Term
| The interaction between magnetized solar wind and planets depend on the planets: |
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Definition
| magnetic field, size (gravity), atmosphere |
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Term
| What is the magnetosphere? |
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Definition
| Region where the local magnetic field dominates instead of the sun’s magnetic field. |
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Term
Magnetized solar wind slows down and changes direction upon coming in contact with..?
What does it provide? |
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Definition
Earth’s magnetic field around 10-15 Earth radii (100-150 AU)
It provides a protective cocoon around earth. |
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Term
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Definition
| where the solar wind begins to slow down from supersonic to subsonic and bends around Earth’s magnetic field (100-1000 km thick) |
|
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Term
| What is the magnetosheath? |
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Definition
| the area of subsonic flow of solar wind after the bow shock |
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Term
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Definition
| the night side elongation of the magnetosphere with ‘r’ of 20-25 Earth radii (200-250 AU) and length of around 200 earth radii (2000 AU) |
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Term
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Definition
| form when energetic electros (6 keV) from solar wind follow magnetic field lines into the poles. Collision between electrons and N and O atoms excite the N and O atoms and thus relaxing of the atoms forms Auroras |
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Term
Color of Auroras depend on each atom or molecule
What color is oxygen and nitrogen? |
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Definition
o Oxygen: green (100km) and Red (200-400 km)
o Nitrogen: pink glow (neutral N2) and blue/violet (ionized N2) |
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Term
| How do auroral ovals relate to one another? |
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Definition
| • The Auroral ovals are nearly identical on both poles; they are sronger on the night side and their intensity and position changes with solar activity |
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Term
| Why are auroras brighter on the night side? |
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Definition
| • When an Aurora forms, energetic electrons come from the tall of the magnetosphere. The reconnection of the solar wind B-field with Earth’s B-field causes the solar wind to enter magnetosphere in the tail section and solar wind particles are accelerated towards the aurora zones, near the poles, thus explaining why Auroras are brighter on the night side. |
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Term
| T/F: Each moon and planet has the same magnetosphere |
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Definition
| • Each moon and planet has different magnetospheres and these are found throughout the solar system |
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Term
| How are van allen radiation belts formed? |
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Definition
| are formed when Earth’s magnetic field lines trap charged particles. |
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Term
| What are two types of Van allen belts? |
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Definition
| o Proton belt or the inner belt – mostly consists of high en |
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Term
What does this mean?
The charged particles in earth’s magnetic field acts like a magnetic mirror |
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Definition
| • As particles travel along these field lines and get closer to Earth, the magnetic field lines get stronger and thus the particles slow down until they stop and reflect back the other way, thus are always bounced back and forth. |
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Term
| Describe a geomagnetic storm in a solar min and solar max |
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Definition
o Solar min: Fast solar wind catches up with slow solar wind, this magnetic shock produces intence B-fields and rotates with the sun (period – 27 days)
o Solar Max: CME’s dominate variations to B field |
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Term
| Describe hazards from space weather |
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Definition
| happen when flights take polar flights, fly at high altitudes (less of atmosphere protecting). Also this affects astronauts as they can have increased chances of cancer, genetic mutations (thus are recommended to have family before space walks |
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Term
| How do space hazards effect communication? |
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Definition
o Storms increase the e-density in the ionosphere, this absorbs or reflects long wavelengths and this problem can be avoided by using short wavelengths
o Satellite problems: high-energy e can damage satellites. The solution is radiation hardening and metal protection
