1. The newspaper said the scientists want to make sure that their crews return home in good health.

make sure 把事情弄清楚，核实或查明某事物; 设法确保出现某事物; 务使;
例句：But make sure your goals are measurable and realistic.
但要确定你的目标是可行和现实的。

2. Their research is aimed at learning if such changes in physical condition will remain or will return to normal a few months after they have returned to Earth.

aim at （以…）瞄准; 针对; 以…为目标; 计划;
例句：As an open-source system based on freely available linux software, chrome os takes aim at that.
作为基于免费linux软件的开放源代码系统，chrome操作系统正是瞄准这个靶子。