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categories: ["foundations"]categories: ["foundations"]tags: ["forecasting", "translation", "regulation", "engineering", "clinical trials", "methodology"]tags: ["forecasting", "translation", "regulation", "engineering", "clinical trials", "methodology"]summary: "A nine-point scale, originating at NASA, that rates how far a technology has moved from observed basic principles to proven operational use."summary: "A nine-point scale, originating at NASA, that rates how far a technology has moved from observed basic principles to proven operational use."updated: "2026-07-27"updated: "2026-10-29"issues: ["Adoption dates for ISO 16290 and the European Commission are stated without citations."]issues: ["Adoption dates for ISO 16290 and the European Commission are stated without citations."]------ lines 30–36 → 30–3616 unchanged lines not shown
```keyfacts```keyfacts[[ { "value": "9", "label": "Levels in the standard scale", "note": "expanded from an original seven at NASA" }, { "value": "9", "label": "Levels in the standard scale", "note": "expanded from an original seven at NASA" }, { "value": "~1 in 7", "label": "Drugs entering Phase I that reach approval", "note": "Wong, Siah and Lo, across 2000–2015" }, { "value": "~1 in 7", "label": "Drugs entering Phase I that reach approval", "note": "Wong, Siah and Lo, across 2000-2015" }, { "value": "1,026", "label": "Experimental acute-stroke treatments tested in animals", "note": "O'Collins et al.; essentially none succeeded in humans" } { "value": "1,026", "label": "Experimental acute-stroke treatments tested in animals", "note": "O'Collins et al.; essentially none succeeded in humans" }]]``````lines 39–53 → 39–532 unchanged lines not shown
The canonical definitions are: 1, basic principles observed; 2, technology concept formulated; 3, experimental proof of concept; 4, component validated in a laboratory; 5, component validated in a relevant environment; 6, system or subsystem demonstrated in a relevant environment; 7, prototype demonstrated in an operational environment; 8, system complete and qualified; 9, system proven in operation.The canonical definitions are: 1, basic principles observed; 2, technology concept formulated; 3, experimental proof of concept; 4, component validated in a laboratory; 5, component validated in a relevant environment; 6, system or subsystem demonstrated in a relevant environment; 7, prototype demonstrated in an operational environment; 8, system complete and qualified; 9, system proven in operation. Two words carry most of the weight. *Relevant environment* means conditions that reproduce the stresses of the real setting in the respects that matter — vacuum and thermal cycling for a spacecraft component, a living organism for a therapeutic. *Operational environment* means the actual setting, with all of its uncontrolled variables. The distinction between levels 5 and 7 is therefore a claim about how much of the real world has been let in, and it is where assessments most often disagree.Two words carry most of the weight. *Relevant environment* means conditions that reproduce the stresses of the real setting in the respects that matter: vacuum and thermal cycling for a spacecraft component, a living organism for a therapeutic. *Operational environment* means the actual setting, with all of its uncontrolled variables. The distinction between levels 5 and 7 is therefore a claim about how much of the real world has been let in, and it is where assessments most often disagree. ## Origins and spread## Origins and spread Stan Sadin at NASA Headquarters introduced a seven-level formulation in the mid-1970s to compare the maturity of candidate technologies for future missions. John Mankins expanded and documented the nine-level version in a 1995 NASA white paper that remains the reference text for the definitions.[^mankins1995]Stan Sadin at NASA Headquarters introduced a seven-level formulation in the mid-1970s to compare the maturity of candidate technologies for future missions. John Mankins expanded and documented the nine-level version in a 1995 NASA white paper that remains the reference text for the definitions.