Author Topic: IAC 2017 -- ITS v0.2  (Read 17789 times)

Offline Lars-J

  • Senior Member
  • *****
  • Posts: 3152
  • California
  • Liked: 2472
  • Likes Given: 1454
Re: IAC 2017 -- ITS v0.2
« Reply #20 on: 05/29/2017 08:05 PM »
A more plausible scale-up would use a 12 m diameter landing capsule, which could be sent to Mars by a single launch of a 200-300 ton-to-LEO rocket.  Trans-Mars mass would be around 60-90 t (to stay in the 0.8t/m^2 range that is talked about), and the surface payload about half that.  This would align with Zubrin's suggestion that the initial trans-Mars habitat should stay on Mars as crew housing.  This also allows stockpiling supplies on Mars prior to crew arrival, to make the Mars base the "second safest place in the solar system" (to quote an old Zubrin statement).  A crew capsule also allows implementation of a launch escape system.

So... You think the intermediate step should be something completely different?  ???

Yeah, I get that people don't like the ITS system as described. But going from there to wishfully thinking that Elon will make a 180 turn to your own dream architecture...  :o

A crew capsule also allows implementation of a launch escape system.

A 12 m crew capsule abort system. Good luck with that.  :o  Apollo architecture and capsules in general do not scale well. Orion is finding this out, and that is for a minor scale up of 3.9m to 5m. A 12m capsule... Does not compute.

With the upcoming debut of the Falcon Heavy, there is also a chance that SpaceX will start with a smaller 3-core ITS variant, to allow a set of 9.5 m diameter cores to loft the same 300 tons-LEO (90-100t to Mars).  This suggestion would make Zubrin happier

3 core ITS? Nope. They are having hard enough time with FH.

No one at SpaceX cares about making Zubrin happy. (thankfully)
« Last Edit: 05/29/2017 08:37 PM by Lars-J »

Online Kenp51d

  • Member
  • Posts: 20
  • Modesto, CA
  • Liked: 0
  • Likes Given: 0
Re: IAC 2017 -- ITS v0.2
« Reply #21 on: 05/29/2017 08:12 PM »

I would add 1 more required technology improvement to the list.
5) Long term storage of deep cryogenic propellants

1) Full and rapid reuse
2) orbital refueling
3) Mars ISRU for methalox
4) lifting entry and hypersonic retropropulsion

Sent from my XT1565 using Tapatalk


Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26241
  • Minnesota
  • Liked: 6208
  • Likes Given: 4562
Re: IAC 2017 -- ITS v0.2
« Reply #22 on: 05/29/2017 08:16 PM »
The ITS as described at IAC 2016 is awesome. The only two things I think you could reasonably object to are the raw size (impracticality large thrust for LC39a and Brownsville), the ambitious landing tech, and maybe the lack of abort.

A descoped ITS could resolve the first two issues, giving them time to develop some other launch site for the full ITS and test out the landing cradle concept. I have a feeling that Block 5 Falcon 9 is giving them other ideas for how to improve turnaround time other than the launch cradle (although the launch cradle could still be an upgrade option). Crew abort could be addressed on a customer by customer basis, perhaps partially resolved by just having a very solid launch history (since the vast majority of launches will be uncrewed).
« Last Edit: 05/29/2017 08:20 PM by Robotbeat »
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

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26241
  • Minnesota
  • Liked: 6208
  • Likes Given: 4562
Re: IAC 2017 -- ITS v0.2
« Reply #23 on: 05/29/2017 08:25 PM »
But the basic idea behind ITS just kicks most architectures' butts so hard that I don't think people have yet realized how much better this approach is. Just two stages, with a couple variants of the upper stage, is all the vehicle you need. That's dramatically simpler than anything else (only exception would be, say, Delta Clipper doing SSTO and refueling... This is very similar to ITS but SSTO), and frankly makes a lot of other approaches look like a complex waste of time and money.

I mean look at Lockheed's Mars orbital basecamp idea. You have multiple SLS launches, which is 3 different stages (all expended), plus Orion and the orbital base thing and the in-space propulsion. But you're stuck in Mars orbit. Lockheed's lander concept will get you flag and footprints but no lasting presence anywhere on the surface. It looks enormously expensive for a tiny fraction of the capability. Being in Mars orbit makes you exposed to microgravity and deep space radiation the whole time, so it's much worse for astronaut health.
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

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26241
  • Minnesota
  • Liked: 6208
  • Likes Given: 4562
Re: IAC 2017 -- ITS v0.2
« Reply #24 on: 05/29/2017 08:26 PM »

I would add 1 more required technology improvement to the list.
5) Long term storage of deep cryogenic propellants

1) Full and rapid reuse
2) orbital refueling
3) Mars ISRU for methalox
4) lifting entry and hypersonic retropropulsion

Sent from my XT1565 using Tapatalk
Methane isn't a deep cryogen. It's relatively easy to get zero boil off passively with methane.
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

Online Kenp51d

  • Member
  • Posts: 20
  • Modesto, CA
  • Liked: 0
  • Likes Given: 0
Re: IAC 2017 -- ITS v0.2
« Reply #25 on: 05/29/2017 08:42 PM »
Is LOX? Kinda need some of that too.
Cislunar shouldn't​ be defficult, but Mars would be more demanding.
Shading, and insulation are part of the answer.


