NASA计划25年内将人类送上火星
Martian wannabes will have to wait a little bit longer before landing on the enigmatic red planet, according to NASA. The space agency says it's about 25 years away from sending the first human to Mars and has spelled out what it will take to make this space travel plan pan out. Scientists still have to work out major kinks -- such as deadly radiation from the cosmos, potential vision loss, and atrophying bones -- before sending a human to Mars, known for its uNPRedictable atmosphere. They're also trying to shave some time off the commute: It could take nine months or so to reach the red planet, which is located about 140 million miles from Earth. Also, floating in prolonged zero gravity can cause acute medical conditions, such as irreversible changes to blood vessels in the retina, leading to vision degradation, and the skeleton can leach calcium and bone mass. With former astronaut Tom Jones admitting budget constraints will hobble NASA's attempts to send its first human for about 25 years, those of us dreaming of a vacation to Mars dubiously look to SpaceX as our only hope. |