人类对于宇宙探索的脚步从未停止过，太空中辛勤工作着的众多卫星和宇宙空间站就是最好例证。当然，这些卫星和空间站也会有“生病”的时候。
% Q" f7 H0 t3 A* t e7 _ ? The crew of the International Space Station have been forced to reduce power after half the cooling system suddenly shut down over the weekend.
7 o) v* r! z; X& ~; G0 H$ D2 w9 u* m
' B7 a$ V8 Q* {2 Y: ], `0 ? Nasa officials insisted the three Americans and three Russians aboard were not in danger.
( ~/ a' S9 P* h5 H+ U , m* |% ~" w/ X1 q3 W+ H6 r
Urgent spacewalk repairs are being discussed for this week.
8 b# ^: d8 z4 f7 v% Z7 K2 M
/ k: E0 V' }! y8 X7 P; v+ x! W Without thermal controls, temperatures on the ISS's Sun-facing side can soar to 121C (250F), plunging to minus 157C (-250F) on the dark side, Nasa says.
7 O0 x. R1 \7 v5 I
* k; r0 D6 e2 p2 e, q- d, d "There might be a comfortable spot somewhere in the middle of the station, but searching for it wouldn't be much fun," a statement on its website adds.( ^' N+ v+ X. O- }' j
+ y* Q* A1 j# \8 Y, _
The station is now operating on a single string, the Associated Press reports, and has no safeguard in case of further cooling system failures.0 a3 P) | b5 E2 L
3 W: a" b# {2 i- |9 M Alarms sound; t( C1 z; H* B' j& i2 H
$ C* x; V) e. y
Trouble arose on Saturday night when one of the two ammonia-fed cooling loops shut down, triggering alarms throughout the ISS& p, t) Z: H* O- Q) m$ @6 J
: ^/ h8 Y% x4 ~8 P. l7 l
The two ammonia lines ensure that all the station's electronic equipment does not overheat.
5 M- n' a8 O2 N" E
4 ?# S. H" v- b3 w7 z$ L Astronaut Tracy Caldwell Dyson set in motion equipment shutdown procedures and, with crewmate Douglas Wheelock, installed a jumper cable to keep all the rooms cool.0 e+ _- Y( ^/ u0 F" X9 Q
1 E8 P! S8 x# m* Y3 @ The Global Positioning System circuit, several power converters and a set of devices that route commands to various pieces of equipment were switched off.
4 w- G: }. q z) P/ v& Y; q , I, @6 E) ~4 i" Y2 C
Two of the four gyroscopes - part of the space station's pointing and navigating system - were initially shut down but the crew installed a jumper cable to bring up a third gyroscope, leaving the station in a much more stable position, AP says.
, j1 R+ z& s; D' t
, b+ p( C0 q$ O Flight controllers tried to restart the disabled ammonia pump early on Sunday but the circuit breaker tripped again.
" o1 u+ h$ T1 M& F- f# I
! Z2 N- l# o2 h C! ^+ Z& W Any repairs later this week almost certainly will involve replacing the faulty ammonia pump, a difficult job that would require two spacewalks, AP adds.: u. N: B1 G) v' a, `9 H1 C+ c
6 m4 }# J" a5 G P7 J: N% t% _2 c "It's pretty clear that we're going to want to have a course of action to take as quickly as possible," Nasa spokesman Rob Navias said at the Johnson Space Center in Houston, Texas.' t. S" r7 B6 z
, ^6 C0 |( ~" v" i9 v "This is not something we want to linger over."
' `, B7 v6 F3 u' W
r6 k2 y5 i4 C Two spare pumps are stored on the outside of the station. Two of the Americans on board are already scheduled to conduct a spacewalk on Thursday for routine maintenance.' P% e) [ N2 z) l, d/ a# S
1 K5 b1 r: l! Y* F, u( v
No space shuttle visits to the ISS are planned before November. |
发表于 2012-8-14 23:21:39