• Can affect transformers and cause power grid failures |
|
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Term
|
Definition
| reconsidered Aristarchus’s idea of a heliocentric solar system and put forward the idea that the retrograde motion on by suggesting a planet on a smaller orbit overtaking another planet. He could also calculate distances to other planets based on the distance between earth and sun. |
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Term
| How did Brahe differ from copernicus? |
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Definition
| stubbornly disagreed with Copernicus and believed in an Earth-centric model of the solar system. Took a lot of good observations later to be inherited by Kepler. |
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Term
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Definition
| inherited Brahe’s observations after his death and determined that all planets follow an elliptical orbits and not circular and thus came up with three laws. |
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Term
| What is kepler's first law? |
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Definition
| planets move in elliptical orbits with the sun at one focus of the ellipse |
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Term
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Definition
| the orbital period of a planet varies such that a line joining the Sun and the planet will sweep equal areas in equal time. Thus when a planet orbits closer to the sun, it speeds up and slows down as it moves away from the sun. |
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Term
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Definition
| the amount of time a planet takes to orbit the Sun is proportional to its orbit size, such that the period (P), squared, is proportional to its semi-major axis (a) cubed. This P^2=a^3 (planets around the sun) where ‘P’ is in years and ‘a’ is in AU. In general P^2αa^3 |
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Term
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Definition
| came in and formed his three laws of motion |
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Term
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Definition
| An object will remain at rest or at constant motion unless it is acted upon by an external and unbalanced force. |
|
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Term
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Definition
| the change of momentum of a body is proportional to the impulse impressed on the body, and happens along the straight line on which that impulse is impressed. |
|
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Term
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Definition
| for a force there is always an equal and opposite reaction; or the forces of two bodies on each other are always equal and directed in opposite directions |
|
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Term
| What was newtons law of universal gravity? |
|
Definition
massive objects attract
• F= GMm
r^2
o F is gravitational force of attraction (Netwon)
o M = mass (kg) of one object
o m is mass (kg) of second object
o r = distance (m) between the two objects
o G = 6.7 x 10^-11 m^3 kg ^-1 s^-2 (gravitational costant)
• Newton discovered that planets are moving and are attracted towards the sun.
This allows for elliptical orbits and allows for Kepler’s third law |
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Term
| What is newtons rendition of the formula kepler used in his third law? |
|
Definition
p^2=4(pi)^2a^3/GM
p=period
g=g constant (will be given)
a=semimajor axis |
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Term
| What is the formula for orbital velocity? |
|
Definition
• Orbital velocity is measured by the formula:
V orbit= 2πa
P
• Where ‘a’ is the distance between the object and the central object and ‘P’ is the period. |
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Term
| Kinetic energy needs to be ______ potential energy in order to escape earth's gravity. |
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Definition
|
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Term
| The escape velocity is _________ of the rocket mass. |
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Definition
|
|
Term
| What factors does escape velocity depend on? |
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Definition
|
|
Term
| What is the formula for espace velocity? |
|
Definition
|
|
Term
| What is the hohmann transfer? |
|
Definition
| transfer orbit that requires the minimum amount of energy. |
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Term
| What is a geosynchronus orbit? |
|
Definition
| When the satellite is kept over a single point over earth |
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Term
| What are the two velocity requirements for getting into transfer orbit? |
|
Definition
o Spacecraft must change its velocity to get into Low-Earth orbit (LEO). Note that this change in velocity is less than the escape velocity of the Earth
o Spacecraft also needs an additional change in velocity to get into the transfer orbit. |
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Term
| How does a spacecraft make the two changes needed to get into transfer orbit? |
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Definition
