What Happens When Space Debris Impacts the Far Side of the Moon?


Background

On March 4, 2022, an unidentified rocket booster impacted the far side of the Moon near its Hertzsprung crater. The far side of the Moon permanently faces away from the Earth because it is tidally locked to the Earth. After years in a Highly Elliptical Orbit (HEO) the booster made a series of lunar flybys that put it on a collision course with the Moon.

Although unintentional, this impact brought attention to the need for mission analysis that extends beyond the nominal lifetime of a mission and captures the risk posed by jettisoned space debris. The accelerating frequency of lunar missions, including NASA’s Artemis missions, exacerbates this need. By utilizing commercial software for space mission design, analysis, and operations, users can perform the analysis required to ensure both the safety and success of future space missions

Moon Inertial View

Moon Inertial View

 

Model Configuration

Users can quickly and easily model the trajectory of objects in space with minimal information by leveraging the orbit determination and 3D visualization capabilities of FreeFlyer®. The only input information required to get started is an initial state observation. FreeFlyer combines a set of standard astrodynamics models, gravity potential models, mathematical propagators, and 2D/3D visualization tools to rapidly simulate the trajectory of objects in space. Users then have the option to configure higher-fidelity models through a suite of customizable parameters for all aspects of the simulation.

For the Space Debris demonstration, an initial state of the booster was sourced from Project Pluto which has documented observations of the booster beginning mid-January 2022. Beyond the default configurations in FreeFlyer, the only adjustments made were to configure a higher fidelity force model. To configure a higher fidelity force model, NASA’s GRAIL Lunar Gravity model (GL0600B) was used for the Moon’s gravitational model, and Solar Radiation Pressure (SRP) modeling was added. This quick configuration is everything required by FreeFlyer to simulate the trajectory of the booster, which eventually impacts near the Hertzsprung Crater on the far side of the Moon.

 

Earth Inertial View

Earth Initial View

Earth Inertial View

The Earth Inertial View demonstrates the booster in an HEO trajectory that briefly enters the Moon’s Sphere of Influence (SOI) with each lunar flyby. The red flight segment highlights the portion of the trajectory where the primary gravitational force influencing the booster comes from the Moon. By referring to the Earth Inertial View, users can visualize the effects of lunar flybys on the booster. The pass through the Moon’s SOI on February 5, 2022, drastically changes the booster’s orbit. With respect to the Earth, the booster transitions into a larger orbit with a longer orbital period and a more inclined orbital plane. The February 5 flyby alters the booster’s orbit just enough to put it on a collision course with the Moon.

 

Earth-Moon Rotating Pulsating View

Rotating Pulsating View

Rotating Pulsating View

The Earth-Moon Rotating-Pulsating View provides a visual of the Earth-Moon celestial system and how the booster interacts with it. This system demonstrates a fixed vantage point that highlights both segments where the booster is contained within the Moon’s SOI. It also demonstrates the size and scale of the booster’s orbit in relation to the distance and position between the Earth and Moon.

 

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