- The paper simulates asteroid trajectories to evaluate and quantify the comparative observability of potentially hazardous asteroids (PHAs) from Mars versus Earth.
- Results show Mars can observe approximately 3.6 times more close-approach asteroids (16910 vs 4675) with an annual frequency 2.6 times higher than Earth.
- This increased observability is due to shorter relative distances and lower relative velocities of Mars-bound asteroids compared to Earth-bound ones.
An Evaluation of Mars-Based Observations of Potentially Hazardous Asteroids
This paper investigates the comparative observability of Potentially Hazardous Asteroids (PHAs) from Mars and Earth. The research expands the traditional focus on Earth-PHAs to include Mars-PHAs, termed CAPHAs for those asteroids undergoing close approaches to Mars. Through a detailed set of numerical simulations that account for gravitational influences and the Yarkovsky effect, the paper provides quantitative insight into the number and frequency of CAPHAs observable from Mars compared to Earth.
The analysis begins with the redefinition of CAPHAs for Mars, setting the minimum close-approach distance at 0.036 AU, whereas for Earth it remains at 0.05 AU. This difference acknowledges Mars’s smaller Hill sphere compared to Earth's. Through N-body simulations using the Mercury6 software, the authors simulate the trajectories of asteroids from the main asteroid belt accounting for the Yarkovsky effect, which causes gradual drift in asteroid orbits due to asymmetric thermal emissions.
The results indicate a significant disparity in the numbers and occurrence frequencies of Earth-CAPHAs and Mars-CAPHAs. Mars-CAPHAs outnumber Earth-CAPHAs by approximately 3.6 times, with numerical estimates of 16910 Mars-CAPHAs compared to 4675 Earth-CAPHAs. Furthermore, the annual occurrence frequency of encountering a Mars-CAPHA is suggested to be 2.6 times higher than that of Earth-CAPHAs, with figures of about 52 and 20 per year, respectively.
The paper elucidates two critical characteristics fundamental to the increased observability of Mars-CAPHAs. First, the relative distances of CAPHAs to Mars tend to be shorter than those to Earth. Second, the relative velocities of Mars-CAPHAs are systematically lower, which is beneficial for tracking and observing these objects from a Mars-based perspective. These factors make Mars a strategically advantageous location for observing PHAs, which can enrich understanding not only of asteroid dynamics but also of the Martian environment and its potential hazards.
Another substantial finding is the potential for Earth-based observation opportunities of Mars-CAPHAs during the Mars opposition in 2025. The simulations project that some Mars-CAPHAs will be observable from Earth, rendering potential targets for telescopes such as LSST and WFST, which can help bridge observations from Earth and inform future Mars-based missions.
Overall, this paper effectively demonstrates the robust potential for Mars observations to contribute significantly to PHA tracking and risk assessment. This expansion of focus marks a valuable contribution to planetary defense strategies and enhances the scientific potential of Mars exploration missions, such as Mars2020, Tianwen-3, and others that may leverage these observations for broader scientific inquiries into Solar System dynamics.