| • The spacecraft accelerates (remember that acceleration is the change in velocity over time) to these velocities using propulsion. |
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Term
| What is the formula for orbital velocity? |
|
Definition
|
|
Term
| What are the 3 parts of a rocket? |
|
Definition
o Payload: science, human, life support, communications…
o Structure: rocket, pumps, tanks, structural support…
o Fuel: expelled for propulsion |
|
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Term
| What are the 3 parts of a rocket? |
|
Definition
o Payload: science, human, life support, communications…
o Structure: rocket, pumps, tanks, structural support…
o Fuel: expelled for propulsion |
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Term
|
Definition
|
|
Term
| What is meant by the phrase "momentum is conserved? |
|
Definition
| initial momentum equals final momentum |
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Term
| What 3 components are necessary to go faster? |
|
Definition
o Maximize fuel speed
o Maximize fuel mass
o Minimize craft mass |
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Term
|
Definition
| a trick used to help the situation as used up tanks do not have to be carried and can be shed. Once the fuel in the first stage is used up, we can drop that stage. Now we no longer need to carry that structure into space. |
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Term
| How do chemical rockets work? |
|
Definition
| • Chemical rockets work by heating a gas through a chemical reaction. This gas is expanded through a nozzle. Chemical rockets can be classified based on the form of the fuel they use. |
|
|
Term
| What are the three types of chemical rockets? |
|
Definition
o Solid propellant
o Liquid propellant: a) monopropellant b) biporpellant
o Hybrid rockets |
|
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Term
| What are solid propellant motors? |
|
Definition
| in this type of fuel the fuel and the oxidizer are mixed together to form a grain. This has to be ignited in order to start mixture burning. Exhaust speed = 2.8 kms^-1. Propellant example = ammonium perchlorate (oxidizer) and HTPB or PBAN (fuels). Xhaust example = HCl, Al2O3. Uses: booster (space shuttle, delta V) |
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Term
| What are advantages of solid propellant motors? |
|
Definition
| Very simple designs, lots of heritage, reliable, compact, long storage times, high payload mass fraction, low costs. |
|
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Term
| What are disadvantages of solid propellant motors? |
|
Definition
| Impossible to turn off, low exhaust speed compared to liquid fuels, air pockets can explode (which ruptures the casing), seals can rupture causing failure. |
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Term
| How do Liquid Propellant: monopropellant engines work? |
|
Definition
| These engines work by passing a monopropellant through a catalyst, Catalyst causes a reaction, generating heat, the heated products are then expelled through a nozzle. Typical fuel is hydrazine (N2H4). Exhaust speeds are up to 2.3 kms-1. These engines are usually used for attitude control |
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Term
| What are some advantages of liquid propellant monopropellant engines? |
|
Definition
| simple design, robust design, reliable, not a lot of plumbing required, can turn them off. |
|
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Term
| What are some disadvantages of liquid propellant mononpropellant engines? |
|
Definition
| Most fuels are toxic, catalyst life time issues, low thrust, low exhaust speeds |
|
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Term
| How do Liquid Propellant: Bi-propellant Engines work? |
|
Definition
| Fuel and oxidizer are pumped into the combustion chamber (often uses turbopumps and power tapped off of main combustion), injectors mix propellant to provide stable and thorough combustion, heat is generated from combustion and heated products are expelled from nozzle. Example fuels include liquid hydrogen and kerosene, example oxidizers include liquid oxygen, example rockets: space shuttle main engine, atlas rockets. |
|
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Term
| what are some advantages of liquid propellant bipropellant engines |
|
Definition
| typically more efficient than solid or hybrid rockets, high exhaust velocity (3.6-4.4 kms-1), throttled, can turn them off, lots of flight heritage |
|
|
Term
| what are some disadvantages of liquid propellant bi-propellant engines? |
|
Definition
| More complex than hybrids or solid rockets, cryogenic systems often needed (icing issues) difficulty storing, system complecity |
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Term
| How do hybrid motor rockets work? |
|
Definition
| A solid fuel is used, but a liquid oxidizer is pumped into the thrust chamber where the solid fuel grain resides. A combustion reaction occurs heating the reactants, which are expelled through a nozzle. Some of the propellants used are LOX or nitrous oxide (oxidizer). This type of motor was used on space ship one. |
|
|
Term
| what are some advantages of hybrid motor rockets? |
|
Definition
| Can shut them down, simple to use, safe propellants |
|
|
Term
| what are some disadvantages of hybrid motor rockets? |
|
Definition
| complex fuel/combustion, lower performance than bi-propellant, little/no flight heritage. |
