麻省理工学院：《Satellite Engineering》Lecture 5 THE ENVIRONMENT OF SPACE

THE ENVIRONMENT OF SPACE magnetosheath trapping region neutral sheet lobes Image courtesy of NASA Col John Keesee

THE ENVIRONMENT OF SPACE Col. John Keesee 1 Image courtesy of NASA

OUTLINE · Overview of effects olar cycle Gravity · Neutral atmosphere Ionosphere GeoMagnetic Field · Plasma Radiation

OUTLINE • Overview of effects • Solar Cycle • Gravity • Neutral Atmosphere • Ionosphere • GeoMagnetic Field • Plasma • Radiation 2

OVERVIEW OF THE EFFECTS OF THE SPACE ENVIRONMENT Outgassing in near vacuum Atmospheric drag Chemical reactions Plasma-induced charging Radiation damage of microcircuits, solar arrays, and sensors single event upsets in digital devices Hyper-velocity impacts

OVERVIEW OF THE EFFECTS OF THE SPACE ENVIRONMENT • Outgassing in near vacuum • Atmospheric drag • Chemical reactions • Plasma-induced charging • Radiation damage of microcircuits, solar arrays, and sensors • Single event upsets in digital devices • Hyper-velocity impacts 3

Solar cycle Solar Cycle affects all space environments Solar intensity is highly variable Variability caused by distortions in magnetic field caused by differential rotation Indicators are sunspots and flares

4 • Solar Cycle affects all space environments. • Solar intensity is highly variable • Variability caused by distortions in magnetic field caused by differential rotation • Indicators are sunspots and flares Solar Cycle

LONG TERM SOLAR CYCLE INDICES Sunspot number R 10( solar min)≤R≤150( olar max) olar flux 10.7 Radio emission line of fe (2800 MHz) Related to variation in euv Measures effect of sun on our atmosphere Measured in solar flux units(10-22 w/m2 50(solar min)sF107 s240(solar max

LONG TERM SOLAR CYCLE INDICES 5 • Sunspot number R 10 (solar min) d R d 150 (solar max) • Solar flux F10.7 Radio emission line of Fe (2800 MHz) Related to variation in EUV Measures effect of sun on our atmosphere Measured in solar flux units (10-22 w/m2) 50 (solar min) d F10.7 d 240 (solar max)

SHORT TERM SOLAR CYCLE INDEX · Geomagnetic Index Daily average of maximum variation in the earths surface magnetic field at mid lattitude(units of 2×10-9T Ap=o quiet l5 to 30 active >50 major solar storm

SHORT TERM SOLAR CYCLE INDEX • Geomagnetic Index Ap – Daily average of maximum variation in the earth’s surface magnetic field at mid lattitude (units of 2 u 10-9 T) Ap = 0 quiet Ap = 15 to 30 active Ap > 50 major solar storm 6

GRAVITY force G=6.672×10mkg At surface of earth gm G g e≈9.8m R2 sec 2

GRAVITY force At surface of earth  Gm1m2 r2  r G 6.672u 1011m3kg1 2 2 E e 2 E e g sec 9.8 m RGm g RGm f  m | 7

MICROGRAVITY Satellites in orbit are in free fall -accelerating radially toward earth at the rate of free fall Deviations from zero-g Atmospheric drag x=0.5 (C Ao a-ap Gravity gradient 义=-XW2义=yW2艺=2Ww Spacecraft rotation x=x22=202 (rotation about Y axis) Coriolis forces x=∠z0y=02=-zXO

MICROGRAVITY 8 • Satellites in orbit are in free fall - accelerating radially toward earth at the rate of free fall. • Deviations from zero-g – Atmospheric drag – Gravity gradient – Spacecraft rotation (rotation about Y axis) – Coriolis forces 5 2 2 0. U a Z m C A x D ¸ ¸ ¸ ¸ ¸ ¹ · ¨ ¨ ¨ ¨ ¨ © §   x xw 2  x  y w 2 z 2zw 2  x x Z2 z z Z2  x 2 z Z  y o z  zxZ

ATMOSPHERIC MODEL NEUTRAL ATMOSPHERE Turbo sphere(0- 120Km)is well mixed (78%N2, 21% O Troposphere(0 10Km) warmed by earth as heated by sun Stratosphere(10 50 Km) heated from above by absorption of uv by o Mesosphere(50x90Km) heated by radiation from stratosphere, cooled by radiation into space Thermosphere (90 600Km)very sensitive to solar cycle, heated by absorption of EUV Neutral atmosphere varies with season and time of da

ATMOSPHERIC MODEL NEUTRAL ATMOSPHERE 9 • Turbo sphere (0 ~ 120Km) is well mixed (78% N 2, 21% O 2 ) – Troposphere (0 ~ 10Km) warmed by earth as heated by sun – Stratosphere (10 ~ 50 Km) heated from above by absorption of UV by 0 3 – Mesosphere (50 ~ 90Km) heated by radiation from stratosphere, cooled by radiation into space – Thermosphere (90 ~ 600Km) very sensitive to solar cycle, heated by absorption of EUV. • Neutral atmosphere varies with season and time of day

5,000 MAGNETOSPHERE Layers of the Earth 200THERMO nD km Atmosphere 200 reflected here Ozone region mb 1o- STRATOSPHERE cloudsptar! 100 10.000 clouds 5,000

10 Layers of the Earth’s Atmosphere TEMPERATURE MAGNETOSPHERE Pressure Molecular mean free path EXOSPHERE Sunlit Spray region Warm region Maximum height for balloons THERMOSPHERE Aurora Aurora Airglow MESOSPHERE IONOSPHERE Noctilucent cloud D E F1 F2 Ozone region Sound waves reflected here Mother-of-pearl clouds Cirrus clouds Altocumulus clouds cumulus clouds Stratus clouds Tropopause STRATOSPHERE Mount Blanc Ben Nevis Temperature curve -1000C -500C 00C 500C 1000C 1,000 mb 10-8 mb 10-6 cm 10-4 cm 1cm 1km 100 km 100 mb 1 mb 10-2 mb 10-4 mb 10-6 mb 10-10 mb Miles 10,000 5,000 5,000 2,000 2,000 1,000 1,000 500 500 200 200 100 100 50 50 20 20 10 50,000 30,000 20,000 10,000 5 ,000 10 5 2 1 Kilometers Feet Mount Everest TROPOSPHERE