The Air Force thinks that it is guaranteed to kill crew in an early abort.
One of the criteria for “human rating” (I sure wish that we could purge the language of that phrase) is that the vehicle have zero-zero (from zero altitude, zero velocity all the way to orbit) abort capability. The lack of this is why the Shuttle was never human rated, because it cannot abort for the first two minutes, until after the SRBs have burned out and separated. You might think that someone would have thought about this long-known fact and said “hmmmmmmm…” when one of the things was chosen as a first stage for a vehicle that was supposed to be human rated. You might think that, if NASA and particularly Marshall weren’t involved, in which case, it wouldn’t surprise you at all that no one did, or if they did, they weren’t listened to.
I’m sure that the usual defenders will have their usual defense: “Every rocket has development issues — stop picking on poor Ares.” Well, this is a simple issue to fix, fortunately. All they have to do is replace the propellant in the first stage with something non-explosive.
“All they have to do is replace the propellant in the first stage with something non-explosive.” — Now that is funny!
The DIRECT people aren’t pleased either. Imagine having to dodge two expanding shells of white hot debris instead of just one. On the other hand, their maximum dynamic pressure is lower, so they should have a better chance of out-running the debris.
For comparison, here’s a video of a Delta 2 with plenty of smaller solids going kaboom: http://www.youtube.com/watch?v=WsVzpE7ltb8. Now imagine what that’s going to look like with two SRBs. Then add an ET which could detonate, not just deflagrate like a Delta 2 upper stage.
The likelyhood of two catastropic SRB failurs would seem remote. The SRB’s were somewhat intact untill range popped them during Challenger.
The concern is not so much a catastrophic failure of the SRBs, but the effects of the RSO destroying them. In the case of Challenger they were something like 10 seconds before burnout. In the Titan IV case it was only 40 seconds into the flight and in the Delta video only 13 seconds. Whatever the cause of the abort, the SRBs will have to be destroyed. According to the report it is not the explosion that kills the crew, it’s the radiant heat from the SRB propellant that will melt the nylon parachutes so the astronauts would plummet to their deaths.
Direct’s Jupiter also has enough “excess” lifting capacity that would enable a more robust LES to be used that could lift the Orion up to a higher altitude and down or cross range so that the capsule would not be descending through the anticipated rain of burning propellant.
Why would there not be a second so so delay between initating the range destruct to allow the LES clear the stack before it terminates it?
I cannot see how the booster is going to turn and head back to the cape in that second.
Is it at all possible for the USAF range control rules to be reviewed / revised? Do the destruct during solid thrusting only when the risk to non-exclusion areas cross some threshold.
This, however, is not “my area”, so…
I glanced through the slides, and I hope there’s more to the report than what’s shown. I’m not a big Ares fan, but this report is missing a lot of information that would make the analysis more useful. I was in Air Force Titan launch operations (on the other coast) when we lost the booster they discuss, and it had effects on the launch I was working at the time. The A-20 disaster took place when the guidance system rebooted inflight (this is generally considered to be a bad thing) and veered off course by 13 degrees (slide 8). The Inadvertent Separation Destruct System (ISDS) split the solids as they separated from the core vehicle. In the case of Ares, such a system could be timed differently to give the capsule more time to clear the fireball.
As for range officer commanded destructs (they’re actually pretty rare nowadays, as the event is usually over and then the RSO sends the destruct commands to make sure nothing is left…note these slides don’t talk about the RSO commanding the destruct, though Wikipedia does as does a YouTube video from “Destroyed in Seconds” that I found), there are actually two buttons to press “Arm” which shuts down the engines (moot with a solid, of course) and “Destruct” which actually fires the charges to split the vehicle. As an aside, Elon Musk scored a major victory earlier when he asked for (and it’s my understanding that he got) permission to only have his engines shut down on Falcon launches. Anyway, the escape system on top of Ares would fire on the “Arm” command, which would give the crew a chance to gain some distance. Again, whether or not it’s enough distance is a question this report could/should have answered.
If I’m reading the charts right, they seem to assume that the capsule is under parachute at 3.5 seconds (slides 8-15) and that seems a little short. Does anyone have an LES timeline?
The geometry differences here are not trivial either. The larger upper stage on top of Ares I would ‘shield’ the capsule from debris during at least part of its escape. This is kind of a non-player for the period of time that they’re talking about when the capsule is falling through the burning debris.
Once again, I’m not a big fan of Ares. There are plenty of problems with the rocket, but this report needs more meat on it before I fully buy it.
NASA’s comeback to this finding?
“The SRB is going to be so reliable that a first stage failure is a remote possibility.”
A Challenger-type failure could be dismissed as a remote possibility, and NASA may even claim that the Ares TVC and guidance systems would be able to compensate for SRB exhaust escaping through a small breach in a field joint. Of course, the Titan 34D failure of April 1986 and the Titan 403 failure (1993) show that SRM’s can fail catastrophically.
It would be interesting to know if there could be a delay. On the other hand, with a delay the boosters would still be accelerating, which could make it more difficult to outrun them. Is there any risk a longer delay may result in the self destruct mechanism being destroyed? The AF is worried about the thrust oscillation on Ares I having that effect.
The LAS timeline depends on when during ascent occurs. If it’s early, at low altitude (particularly off the pad) 3.5s might be a maximum to ensure that the chutes open and terminal velocity is achieved before it hits the ground.
Aries is keeping the parts of the shuttle stack that actually killed crew, and drops the orbiter – which always worked fine as long as the SRBs and ETs didn’t tear it apart!
Yeah, that makes sense!!!