Astronomy current events question: Dawn spacecraft propulsion

Astronomy 210L, fall semester 2012
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)

Jia-Rui Cook and Dwayne Brown, "NASA's Dawn Prepares for Trek Toward Dwarf Planet," August 30, 2012
http://www.nasa.gov/mission_pages/dawn/news/dawn20120830.html

The NASA Dawn spacecraft is using __________ to leave the asteroid Vesta and visit the dwarf planet Ceres:
(A) solar sails.
(B) ion propulsion thrusters.
(C) a gravitational slingshot effect.
(D) fuel harvested from Vesta's ice deposits.
(E) tidal forces from Jupiter.

Correct answer: (B)

Student responses
Sections 70178, 70186, 70200
(A) : 3 students
(B) : 43 students
(C) : 9 students
(D) : 0 students
(E) : 1 student