[^mankins1995] Adoption spread through defence acquisition after the US Government Accountability Office recommended maturity assessment as a corrective to programmes that committed to production before their key technologies worked. The US Department of Defense built TRLs into its acquisition process and added companion scales, notably manufacturing readiness levels, on the observation that a technology can be demonstrated and still be unbuildable at volume. The European Commission adopted the definitions across its research framework programmes in 2014, which made TRL a routine field in grant applications across European science. ISO published a space-systems standard for the levels and their assessment criteria in 2013.Adoption spread through defence acquisition after the US Government Accountability Office recommended maturity assessment as a corrective to programmes that committed to production before their key technologies worked. The US Department of Defense built TRLs into its acquisition process and added companion scales, among them manufacturing readiness levels, on the observation that a technology can be demonstrated and still be unbuildable at volume. The European Commission adopted the definitions across its research framework programmes in 2014, which made TRL a routine field in grant applications across European science. ISO published a space-systems standard for the levels and their assessment criteria in 2013. The consequence is that TRL now functions as an administrative currency far outside the domain it was designed for, including in fields where its central metaphor — a component moving toward integration in a system — does not obviously apply.As a result, TRL now works as an administrative currency far outside the domain it was designed for. That includes fields where its central metaphor, a component moving toward integration in a system, does not obviously apply. ## Adaptation to biomedicine## Adaptation to biomedicine lines 70–76 → 70–7616 unchanged lines not shown
## The valley of death## The valley of death The gap between laboratory validation and operational prototype — roughly TRL 4 through 7 — is where most technologies die, and the reason is structural rather than scientific. Basic research is funded by science agencies that stop at proof of concept. Product development is funded by firms and investors who require a defined path to revenue. Between the two sits work that is too applied to be publishable and too unproven to be financeable, and it is expensive.Most technologies die in the gap between laboratory validation and operational prototype, roughly TRL 4 through 7, and the reason is structural rather than scientific. Basic research is funded by science agencies that stop at proof of concept. Product development is funded by firms and investors who require a defined path to revenue. Between the two sits work that is too applied to be publishable and too unproven to be financeable, and it is expensive. In biomedicine the valley has a measurable shape. Across a large sample of development programmes, roughly one in seven drugs entering Phase I trials reached approval, with the largest single loss at Phase II, where efficacy is tested for the first time in patients.[^wong2019] Fields relevant to this wiki show the pattern clearly. [[senolytics]] cleared TRL 4 convincingly in mice and have produced modest or null results in the small human trials run so far. [[gene-therapy-for-aging]] has strong animal data and no controlled human efficacy evidence. [[organ-bioprinting]] and [[tissue-engineering]] are stuck between validated tissue constructs and anything approaching a vascularised organ. [[artificial-womb]] devices have kept premature lambs alive for weeks in animal studies since the late 2010s, and as of 2026 no first-in-human trial has been publicly reported.In biomedicine the valley has a measurable shape. Across a large sample of development programmes, roughly one in seven drugs entering Phase I trials reached approval, with the largest single loss at Phase II, where efficacy is tested for the first time in patients.[^wong2019] Fields relevant to this wiki show the pattern clearly. [[senolytics]] cleared TRL 4 convincingly in mice and have produced modest or null results in the small human trials run so far. [[gene-therapy-for-aging]] has strong animal data and no controlled human efficacy evidence. [[organ-bioprinting]] and [[tissue-engineering]] are stuck between validated tissue constructs and anything approaching a vascularised organ. [[artificial-womb]] devices have kept premature lambs alive for weeks in animal studies since the late 2010s, and as of 2026 no first-in-human trial has been publicly reported. lines 78–84 → 78–841 unchanged line not shown
A 2015 review of TRL practice across aerospace, defence and other sectors identified recurring problems: the scale collapses many dimensions of maturity into one number, it assumes a linear progression that real programmes do not follow, and it is routinely used as a risk measure although it says nothing about how difficult the remaining steps are.[^olechowski2015]A 2015 review of TRL practice across aerospace, defence and other sectors identified recurring problems: the scale collapses many dimensions of maturity into one number, it assumes a linear progression that real programmes do not follow, and it is routinely used as a risk measure although it says nothing about how difficult the remaining steps are.