Methane dropped from CEV plans

• #60 by josh_simonson on 11 Jan, 2006 20:19
• Griffin has very recently stated that he'd like to do the lions share of the work to enable an orbital fuel depot, mainly zero-g fuel transfer and reliquification.  Perhaps he feels that dropping the methane for LH2 and picking up reliquification technology instead would have similar risk, but better short term payout in terms of infrastructure.  Of course I'm being optimistic here.
  
  On the other hand, one of the big points for the new methane engine was that it was to be pressure fed.  Fewer moving parts than an engine with a turbopump, hence more reliable.  Most of the available LO2/LH2 engines are turbopump engines, so that may indicate they'd go with pressure-fed hypergolics for maximum reliability.
• #61 by CuddlyRocket on 11 Jan, 2006 20:41
• The SM for a Lunar CEV need not be the same SM as that for an LEO CEV.  The latter can be a lot less capable, as it doesn't have to do the heavy work of EOI from lunar orbit.  If money and time is really tight, they should create an SM for LEO CEV's that can carry out that mission. They can develop the Lunar-mission SM, LOX/Methane engines and all, at a later date.
  
  Granted, this means a greater cost inthe long run (although there would be some commonality between the two types of SM, and presumably a smaller LEO SM would make those missions - the greater number - cheaper), but the limiting factors here are time and the next five year's annual budgets.
• #62 by HarryM on 11 Jan, 2006 20:53
• The RCS system in the original spec was also supposed to use LO2/LCH4 to have commonality with main propulsion (IIRC), so wonder what will happen with that. It was the hypergolic RCS system, after all, that caused the minor problems in Apollo/CSM with leakage into the command module in ASTP.
• #63 by Chris Bergin on 11 Jan, 2006 22:19
• Source info: Stennis apparently had a hand in the decision to move away from methane. One source, hence not viable as an addition to the current report (as with most one-source info). We have to stick with an "unknown" on the alternative to methane (either LOX/LH2 or Hypergols) as I'd prefer several in-the-know sources to confirm.
  
  That's not dismissing information posted here, that's just due diligence as a journalist.
• #64 by Super George on 11 Jan, 2006 22:36
• NASA confirms your methane removal:
  
  http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=1242&posts=8#M15864
• #65 by Bruce H on 12 Jan, 2006 00:44
• Quote

  Chris Bergin - 11/1/2006  5:19 PM
  
  Source info: Stennis apparently had a hand in the decision to move away from methane. One source, hence not viable as an addition to the current report (as with most one-source info). We have to stick with an "unknown" on the alternative to methane (either LOX/LH2 or Hypergols) as I'd prefer several in-the-know sources to confirm.
  
  That's not dismissing information posted here, that's just due diligence as a journalist.

  
  Performance issue with a methane/LOX engine, possibily?
• #66 by Flightstar on 12 Jan, 2006 01:19
• The downselect and wining contractor's timeline is now very important. It'll be Lockheed Martin, by the way.
• #67 by rsp1202 on 12 Jan, 2006 02:20
• With Northrop Grumman grabbing the LSAM?
  
  Re: Lockheed. Over the last decade or more they've continued to struggle with a number of reoccurring quality control issues in their space division programs. If they do grab this contract, it will give them a chance to acquit themselves admirably for manned spaceflight.
• #68 by Flightstar on 12 Jan, 2006 02:38
• That is correct.
• #69 by Shuttle Man on 12 Jan, 2006 02:45
• Quote

  Flightstar - 11/1/2006  8:19 PM
  
  It'll be Lockheed Martin, by the way.

  
  They sure seem to be acting like they've got it.
• #70 by Tony T. Harris on 12 Jan, 2006 03:03
• It would appear they are trying to avoid the multiple companies working on sections of the launch system. That was a problem with the Saturn Vs. You never got to see all of the rocket, it was gang land rules for a multi-stage Moon rocket.
• #71 by Avron on 12 Jan, 2006 04:08
• Quote

  Flightstar - 11/1/2006  9:19 PM
  
  The downselect and wining contractor's timeline is now very important. It'll be Lockheed Martin, by the way.

  
  
  How good is that info?
• #72 by Jason Sole on 12 Jan, 2006 04:25
• Quote

  Avron - 11/1/2006  11:08 PM
  
  

  Quote

  Flightstar - 11/1/2006  9:19 PM
  
  The downselect and wining contractor's timeline is now very important. It'll be Lockheed Martin, by the way.

  
  How good is that info?

  
  I'll field this. Answer: Better than what we could find out.
• #73 by rcaron on 12 Jan, 2006 05:24
• Hey guys, joined the community when NASAWatch mentioned the alternative CEV thruster/solar panel design.  I'm an Aerospace Engineering student, and I've read through chapter 5 in the ESAS report.
  
