On NASA website it says to get TRL 9 the technology must be flight proven, now, to be "flight proven" is there any specific criteria for that? like a defined amount of time of functioning, radiation, altitude, etc.? Or is it once the technology (let's say a PCB) is in space then that is it, it is certified as space-qualified?

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    $\begingroup$ In addition to passing the specific requirements for TRL 9 to attain TRL 9, the technology in question has to pass the requirements for technology readiness levels one to eight. $\endgroup$ Jul 25, 2022 at 20:03

1 Answer 1


You seek Appendix E of NASA Systems Engineering Processes and Requirements (NPR 7123.1C) which defines the technology readiness levels.

You can find the official definitions here. Effective Date: February 14, 2020

tl;dr It had to have flown in space and worked right

TRL Definition Hardware Description Software Description Exit Criteria
9 Actual system flight proven through successful mission operations. The final product is successfully operated in an actual mission. All software has been thoroughly debugged and fully integrated with all operational hardware and software systems. All documentation has been completed. Sustaining software support is in place. System has been successfully operated in the operational environment. Documented mission operational results.
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    $\begingroup$ interesting that "Verification and Validation completed" was added to Software. All the rest of that is pretty sad. I wonder who was upset enough that things aren't TRL 9 the first time you operate them to put those changes through. $\endgroup$
    – Erin Anne
    Jul 25, 2022 at 3:16
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    $\begingroup$ @Brondahl thanks! I misread the new chart. Apologies to all. $\endgroup$ Jul 25, 2022 at 12:33
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    $\begingroup$ @MohamedAbduljawad: I assume it's so vague because it's meant to be general and not assume a specific application. Something that's TRL 9 for a satellite in LEO may not be TRL 9 for, say, a Venus lander. Heck, the definitions don't even assume that the relevant application is in space. The coffee maker in the mission control break room is probably TRL 9 for its operational environment, but you wouldn't want to send it to space. $\endgroup$ Jul 25, 2022 at 15:33
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    $\begingroup$ Re Now, it doesn't actually have to fly to be flight proven: The concept of technology readiness level has turned out to be so useful that it now applies to much more than flight hardware, which was the original target. Flight software was an add-on, and non-flight hardware / software were even later add-ons. How do you qualify non-flight hardware as TRL 9 if only flight-tested hardware can qualify as TRL 9? The answer is simple: Expand what it means to qualify as TRL 9. Flight hardware still needs to be flown to qualify as TRL 9. $\endgroup$ Jul 25, 2022 at 18:33
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    $\begingroup$ @MohamedAbduljawad: That would mean that almost no first stage system would ever become TRL9, since they only ever operate for 2–5 minutes and then get destroyed*. Requiring something which only operates for 2–5 minutes total (and only spends half of that time in space) to be tested in space for a month would be totally ridiculous. You would need to add literally tons of useless and extremely expensive radiation shielding, tank insulation, batteries, solar panels, heating elements, radiators, etc. for the sole purpose of passing TRL9, and then never, ever use that stuff again operationally. $\endgroup$ Jul 25, 2022 at 20:10

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