[^olechowski2015] That last point is the important one. TRL measures distance travelled, not distance remaining. Two technologies at TRL 4 may be separated by two years and by thirty. Nothing in the scale distinguishes a component awaiting an engineering iteration from one awaiting a scientific result nobody knows how to obtain. Attempts to patch this have produced companion scales — integration readiness, system readiness, manufacturing readiness — each of which adds information and none of which is widely used outside defence.The last of these matters most. TRL measures distance travelled rather than distance remaining. Two technologies at TRL 4 may be separated by two years and by thirty. Nothing in the scale distinguishes a component awaiting an engineering iteration from one awaiting a scientific result nobody knows how to obtain. Attempts to patch this have produced companion scales for integration readiness, system readiness and manufacturing readiness. Each adds information, and none is widely used outside defence. The scale is also gameable. Because funding decisions depend on it, self-assessed TRLs drift upward, and the boundary terms are elastic enough to support optimistic readings. Independent technology readiness assessments exist precisely because self-reporting is unreliable.The scale is also gameable. Because funding decisions depend on it, self-assessed TRLs drift upward, and the boundary terms are elastic enough to support optimistic readings. Independent technology readiness assessments exist precisely because self-reporting is unreliable. lines 95–105 → 95–10510 unchanged lines not shown
## Use on this wiki## Use on this wiki TRLs on this site are assigned conservatively and mean what the standard definitions say. A rating of 1 to 3 marks a subject that exists as argument, calculation or laboratory proof of concept — the position of [[medical-nanorobots]] and [[cryonics]] among the technologies covered here. Subjects typed as concepts rather than technologies, such as [[respirocytes]] and [[whole-brain-emulation]], carry no rating at all, which is itself informative: there is no artefact to assess. A rating of 4 to 6 marks animal or early human evidence, the position of most of the longevity interventions covered here. A rating of 7 to 9 marks clinical or commercial deployment, which applies to a small minority of the wiki's subjects, among them [[cochlear-implant|cochlear implants]], [[casgevy]] and [[induced-pluripotent-stem-cells|iPSC]]-derived products in their first approved uses.TRLs on this site are assigned conservatively and mean what the standard definitions say. A rating of 1 to 3 marks a subject that exists as argument, calculation or laboratory proof of concept, which is the position of [[medical-nanorobots]] and [[cryonics]] among the technologies covered here. Subjects typed as concepts rather than technologies, such as [[respirocytes]] and [[whole-brain-emulation]], carry no rating at all, which is itself informative: there is no artefact to assess. A rating of 4 to 6 marks animal or early human evidence, the position of most of the longevity interventions covered here. A rating of 7 to 9 marks clinical or commercial deployment, which applies to a small minority of the wiki's subjects, among them [[cochlear-implant|cochlear implants]], [[casgevy]] and [[induced-pluripotent-stem-cells|iPSC]]-derived products in their first approved uses. ## Outlook## Outlook The scale's persistence despite well-documented flaws is a fact about institutions rather than about measurement. It survives because it is cheap, comparable across proposals and legible to non-specialists, and because no proposed replacement has offered the same three properties. The open question is whether a maturity measure can be built that captures remaining difficulty rather than accumulated progress — which would require forecasting the very thing the scale exists to avoid forecasting, and which is why forty years of criticism have produced supplements rather than successors.The scale's persistence despite well-documented flaws is a fact about institutions rather than about measurement. It survives because it is cheap, comparable across proposals and legible to non-specialists, and because no proposed replacement has offered the same three properties. The open question is whether a maturity measure can be built that captures remaining difficulty rather than accumulated progress. Such a measure would have to forecast the very thing the scale exists to avoid forecasting, which is why forty years of criticism have produced supplements rather than successors. ## See also## See also removed, struck through added, underlinedLine numbers count the serialised markdown of each revision, frontmatter included.
112 lines are the same in both revisions, and 67 of them are not shown. Neither revision here is necessarily the current article — read Technology readiness level for the text this wiki stands behind today.