Astro Complete

Kepler (not including his laws)

Sun = center of universe

Planets rotate around the sun in elliptical orbits

What are keplers laws

1) The orbit of each planet about the Sun is an ellipse with the Sun at one focus

2) A planet moves faster in the part of its orbit nearer the Sun and slower when farther from the Sun, sweeping out equal areas in equal times.

3) Most distant planets orbit the Sun at slower average speeds, obeying the relationship p2=a3

Newton

1665:

Invented calculus

Law of gravitation

First reflective telescope

1667:

Mathematical principals of natural philosophy

Newton's laws of motion

Key people (ancient)

What chronological order do the ancients go in?

Aristotle, Ptolemy, Copernicus, Brahe, Kepler, Galileo, Newton

What chronological order do the moderns go in?

Tsiolkovsky, Goddard, Von Brahn

Konstantin Tsiolkovsky

Father of Russian cosmonautics

Invented the delta v equation

Demonstrated why rockets would be needed for space exploration

Robert Goddard

Father of modern rocketry

Experiments with both solid and liquid fueled rockets were basis for development of ballistic missile, earth-orbiting satellites, and interplanetary exploration

Werner von Braun

Created the V2 rocket

What year was Sputnik

1957

What year was laika

1957

What year was Sputnik 3

1958

In what order were GRAB-1 (first successful recon sat), Sputnik, and USAFA Dept. Astro created?

Sputnik, Dept Astro, GRAB-1

In what order were GPS, returnable first-stage rocket, and sea-launched ASAT created?

GPS, ASAT, first stage

What year did the us launch their first satellite, and what was the name

Explorer 1, 1958

In 1958 & 1960, what programs did the US create

1958:

Air force's space and ballistic missile program

NASA

1960:

NRO

When was AF space command first established

1982

When was the US space command and US space force established

2019

What altitude is orbit sustained

130 km

What altitude does space begin, what it it called

100 km, karman line

Why do objects stay in orbit at 130 km

Drag decreases as density decreases

What are the effects on spacecraft from Charged particles

Spacecraft charging, Sputtering (sandblasting): Degrade solar panels, impact optics sensing. Mitigate by making redundant systems or shielding components

What are the effects of EM radiation

Generate electrical power = good, Heats up spacecraft = good and bad, Damage electrical equipment = bad, Disrupt communications = bad

Mitigate by making redundant systems or shielding components

What are the effects of a Free fall environment

Makes fluid measurements and delivery more difficult "sloshy" = bad, but allows us to develop super alloys and medicines = good.

No mitigation

What are the effects of Earth’s atmosphere

Drag: Difficult to predict but negligible above 600 km. Atomic oxygen: weakens structures and degrades sensors.

Mitigate through new coatings and physical protections.

What are the effects of the vacuum of space

Outgassing, cold welding, Limited heat transfer: conduction (can lead to cold welding), convection (there's no airflow), radiation (works great)

Mitigation: none

What are the effects of micrometeoroids and space junk

Can cause lots of damage at high speeds, difficult to track (the SSN is tracking 60,000 pieces)

What are the different manmade hazards

Space debris (old satellites, rocket bodies, launch vehicle shrouds), EM interference, and EMP

What are all orbits shaped like

Conic sections:

Circle

Ellipse

Parabola

Hyperbola

When does a satellite stay in orbit

Horizontal velocity allows the horizon to drop away before the spacecraft

For a orbit, what is the tradeoff for a satellite between

Coverage, latency, and vulnerability

What are LEO orbits and give some characteristics and missions

Low earth orbits

Closer and faster

Better resolution with worse coverage

ISR, communications

What are MEO orbits, give characteristics, and missions

Medium earth orbit: between leo and geo

Moderate coverage, affected by radiation belts

PNT (GPS, Galileo, GLONASS, BeiDou)

What are GEO orbits and give some characteristics and missions

Geo-synchronous/stationary earth orbits Closer

Farther away and slower

Better coverage and worse resolution

Continuous comms, missile warning, weather

What are HEO orbits and give some characteristics and missions

Highly elliptical orbit with long dwell over high latitudes

Great for polar coverage

Communications, ISR, missile warnings

What are the 6 Military Space Ops

SATCOM, PNT, Combat Power Projection, SDA, ISR, Detections Monitoring and Warning

Describe PNT usage, satellite coverage, and examples

Precision strike, logistics, maneuver support

Requires 4 satellites for location and time

GPS, JDAM, Blue force tracker

Describe SATCOM usage and examples

Beyond line of sight communications

Enables global C2 and secure links

Military SATCOM networks, AEHF

Describe ISR usage

Imagery and signals intelligence

Detects changes across the em spectrum

Supports operation planning and situational awareness

What does the SDA do

Tracks over 60000 objects in orbit

Prevents collisions and identifies threats

Uses ground and space based sensors

Describe the core military mission of Detections Monitoring and Warning usage and examples

Infrared sensors detect launches

Strategic and tactical alerting

Weather satellites aid mission planning

SBIRS constellation

Describe core military mission of Combat Power Projection usage

Space superiority is necessary precondition for joint force success

Space control includes

Orbital strike, space link interdiction, and terrestrial strike via jamming, EM, cyber, kinetic strikes

