Question

5. Asteroid 101955 Bennu is potentially hazardous – it is in an Earth-crossing orbit and has a 1 in 2700
chance of hitting Earth about 150 years from now. The OSIRIS-REx spacecraft is currently in orbit
around Bennu to study it. One of the goals of the OSIRIS-Rex mission is to get a better idea of Bennu’s
shape and composition, so we can refine our probability of impact and better determine whether it will
hit us and if so, how we can stop that from happening.
a) Bennu’s orbital period is 1.20 years. What is its semimajor axis? Show your work.
b) Make a sketch of the Sun, Earth’s orbit, and Bennu’s orbit ASSUMING Bennu’s orbit is nearly
circular.
c) Look up Bennu’s orbital eccentricity (Wikipedia is fine). Make a new sketch of the Sun, Earth’s
orbit, and Bennu’s orbit. Why is the eccentricity relevant for assessing the risk of Bennu hitting Earth?

EDIT: For Part C orbital eccentricity is :0.20375

Answer 1