Unit 5

Question 1

Methods of propulsion

Answer 1

Chemical
Ion
Solar

More fanciful:

Warp Drive
Quantum Drive

Question 2

Newtons Laws

Answer 2

First: Inertia

Second: F = ma

Third: Law of opposite

Question 3

LEO

Answer 3

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

Question 4

The Kessler Syndrome

Answer 4

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)

Question 5

MEO

Answer 5

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

Question 6

Van Allen Radiation Belts

Answer 6

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

Question 7

GSO

Answer 7

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

Question 8

GEO

Answer 8

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

Question 9

HEO

Answer 9

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

Question 10

Periods of Orbit

Answer 10

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

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

Question 11

Escape Velocity

Answer 11

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

Vsec = root (2GM/R)

Question 12

Chemical Rocket Fuel

Answer 12

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)

Question 13

Chemical fuel parts

Answer 13

Liquid Oxidizer is always liquid oxygen

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

Question 14

Ion Propulsion

Answer 14

Chemical rocket propulsion is essential for lifting a rocket

Ion engines produce low thrust and thus low acceleration

Same for chemical rocket propulsion

Question 15

How does Ion propulsion work

Answer 15

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

Question 16

Ion propulsion used in spacecraft

Answer 16

Dawn spacecraft

• Most successful ion propulsion to date

Lunar Gateway

• Set to use the most powerful ion engines yet

Question 17

Solar sailing

Answer 17

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

Question 18

Matter - Anti-Matter propulsion

Answer 18

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

Question 19

Nuclear powered rocket

Answer 19

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

Question 20

Power for spacecraft

Answer 20

Power comes from solar panels that convert sunlight into electricity

Most efficient when close to the sun

Question 21

Radioisotopes thermoelectric generators

Answer 21

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

Question 22

Exploring our solar system

Answer 22

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

Question 23

Artemis 1

Answer 23

Launched 2022

To the moon and back (uncrewed)

25 days

Question 24

Artemis 2

Answer 24

Proposed launch 2025

To the moon and back with a crew of 4

• including a Canadian

~10 Days

Question 25

Artemis 3

Answer 25

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

Question 26

Artemis 4 and Beyond

Answer 26

Similar to Artemis 3 Use of lunar gateway, an orbiting station to facilitate long term stays on the moon

Question 27

Lunar Living

Answer 27

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

Question 28

Spacecraft Sterilization

Answer 28

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...

Question 29

Outer Space treaty

Answer 29

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

Question 30

Current interstellar spacecraft

Answer 30

Pioneer 10, 11 Voyagers 1, 2 Soon New Horizons will take 10s of thousands of years to reach our nearest star

Question 31

Interstellar travel

Answer 31

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

Question 32

Time dilation

Answer 32

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))

Question 33

Starshot initiative

Answer 33

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