资源描述：
《Chapter 2 Space and Planetary Environment》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、Chapter2SpaceandPlanetaryEnvironmentTheenvironmentsinwhichexplorationandexploitationrobotsoperatecanberoughlysubdividedintofourtypes•LowEarthorbit•Deepspace•Interstellarmedium•PlanetsandsmallcelestialbodiesThelattercanbefurthersubdividedin•Moon•Rockyplanets•Giantplanets
2、•Satellitesofgiantplanets•Smallbodies2.1LowEarthOrbitEnvironmentUsuallyLowEarthOrbits(LEO)areorbitswithaheightlowerthan1,000km.However,theenvironmentencounteredinLEOisroughlythesameencounteredinorbitsuptotheVanAllenbelts(Fig.2.1)surroundingourplanet.TheEarthmagnetospher
3、eprotectsourplanetandallspacebelowtheVanAllenbeltsfrommostradiationscomingfromtheSunanddeepspace.AdiagramoftheEarthsmagnetosphereisshowninFig.2.2.Owingtotheprotectionbythemagnetosphere,radiationismoderateinLEO,evenduringstrongsolaractivity(solarflares).However,thereisana
4、nomalyinEarthmagneticfieldoffthecostofBrazilandinthatzonemuchstrongerradiationreachtheupperatmosphere.TheVanAllenradiationbeltsaresymmetricabouttheEarthsmagneticaxis,whichistiltedwithrespecttotheEarthsrotationalaxisbyanangleof≈11degrees.Thistilt,togetherwithanoffsetof≈45
5、0kilometerscausestheinnerVanAllenbelttobeclosertotheEarthssurfaceoverthesouthAtlanticG.Genta,IntroductiontotheMechanicsofSpaceRobots,SpaceTechnologyLibrary26,21DOI10.1007/978-94-007-1796-1_2,©SpringerScience+BusinessMediaB.V.2012222SpaceandPlanetaryEnvironmentFig.2.1(a)
6、SchematiccrosssectionoftheVanAllenradiationbelts.(b)EarthzoneinterestedbytheSouthAtlanticAnomalyFig.2.2DiagramoftheEarthsmagnetospherethevolumeoccupiedbythegeomagneticfieldinspaceand,intheupperleft,thenorthernpolarregion.Largeelectriccurrents(millionsofAmperes)flowthrough
7、space(fromG.Genta,M.Rycroft,Space,TheFinalFrontier?CambridgeUniversityPress,Cambridge,2003)2.1LowEarthOrbitEnvironment23Table2.1Somevaluesofatmospherictemperature,Altitude(km)T(K)p(Pa)ρ(kg/m3)pressureanddensityinLEOfromtheUSStandard0288.151.01×1051.23atmosphere100195.08
8、3.20×10−25.60×10−7200854.568.47×10−52.08×10−9300976.018.77×10−61.92×10−11400995.831.45×10−62.80×10−12ocean,cau
