Verification of Upper Air Forecasts for the Space Shuttle and the X38 Flight Tests

Meteorologists in the Spaceflight Meteorology Group (SMG) at the Johnson Space Center (JSC) in Houston, Texas issue upper air forecasts prior to each Shuttle launch and landing and each X-38 Vehicle flight test. Forecasts are issued for winds at specific heights AGL above each possible landing site and are produced at launch -1 day, launch day, touchdown - 1 day, and landing day for Space Shuttle operations and at touchdown- 6 hours for X-38 flight tests.

Upper air data are collected throughout the launch and landing counts of the Shuttle and the X-38 flight test via rawinsondes, jimspheres, and wind profilers. These data along with SMG generated forecasts are used by various flight controllers and mission managers to determine the characteristics of the environment through which the Shuttle and X-38 will fly. Flight rules are used to specify safety constraints. The upper air data are evaluated against flight rules as an aid in predicting touchdown and rollout margins and against criteria established by NASA managers to assure safe and successful launches.

SMG has not routinely nor rigorously verified its Shuttle upper air forecasts. NASA descent analysis engineers have performed limited verification. More importance is being placed on these forecasts as the International Space Station (ISS) and the Crew Recovery Vehicle (CRV) become reality. Knowledge of the upper level wind environment is important in Shuttle landings and X-38 flight tests, and will be even more critical for safe CRV operations, since many of the proposed landing sites are in remote and data sparse areas. Given the proposed CRV operational state, use of numerical model data and remote sensing of upper winds will be necessary.

This presentation describes SMG's effort to verify upper air forecasts for Shuttle and X-38 operations. Scalar differencing comparing SMG forecasts to the latest upper air sounding for the launch and landing times is used to generate forecast accuracies for the various forecast levels.