对于不少的中国考生来说，
The reading material argues that before human beings could send people on a journey to Mars and back, three obstacles must be addressed. In contrast, the listening states that although the mission does seem challenging, scientists have come up with clever ways of dealing with the obstacles.
Primarily, the passage uses the failure of robot spacecrafts to demonstrate that it is risky and difficult to land on Mars safely. However, the lecture points out that a future Mars mission will have several advantages over the previous ailed ones. First, the accuracy of computer accuracy programming has been improved. No Mars robot has crashed since 1999. Second, the proposed future mission will have people on board, who will guide the spacecraft and make adjustments according to the changing conditions.
Further, the reading suggests that it is impossible for the spacecraft to store all the fuel needed for a Mars mission. Although the professor admits the fact, she asserts that there is at least one potential solution --- gathering fuel on Mars itself. Rocket fuel is made up of hydrogen and oxygen, which can be found in ice. And there is a lot of ice on Mars. The possible solution could be making the fuel that is necessary for the journey back out of ice on Mars. Thus, the spacecraft only need to carry enough fuel to reach Mars.
Last, the writer talks about the harm that direct sun radiation will have on human body. The listening responds that scientists have recently discovered ways to create powerful magnets that can create a strong magnetic field in the spaceship, which can protect the astronauts inside the spaceship from direct sun radiation.
