to attempt to get more toward a balance.

On to something more on-topic.

It is been said that once you are in orbit around the earth that you are 50 to 70% of the way to anyplace else in the solar system.  This would be measured not only in energy but also in dollars.  If nuclear rockets are only built and operated in space you are essentially 95% plus of the way to every place in the solar system.  Building these nuclear rockets at that time might be financially impossible/unnecessary due to the upfront costs necessary before you even have your 1st rocket.

The biggest problem with building any kind of nuclear rocket on earth (aside from the anti-nuclear paranoia groups) is the extremely large upfront costs and the generally unacceptable thrust to weight ratios of the most easily built (and low risk, acceptable) Nuclear Thermal Rocket.  The nuclear lightbulb, nuclear saltwater rocket, or the nuclear pulsed detonation (Orion) rocket would probably be more effective but much higher risk/danger that even the general public would not accept.  Their costs would also be many orders of magnitude higher to build even the smallest versions.

The Air Enhanced Nuclear Thermal Rocket would overcome much of this.  Much of the biggest uncertainties have already been built and tested in full-scale working prototypes like NERVA (Nuclear Engine for Rocket Vehicle Application).  The other parts of this system that are non-nuclear could be built and tested in non-nuclear forms.  These would be the turbocharged parts (air enhanced) of the Nuclear Thermal Rocket.  The system as described by John Bucknell would have many times the mass fraction of any other conceived non-nuclear system.  Including even a much bigger ITS type rocket.  If scaled up could achieve payloads to the moon many times larger than the ITS could achieve even with multiple refueling’s in orbit and it could do this from a direct launch on the earth.  This could mean the costs to orbit could be in the tens of dollars per pound on the low side to maybe only a few hundreds of dollars per pound on the high side.  This could make it cheaper to go to orbit than to fly from the United States to Australia.

So once in space, you can come up with all kinds of relatively cheaper more efficient ways to get around but unless you can tackle the problem of getting from the Earth’s surface into orbit you are essentially dealing with the smaller part of the problem.  And that’s what makes this concept so interesting as it takes such a large upfront bite out of the problem.

But that is also the biggest part of the problem as you have to eat the entire elephant all in one bite.  This is been part of the genius that SpaceX and Blue Origin are trying to accomplish.  They have found a way to eat the elephant in smaller bite-size pieces.  For example, SpaceX is not starting with the ITS it started with the Falcon 1.  SpaceX incrementally increased and improved their system and found ways to pay for it as they were going.  The problem with the NTTR (Nuclear thermal turbo rocket) is that you essentially have to do this as in all up project.  You have to find all of the money(s) to build your entire project before you can really start earning money from the project.  Now, this is not normally inconceivable or even an extremely difficult problem.  We do this all the time with things like cars, cell phones, and airplanes.  But normally you have a proven market, as it were, in order to attract financing.  This is why I think this would be a follow-up project for somebody (to possibly leapfrog past) the ITS.  The ITS opens and shows the possible market potentials.  But something like the NTTR is what may follow and be the equivalent of the airplane that eventually ended the era of the liner crossing the Atlantic.

Tags: ITS SpaceX Mars BFR