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Term
| What are some overall points about chemical rockets? |
|
Definition
| there are three types of chemical rockets: solid propellants, liquid propellants and hybrid propellants. Most have a lot of flight heritage in launching vehicles, using as orbit transfer thrusters and as station keeping. Also they have variable exhaust speeds (2-5 kms-1) |
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Term
| Why does electric propulsion make good economic sense? |
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Definition
| • Launch costs are very high and thus there is a need to find a way to make space travel more affordable. Electric propulsion is one option, as it uses onboard electric power to generate and accelerate plasma to generate thrust. |
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|
Term
| What are the advantages of electric propulsion? |
|
Definition
| The advantages of electric propulsion are that they have high exhaust velocity, high propellant efficiency and high spacecraft speeds. |
|
|
Term
| What are the disadvantages of electric propulsion? |
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Definition
| The disadvantages of electric propulsion are that they are power intensive, very low in thrust (can only be used in space), acceleration takes time and potential lifetime issues. |
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Term
| What are the three types of electric propulsion? |
|
Definition
o Electrothermal – uses electricity to heat a neutral gas; examples include arcjet
o Electrostatic – uses a static electric field to accelerate plasma. Static magnetic fields are sometimes used to confine plasma, not accelerate it. Eg gridded ion thruster
o Electromagnetic – uses electric and magnetic fields to accelerate plasma. Eg hall thruster and pulsed plasma thruster. |
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Term
| How does electrothermal - arcjet propulsion work? |
|
Definition
| Neutral gas flows through the propellant flow, an electric arc forms between the anode and the cathode, a small amount of neutral gas is ionized to form the arc and the remaining gas is heated as it passes through the arc. The exhaust speeds vary from 4-10 kms-1, and main propellants used are hydrazine and ammonia. Efficiency is around 30-50% |
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Term
| What are some advantages of electrothermal propulsion? |
|
Definition
| higher exhaust speeds than resistojets, scalable to higher power levels, simple design, low voltage, can use hydrazine. |
|
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Term
| What are disadvantages of electrothermal propulsion? |
|
Definition
| less efficicne than resistojets, more complex power processing, electrode erosion and high current (heat, wiring) |
|
|
Term
| How is electrothermal propulsion used? |
|
Definition
|
|
Term
| How does Electrostatic: Gridded Ion Thruster propulsion work? |
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Definition
| Propellant is injected into a chamber, where electrons are emitted by hollow cathode traverse discharge and are collected by anode. Electrons impact the atoms to create ions, the magnetic field enhances the ionization efficiency and the ions are electrostatically accelerated away from chamber where electrons injected into beam for neutralization. Typical propellants include argon, krypton and xenon. Exhaust speeds are from 15-50 kms-1 and efficiency is around 60-80% |
|
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Term
| what are some advantages to electrostatic propulsion? |
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Definition
| high exhaust speeds, high efficiency, inert propellant |
|
|
Term
| What are some disadvantages of electrothermal propulsion? |
|
Definition
| complex power processing, low thrust, grid and cathode lifetime issues, high voltage, thrust density is limited |
|
|
Term
| What are some uses of electrostatic propulsion? |
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Definition
| station keeping, orbital change from LEO to GEO and primary propulsion. |
|
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Term
| How does Electromagnetic: Hall Thruster propulsion work? |
|
Definition
| Cathode releases electrons which ionize propellant, electrons from ionization move in a circular pattern (create current), current interacts with radial magnetic field to produce ion acceleration, cathode electrons neutralize the beam. Typical propellants include xenon or argon, and exhaust speeds range from 15-20 kms-1 and efficiency 30-50% |
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|
Term
| What are some advantages of electromagnetic propulsion? |
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Definition
| high exhaust velocity, simple power supply, inert propellant, high efficiency and desirable exhaust velocity |
|
|
Term
| What are some disadvantages of electromagnetic propulsion? |
|
Definition
| high beam divergence, lifetime issues (erosion) |
|
|
Term
| What are some uses of electromagnetic propulsion? |
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Definition
| station keeping, orbital transfer (LEO to GEO) and primary propulsion (SMART – 1) |
|
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Term
| Describe the process involved in VASIMR |
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Definition
