I just noticed an interesting point brought up in the comments section of a recent post on Jeff Foust’s Space Politics blog. The commenter linked to article with an old quote (emphasis mine) by Mike Griffin on human rating:
In other testimony, Griffin has made it clear that he is not opposed to using EELV vehicles effectively unmodified from their current versions to launch crewed vehicles. In a May 2003 hearing by the House Science Committee’s space subcommittee on NASA’s Orbital Space Plane (OSP) program—a short-lived effort to develop a manned spacecraft that was superseded by the CEV—Griffin noted that the term “man rating” dated back to efforts in the 1950s and 1960s to modify ICBMs to carry capsules. “This involved a number of factors such as pogo suppression, structural stiffening, and other details not particularly germane to today’s expendable vehicles. The concept of ‘man rating’ in this sense is, I believe, no longer very relevant.”
He argued that EELVs and other expendable vehicles are already called upon to launch high-value unmanned payloads. “What, precisely, are the precautions that we would take to safeguard a human crew that we would deliberately omit when launching, say, a billion-dollar Mars Exploration Rover (MER) mission?” he asked. “The answer is, of course, ‘none’. While we appropriately value human life very highly, the investment we make in most unmanned missions is quite sufficient to capture our full attention.”
The Atlas 5 and Delta 4 EELVs, he noted, have a specified design reliability of 98 percent, in line with experience with the premier expendable vehicles to date. If such a vehicle was used to launch a crewed spacecraft equipped with an escape system of just 90 percent reliability, he noted, the combined system would have a 1-in-500 chance of a fatal accident, “substantially better than for the Shuttle.”
So, here Griffin is more or less saying that the Delta IV and Atlas V could be used pretty much as is for launching people. However, not too much later, when he started getting into full swing with his pitch of The Stick, and the in-line SDV (now apparently dubbed the “ILV” by NASA), he completely switched tunes, as can be seen from this article. Once again, quoting Griffin:
[T]here would be a bunch of changes that would have to be put into the EELV to human rate it, and I don’t know that that’s the most fiscally sound path for NASA to go down. And frankly, I don’t know that the EELV community would welcome us getting into their production lines in order to make those kinds of modifications.
I’m confused now. Which is it? Are Delta IV and Atlas V good to go right out of
the box? Is man-rating an antequated concept that mostly dealt with converting old ICBMs into launch vehicles? Or is man-rating a launcher a process so onerous and difficult that the costs justify a $5B launcher development project instead?
Realistically speaking, the main add-ons that have been suggested were engine health monitoring systems. These let you know if something is going wrong with the engine, so you can shut it down, and in this case eject the capsule. Usually engines don’t fail instantly, there is often tell-tale signs that something is going awry long before a catastrophic failure can occur (even for engines designed at the bleeding edge of technology with razor thin margins like the SSME). One suggested system uses spectroscopy on the engine plume to detect problems, such as if the mixture ratio is shifting from what the vehicle thinks its delivering to the engines. This might be indicative of a chamber burn through that is now leaking extra propellant into the chamber. The problem is that doing this doesn’t require billions of dollars, thousands of pounds, or tons of modifications to the launch vehicle. When the DC-X program was moved to NASA and they upgraded it to its DC-XA configuration, they added several of these sensor systems for a trivial cost and time expenditure. We’re talking low millions, and a couple dozen pounds. All you’re doing is mounting another sensor or two or three, and some wiring to send that data up to the payload fairing. This isn’t something that should take billions of dollars or require subtantial rework. Basically, this argument is bogus.
The real answer to why Griffin is changing his tune may have come out in his next sentance (emphasis again mine):
Right now the path we think is the most favorable is the shuttle-derived, in part because that gives us the best work force transition issues.
Basically, the real reason why the VSE architecture is being diverted into a shuttle-derived direction is entirely due to jobs issues. In order to maintain support, NASA needs to keep people employed in key congressional districts. It isn’t the difficulty of earth orbit rendezvous, it isn’t the difficulty or cost of man-rating, it isn’t even the “unreliability” of private enterprise. It’s entirely about making sure that enough pork is distributed to the right places.
We should support this why?
Latest posts by Jonathan Goff (see all)
- SBIR Proposaling Advice - March 8, 2019
- FISO Telecon Lecture on LEO Propellant Depots for Interplanetary Smallsat Launch - November 28, 2018
- AAS Paper Review: RAAN Agnostic 3-Burn Departure Methodology for Deep Space Missions from LEO Depots (Part 2 of 2) - September 17, 2018