According to NASA, there are now more than 500 working (1) 2,000 defunct satellites, 1,400 used (2)
and 1,100 smaller objects (3)
Since the beginning of (4) exploration in
1957, more than 137 (5) _have exploded or broken apart while in (6) around the Earth.
Over time, even working spacecraft lose (7) and screws.
And (8)
moves fast-several thousand kilometers per second. At that speed, even the tiniest,
(9)
can cause huge problems. NASA engineers think an electronic (10) hit the Columbia
space shuttle, leaving a 6-milimeter dent in the door of the shuttle's (11) _ba' Had the door been
open, the speeding projectile could have pierced the shuttle's vulnerable (12).
So much (13) has bounced off the shuttles that NASA has had to replace 63 shuttle windows
since 1981. Several thousand near-misses involving (14) and satellites happen every day. NASA
fears the situation will get worse. What do you think? How can we (15)
space?