| helicon ionizes neutral gas, plasma flows along field lines and is compressed, ICRH is used to heat the ions, magnetic nozzle converts temperature into directed flow, plasma detaches from the magnetic field. |
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Term
| What are some advantages to VASIMR? |
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Definition
| Variable exhaust speeds, high exhaust speeds, variable thrust, high thruster, no grids or anode/cathode, variety of fuels (H, Ar, Ne) |
|
|
Term
| What are some disadvantages to VASIMR? |
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Definition
| superconducting magnets required, potential detachment issues, potential energy conservation issues, requires nuclear reactor. |
|
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Term
| What are some overall points of electric propulsion? |
|
Definition
| types of EP: electrothermal (arcjet), electrostatic (gridded ion thruster) and electromagnetic (hall thruster). Advantages: high exhaust velocity, high propellant efficiency, high spacecraft speeds. Disadvantage: power intensive, very low thrust (only in space), acceleration takes time and potential lifetime issues. |
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Term
| Which kind of generators have been used in space before? What is an example of this? |
|
Definition
| • Nuclear generators have been used in space before, such as RTGs. |
|
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Term
|
Definition
| These work by allowing radioactive decay (238Pu), heat is generated through decay and thermocouples convert heat to electricity. Flight heritage: voyager 1 and 2 |
|
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Term
| What are 3 types of nuclear propulsion? |
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Definition
o Nuclear pulse propulsion – uses nuclear explosions to propel a spacecraft
o Nuclear thermal propulsion – uses the heat of a nuclear reactor to heat a gas which is expelled for thrust
o Nuclear electric propulsion – uses electric power from a nuclear reactor to power an electric thruster. |
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Term
| Which type of nuclear propulsion is included in the 3 projects? Also name the 3 projects |
|
Definition
| Nuclear pulse propulsion; project orion, project daedalus, project longshot |
|
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Term
|
Definition
| the goal of project orion was to achieve high thrust with high exhaust speeds. This worked by dropping a nuclear bomb out of the back of the spacecraft, the nuclear bomb detonates about 60 m behind the spacecraft, and explosion hits a steel plate which propels the spacecraft forward. It was expected to have thrust of over 1 mega N. Also estimated exhaust velocity: 20-30,000 kms-1 and estimated speeds of spacecraft were 0.03-0.1c and this could be used for fast travel through solar system. The potential problems with this project were that plate damage, nuclear fallout on earth, high acceleration rate, crew shielding. |
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Term
| Describe project Daedalus |
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Definition
| stud of potential instersteller flyby unmanned spacecraft. This was to be constructed in orbit, was going to use deuterium pellets (to be mined in Jupiter), 250 pellets/s detonated using electron beams (interial confinement fusion) |
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Term
| Describe project longshot |
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Definition
| study of interstellar unmanned spacecraft by NASA and US Navel Academy. Its mission was to go to Alpha Centauri (orbit rather than fly by). Onboard nuclear fission reaction would provide power, and laser would be used for intertial confinement fusion propulsion (like project daedalus) |
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Term
| Describe Nuclear thermal propulsion |
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Definition
| three types – solid core, liquid core and gas core. These work by pumping propellant from the tanks to the nuclear reactor. The propellant is then passed through the reactor, which heats the propellant, hot gas is then expanded through a nozzle and a small amount of gas goes back to drive the turbo pump. The exhaust velocity is limited by materials used (heat), exhaust velocity: 8-20 kms^-1, the total thrust is only good for upper stage of multistage rockets. |
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Term
| Describe the goals of NERVA |
|
Definition
| The goals for NERVA were: multi-mission capability, man-rated, minimum 75,000 Ibf thrust, storable for long periods of time. The results were that it produced 8.5 kms^-1 exhaust speed, 90 min of burn time and 250,000 pounds of thrust. |
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Term
|
Definition
| Is a recent attempt at mating nuclear power and plasma thrust, technology that uses nuclear fission to power and move a spacecraft. It would have been able to move between targets with its greater thrust-fuel ratio. It’s goal is to explore moons of Jupiter, funding was cut by 80% |
|
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Term
|
Definition
| picks up fuel from interstellar space as it flies and burns in a nuclear reaction, providing power. Magnetic fields could be used to collect only ionized H and not atomic H, technical challenges to collect H remain |