  Dropping methane is a huge mistake.  Going back to the Moon is supposed to give us the confidence in our manned operations and provide a technology infrastructure for Mars flights.  Without the methane engines pretty much all we have left is the HLLV (otherwise known as CaLV) and the CLV.
  
  Not to mention that putting LH2 on the ascent stage of LSAM will really suck.  The tank volume will go through the roof, increasing ascent stage mass and in turn limiting the useful payload the descent stage can bring to the surface.
  
  Hypergols would solve that problem, but then there is no expandability for ISRU systems.  We still could have used LOX on the Moon, which would have been a big deal since its the largest mass fraction of the ascent stage wet mass.
  
  There are comments that since the SM is disposable that we can implement methane later.  I'd have to disagree.  Switching propellant types requires new tanking, new engines, everything.  Its a whole new spacecraft, just with the same outer mold line.  With the costs and timeline associated with LCH4 engine development, if it isn't done now it won't get done until we're considering Mars flights in 2025.
  
  Dr. Griffin has some extremely difficult decisions ahead of him, and I'm first to say that now that NASA has direction its probably one of the worst times to work for the agency as everything is being turned inside out.  But, looking at the unpressurized CEV variant for ISS operations, we're not too far off from being able to launch ISS modules of Destiny's mass.  I say its time to close the book on the Shuttle and let the funds divert to where they need to be.  We're only going to get 2 Shuttle flights this year if we're lucky, a dozen at most by the 2010 date.
• #74 by nacnud on 12 Jan, 2006 09:27

• Quote

  Looking at the unpressurized CEV variant for ISS operations, we're not too far off from being able to launch ISS modules of Destiny's mass.

  From the RFP summary: The Cargo Delivery Vehicle (CDV) Option is removed from the final RFP. Link
  

• #75 by CuddlyRocket on 12 Jan, 2006 12:08
• Quote

  rcaron - 12/1/2006  6:24 AM
  
  Dropping methane is a huge mistake.

  Quoting spacester from space.com: "They dropped the requirement for that particular fuel but they are not excluding it from the list of possiblities. The contractors can still propose methane engines from what I can tell."
  
  Quoting myself : "Perhaps the contractors ... approached NASA and said: Look, we can perform the missions much more cheaply, or get the thing built much quicker, if you let us use something other than LOX/Methane? Given that Mars is decades away, that might be difficult to resist in this climate of limited budgets and development time."
• #76 by FransonUK on 12 Jan, 2006 12:14
• Quote

  CuddlyRocket - 12/1/2006  7:08 AM
  
  Quoting myself : "Perhaps the contractors ... approached NASA and said: Look, we can perform the missions much more cheaply, or get the thing built much quicker, if you let us use something other than LOX/Methane? Given that Mars is decades away, that might be difficult to resist in this climate of limited budgets and development time."

  
  I like your quote, that you quoted
• #77 by rcaron on 12 Jan, 2006 13:29
• I'm going to have to read the RFP in more detail; I was hoping I could finish the ESAS report first.
  
  Concerning the lack of CDV, that's too bad.  Those CMGs wear out must faster than originally planned, and post-Shuttle the only way to get new ones up there would be with the CDV.
  
  However, the CDV cancellation does not impact the potential for launching ISS modules on the CLV.  These modules are already designed to withstand the loads of a Shuttle launch, and a launch from the pogo-stick will have similar loads since they too have depressed launch profiles (as evidenced by the end of ESAS Ch5).  
  
  In fact, the SM would not be able to carry the CDV and a module; the removal of the CDV is what makes this even remotely possible.  The structural interface between the SM and said module will be minimal, literally just having some Al-Ti alloy load bearing members, release bolts, and a small amount of empty volume for the avoinics suite that would otherwise reside in the CEV.
• #78 by Chris Bergin on 12 Jan, 2006 13:35
• Welcome to the site RCaron.
  
  I agree on the CDV - it's not important in the context of getting the Moon element of the VSE/ESAS on line and running,
• #79 by rcaron on 12 Jan, 2006 13:38
• Your quotes only demonstrate that without the LCH4 requirement that these engines will not be developed.  Of course it will be cheaper to use LH2 or hypergolics.  One can't "soften the blow" by saying NASA isn't prohibiting LCH4 development.  It won't get done unless it is a requirement.
  
  Imagine us 2030, finally ready to switch from a gray vista to a red one.  We can either :
  
  a) have decades of flight experience with ISS and lunar derived LCH4 engines or
  b) have 0 flight experience and have to undergo a seperate development and extensive flight certification program.  We would have to build up the necessary confidence to put these "high risk" engines in the critical path of a Mars flight return trip.
  
  Let there me no mistake, ISRU is required if a Mars mission is going to be feasible, and the best ISRU option is LCH4/LOX.