Boots on the Moon "SPACE_200" Flashcards
(119 cards)
1
Q
Define a System as it applies to the system engineering process?
A
An integrated composite of people, products & processes that provide a capability to satisfy…
2
Q
Systems Engineering Turns…?
A
Needs into Capabilities
3
Q
What are the three basic elements illustrated in the systems Engineering “V”?
A
Design
Control
Realize
4
Q
4 parts of the systems engineering universe?
A
Cost
schedule
Performance
Risk
5
Q
Six tasks in the space mission design process?
A
- Develop a clear mission need statement
- From users goals define mission objectives
- Develop a logical conops
- Derive Mission Requirements
- Investigate alternative mission conops
- Select baseline concept
6
Q
Purpose of CONOPS/ Operational View 1 (OV-1)?
A
Scope the system
Identify Integration/parts
Share with stakeholders
7
Q
3 cost estimation methods?
A
Detailed bottoms up
Parametric Estimating
Analogy Based Estimating
8
Q
Describe weightless feeling on orbit?
A
Free fall, velocity maintains a constant fall around the earth.
9
Q
What happens to a satellites speed as it gets closer to earth?
A
Speeds up, faster
Kepler’s Second Law “equal areas covered”
10
Q
According to Kepler’s third law, the square of the satellites orbital period is proportional to what?
A
Cube of the average distance to the sun
11
Q
If the distance between two masses triples, will the gravitational force between the two objects increase or decrease? by how much?
A
Decrease
Inverse Square Law
1/R^2 AKA decrease by a factor of 9
12
Q
How does an orbit’s total energy at perigee compare to its total energy at apogee?
A
Total energy remains unchanged KE+PE=Total energy // At perigee KE is greater At apogee PE is greater
13
Q
How does angular momentum compare at perigee compare to at apogee?
A
Angular momentum must remain constant
Equal
?
14
Q
Classical Orbital Elements (COE)
A
Semimajor Axis (a)- Orbit size Eccentricity (e)- Shape/ellipse Inclination(i)- Tilt, measured at ? Right ascension of the ASC node() - Argument at perigee()- Ture Anomaly (v)-
15
Q
4 Common Orbit Types?
A
Sunsync
MEO Semi Sync
HIO
Geosynchronous
16
Q
The Six Space Environment Effects Areas?
A
Gravity (covered previously) Atmosphere/Neutral Vacuum Micrometeoroids and Orbital Debris Plasma/Charged Particles Radiation
17
Q
Levels of Earths Atmosphere?
A
Exosphere Thermosphere Mesosphere Stratosphere Troposphere
18
Q
Orbit changed from LEO to MEO would change what hazards?
- Vacuum
- EM Radiation
- Charged Particles
- Neutral Atm particles
- MMOD
A
#3 charged particles Worse #4 Drag better #5 MMOD better
19
Q
How does atmospheric drag affect spacecraft?
A
Slows and deorbits
20
Q
How does the solar cycle affect the frag forces experienced by a spacecraft?
A
Solar cycle affects expansion and contraction of the drag area…
21
Q
Most significant impact of the plasma environment on the spacecraft?
A
Charges the surface of he satellite, EM interference and arcing
22
Q
What are the Van Allen radiation Belts?
A
Magnetic belt influenced charged particle collection zones
23
Q
Why is man made orbital debris more serious than natural debris?
A
?
24
Q
What part of the radio frequency spectrum is most affected by scintillation?
A
UHF
GPS if receiving on ground
25
Where and when does scintillation typically cause problems?
Equator and poles
| Dawn and Dusk
26
How are wavelength and frequency related?
Inversely Proportional
27
International organization that controls frequency allocations?
FCC
| Federal Communications Commission
28
Atmospheric effects that impact laser performance?
Distortion
Absorption
Thermal Blooming
Diffraction
29
Advantages of laser communications?
High data rates
| Hard to Jam
30
Disadvantages of laser communications?
Signal attenuated by atmosphere
Requires accurate pointing
large power source
31
GPS inclination?
55 degrees
| Fun fact: highest inclination from florida launch due to political marriage to shuttle
32
Inclination of the International Space Stations?
51.6 degrees
Fun fact: So the Russians could have easy access to said hanging BnB.
33
How many GPS satellites are required to be accurate?
4
| 3 is enough in a perfect world. The fourth is for timing.
34
List the 4 key issues in communication?
Distance
Language
Speed
Environment
35
What is the primary figure of merit for a digital communication link?
Bit Error Rate
Eb/No
Eb= Energy Per Bit
No=Noise Density
36
Identify two ways to increase the gain of a directional antenna?
Power & antenna size
| ?
37
Define bit error rate?
Bit Error Rate
Eb/No
Eb= Energy Per Bit
No=Noise Density
38
Open Loop Control system?
Fire and forget?
39
Closed Loop Control System?
Controller (thermostat), actuator (furnace), plant (house), sensor (Thermometer).
40
Generic components of a closed loop system?
Controller
Actuator
Plant
Sensor
41
Estimation method that utilizes mathematical relationships to relate costs to physical, technical and performance parameters
Parametric Estimating
42
Restricted two-body assumptions applied, what is the only satellite characteristic required to ....something
???
F=MA
Answer:MASS?
43
Restricted two-body assumptions applied, what is the only satellite characteristic required to ....something
???
F=MA
Answer:MASS?
44
Which COE describes the Shape of an orbit?
Eccentricity
45
Which COE describes the Shape of an orbit?
Eccentricity
46
Which COE(s) describes the orientation of orbital plane?
Inclination
| Right ascension of the Ascending Node (RAAN)
47
Argument of perigee is?
Location of perigee within the orbital plan
| Expressed in degrees starting from RAAN
48
Which COE defines the location of a spacecraft in its orbit?
True anomaly
| 0-360 Measured from Perigee
49
Describe CEO that make a Geostationary comms sat?
eccentricity 0
inclination 0
semi maj axis 42164 KM
50
Orbital perturbation that has small drag near perigee that leads to a more circular orbit?
Drag
51
Orbital perturbation that makes sun synchronous possible?
J2
52
Orbital perturbation that makes sun synchronous possible?
J2
53
Orbital perturbation that makes Molniya orbit to be 63.4 degrees?
J2
| ?
54
A satellite that is Sun Synchronous will always be illuminated by the sun?
F
55
A satellite that is Sun Synchronous will always be a retrograde orbit?
T
56
A satellite that is Sun Synchronous will pass over the same spot on the earth once every day?
F
57
List the four sources of energy (heat) that cause temperature changes in a spacecraft.
Sun
Earth
Internal Dissipation
58
Which heat transfer method is the ONLY one that removes heat from a spacecraft?
Radiation
59
List four design approaches used to control temperature on a spacecraft.
```
Insulation
Louvers
Radiators
Phase change Materials
Heat pipes
```
60
For most space missions, when are the most demanding loads applied to a spacecraft?
Launch
61
What issues make moving mechanisms on spacecraft problematic?
hard to test in relevant environment, failure point
62
What are some challenges that make successful software development for space systems so difficult?
Time
| Complexity
63
What is the relationship between orbital inclination and launch site latitude that must exist to ensure two launch windows each day for direct orbits?
launch site latitude must be below the inclination
64
For the launch conditions below, answer true or false and briefly explain why:
a) We have two opportunities per day to launch directly into an inclination less than the launch site’s latitude.
False
65
For the launch conditions below, answer true or false and briefly explain why:
b) From Kennedy Space Center (L0=28.5°) we can launch directly into an inclination of 28.5° any time of day that weather permits and still obtain the specified right ascension of ascending node ().
False
You only have 1 window to launch into the exact inclination
66
For the launch conditions below, answer true or false and briefly explain why:
c) We cannot launch directly into an inclination less than a launch site’s latitude.
False
67
For the launch conditions below, answer true or false and briefly explain why:
d) We cannot launch directly into an inclination greater than the launch site’s latitude.
False
68
Why isn’t Kennedy Space Center used to launch satellites into retrograde orbits?
Danger, would go over CONUS
69
What launch azimuth (or direction) maximizes mass to orbit for a given launch vehicle?
East
70
Delta V required to get to orbit?
9.3 km/sec
71
Which of Newton’s three laws of motion best describes how rockets work?
3rd law-Every action has an opposite and equal reaction.
| Thrust depends on how much "stuff" mass is thrown away from rocket
72
What two parameters determine the thrust produced by a rocket?
Mass
| Exhaust velocity
73
What parameter describes rocket efficiency?
Specific Impulse
| Isp = F(thrust)/MGo
74
What determines the amount of delta V produced by a rocket?
```
propellent efficiency (Isp)
Initial mass (full tank)
Final Mass (fuel expended tank)
```
75
Why can multiple-stage launch vehicles put more payload mass into orbit than single-stage launch vehicles?
Reduces total mass
76
How do thermodynamic rockets produce thrust?
Heat/pressure energy
77
Which type of rocket cannot be stopped and restarted?
Thermodynamic
78
Which type of rocket cannot be stopped and restarted?
Solid rockets (chemical)
79
What is the key advantage and associated disadvantage of electrodynamic rockets?
Adv:
high Isp (efficency)
Long life
Unlimited cycling
Dis:
Low thrust Mouse farts
High power
80
Describe the two elements of the mission operations system.
1. Command, control and communications (C3)
| 2. Mission Management operations
81
What are the three activities performed by satellite control networks?
Tracking, Telemetry and Commanding (TT&C)
82
What are the five measurements are made to track a satellite?
Time, Elevation, Azimuth, Range & Range Rate(TEARR)
83
What are the two types of telemetry data?
State of Health
| Payload or Mission Data
84
What are the two types of satellite control networks, and what is the basic difference between the two?
Common User Network (shared)
| Dedicated User Network (not shared)
85
Describe the role of 22 SOPS. What is the “product” they produce of interest to satellite operators?
Network Tasking Order (NTO)
| 24 hour schedule
86
Describe the two segments of the NASA Space Network.
```
Space Segment (TDRS)
Ground Segment (white sands/Guam)
```
87
What are the benefits of using a concurrent approach for space mission operations planning?
Critical
Grounds nerds in reality
Relevant experience
88
5. When the restricted two-body assumptions are applied, what is the only satellite characteristic required to completely describe the acceleration (and, thereby, future changes in position and velocity) of a satellite in Earth orbit?
Distance
| R^2
89
Sunsync Inclination
97 deg ish
90
Give example COE of Geostationary
42K
91
What characteristic of a Hohmann Transfer is the “key” to its efficiency?
tangential & in plane
92
Describe the velocity changes (number and direction) that must be generated to perform a Hohmann Transfer from a low-altitude circular orbit to a high-altitude circular orbit.
1 burn at perigee to get elliptical
1 burn at apogee to get circular
93
What is the most propellant (energy)-efficient way to change both the size and inclination of an orbit?
Combined plane change
94
If the final ΔV of a Hohmann Transfer is not performed, describe the resulting satellite motion.
Stuck in elliptical
95
What is the foundation of rendezvous and all space control missions?
SDA
96
List three types of rendezvous?
Hohmman
Fast Transfer
Co-Orbital
97
What are the two parameters that are traded in most rendezvous maneuvers?
Time
| Propellent
98
Linear drift
Smaller semi major axis
99
Natural motion circumnavigation
Doing circles around target. More eccentric.
100
Where and when does scintillation typically cause problems?
Dusk
| Equator and Poles
101
What two agencies provide space environmental support in the United States?
NOAA
| 557th Weather wing (USAF)
102
What is the best wavelength for detecting a missile plume at a temperature of 724 K?
4 Microns
103
Which type of observation resolution quantifies the minimum separation between features that must exist to differentiate one from the other?
Spatial resolution
104
Identify the parameters that determine diffraction-limited (or angular) resolution?
Distance from ground
Wavelength
Camera Aperture
105
12. If the distance between a radar and its target object increases by a factor of 3, what happens to the strength of the reflected pulse when it returns to the radar?
R^4
106
How does a radar determine the range to a target object?
(Time/2) * Speed of light)
107
Identify two ways to increase the gain of a directional antenna.
Bigger antenna
| Shorter wavelength
108
What are some methods that could be employed to increase the Eb/N0 (signal-to-noise ratio) at the receiver of a ground terminal?
Antenna size
Electronics temp
Drop altitude
109
What are the tradeoffs a comm subsystem designer must consider if she decides to use a high-gain, low-power antenna on the satellite?
Narrow pointing
110
Which multiple access strategy allows users to share the same frequency band by designating the specific time interval during which each user can transmit digitized data packets?
Time division Multiple access
111
What international organization controls frequency allocations for satellite communication systems?
ITU
112
Which spacecraft subsystem compensates for orbital perturbations to keep a spacecraft in the right orbit?
NGC
| Navigation Guidance Control
113
Which spacecraft subsystem compensates for disturbance torques to keep a spacecraft pointed in the right direction?
ADCS
114
What external references do attitude control sensors typically use to determine a spacecraft’s orientation? Which provides the highest precision?
STARS (Most Precise)
Sun
Earth
115
List three characteristics that determine the amount of power per unit area (W/m2) produced by a solar panel?
Solar available
Solar cell material
Orientation
116
6. List three momentum-based closed-loop attitude control systems.
Bias momentum
Reaction Wheels
Control Moment Gyro (CMG)
117
What are some of the key considerations in the design or choice of secondary (rechargeable) batteries?
Specific Energy Density
118
What are some of the key considerations in the design or choice of secondary (rechargeable) batteries?
```
Specific Energy Density
#/Depth of discharges
```
119
What are some improvements being tested and/or considered for DoD satellite command and control (AFSCN upgrades)?
Phased array antennas
| Interoperable Network
