One In Thirty?

So right!

Do you know what NASA in a nutshell is? ^_^

"C:\>Abort, Retry, Ignore?"

Smells funny to me.

1) We don't know the source of the story nor why it is considered reliable.

2) A loss of crew rate of 1/30 for reentry from LEO is crazy. Hard to believe that the CEV has been compromised that much.

3) As far as I can tell, nobody has the launch vehicle design nailed down enough to make such claims about the safety of it. They're still suffering through the throes of vehicle redesign and changing requirements.

OTOH, the safety and reliability of the CEV has always been the "shoe" that we've been waiting for to drop. In other words, the Ares I vehicle grows less capable and imposes growing requirements (eg, thrust oscillation protection for crew and electronics) and mass constraints on the CEV. Meanwhile the CEV continues to hold the same amount of crew. Even if they increase spending on the CEV, they'll have to remove redundacy of the CEV's systems in order to meet the lower mass numbers. That means adding risk somewhere in the mission to compensate for the launch vehicle's weaknesses.

If this story is for real, it'll help make the next NASA administrator's job a bit easier since they can dodge the worst case scenario of being expected to make it work with Ares I as is and the CEV as is. There's no way that the status quo will go on with a 1/30 LOC rate looming over it.

I think he may have gotten LOC and LOM mixed up? The old presentation I saw was saying a 1:19 LOM probability for an ISS mission. If it's at 1:30 now it means its headed back in the right direction. Still pathetically low.

~Jon

I think he may have gotten LOC and LOM mixed up? The old presentation I saw was saying a 1:19 LOM probability for an ISS mission.

Maybe, but he generally seems to know what he's talking about, and the implication is that this is a new number, not an old one.

Rand,
I just don't see how any vehicle with a launch escape system could possibly have a 1/30 chance of killing the crew. That just doesn't make sense. While I may think that the Ares I is an abomination that should be killed ASAP, I give them more credit than that.

~Jon

I just don't see how any vehicle with a launch escape system could possibly have a 1/30 chance of killing the crew. That just doesn't make sense.

Three points. First, I think that you have far too much faith in the reliability of a launch escape system, particularly its reliability to not cause you problems on a nominal launch (as just one example, what happens to crew if the LAS fails to separate?)

The second is that LOC doesn't necessarily mean all crew are killed (at least, as I understand NASA's use of the term). Killing just one crew member would constitute LOC. In addition, I'm not sure that it's even necessary to kill them (again, depending on the definition). When I've done S&MA in the recent past, we included injury severe enough to render them unable to fly again as LOC.

Third (in light of the second point), think of an abort as Mitch Clapp used to define an ejection--attempted suicide to avoid certain death.

All of which is why this back-to-the-sixties approach that, rather than trying to develop reliable systems, is putting band aids on unreliable ones, is fundamentally flawed.

Why the doom and gloom ? Im sure they will put a crew escape escape system on it next and rerun the numbers soon .. Also, reportedly they are working on developing a more survivable crew to get the LOC numbers up again.

"reportedly they are working on developing a more survivable crew to get the LOC numbers up again."

What, robots?

(Just kidding; I assume you meant 'more survivable CES')

Rand,
Oh, I agree that the standard techniques for launch escape do have issues with them, especially when you've got solids on the first stage. I just have a hard time believing that even NASA is that incompetent. Well...hmm...I guess a 3% chance of failure isn't completely impossible with such a crappy design, I'm just still skeptical. The report I saw showed a 170:1 LOC probability for ISS. Seeing that get worse by a factor of 6 all of the sudden just really doesn't seem likely. Undocumented claims from anonymous authors that don't even jibe with the most pessimistic previous data need to be taken with the appropriate sized grain of salt. He could be right, but that's really scanty evidence you're going off of.

~Jon

Well...hmm...I guess a 3% chance of failure isn't completely impossible with such a crappy design, I'm just still skeptical.

Well...when I look at this "design" (such as it is), I think that estimate low, considering all of the kludges and waivers that will be necessary to get it to fly at all. You also seem to have a higher opinion of current upper-level NASA management than I do.

Given your low opinion of the government in general, I'm wondering why?

Perhaps they should just beef up the escape system and eliminate the rocket?

