The Space Environment Planetary environments Gravitation Electromagnetic radiation Atmospheric particles Newtonian flow Solar wind particles Ionizing radiation Micrometeoroids/orbital debris Spacecraft charging 1 2014 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu
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. 1979 Douglas Adams, The Hitchhiker's Guide to the Galaxy, 2
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
In The Same Scale... Sun Mercury Venus Earth-Moon Mars 4
Still In The Same Scale Pluto Neptune Uranus Jupiter Saturn 5
Comparison of Basic Characteristics 6
The Electromagnetic Spectrum Ref: Alan C. Tribble, The Space Environment Princeton University Press, 1995 9
The Solar Spectrum Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 10
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
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, 1994 12
Atmospheric Density with Altitude Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 13
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
Newtonian Analysis V A sin(αα) A αα 15
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
Lift and Drag F V αα D L 17
Flat Plate Newtonian Aerodynamics 18
Example of Newtonian Flow Calcs Consider a cylinder of length l, entering atmosphere transverse to flow r V df dl dd 19
Integration to Find Drag Coefficient Integrate from By definition, and, for a cylinder 20
Orbit Decay from Atmospheric Drag Ref: Alan C. Tribble, The Space Environment Princeton University Press, 1995 21
Makeup V Due To Atmospheric Drag Ref: Alan C. Tribble, The Space Environment Princeton University Press, 1995 22
Atmospheric Constituents at Altitude Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 23
Atomic Oxygen Erosion Rates Annual surface erosion at solar max Orbital altitude 500 km Material Erosion Rate (mm/yr) Silver.22 Chemglaze Z302.079 Mylar.071 Kapton.061 Epoxy.048 Carbon.020 Teflon.00064 Aluminum.0000076 24
The Earth s Magnetic Field Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 25
The Van Allen Radiation Belts Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 26
Cross-section of Van Allen Radiation Belts Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 27
Mars Magnetic Field (There isn t one) Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994 28
Martian Radiation Environment Ref: Hassler, D., et al., Science, 2014 29
The Origin of a Class X1 Solar Flare 30
What are Solar Flares? Ref: What are Solar Flares? - Dr. James Webb FIU (YouTube Video) 31
Heavy Ion Flux Background Solar Flare Ref: Neville J. Barter, ed., TRW Space Data, TRW Space and Electronics Group, 1999 32
Galactic Cosmic Rays (GCR) and Coronal Mass Ejections (CME) Ref: "SpaceEnvironmentOverview From 19830101" by Daniel Wilkinson - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/file:spaceenvironmentoverview_from_19830101.jpg#mediaviewer/file:spaceenvironmentoverview_from_19830101. 33 jpg
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, 1999 34
Trackable Objects On-orbit 35
Orbital Debris and Removal Ref: Space Debris Piles Up, euronews.com https://www.youtube.com/watch?v=jskl9bbez0w 36
Micrometeoroids and Orbital Debris 37
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
MMOD Impact with Russian BLITS http://www.space.com/20135-china-s-anti-satelliteweapon-test-debris-hits-russian-satelliteanimation.html 39
Damage from MMOD Impacts 40
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
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
Typical MMOD Penetration from LDEF 43
Spacecraft Charging Ref: Alan C. Tribble, The Space Environment Princeton University Press, 1995 44
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
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, 1961 46