What are the components of a space system (threat assessment)

Space segment, link segment, ground segment, user segment

What is the USSF doctrine

Maps the operational environment of space to provide warfighters a complete picture of the threat environments fused with intelligence

What are the four dimensions of space domain awareness

Physical, virtual, information, and human

What is the defense/mitigaiton against electronic warfare

Nulling, frequency hopping, proliferation, direct attack

Defense/mitigation for cyber attacks

Cybersecurity, Encryption, Nulling

What is directed energy

Offer broad range of effects using lasers, high powered microwave or millimeter wave emitters, and particle beam weapons

Defense/mitigation for directed energy

Physical hardening, shielding, coatings

Proliferation

Decoys

Direct attacks

Defense/mitigation against orbital threats

Proliferation

Maneuver

Decoys

Direct attacks

Defense/mitigation against ASAT kinetic weapons

Proliferation

Maneuver

Decoys

Direct attack

Defense/mitigation against high altitude nuclear detonation

Radiation hardening

What are the 2BEOM assumptions?

• Drag negligible​

• No Maneuvers​

• No 3rd body​

• Only Forces are due to gravity​

• Mass of Earth >> Satellite​

• Earth is a point mass​

• Mass of Satellite is constant​

• Inertial Frame

Which assumptions are false?

Earth as point mass - it is actually oblate, causing the J2 effect, affecting RAAN and Arg. Perigee

Drag as negligible - it is not, it actually affects a (semimajor axis) and e (eccentricity)

What orbits take advantage of the J2 effect?

Molniya (63 degrees, highly eccentric, focuses on northern hemisphere)

Tundra (115 degrees, almost geostationary but not over equator)

Sun-synchronous (passes same spot at same time every day)

Active Sensor and examples

Emit electromagnetic radiation and collect reflection - SAR, liDar

Passive Sensor and examples

Collect electromagnetic radiation emitted or reflected by subject - visible, infrared

Stephan Boltzmann Law

Defines the total power (W) emitted by an object given a temperature

Weins Law

Defines the wavelength of peak emission

Field of View

Angle that a satellite can see

Swath Width

The distance the satellite can see on the ground

What limits the minimum altitude of a satellite?

Swath width

What limits the maximum altitude of a satellite?

Resolution

Spatial Resolution

The size of the smallest object that can be identified in an image

Ground Sampling Distance

Distance between the centers of two consecutive pixel measurements on the ground. Ex: GSD=1 then each pixel is 1m x 1m

National Image Interpretability Rating Scale (NIIRS)

Subjective scale of readability assigned to an image by an analyst

Electromagnetic Field

Accelerated electric charge that creates radiation waves that convey/carry energy

Antennas

Transducer between guided RF wave and Free space RF wave, usually metallic

Gain

the ratio of power/RF energy directed in a particular direction, ie how strong your RF energy is

Loss

Gain less than 1

Isotropic Radiator

The baseline measurement where gain=0 and goes in any direction

Modulation

Putting information (the message signal) onto an RF carrier by altering the pure carrier signal (wave)

AM (amplitude modulation)

a high or low amplitude corresponds to 0 or 1

FM (frequency modulation)

where the instantaneous frequency shifts to, compared to the carrier frequency, corresponds to 0 or 1

Phase shift keying

the length of the phase corresponds to a 0 or 1

Uplink

ground station to satellite

Crosslink

satellite to satellite

Downlink

satellite to ground station

Wien’s Law

max wavelength (lambda max) = 2898/T (temp in Kelvin)

Free Space Loss

Signal spread out on surface of a sphere centered on the transmit antenna, as signal goes further the sphere expands and the power is dispersed, leading to loss

Figure of Merit for an Antenna

A single quantitative measure that combines the most important antenna performance characteristics into one value so different antennas can be compared for a specific mission or application

Gr/T

Figure of Merit for receive antennas, gain of antenna over Temperature, measures how well it can receive weak signals compared to the noise it produces

RF noise

Pn = k *T * B , more noise = higher equivalent temperature

Signal to Noise Ratio (SNR)

Quality rating of RF link, bigger is better, C/N = Signal power/ noise power

Eb/No

The SNR in digital satcom

Equivalent Isotropic Radiated Power (EIRP)

Figure of merit for transmit antennas, RF power equivalent to that radiated from a single point in all directions

Closed loop control system

Input, Controller, Actuator, Plant, Output, Sensor

Difference between open and closed loop systems

Open loop systems do not have a sensor - they cannot gather feedback from the system and use it to make decisions in the future

Input

An order

Controller

Translates and inputs order into an action command

Actuator

Takes commands from controller

Plant

System being manipulated

Output

desired effect

Sensor

Measures output and gives info to controller

Attitude

The rotational orientation of an object with respect to a particular reference frame

Disturbance Torques

Aerodynamic Drag, Gravity Gradient, Solar Radiation Pressure, Magnetic Torque

Active Actuators

Thrusters, Magnetorquers, Reaction wheel, Momentum wheel, Control Moment Gyro

Passive Actuators

Gravity-gradient stabilization, spin stabilization, dampers

Attitude Sensors

sun/earth/star sensors, gyroscope, magnetometer, differential GPS

Equation to find period from altitude/height

where a = Radius(earth) + h