Rand, you wrote:

Well...when I look at this "design" (such as it is), I think that estimate low, considering all of the kludges and waivers that will be necessary to get it to fly at all. You also seem to have a higher opinion of current upper-level NASA management than I do.

I agree with Jon. Hard to believe that even with the current train wreck that the Ares I design is this screwed up. I think it'll be educational to see where the increase in risk comes from. I misread the article earlier and had thought that the 1/30 chance was only the return from orbit.

So I see two places where the risk could be coming from. The thrust oscillation mitigation systems, a launch issue and the mass shaving on the CEV, which adds most of the risk to later stages of the mission. If we're actually seeing that much risk in the launch phase of the Ares I, then that really should be the end of it. At least, if the risk is due to CEV problems, one can always cut back on the payload (fewer astronauts). But launch is already pretty damn marginal. That means you'd need to take away even more performance and go through this design process again.

Let's assume this story is true. Compared to a future manned version of the Delta IV Heavy, a rocket which has launched twice already (with 1 success and 1 partial success), I don't see the value in bothering with the Ares I. Even before, with three years of development and no serious effort towards "man-rating" the Delta IV Heavy, the Ares I looked years behind to me. With a 1 in 30 chance of LOC, the Ares I completely abandons the main excuse it was adopted in the first place, its hypothetical high reliability.

Karl,

You mentioned 2 places of risk but then seemed to list three. I'm not certain if you gave this concern a nod by citing "a launch issue" but it appears that Ares I is unable to cope with strong winds very well. If a strong gust of wind can blow Ares I into the launch tower at lift off. Then, I can't help but think what would happen as it tries to fly through a transitional boundary layer of a jet stream. Hell, even just a random gust of wind. I know that other launch systems face aborts due to high upper level winds. But Ares I maybe so top heavy that it won't be able to launch in anything but the calmest of weather.

Aside from loss of crew issues. What about loss of mission? Is the goal of the a lunar mission to launch Ares V and then within a few days launch Ares I for a rendezvous? It sounds like Ares I is going to be so finicky that the likelihood of loosing a whole Moon shot to some strong winds is pretty high.

Actually, I meant the thrust oscillation to be the "launch issue". To be honest, I don't see the strong wind problem as being that severe. NASA has a number of approaches for handling it. First, a redesign of the launch tower so that there's more room to handle a gust of wind. Second, just go as is, though I think that's unfeasible in the long term. Third, there are means to slow winds flow before it gets to the launch pad, say with huge barriers or giant blowers. Each one has significant costs associated with it, but you could spread those out over many launches.

Each one has significant costs associated with it, but you could spread those out over many launches.

NASA doesn't plan, or have budget for "many" launches. I haven't seen plans for more than four lunar missions per year. This is one of the reasons that spending so much money to develop the Ares series is neither affordable or sustainable.

I guess I'm late to put in my more then 2 cents worth but..

When I was on Orion (I wrote requirements specs) The scariest thing for me was the degree of cynical jokes, and how often in meetings I saw senior managers and engineers (bitterly) remind folks not to be as careful, not to worry as much about potential problems, as was standard on the other NASA projects they had worked on. Where for Shuttle they were to make sure no combination of any two components or subsystems failure, could cripple these systems (life support and thermal control specifically in this case). For Orion they kept having to remind people that the standard was no SINGLE failure could cripple the systems (in some cases they allowed single point failures), but combinations of failure - even when recognized in the reviews - were not to be considered or designed out.

Note that they also noted that even in the past NASA programs, NASA demanded LOWER reliability and safe standards then was industrial standard. Demanded safety margins designed into first drafts of designs be cut back to lower standards to save weight or something.

As a contractor I've worked on a lot of programs - 787, to mil helicopters, to Sprint networking systems, to tanks, etc.
On all these programs folks have had some cynical humor about how its going, or issues that frustrate them. But nothing like this. Nothing to the point that senior engineers openly hoped it would not be finished or fly.

This thing is dangerous, and I gather its projected to have a higher to MUCH higher failure/accident rate then Shuttle or Soyuz.

Kelly

>>NASA doesn't plan, or have budget for "many" launches. I haven't seen plans for more than four lunar missions per year. This is one of the reasons that spending so much money to develop the Ares series is neither affordable or sustainable.

Last I saw it was 2 flights a year for station, 2 maned, adn 2 unmaned a year for lunar missions starting in the 2020's.