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NATS 1530 > Unit 5 > Flashcards

Unit 5 Flashcards

1
Q

Methods of propulsion

A

Chemical
Ion
Solar

More fanciful:

Warp Drive
Quantum Drive

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2
Q

Newtons Laws

A

First: Inertia

Second: F = ma

Third: Law of opposite

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3
Q

LEO

A

Low Earth Orbit:

  • Majority of satellites
  • Less than 2,000 km above the surface of the earth
  • Orbital period of less than 128min
  • Satellites will fall out of orbit and re-enter on relatively short time frames
  • Mostly communication satellites since low latency
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4
Q

The Kessler Syndrome

A

The Kessler effect

The increase in density of objects in LEO, due to space position is high enough that collision between objects could cause a cascade (cause further collisions)

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5
Q

MEO

A

Medium Earth Orbit:

  • Higher than LEO
  • Above 2,000 km to 35,786km from the surface of the earth
  • Orbital period between ~2 hours and exactly 23h 56m and 4s
  • contains Van Allen radiation belts
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6
Q

Van Allen Radiation Belts

A

Collection of charged particles emanating from the sun and carried by the solar wind

Communications and GPS satellites use this region as it encompasses an orbital period of 12 hours

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7
Q

GSO

A

Geosynchronous Orbit:

  • A Earth centererd orbit with an orbital period that matches Earth’s rotation of 23h 56m and 4s
  • Satellites in this orbit return to the same location each day seen from the surface of the earth
  • East-west drift associated with elliptical orbit
  • North-South motion from inclination
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8
Q

GEO

A

Clarke Orbit or Geostationary Earth Orbit:

  • A special case of GSO when the satellite is orbiting the Equatorial plane
  • Satellites seen appear stationary
  • Used widely by telecommunication satellites
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9
Q

HEO

A

High Earth Orbit:

  • Satellites are rare
  • Orbital period greater than 24 hours
  • From Earth appears to move westward
  • Will never re-enter Earth’s atmosphere
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10
Q

Periods of Orbit

A

The orbital periods depend upon the major axis of the orbital ellipse and the mass

P^2 = 4pi^2 a^3 / G M2

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11
Q

Escape Velocity

A

For a satellite to escape from the gravitational fields of the Earth must reach escape velocity

Vsec = root (2GM/R)

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12
Q

Chemical Rocket Fuel

A

Combustion

  • A chemical process that releases energy, often in the form of heat

An oxidizer is important since there is no air in space

Liquid fuel can be stopped and started potentially many times

Solid rocket fuel can not be stopped when ignited

  • Also it also interacts minimally with their environment (more stable)
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13
Q

Chemical fuel parts

A

Liquid Oxidizer is always liquid oxygen

Liquid fuel can be hydrogen (commonly) or Kerosene (RP - 1)

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14
Q

Ion Propulsion

A

Chemical rocket propulsion is essential for lifting a rocket

Ion engines produce low thrust and thus low acceleration

Same for chemical rocket propulsion

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15
Q

How does Ion propulsion work

A

Step 1: Electrons are remitted by the discharge hollow cathode, traverse the disc charge chamber, and are collected by the anode walls

step 2:propellant is injected from the plenum and travels towards the discharge cathode

Step 3: Electrons impact the propellant atoms to create ions

Step 4: Ions are pulled out of the discharge chamber by the ion optics

  • Note that the higher the voltage of the discharge optics, the faster the exhaust speed of the ions

Step 5: Electrons are injected into the beam for neutralization

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16
Q

Ion propulsion used in spacecraft

A

Dawn spacecraft

  • Most successful ion propulsion to date

Lunar Gateway

  • Set to use the most powerful ion engines yet
17
Q

Solar sailing

A

Arthur C. Clarke’s science fiction

Deployment of a large area, low mass “Solar sail”

Use the pressure of sunlight to change speed and direction

Acceleration generated is very small

18
Q

Matter - Anti-Matter propulsion

A

When matter comes into contact with any matter, complete and spontaneous annihilation occurs

It offers 100% conversion of matter into energy

we can produce some anti-matter particles but strong them is the challenge

19
Q

Nuclear powered rocket

A

Nuclear thermal rocket

The nuclear fission reactor heats and vaporizes the liquid hydrogen and generates thrust

Relatively low but long-term thrust

Concerns include safety of the environment during a lunch failure

20
Q

Power for spacecraft

A

Power comes from solar panels that convert sunlight into electricity

Most efficient when close to the sun

21
Q

Radioisotopes thermoelectric generators

A

RTG:

  • A type of nuclear battery

Any radiation emitted must be easily absorbed so it wont impact the rest of the spacecraft

Only 3 isotopes are commonly used:

  • Plutonium
  • Strontium
  • Americium
22
Q

Exploring our solar system

A

Artemis project plans on return to the moon

  • a permanent settlement seems likely within this decade

A human mission to Mars in the 2030s

Human settlements through our solar system are likey within this century

23
Q

Artemis 1

A

Launched 2022

To the moon and back (uncrewed)

25 days

24
Q

Artemis 2

A

Proposed launch 2025

To the moon and back with a crew of 4

  • including a Canadian

~10 Days

25
Q

Artemis 3

A

proposed launch 2026

to the moon and back with Crew 4 and with 2 astronauts landing on the moon

  • First woman on the moon

~12 days

26
Q

Artemis 4 and Beyond

A

Similar to Artemis 3

Use of lunar gateway, an orbiting station to facilitate long term stays on the moon

27
Q

Lunar Living

A

Will not be self-sufficient in the short term

  • But should be as soon as practical

Ice near the lunar poles provides water

Protection against harsh radiation is essential

2 weeks of sunlight and 2 weeks of night

  • Battery power is important
28
Q

Spacecraft Sterilization

A

Forwards contamination:

  • The transfer of terrestrial organisms to another celestial body

Backward contamination:

  • Aline life could be brought back into the Earth’s biosphere

How:

  • Use of a clean room
  • Heating to ~115C
  • UV radiation
  • etc…
29
Q

Outer Space treaty

A

Came into effect on 10 October 1967 and has 112 signatures now

Attempts to guide a peaceful and free use of space for the benefit of humanity

  • Weapons, specifically nuclear, will not be placed in space
  • States will be responsible for nongovernment entities
  • States will be liable for damages caused by their activity
30
Q

Current interstellar spacecraft

A

Pioneer 10, 11

Voyagers 1, 2

Soon New Horizons

will take 10s of thousands of years to reach our nearest star

31
Q

Interstellar travel

A

One way trip

  • multi-generational ship ark is most likely

Sufficient number of people

  • 100 or more likely 1000

Energy requirement for the trip

  • Life support entails
  • Air purification
  • Heating
  • Water purification
  • Farming

Consumables for the trip

Interstellar hazards

  • radiation
  • particle
  • collisions
32
Q

Time dilation

A

Special relativity asserts that time measured by a moving clock appears to advance slower than for a clock in a rest frame

  • For example, for astronauts aboard the international space station, time lags by about 0.01s for every 21 months elapsed on the Earth’s surface

The realistic time elapsed, T, for a clock moving at a speed v when compared to a reference clock elapsed time T0

T = T0/(root(1 - V^2/C^2))

33
Q

Starshot initiative

A

Proposed that a nanocraft with a mass of a few grams could be accelerated to 20% of the speed of light

Which will reach a nearby star within 20 years

NATS 1530 (13 decks)

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