Sent from my XT1565 using Tapatalk


Offline envy887

  • Senior Member
  • *****
  • Posts: 2135
  • Liked: 929
  • Likes Given: 603
Re: IAC 2017 -- ITS v0.2
« Reply #26 on: 05/29/2017 08:45 PM »
Storing a small amount of methalox in what are basically Dewars inside the main tanks should be pretty straightforward.

If SpaceX were trying to store methalox in the main tanks, I would say that's pretty low TRL. But storage in small vacuum lined tanks has been proven in operational flight systems.

Both Shuttle and Apollo demonstrated LOX storage for weeks on orbit. Shuttle even demonstrated cryo LH2 storage for up to about a month at -420 degrees F for the fuel cells.
« Last Edit: 05/29/2017 08:46 PM by envy887 »

Offline spacenut

  • Full Member
  • ****
  • Posts: 1913
  • East Alabama
  • Liked: 240
  • Likes Given: 174
Re: IAC 2017 -- ITS v0.2
« Reply #27 on: 05/29/2017 09:26 PM »
LOX and liquid methane are only about 20 degrees apart.  Storage would be the same.  Liquid Hydrogen is deep cryogen, and much harder to keep cool.   

I like the idea of refueling FH 2nd stage for larger payloads to Mars or even the moon.  Therefore a lot of equipment could be sent to Mars before ITS or a Mini-ITS.  Same with the moon. 

Online scienceguy

  • Regular
  • Full Member
  • ****
  • Posts: 721
  • Lethbridge, Alberta
  • Liked: 57
  • Likes Given: 92
Re: IAC 2017 -- ITS v0.2
« Reply #28 on: 05/29/2017 09:29 PM »
methane is a bigger molecule than hydrogen
e^(pi)i = -1

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26241
  • Minnesota
  • Liked: 6208
  • Likes Given: 4562
Re: IAC 2017 -- ITS v0.2
« Reply #29 on: 05/29/2017 09:45 PM »
Is LOX? Kinda need some of that too.
Cislunar shouldn't​ be defficult, but Mars would be more demanding.
Shading, and insulation are part of the answer.


Sent from my XT1565 using Tapatalk
No. LOx is not a deep cryogen. Deep cryogens are basically just liquid hydrogen and helium.
« Last Edit: 05/29/2017 10:03 PM by Robotbeat »
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

Online Kenp51d

  • Member
  • Posts: 20
  • Modesto, CA
  • Liked: 0
  • Likes Given: 0
Re: IAC 2017 -- ITS v0.2
« Reply #30 on: 05/29/2017 09:51 PM »
Thanks, did not research definitions before posting.


Sent from my XT1565 using Tapatalk


Online AncientU

  • Senior Member
  • *****
  • Posts: 4182
  • Liked: 2499
  • Likes Given: 3513
Re: IAC 2017 -- ITS v0.2
« Reply #31 on: 05/29/2017 10:57 PM »
Storing a small amount of methalox in what are basically Dewars inside the main tanks should be pretty straightforward.

If SpaceX were trying to store methalox in the main tanks, I would say that's pretty low TRL. But storage in small vacuum lined tanks has been proven in operational flight systems.

Both Shuttle and Apollo demonstrated LOX storage for weeks on orbit. Shuttle even demonstrated cryo LH2 storage for up to about a month at -420 degrees F for the fuel cells.

Interesting how rarely TRL* comes up in SpaceX discussions...
What TRL was supersonic retro-propulsion when they did it?
3D printed engines and engine parts?
Red Dragon's EDL profile?
Pusher abort system?
Landing legs on an orbital-class booster?
ASDS?
Full flow staged combustion engines? ...using methlox?
Refueling cryogens on orbit?
Landing the whole thing?
ISRU... on Mars?
Don't see much in the way of entire phases being devoted to 'risk reduction' during their development cycle either.

They aren't afraid to do new things if they need to be done -- maybe ignoring TRL is their key to success. 

Kinda OT for this discussion, but IAC v0.1 didn't dwell on low TRL as a barrier and expect neither will v0.2.