|
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Term
|
Definition
| uses a sail and is pushed by photons. No fuel required, simple design, can move towards and away from the sun, large scale structure required, would need to be built in space, thrust decreases as you move away as intensity falls (1/r^2) |
|
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Term
|
Definition
| uses a large extended magnetic sail interacting with SW. As spacecraft gets further away from sun, size of sail changes, but thrust doesn’t. Potential challenges – requires superconducting magnets, large structures in space. |
|
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Term
|
Definition
| uses plasma to inflate magnetic field, only small structures and no superconducting magnets required. Dipole magnetic field generated by large current loop, magnetic field looks like mini magnetosphere |
|
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Term
|
Definition
| uses a beam of plasma to propel a spacecraft, a large spacecraft generates plasma and magnetized plasma beam intercepted by a magnetic field (M2P2) and the beam pushes spacecraft, producing thrust. Adv. Include no fel required, low power for spacecraft, 90-day roundtrip to mars is possible. |
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Term
|
Definition
| a sail similar to solar sail, excdpt photon source is a station. No fuel or onboard power required. More control as laser is controlled. A lightcraft has a parabolic mirror that is hit by a laser on ground, heating the air under the craft, thus generating thrust. |
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Term
|
Definition
| Long tether is deployed, current is run along tether, which interacts with Earth’s magnetic field, producing thrust. This can be done in reverse, but it lowers the orbit of spacecraft. Tether assisted launches are also a possibility where spacecraft is launched by low power rocket, satellite in orbit reaches down with tether and grabs the spacecraft and swings the spacecraft into higher orbit. This will lower the orbital altitude of satellite but uPET can be used to go back into higher orbit |
|
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Term
|
Definition
| stretches from Earth to geosynchronous orbit and higher. A climber ascends to bring payload from Earth surface to orbit. Carbon nanotubes might be used as cables. Can be built from mobile and stationary platforms, the climber must be able to climb variable size cable. Speed and mass must be adjusted to minimize oscillations |
|
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Term
|
Definition
| reaction to matter and antimatter creates electricity, generates thrust by expelling products or heats a gas, expelled for thrust. Antimatter has very high density; rockets would have really high exhaust speeds. Trapping antimatter is very hard (10 nano grams per year) |
|
|
Term
| how long does it take for CME's and solar flares to reach Earth? |
|
Definition
|
|
Term
| What are galactic cosmic rays? |
|
Definition
| very high energy ions, causing ionization in material as they pass through. Spacecraft walls and skin cannot stop these, they occur more during solar min and are more hazardous than protons from sun but are easier to predict. |
|
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Term
|
Definition
| are that these particles ionize particles in the body, which causes damage to DNA molecules; this damage is mostly not repairable. |
|
|
Term
| What are secondary effects? |
|
Definition
are that it causes particle shower – high energy particles collide with other particles and produce a particle shower
• Factors that effect how much radiation an astronaut gets: |
|
|
Term
| What are the factors that contribute to how much radiation an astronaut gets? |
|
Definition
o Orbital inclination – the larger the inclination – closer to the poles, thus more energetic particles in this region
o Orbital altitude – less of Earth’s magnetic field as you go higher → less protection
o Solar cycle – Solar Max → CME’s and solar flares and at solar min → galactic cosmic rays
o Individual susceptibility – everyone responds to radiation differently |
|
|
Term
|
Definition
unit of measurement for radiation
(SI units) = 1 J of energy absorber per kilo. |
|
|
Term
| What are ways to combat radiation for astronauts? |
|
Definition
| • Astronauts have to wear dosimeters (keeping tack of dosage), healthy diet and exercise including antioxidants flight radiation effects |
|
|
Term
| Describe Mars' magnetic field and atmosphere |
|
Definition
| • Mars has no magnetic field, and a thinner atmosphere (very low protection) |
|
|
Term
| What are some possible methods of shielding radiation? |
|
Definition
| • Shielding possibilities include hydrogen (cryogenic tanking and leaking issues) and polyethene are better options (lighter elements have fewer neutrons) |
|
|
Term
| What is magnetic shielding and what is its problem? |
|
Definition
| deflect solar wind. Problem is large amounts of superconducting magnets required and also magnetic field needs to be generated by large coils. Magnetosphere concepts like M2P2 can protect astronauts. |
|
|
Term
| What are the effects of microgravity? |
|
Definition
| Microgravity causes puffy face syndrome - heart pumps more blood to upper body hence puffy face. Equalizes in a couple of days. |
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