Correct: B. Voyager 2

Voyager 2 is the only spacecraft to have studied Jupiter, Saturn, Uranus, and Neptune at close range. Its trajectory exploited gravity assists and a favorable arrangement of the outer planets to continue from one giant planet to the next.

Correct: A. 24-Jan-86

Voyager 2 made its closest approach to Uranus on January 24, 1986. It passed approximately 81,500 kilometers from the planet's cloud tops during the historic flyby.

Correct: C. 83 days

Sojourner operated on Mars for 83 days despite a planned mission of only seven days. The small rover examined rocks and demonstrated mobility and technology that influenced later robotic Mars missions.

Correct: A. Edgar Evans

Edgar Evans was the first member of Scott's South Pole party to die on the return journey. His condition deteriorated after injuries and severe physical exhaustion during the march north.

Correct: B. About 11 miles

Scott, Wilson, and Bowers died only about 11 miles from One Ton Depot. Severe weather, exhaustion, cold, and dwindling supplies prevented them from reaching the food and fuel stored there.

Correct: C. 70,000

Nearly 70,000 Mormon emigrants followed the trail to the Great Salt Lake Valley between 1847 and 1868. The migration continued until the arrival of the transcontinental railroad substantially changed overland travel.

Correct: A. Bidwell-Bartleson Party

The Bidwell-Bartleson Party became the first organized emigrant group to travel overland toward California in 1841. The group gathered near Independence, Missouri, and headed west without an established wagon route all the way to California.

Correct: A. Africa

Zheng He's later voyages reached ports on the eastern coast of Africa. The fourth, fifth, and sixth expeditions extended Ming maritime activity farther across the Indian Ocean than earlier voyages.

Correct: B. Pioneer 10

Pioneer 10 became the first human-made object to travel beyond the orbit of Neptune. It crossed that distance in 1983 while continuing outward from the solar system after completing its Jupiter mission.

Correct: B. About 6,100 miles

Mariner 4 passed approximately 6,100 miles from Mars at closest approach. NASA gives the precise distance as about 6,118 miles, or 9,846 kilometers.

Correct: C. 34

Galileo completed 34 orbits of Jupiter during its extended mission. These repeated circuits enabled close encounters with the Galilean moons and long-term observations of Jupiter's atmosphere and magnetosphere.

Correct: B. Europa

Europa received the greatest number of close flybys during Galileo's Jupiter mission. NASA records 11 close encounters with Europa, compared with fewer for Io, Ganymede, and Callisto.

Correct: C. About 84%

Magellan mapped about 84 percent of Venus during its first 243-day mapping cycle. NASA gives the more precise figure as approximately 83.7 percent of the planet's surface.

Correct: A. Burke, Wills, Gray, and King

Robert Burke, William Wills, Charles Gray, and John King left Cooper Creek in December 1860 for the expedition's final push north. The four-man group travelled toward the Gulf of Carpentaria while other expedition members remained at the depot.

Correct: A. Alfred Howitt

Alfred Howitt led the relief expedition that found and rescued John King. Howitt also located the bodies of Burke and Wills and later returned to recover their remains for burial in Melbourne.