* Has Elon Musk ever actually said 'technology readiness level' in public?  (He'd not say TRL because he hates acronyms.)
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Offline Lars-J

  • Senior Member
  • *****
  • Posts: 3152
  • California
  • Liked: 2472
  • Likes Given: 1454
Re: IAC 2017 -- ITS v0.2
« Reply #32 on: 05/29/2017 11:21 PM »
Storing a small amount of methalox in what are basically Dewars inside the main tanks should be pretty straightforward.

If SpaceX were trying to store methalox in the main tanks, I would say that's pretty low TRL. But storage in small vacuum lined tanks has been proven in operational flight systems.

Both Shuttle and Apollo demonstrated LOX storage for weeks on orbit. Shuttle even demonstrated cryo LH2 storage for up to about a month at -420 degrees F for the fuel cells.

Interesting how rarely TRL* comes up in SpaceX discussions...
What TRL was supersonic retro-propulsion when they did it?
3D printed engines and engine parts?
Red Dragon's EDL profile?
Pusher abort system?
Landing legs on an orbital-class booster?
ASDS?
Full flow staged combustion engines? ...using methlox?
Refueling cryogens on orbit?
Landing the whole thing?
ISRU... on Mars?
Don't see much in the way of entire phases being devoted to 'risk reduction' during their development cycle either.

They aren't afraid to do new things if they need to be done -- maybe ignoring TRL is their key to success. 

Kinda OT for this discussion, but IAC v0.1 didn't dwell on low TRL as a barrier and expect neither will v0.2.


* Has Elon Musk ever actually said 'technology readiness level' in public?  (He'd not say TRL because he hates acronyms.)

I think you misunderstand what TRL means. SpaceX isn't ignoring it. They are simply choosing to develop some of these technologies where other are too cautious. Ignoring TRL doesn't make things easier, it is just a way to express how far from the current state of the art something is.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26241
  • Minnesota
  • Liked: 6208
  • Likes Given: 4562
Re: IAC 2017 -- ITS v0.2
« Reply #33 on: 05/29/2017 11:25 PM »
I do think there's some unnecessary ritual in the whole concept of the Technology Readiness Level formalism. It seems primarily a tool for getting multiple stakeholders to agree on whether a certain technology is mature enough for some application, whereas SpaceX is free to just try something.
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 envy887

  • Senior Member
  • *****
  • Posts: 2135
  • Liked: 929
  • Likes Given: 603
Re: IAC 2017 -- ITS v0.2
« Reply #34 on: 05/29/2017 11:31 PM »
Technology development is SpaceX's key competency, so current readiness probably weights lower in their trades when evaluating what options to pursue.

But they definitely factor it in, and they definitely do not develop low readiness technologies unless they deem them critical to a larger objective.

I don't expect development of long term on orbit main tank cryo storage because it's not critical to ITS.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26241
  • Minnesota
  • Liked: 6208
  • Likes Given: 4562
Re: IAC 2017 -- ITS v0.2
« Reply #35 on: 05/29/2017 11:33 PM »
Of course SpaceX considers how practical some technology is. But I doubt the TRL formalism is as commonly used as it is at a place like NASA.
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 stcks

  • Full Member
  • *
  • Posts: 128
  • Liked: 89
  • Likes Given: 130
Re: IAC 2017 -- ITS v0.2
« Reply #36 on: 05/29/2017 11:36 PM »
I don't expect development of long term on orbit main tank cryo storage because it's not critical to ITS.

It is though, for varying definitions of long term. ITS will need to be refueled over a handful of tanker flights which could take a bit of time

Online RobW

  • Member
  • Posts: 18
  • Melbourne, Australia
  • Liked: 6
  • Likes Given: 34
Re: IAC 2017 -- ITS v0.2
« Reply #37 on: 05/30/2017 12:05 AM »
I don't expect development of long term on orbit main tank cryo storage because it's not critical to ITS.

It is though, for varying definitions of long term. ITS will need to be refueled over a handful of tanker flights which could take a bit of time

Not if you can live with the boil-off losses during the fueling campaign. The trade-off is between developing long-term, main tank cryo management, and launching a bit more fuel during the refueling campaign. If the fuel needed for the Mars ship is not an exact multiple of the tanker capacity, you already have some 'free' excess fuel that can go toward making up for the boil-off.
Science fiction writer, spaceflight blogger, and unrepentant technological optimist.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 26241
  • Minnesota
  • Liked: 6208
  • Likes Given: 4562
Re: IAC 2017 -- ITS v0.2
« Reply #38 on: 05/30/2017 12:07 AM »
All propellant would be used for speeding the transit (or for slowing down). There wouldn't be extra except for safety margin.
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 TripD

  • Full Member
  • ****
  • Posts: 490
  • E. Clampus Launchus
  • Liked: 365
  • Likes Given: 241
Re: IAC 2017 -- ITS v0.2
« Reply #39 on: 05/30/2017 02:42 AM »
I think RobW was talking about the tanker.

Tags: