c. hall, randolph 224d cdhall@vt.edu aoe 2104 - the space part introduction to space systems...
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C. Hall, Randolph 224Dcdhall@vt.edu
AOE 2104 - The Space Part• Introduction to space systems
concepts• Space environment• Orbital mechanics• Launch vehicles• Space law and policy• Space industry• Daily Quizzes• Final Exam (Comprehensive)
• Introduction to space systems concepts
• Space environment• Orbital mechanics• Launch vehicles• Space law and policy• Space industry• Daily Quizzes• Final Exam (Comprehensive)
C. Hall, Randolph 224Dcdhall@vt.edu
ReadingDava Newman, Interactive
Aerospace Engineering and Design, McGraw-Hill, 2002
• Background: Sections 1.7 – 1.10, Chapter 2
• Space Environment: Chapter 8• Orbital Mechanics: Chapter 9• Satellite Systems Engineering:
Chapter 10• Human Space Exploration: Chapter
11
Dava Newman, Interactive Aerospace Engineering and Design, McGraw-Hill, 2002
• Background: Sections 1.7 – 1.10, Chapter 2
• Space Environment: Chapter 8• Orbital Mechanics: Chapter 9• Satellite Systems Engineering:
Chapter 10• Human Space Exploration: Chapter
11
C. Hall, Randolph 224Dcdhall@vt.edu
Sample Space Applications
Communications Navigation RelayWeather Surveillance ScienceMaterials processing Search &
rescueAstronomy Weapons
TourismSpace Exploration Solar PowerTransportation Colonization
Mapping
Communications Navigation RelayWeather Surveillance ScienceMaterials processing Search &
rescueAstronomy Weapons
TourismSpace Exploration Solar PowerTransportation Colonization
Mapping
C. Hall, Randolph 224Dcdhall@vt.edu
Basic Elements of Space Missions
• Subject - the “thing” which interacts with or is sensed by the payload
• Space segment - spacecraft comprised of payload and spacecraft bus
• Launch segment - launch facilities, launch vehicle, upper stage. Constrains spacecraft size.
• Orbit/constellation - spacecraft’s trajectory or path through space
• C3 Architecture - command, control and communications
• Ground segment - fixed and mobile ground stations necessary for TT&C
• Mission operations - the people, policies and procedures occupying the ground (and possibly space) segments
• Subject - the “thing” which interacts with or is sensed by the payload
• Space segment - spacecraft comprised of payload and spacecraft bus
• Launch segment - launch facilities, launch vehicle, upper stage. Constrains spacecraft size.
• Orbit/constellation - spacecraft’s trajectory or path through space
• C3 Architecture - command, control and communications
• Ground segment - fixed and mobile ground stations necessary for TT&C
• Mission operations - the people, policies and procedures occupying the ground (and possibly space) segments
C. Hall, Randolph 224Dcdhall@vt.edu
Space segment
Payload
Bus
Ground Segment
MissionOperations
LaunchSegment
Orbit andConstellation
Subject
Command, Control andCommunications
Architecture
Reference: Larson & Wertz, Space Mission Analysis and Design
Reference: Larson & Wertz, Space Mission Analysis and Design
C. Hall, Randolph 224Dcdhall@vt.edu
Payload and Bus Subsystems
S e n so rsC a m e rasA n te nn as
R a d ar
Payload
Pow erS o la r a rra ys
B a tte riesP M A D
ADC SS e n so rs
A c tua to rsP ro ce sso rs
Therm al ControlC o atin gsIn su la tion
A c tive co n tro l
TT& CP o w e r sw itch ingE n cod e r/d e co d er
P ro ce sso rs
PropulsionO rb it in je c tion
S ta tio nke ep ingA tt itu d e co n tro l
StructureP rim a ry s tru c tu re
D e p loym e ntm e ch an ism s
Bus
Spacecraft
Basic requirements• Payload must be
pointed• Payload must be
operable• Data must be
transmitted to users
• Orbit must be maintained
• Payload must be “held together”
• Energy must be provided
Basic requirements• Payload must be
pointed• Payload must be
operable• Data must be
transmitted to users
• Orbit must be maintained
• Payload must be “held together”
• Energy must be provided
C. Hall, Randolph 224Dcdhall@vt.edu
Thoughts on SpaceSome comments overhead at the Officer’s Club
• It’s a really big place with no air.
• There’s nothing out there, is there?
• How many g’s is that satellite pullingwhen the ground track makes those turns?
• Why can’t I have my spy satellitepermanently positioned over Moscow?
• It’s a really big place with no air.
• There’s nothing out there, is there?
• How many g’s is that satellite pullingwhen the ground track makes those turns?
• Why can’t I have my spy satellitepermanently positioned over Moscow?
C. Hall, Randolph 224Dcdhall@vt.edu
Useful Characteristics of Space
• Global perspective or “There’s nothin’ there to block your view”
• Above the atmosphere or “There’s no air to mess up your view”
• Gravity-free environment or “In free-fall, you don’t notice the gravity”
• Abundant resources or “Eventually, we will mine the asteroids, collect more solar power, colonize the moon, . . .”
