The escape system is that thin pointy part at the very top of the rocket. It has powerful solid rockets that basically act as an "ejection seat" for the entire crew capsule.

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So when we talk about "human-rating" a rocket, doesn't this mean the same thing as the escape system? It's supposed to pull you away really fast (15 g's in Soyuz case) so it can outrun an exploding rocket.

To me that seems like the main thing. If the escape system is reliable, it will save you no matter what the rocket does.

So to sum up, is human-rating the escape system the only thing needed to human-rate the rocket?

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    $\begingroup$ The Space Shuttle didn't have an escape system and it was human rated $\endgroup$ – gillonba Jul 23 '15 at 16:00

While the launch escape system (LES) is important for getting the crew away on ascent there are other thing required for human-rating a craft/launch system (and you do need to pay attention to the entire system and mission, not just the rocket during ascent).

Specifically for Atlas V they needed to: space.com

  • upgrade the emergency detection system (your LES does no good if it doesn't get enough warning to get away in time)
  • figure out how to get astronauts onto the rocket, including options for emergency evacuation
  • develop a different upper stage (no explanation provided on this one)

NASA actually has a document available online that details what all goes into human-rating a spacecraft by their standards: Human-Rating Requirements for Space Systems

It starts off with the very basics:

The space system shall provide the capability to sustain a safe, habitable environment for the crew

Sets expectations for chance of failure:

The space system shall meet probabilistic safety criteria derived from the Agency-level safety goals and safety thresholds with a specified degree of certainty

Insists allowances be made for the fact that humans are operating the craft:

The space system shall be designed to tolerate inadvertent operator action (minimum of one inadvertent action), as identified by the human error analysis, without causing a catastrophic event

There's also an entire section on requirements for the launch escape system (LES). First, there has to be one:

The space system shall provide abort capability from the launch pad until Earth-orbit insertion to protect for the following ascent failure scenarios: ...

And beyond that, it has to be activatable by the crew, the ground control, and the rocket itself (only quoting the last):

The crewed space system shall monitor the Earth ascent launch vehicle performance and automatically initiate an abort when an impending catastrophic failure is detected

And at end of mission:

The space system shall provide recovery forces with the location of the spacecraft after return to Earth

tl;dr The launch escape system is a key requirement but it's intended to be a last-resort, not the only option for crew protection. You also need provisions for supporting a crew on the ground and in space.

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    $\begingroup$ Also things like G-Load and vibrations are also looked into to ensure that a crew can cope. $\endgroup$ – tl8 Jul 23 '15 at 6:39
  • $\begingroup$ @tl8 This is also a concern for unmanned launch systems. Not every payload can sustain intense g-forces and vibrations. Satellites are sensitive, and you usually want to get them into orbit in one piece. $\endgroup$ – Philipp Jul 23 '15 at 13:23
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    $\begingroup$ FWIW, the Shuttle was presumably man-rated, but did not have abort capability from every point from lift-off to orbit. Yes, from some thousands of feet up all the way to orbit, but from launch commit through to the first few thousand feet, there would have been no practical escape. It must have received some sort of waiver for that. $\endgroup$ – Anthony X May 6 '17 at 19:41
  • $\begingroup$ @AnthonyX Someone here did discuss the issue of recertification of the Space Shuttle toward the end of the program, and how that would essentially require a complete redesign, thus effectively shutting down the program without ever really saying to shut it down. I forgot which exact report it was, but some digging around the site can probably uncover it. $\endgroup$ – a CVn Jun 28 '17 at 9:54

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