The Mars Exploration Rover, Spirit, is shown in this undated artist's drawing released by NASA. The rock-inspecting rover hurtled toward Mars for a perilous landing on January 3, 2004 on what NASA hopes will become a historic mission to answer the age-old question of whether life existed on the red planet. The robotic explorer's arrival on Mars would be the climax of a weekend of interplanetary discovery after a U.S. spacecraft on January 2, 2004 gathered particles from a comet in a first that could give scientists clues about how Earth began. Photo by Reuters (Handout)

词汇：

rover n.流浪者，漫游者

hurtle v.急飞

perilous adj.危险的

climax n.高潮，顶点

interplanetary adj.行星间的，太阳系内的

particle n.粒子，微粒

comet n.彗星