The Space Environment

Transcription

1 The Space Environment Planetary environments Gravitation Electromagnetic radiation Atmospheric particles Newtonian flow Solar wind particles Ionizing radiation Micrometeoroids/orbital debris Spacecraft charging David L. Akin - All rights reserved

2 The Space Environment Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space Douglas Adams, The Hitchhiker's Guide to the Galaxy, 2

3 The Earth-Moon System L4 Note: Earth and Moon are in scale with size of orbits Geostationary Orbit Moon L3 Earth L1 L2 Photograph of Earth and Moon taken by Mars Odyssey April 19, 2001 from a distance of 3,564,000 km L5 3

4 In The Same Scale... Sun Mercury Venus Earth-Moon Mars 4

5 Still In The Same Scale Pluto Neptune Uranus Jupiter Saturn 5

6 Comparison of Basic Characteristics 6

7 The Electromagnetic Spectrum Ref: Alan C. Tribble, The Space Environment Princeton University Press,

8 The Solar Spectrum Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

9 Solar Cycle Sun is a variable star with 11-year period UV output of sun increases thermal energy of upper atmosphere, accelerating atmospheric drag of LEO spacecraft Measured as solar flux at 10.7 cm wavelength (= F10.7 ) 11 Ref: Alan C. Tribble, The Space Environment Princeton University Press, 1995

10 Diurnal Variation of Atmosphere Ideal gas law for atmospheric science PP = ρρρρρρ ρρ 1 TT Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

11 Atmospheric Density with Altitude Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

12 Newtonian Flow Mean free path of particles much larger than spacecraft --> no appreciable interaction of air molecules Model vehicle/ atmosphere interactions as independent perfectly elastic collisions 14 V V

13 Newtonian Analysis V A sin(αα) A αα 15

14 Momentum Transfer Momentum perpendicular to wall is reversed at impact Bounce momentum is transferred to vehicle Momentum parallel to wall is unchanged Vsin(αα) V V F 16

15 Lift and Drag F V αα D L 17

16 Flat Plate Newtonian Aerodynamics 18

17 Example of Newtonian Flow Calcs Consider a cylinder of length l, entering atmosphere transverse to flow r V df dl dd 19

18 Integration to Find Drag Coefficient Integrate from By definition, and, for a cylinder 20

19 Orbit Decay from Atmospheric Drag Ref: Alan C. Tribble, The Space Environment Princeton University Press,

20 Makeup V Due To Atmospheric Drag Ref: Alan C. Tribble, The Space Environment Princeton University Press,

21 Atmospheric Constituents at Altitude Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

22 Atomic Oxygen Erosion Rates Annual surface erosion at solar max Orbital altitude 500 km Material Erosion Rate (mm/yr) Silver.22 Chemglaze Z Mylar.071 Kapton.061 Epoxy.048 Carbon.020 Teflon Aluminum

23 The Earth s Magnetic Field Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

24 The Van Allen Radiation Belts Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

25 Cross-section of Van Allen Radiation Belts Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

26 Mars Magnetic Field (There isn t one) Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press,

27 Martian Radiation Environment Ref: Hassler, D., et al., Science,

28 The Origin of a Class X1 Solar Flare 30

29 What are Solar Flares? Ref: What are Solar Flares? - Dr. James Webb FIU (YouTube Video) 31

30 Heavy Ion Flux Background Solar Flare Ref: Neville J. Barter, ed., TRW Space Data, TRW Space and Electronics Group,

31 Galactic Cosmic Rays (GCR) and Coronal Mass Ejections (CME) Ref: "SpaceEnvironmentOverview From " by Daniel Wilkinson - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons jpg

32 Radiation Dose vs. Orbital Altitude 300 mil (7.6 mm) Al shielding Ref: Neville J. Barter, ed., TRW Space Data, TRW Space and Electronics Group,

33 Trackable Objects On-orbit 35

34 Orbital Debris and Removal Ref: Space Debris Piles Up, euronews.com 36

35 Micrometeoroids and Orbital Debris 37

36 MMOD Sample Calculation Space Station module - cylindrical, 15 diam. X 43 long Surface area=221 m 2 Flux value for one hit in 20 years Flux=2.26x10-4 hits/m 2 -yr (3mm) For 0.1 hits/20 years, allowable flux= 2.26x10-5 hits/m 2 -yr (9 mm) 38

37 MMOD Impact with Russian BLITS 39

38 Damage from MMOD Impacts 40

39 Long Duration Exposure Facility (LDEF) 41 Passive experiment to test long-term effects of space exposure 57 experiments in 86 trays Deployed April, 1984 Retrieved January, 1990

40 Surprising Results from LDEF Presence of C-60 ( buckeyballs ) on impact site Much higher incidence of MMOD impacts on trailing surfaces than expected Local thermal hot spots did surprising levels of damage to blankets and coatings Thermal blankets are effective barriers to smaller high velocity impacting particles Anomalies are typically due to design and workmanship, rather than materials effects 42

41 Typical MMOD Penetration from LDEF 43

42 Spacecraft Charging Ref: Alan C. Tribble, The Space Environment Princeton University Press,

43 Today s Tools Using today s tools you should be able to understand and use Atmospheric density as a function of altitude Drag/Lift available at those altitudes Rate of orbital decay from drag GCR / CME flux Qualitative understanding of radiation environments (More detail to come) Micrometeoroid flux calculations 45

44 References Alan C. Tribble, The Space Environment: Implications for Spacecraft Design Princeton University Press, 1995 Vincent L. Pisacane and Robert C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 (Chapter 2) Neville J. Barter, ed., TRW Space Data TRW Space and Electronics Group, 1999 Francis S. Johnson, Satellite Environment Handbook Stanford University Press,