• Global perspective or “There’s nothin’ there to block your view”
• Above the atmosphere or “There’s no air to mess up your view”
• Gravity-free environment or “In free-fall, you don’t notice the gravity”
• Abundant resources or “Eventually, we will mine the asteroids, collect more solar power, colonize the moon, . . .”
C. Hall, Randolph 224Dcdhall@vt.edu
Global Perspective
Amount of Earth that can be seen by a satellite is much greater than can be seen by an Earth-bound observer.
Low-Earth orbit is closer than you think.
Amount of Earth that can be seen by a satellite is much greater than can be seen by an Earth-bound observer.
Low-Earth orbit is closer than you think.Space isn't remote at all. It's only an hour's drive away if your car could go straight upwards.
— Fred Hoyle
C. Hall, Randolph 224Dcdhall@vt.edu
Instantaneous Access Area
Example: Space shuttleExample: Space shuttle
HR
R
K
KIAA
e
e
A
A
cos
km 1055604187.2
)cos1(28
2km 628,476,11
24.179551.0cos
km 300H
km 6378
IAA
Re
Re
H
A friend of mine once sent me a post card with a picture of the entire planet Earth taken from space. On the back it said, “Wish you were here.”
— Steven Wright
IAA
C. Hall, Randolph 224Dcdhall@vt.edu
Above the Atmosphere
• This characteristic has several applications Improved astronomical observations“Vacuum” for manufacturing processesLittle or no drag to affect vehicle motion
• However, there really is “air” in space Ionosphere affects communications signals“Pressure” can contaminate some
processesDrag causes satellites to speed up (!) and
orbits to decay, affecting lifetime of LEO satellites
• This characteristic has several applications Improved astronomical observations“Vacuum” for manufacturing processesLittle or no drag to affect vehicle motion
• However, there really is “air” in space Ionosphere affects communications signals“Pressure” can contaminate some
processesDrag causes satellites to speed up (!) and
orbits to decay, affecting lifetime of LEO satellites
C. Hall, Randolph 224Dcdhall@vt.edu
Vacuum Effects• While space is not a perfect vacuum, it is
better than Earth-based facilities200 km altitude: pressure = 10-7 torr = 10-5 PaGoddard vacuum chambers: pressure = 10-7
torr
• Outgassingaffects structural
characteristicspossibility of
vapor condensation
• While space is not a perfect vacuum, it is better than Earth-based facilities200 km altitude: pressure = 10-7 torr = 10-5 PaGoddard vacuum chambers: pressure = 10-7
torr
• Outgassingaffects structural
characteristicspossibility of
vapor condensation
Wake Shield Facility (shuttle experiment)
C. Hall, Randolph 224Dcdhall@vt.edu
Atmospheric Drag• Can be modeled same as with “normal” atmospheric
flight
• Key parameter is the “ballistic coefficient”:
• Larger ballistic coefficient (small massive satellite) implies slower orbital decay
• Smaller ballistic coefficient implies faster orbital decay • Energy loss per orbit is
• Can be modeled same as with “normal” atmospheric flight
• Key parameter is the “ballistic coefficient”:
• Larger ballistic coefficient (small massive satellite) implies slower orbital decay
• Smaller ballistic coefficient implies faster orbital decay • Energy loss per orbit is
HhSL
D
e
VACD/
221
)/( ACm D
rD2
Better not take a dog on the space shuttle, because if he sticks his head out when you're coming home his face might burn up. — Jack Handey
C. Hall, Randolph 224Dcdhall@vt.edu
WeightlessnessThis illustration from Jules Verne’s Round the Moon shows the effects of “weightlessness” on the passengers of The Gun Club’s “bullet” capsule that was fired from a large gun in Florida.
The passengers only experienced this at the half-way point between the Earth and the Moon.Physically accurate?
This illustration from Jules Verne’s Round the Moon shows the effects of “weightlessness” on the passengers of The Gun Club’s “bullet” capsule that was fired from a large gun in Florida.
The passengers only experienced this at the half-way point between the Earth and the Moon.Physically accurate?
C. Hall, Randolph 224Dcdhall@vt.edu
Zero-Gravity?
This plot shows how gravity drops off as altitude increases.Note that at LEO, the gravitational acceleration is about 90% of that at Earth’s surface.
This plot shows how gravity drops off as altitude increases.Note that at LEO, the gravitational acceleration is about 90% of that at Earth’s surface.
C. Hall, Randolph 224Dcdhall@vt.edu
Microgravity• Weightlessness, free fall, or zero-g
• Particles don’t settle out of solution, bubbles don’t rise, convection doesn’t occur
• Microgravity effects in LEO can be reduced to 10-1 g (1 g)
• Weightlessness, free fall, or zero-g
• Particles don’t settle out of solution, bubbles don’t rise, convection doesn’t occur
• Microgravity effects in LEO can be reduced to 10-1 g (1 g)
On Earth, gravity-driven buoyant convection causes a candle flame to be teardrop-shaped (a) and carries soot to the flame's tip, making it yellow. In microgravity, where convective flows are absent, the flame is spherical, soot-free, and blue (b).
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