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The world lost seven astronauts of Space Shuttle Columbia(哥伦比亚号航天飞机) this month. It brought
home the serious risk that 1humans face into the hostile environs beyond our 2sheltered planets, raising the question
of 3 whether exploring the heavens should be left to unmannedmissions. 4 Moreover less exciting, such missions will 5 pose no risks to humans. And already robots have an impressive list of accomplishments 6compared to their flesh and blood
counterparts(职级地位相当的人或物).

“ 7 Unmanned missions are all about specifically targeted scientific 8 explorations of the universe around us.Without exceptions, these efforts rise out of intense competition 9where the most compelling,and answerable questions are 10 posed ,” said Marc
Buie, an astronomer (天文学家) at Lowell Observatory in Flagstaff, Arizona. 11Robots have dug in the dirt on Mars,
flown in the 12atmosphere of Jupiter ( 木星), and driven by the moons of Neptune. A few are 13even approaching the
boundary of the 14solar system .

Humans, 15on the other hand , have mostly been going in circles, 16barely above the surface of theplanet. 17Besides the brief Apollo Mission triumphs on the 18moon , almost 250,000 milesaway, humans have 19never gone farther than 400,000 miles
from the planet, less than aday’s drive, although straight up. Humans fly near home for several reasons. There is
thelogistics(后勤) of sending humans and what they need, like water, air and food, in a closedenvironment that
keeps them 20 alive.