Overview of the Meteoroid Environment
Explore the source record for details and available documents.
Meteoroids↗
Engineering topics
Althea Moorhead
Publications and source records attributed to Althea Moorhead.
Modeling the Meteoroid Environment Far from the Ecliptic Plane: Can a Tilted Plane of Symmetry Explain Seasonal Variations in the Meteoroid Environment?
NASA's Meteoroid Engineering Model (MEM) describes the meteoroid environment encountered by spacecraft in the inner solar system. MEM's algorithms take advantage of the fact that the vast majority of spacecraft remain close to the ecliptic plane in order to make several simplifying assumptions. However, this results in a model that cannot describe the environment for spacecraft such as Ulysses that travel far from the ecliptic, and limits the potential to validate the model using impact signatures from asteroids on inclined orbits. We are in the process of developing a new version of the code, numbered 3.1-alpha, that correctly computes the meteoroid flux and directionality far from the ecliptic. We present a new formulation of the spatial probability distribution function for fully precessed meteoroid models and compare our results with zodiacal light data.
Althea Moorhead↗
The Threshold at which a Meteor Shower Becomes Hazardous to Spacecraft
Although the risk posed to spacecraft due to meteoroid impacts is dominated by the sporadic complex, meteor showers can raise this risk for short periods of time. NASA's Meteoroid Environment Office issues meteor shower forecasts that describe these periods of elevated risk, primarily for the purpose of helping plan extravehicular activities. These forecasts are constructed using a list of meteor shower parameters that has evolved over time to include newly discovered showers and incorporate improved measurements of their characteristics. However, at this point more than a thousand meteor showers have been reported by researchers, many of which are extremely minor, are unconfirmed, or lack critical pieces of data. Thus, a comprehensive approach to forecasting is no longer feasible. In this report we present a quantitative criterion for a potentially hazardous meteor shower and apply this criterion to the list of established meteor showers in order to determine which showers should be included in our annual forecasts
Althea Moorhead↗
Cloud Computing Option for Modeling the Debris Environment
NASA’s Digital Transformation Initiative aims to promote the agency’s adoption of current and evolving digital technologies. Through agency-wide collaboration with other NASA teams, the Office of Safety and Mission Assurance (OSMA) has directed the Orbital Debris Program Office and the Meteoroid Environment Office to integrate cloud computing technologies in their publicly released software models: the Orbital Debris Engineering Model (ORDEM) and the Meteoroid Engineering Model (MEM). Decoupling the user interface from the backend processor was key for the software packages to run on a cloud computing framework. Benefits to this design include horizontal scaling of computing resources, user authentication and authorization, and automated deployment. Both models are hosted on a cloud computing platform supported by the NASA authorized IT security and compliance framework. This paper focuses on the new ORDEM web application, which includes the current features of the publicly released ORDEM software with an upgraded frontend design. The underlying ORDEM processor is run on a cloud container, allowing the user to run multiple spacecraft and telescope/radar mode simulations. Featuresexclusive to the ORDEM web application, such as importing multiple TLEs, auto-generated plotting, and the ability to check runtime progress are discussed. Comparisons between the current ORDEM software and the web application are summarized.
Andrew Vavrin↗
The Meteoroid Environment Encountered By the James Webb Space Telescope
All spacecraft run the risk of being damaged by meteoroids at a rate proportional to the spacecraft's surface area. The exceptionally large James Webb Space Telescope (JWST) has endured 20 impacts on its primary mirror in its first year of operation. While most of the impacts experienced were commensurate with pre-launch predictions, one particularly large impact in May 2022 prompted the program to take a fresh look at the meteoroid environment in order to determine whether potentially unaccounted-for meteoroid risks can be mitigated. In this talk, we present a directional model of the meteoroid environment encountered by the spacecraft and compare it with the observed impact rate. Because of JWST’s ability to measure nanometer-size changes to the primary mirror surface, our results indicate that meteoroids carrying as little as 1 Joule of kinetic energy can produce measurable effects. We also find that the impact rate is highest when JWST faces in the direction of orbital motion about the Sun. By implementing a "meteoroid avoidance zone" that discourages observations within 75° of the ram direction, we estimate that JWST has reduced the impact rate by more than half.
Althea Moorhead↗
Hazardous Meteor Showers and their Fluxes
NASA's meteoroid environment office generates annual forecasts of meteor shower activity. This presentation reviews several recent and current efforts to improve these forecasts by testing the significance of the included showers, validating their mass distributions using observations from independent networks, and examining the relationship between meteoroid mass and peak brightness.
Althea Moorhead↗