>[!summary] Payload Risk Classification [[NASA]] has four distinct risk tolerance levels, or classes, corresponding to the acceptable risk and degree of uncertainty assigned to a payload: ## Class A The lowest risk tolerance missions, normally representing a very high priority mission with very high complexity. Class A payloads will be launched on [[⚖️ NASA Rocket Risk Classification#Category 3|Category 3]] rockets with a more robust flight history, which matches the payloads with the lowest risk tolerance to the rockets with the lowest risk. Example missions for Class A payloads include the [James Webb Space Telescope](https://science.nasa.gov/mission/webb/), [Europa Clipper](https://science.nasa.gov/mission/europa-clipper/), and the [Nancy Grace Roman Space Telescope](https://roman.gsfc.nasa.gov/). ## Class B Low risk tolerance missions, normally representing a high priority mission with high complexity, depending on the case. Class B payloads may be launched on [[⚖️ NASA Rocket Risk Classification#Category 3|Risk Category 3]] rockets or [[⚖️ NASA Rocket Risk Classification#Category 2|Risk Category 2]] rockets. Example missions for Class B payloads are the [Mars Reconnaissance Orbiter](Mars Reconnaissance Orbiter), the [Mars Science Laboratory](https://science.nasa.gov/mission/msl-curiosity/), [Psyche and Geostationary Operational Environmental Satellite-R (GOES-R)](https://www.goes-r.gov/). ## Class C Moderate risk tolerance missions, normally representing a medium priority mission with medium complexity. Class C payloads may be launched on [[⚖️ NASA Rocket Risk Classification#Category 3|Risk Category 3]] rockets or [[⚖️ NASA Rocket Risk Classification#Category 2|Risk Category 2]] rockets. Example missions for Class C payloads include [TESS (Transiting Exoplanet Survey Satellite)](https://exoplanets.nasa.gov/tess/), and [SPHEREx](https://www.jpl.nasa.gov/missions/spherex/) (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer). ## Class D High risk tolerance missions, normally representing a lower priority mission with a medium to low complexity. Class D payloads may be launched on [[⚖️ NASA Rocket Risk Classification#Category 1|Risk Category 1]] rockets or rockets that NASA has not certified. Other high-risk payload launch service options may be pursued through the NASA Flight Planning Board. Example missions for Class D payloads include [CYGNSS](https://science.nasa.gov/mission/cygnss/) (Cyclone Global Navigation Satellite System), [TROPICS](https://weather.ndc.nasa.gov/tropics/) (Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats), and [[ESCAPADE]] (Escape and Plasma Acceleration and Dynamics Explorers). ![[risk-classification-fact-sheet.pdf]]