581 research outputs found
Using prosodic cues to identify dialogue acts: methodological challenges
Using prosodic cues to identify dialogue acts: methodological challenge
The random walk of cars and their collision probabilities with planets
On February 6th, 2018 SpaceX launched a Tesla Roadster on a Mars-crossing
orbit. We perform N-body simulations to determine the fate of the object over
the next 15 Myr. The orbital evolution is initially dominated by close
encounters with the Earth. While a precise orbit can not be predicted beyond
the next several centuries due to these repeated chaotic scatterings, one can
reliably predict the long-term outcomes by statistically analyzing a large
suite of possible trajectories with slightly perturbed initial conditions.
Repeated gravitational scatterings with Earth lead to a random walk. Collisions
with the Earth, Venus and the Sun represent primary sinks for the Roadster's
orbital evolution. Collisions with Mercury and Mars, or ejections from the
Solar System by Jupiter, are highly unlikely. We calculate a dynamical
half-life of the Tesla of approximately 15 Myr, with some 22%, 12% and 12% of
Roadster orbit realizations impacting the Earth, Venus, and the Sun within one
half-life, respectively. Because the eccentricities and inclinations in our
ensemble increase over time due to mean-motion and secular resonances, the
impact rates with the terrestrial planets decrease beyond a few million years,
whereas the impact rate on the Sun remains roughly constant.Comment: 5 pages, 4 figures, plots updated with data from 15Myr simulations,
submitted to MNRA
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