If NASA were to apply the safety standards it is using on the CCtCAP program (Dragon V2 and CST-100 now chosen) would the Space Shuttle have met those standards?

I suppose it helps if we are clear on what the safety standards are?

The Shuttle is now in the past, but would it have been able to pass the standards?

No abort system to speak of. Lots of manned flights already, so demonstrated it could work.

Lots of paperwork required to be filled out though.


2 Answers 2


No. Like in your similar question about Soyuz spacecraft meeting NASA's CTS requirements, I'll quote from Commercial Crew Program: Key Driving Requirements Walkthrough (Powerpoint presentation):

The CTS shall be capable of being docked to the ISS for 210 days to provide an assured crew return capability for four NASA crew. (; R.CTS.12)

CTS stands for Crew Transportation Systems, but what this means is that Space Shuttle wouldn't meet it, since it was capable of a maximum of 12 days of being docked to the station due to its electrical power constraints. Quoting a Boeing Frontiers article Space Shuttle upgrade lets astronauts at ISS stay in space longer:

The Station-Shuttle Power Transfer System (SSPTS) allows the ISS to supplement the shuttle's electrical power using electricity generated by ISS solar arrays. This results in a lower consumption of liquid hydrogen and oxygen, components used by the shuttle's fuel cells for making electricity. The power transfer system upgrade also will result in a 50 percent increase in the amount of time the orbiter can dock to the station: from about seven days to between nine and 12 days, depending on the mission configuration.

So 12 day and a far cry off one of CCDev (Commercial Crew Development) key requirements of being capable of being docked to the ISS for 210 days.

  • $\begingroup$ To be fair I was more interested in the safety aspects, not the crew transfer aspects. So I will modify the question to match. $\endgroup$
    – geoffc
    Commented Sep 17, 2014 at 14:48
  • 4
    $\begingroup$ @geoffc What do you mean with "To be fair"? That's not fair at all! :D $\endgroup$
    – TildalWave
    Commented Sep 17, 2014 at 15:07
  • 2
    $\begingroup$ @TildawlWave Fair enough. $\endgroup$
    – geoffc
    Commented Sep 17, 2014 at 15:09
  • $\begingroup$ ... although presumably one reason that is required is so that it is always there to be used as a lifeboat, right? In case a micro-meteorite strikes the ISS and George Clooney isn't around to save anyone? $\endgroup$
    – kim holder
    Commented Sep 17, 2014 at 22:36
  • 2
    $\begingroup$ @DavidHammen The question was ninja-edited after I posted my answer. I would still argue that assured crew return capability is a safety requirement, since they use same vehicles to return as they did to get there, and doubling as retreat and evacuation vehicles in case something goes awry before the end of mission. $\endgroup$
    – TildalWave
    Commented Sep 23, 2014 at 4:43

The Shuttle did pass human rating standards, and post-Challenger, it did have a (limited) crew escape capability. Pre- and post-Challenger, it had abort modes galore that were designed around human safety concerns.

Every bolt, every wire, every everything used on the Shuttle was controlled from the prior to pouring molten metal into a form the bolt or wire, and on up the manufacturing chain. This is part of what made the Shuttle so expensive to operate.

This also applies to lesser extent to commercial aircraft. Fasteners certified for use in aircraft cost a bunch of money. Oftentimes you can buy exactly the same bolt at your local hardware store, and all you will be missing is a hole in your wallet and a piece of paper that traces the pedigree of the bolt. MIL specs and NASA human rating specs make those FAA specs look like child's play.

The Shuttle did have a few CRIT-1A exceptions, the lack of a reliable launch escape system being one of them. Rules, even human safety rules, always have an out. Sometimes you might have to wait until the next ice age to get a waiver to a rule. Waivers are amazingly easy to get at other times, as was the case with regard to the a reliable launch escape system. The waiver rules are built into the human safety rating standards. Since the Shuttle had the requisite paperwork for those exceptions (with signoffs all the way to the top), it was human rated.

  • 1
    $\begingroup$ At least a couple of air transport crashes have demonstrated the importance of part traceability and vulnerabilities to forgery. If my life depended on it, I'd want to be sure every component down to the last nut and bolt is up to specification. That is the difference between off-the-shelf at your hardware store and FAA, NASA, or MIL-spec compliant. Not sure I'd be too comfortable with anything that had been "waiver"ed. If I'm not mistaken, Challenger's fatal flight launched under waiver. $\endgroup$
    – Anthony X
    Commented Nov 9, 2014 at 20:58
  • $\begingroup$ What made the Shuttle so expensive was that its parts were produced in 50 different states due to political, not engineering, reasons (congressmen want some kickback for their home states before they approve funding). Same goes for the SLS. $\endgroup$ Commented Nov 5, 2019 at 12:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.