托福閱讀背景知識的積累需要大家在備考中好好準備，相信大家在每天不斷的練習中，一定會有不小的進步，一起來看看今天的托福閱讀材料之國際空間站冷卻系統(tǒng)故障吧。

ThecrewoftheInternationalSpaceStationhavebeenforcedtoreducepowerafterhalfthecoolingsystemsuddenlyshutdownovertheweekend.

NasaofficialsinsistedthethreeAmericansandthreeRussiansaboardwerenotindanger.

Urgentspacewalkrepairsarebeingdiscussedforthisweek.

Withoutthermalcontrols，temperaturesontheISS‘sSun-facingsidecansoarto121C(250F)，plungingtominus157C(-250F)onthedarkside，Nasasays.

“Theremightbeafortablespotsomewhereinthemiddleofthestation，butsearchingforitwouldn’tbemuchfun，”astatementonitswebsiteadds.

Thestationisnowoperatingonasinglestring，theAssociatedPressreports，andhasnosafeguardincaseoffurthercoolingsystemfailures.

Alarmssound

TroublearoseonSaturdaynightwhenoneofthetwoammonia-fedcoolingloopsshutdown，triggeringalarmsthroughouttheISS.

Thetwoammonialinesensurethatallthestation‘selectronicequipmentdoesnotoverheat.

AstronautTracyCaldwellDysonsetinmotionequipmentshutdownproceduresand，withcrewmateDouglasWheelock，installedajumpercabletokeepalltheroomscool.

TheGlobalPositioningSystemcircuit，severalpowerconvertersandasetofdevicesthatroutemandstovariouspiecesofequipmentwereswitchedoff.

Twoofthefourgyroscopes-partofthespacestation’spointingandnavigatingsystem-wereinitiallyshutdownbutthecrewinstalledajumpercabletobringupathirdgyroscope，leavingthestationinamuchmorestableposition，APsays.

FlightcontrollerstriedtorestartthedisabledammoniapumpearlyonSundaybutthecircuitbreakertrippedagain.

Anyrepairslaterthisweekalmostcertainlywillinvolvereplacingthefaultyammoniapump，adifficultjobthatwouldrequiretwospacewalks，APadds.

“It‘sprettyclearthatwe’regoingtowanttohaveacourseofactiontotakeasquicklyaspossible，”NasaspokesmanRobNaviassaidattheJohnsonSpaceCenterinHouston，Texas.

“Thisisnotsomethingwewanttolingerover.”

Twosparepumpsarestoredontheoutsideofthestation.TwooftheAmericansonboardarealreadyscheduledtoconductaspacewalkonThursdayforroutinemaintenance.

NospaceshuttlevisitstotheISSareplannedbeforeNovember.

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