单选题 NASA"s Mars rover Opportunity has boldly gone where no rover has gone before—at least in terms of distance. Since arriving on the Red Planet in 2004, Opportunity has traveled 25.01 miles, more than any other wheeled vehicle has on another world.
On July 27, after years of moving about on Martian ground, the golf-cart-sized Opportunity had driven more than 24 miles, beating the previous record holder—a Soviet rover sent to the moon in 1973.
"This is so remarkable considering Opportunity was intended to drive about 1 kilometer and was never designed for distance," says John Callas, the Mars Exploration Rover Project Manager.
He works at NASA"s Jet Propulsion Laboratory in Pasadena, California.
"But what is really importantly is not how many miles the rover has racked up, but how much exploration and discovery we have accomplished over that distance."
OPPORTUNITY
The solar-powered Opportunity and its twin rover, Spirit, landed on Mars 10 years ago on a mission expected to last 3 months. The objective of the rovers was to help scientists learn more about the planet and to search for signs of life, such as the possible presence of water.
Spirit stopped communicating with Earth in March 2010, a few months after it got stuck in a sand pit. But Opportunity has continued to collect and analyze Martian soil and rocks.
During its mission, Opportunity has captured, and sent back to Earth, some 187,000 panoramic and microscopic images of Mars with its cameras. It has also provided scientists with data on the planet"s atmosphere, soil, rocks, and terrain.
MARATHON ROVER
The rover doesn"t seem to be ready to stop just yet. If Opportunity can continue on, it will reach another major investigation site when its odometer hits 26.2 miles. Scientists call this site Marathon Valley, because when the rover reaches the area, it will have traveled the same distance as the length of a marathon since its arrival on Mars.
Researchers believe that clay minerals exposed near Marathon Valley could hold clues to Mars"s ancient environment1. Opportunity"s continuing travels will also help researchers as they plan for an eventual human mission to the Red Planet.

单选题 Opportunity is a record breaking rover in the sense of ______.

单选题 What does John Callas say about Opportunity"s long distance travel?

单选题 One of the objectives of sending Opportunity and Spirit is to ______.

单选题 Which of the following statements is true of Opportunity?

单选题 It can be inferred from the last paragraph that ______.