Discussion Overview
The discussion revolves around the rate of ejecta deposited between planets, particularly focusing on the estimated amounts of rocks ejected from Mars and their impact on Earth. Participants explore various estimates and seek to understand the mechanisms behind planetary ejecta, including the implications of these rates for other celestial bodies like moons.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant cites an estimate of approximately 500 kilograms of rocks ejected from Mars landing on Earth each year and questions the existence of a matrix showing ejecta amounts between planets.
- Another participant suggests searching Google Scholar for estimates of planetary ejecta hitting Earth, indicating the complexity and diversity of the topic.
- Concerns are raised about the extreme nature of claims regarding "billions of tons" of ejecta and the 500 kg/year figure, with a request for references to support these claims.
- A participant calculates that assuming 10^9 metric tons with a surface density of 2000 kg/m^3 results in a significant volume of material ejected annually, but questions the validity of these figures specifically for Martian material.
- Another participant mentions an average rate of 50,000 tonnes/year for all meteoritic material, contrasting it with a lower figure found on Wikipedia.
- One participant reflects on the mechanisms of ejection, noting that collisions are necessary for material to be ejected and speculating on the rarity of such events, particularly for Mars and the Moon.
Areas of Agreement / Disagreement
Participants express uncertainty regarding the accuracy of the estimates for ejecta rates and the mechanisms involved. There is no consensus on the validity of the figures presented or the processes that lead to planetary ejecta.
Contextual Notes
Participants highlight the need for clarity on definitions and parameters when discussing ejecta rates, as well as the potential for significant variability in estimates based on different sources.