Podcast
Questions and Answers
In an elliptical orbit, how does the velocity of a satellite behave as it moves from apoapsis to periapsis?
In an elliptical orbit, how does the velocity of a satellite behave as it moves from apoapsis to periapsis?
- The velocity decreases as it moves from apoapsis to periapsis.
- The velocity increases as it moves from apoapsis to periapsis. (correct)
- The velocity remains constant throughout the orbit.
- The velocity fluctuates randomly, with no predictable pattern.
What is the primary characteristic of a circular orbit regarding the velocity of the orbiting body?
What is the primary characteristic of a circular orbit regarding the velocity of the orbiting body?
- The velocity changes proportionally with the radius of the orbit.
- The velocity remains constant. (correct)
- The velocity varies depending on the gravitational parameter.
- The velocity oscillates between maximum and minimum values.
How does an orbital maneuver primarily alter a spacecraft's trajectory?
How does an orbital maneuver primarily alter a spacecraft's trajectory?
- By changing the spacecraft's mass through fuel consumption.
- By adjusting the spacecraft's velocity and direction using propulsion systems. (correct)
- By deploying aerodynamic control surfaces to interact with the atmosphere.
- By using gravitational forces of other celestial bodies without propulsion.
What distinguishes an impulsive maneuver from other types of orbital maneuvers?
What distinguishes an impulsive maneuver from other types of orbital maneuvers?
If a satellite needs to adjust its position within the same orbit, which type of maneuver is most appropriate?
If a satellite needs to adjust its position within the same orbit, which type of maneuver is most appropriate?
In the context of orbital mechanics, what does the term 'semi-major axis' refer to in an ellipse?
In the context of orbital mechanics, what does the term 'semi-major axis' refer to in an ellipse?
A spacecraft is tasked with intercepting another spacecraft in orbit. What type of maneuver is specifically designed for this purpose?
A spacecraft is tasked with intercepting another spacecraft in orbit. What type of maneuver is specifically designed for this purpose?
What do the variables (r_a) and (r_p) represent in the context of calculating the eccentricity of an orbit?
What do the variables (r_a) and (r_p) represent in the context of calculating the eccentricity of an orbit?
What is the standard gravitational parameter ($\mu$) used for in orbital mechanics calculations?
What is the standard gravitational parameter ($\mu$) used for in orbital mechanics calculations?
What is the primary purpose of the Hohmann transfer maneuver?
What is the primary purpose of the Hohmann transfer maneuver?
What is a key characteristic of the Hohmann transfer maneuver in terms of fuel usage and travel time?
What is a key characteristic of the Hohmann transfer maneuver in terms of fuel usage and travel time?
In an elliptical orbit, at which point is the orbiting body's velocity the highest?
In an elliptical orbit, at which point is the orbiting body's velocity the highest?
What distinguishes an elliptical orbit from a circular orbit?
What distinguishes an elliptical orbit from a circular orbit?
For a spacecraft orbiting a planet, which parameter affects the velocity calculation in a circular orbit?
For a spacecraft orbiting a planet, which parameter affects the velocity calculation in a circular orbit?
A satellite is moved from a Low Earth Orbit (LEO) to a Geostationary Orbit (GEO) using a Hohmann transfer. How many engine burns are required for this maneuver?
A satellite is moved from a Low Earth Orbit (LEO) to a Geostationary Orbit (GEO) using a Hohmann transfer. How many engine burns are required for this maneuver?
How is the eccentricity of an orbit defined mathematically using the distances at apoapsis ($r_a$) and periapsis ($r_p$)?
How is the eccentricity of an orbit defined mathematically using the distances at apoapsis ($r_a$) and periapsis ($r_p$)?
Why do orbital maneuvers typically require precise timing and execution?
Why do orbital maneuvers typically require precise timing and execution?
What factors affect the magnitude of velocity change ($\Delta v$) required for an orbital maneuver?
What factors affect the magnitude of velocity change ($\Delta v$) required for an orbital maneuver?
When planning an orbital maneuver, why is it important to consider the initial and target orbits as coplanar, especially in a Hohmann transfer?
When planning an orbital maneuver, why is it important to consider the initial and target orbits as coplanar, especially in a Hohmann transfer?
Assuming $G$ is gravitational constant, $M_1$ and $M_2$ are the masses of two orbiting bodies, how is the standard gravitational parameter ($\mu$) calculated?
Assuming $G$ is gravitational constant, $M_1$ and $M_2$ are the masses of two orbiting bodies, how is the standard gravitational parameter ($\mu$) calculated?
Flashcards
Orbital Maneuver
Orbital Maneuver
Planned action to change a spacecraft's orbit by adjusting velocity and direction using thrusters.
Semi-major axis
Semi-major axis
The longest diameter of an ellipse, passing through the center and both foci.
Semi-minor axis
Semi-minor axis
The shortest diameter of an ellipse, passing through the center.
Circular Orbit
Circular Orbit
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Apocentre (Apoapsis)
Apocentre (Apoapsis)
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Pericentre (Periapsis)
Pericentre (Periapsis)
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Eccentricity of an Orbit
Eccentricity of an Orbit
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Impulsive Maneuver
Impulsive Maneuver
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Phasing Maneuver
Phasing Maneuver
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Chase Maneuver
Chase Maneuver
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Hohmann Transfer
Hohmann Transfer
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Study Notes
- Orbital maneuver and transfer focuses on how to change a spacecraft's orbit in space.
Geometry of an Ellipse
- Elliptical orbits have specific geometric properties including focus, vertex, co-vertex, center, semi-major axis, semi-minor axis, and linear eccentricity.
Circular Orbits
- Velocity is constant in circular orbits.
- The velocity in a circular orbit is calculated by the square root of GM/r.
Elliptical Orbits
- Velocity is not constant in elliptical orbits.
- The distance between two orbiting bodies changes.
- Key points in an elliptical orbit include the apocentre and pericentre.
- The orbital speed of a body in an elliptical orbit is determined by: v = √μ(2/r - 1/a), where μ is the standard gravitational parameter, r is the distance between orbiting bodies, and a is the length of the semi major axis.
Eccentricity of an Orbit
- Eccentricity can be derived from apoapsis and periapsis distances.
- The formula for eccentricity is e = (ra - rp) / (ra + rp).
Orbital Maneuver
- An orbital maneuver is a planned action to change a spacecraft's orbit using onboard thrusters or engines.
- It is used to adjust a spacecraft's velocity and direction to achieve a different altitude, inclination, or orbital period.
- It involves a controlled change in a spacecraft's trajectory using propulsion systems.
Types of Maneuvers
- Impulsive Maneuver: A quick burst of thrust that changes the velocity of a spacecraft to alter its orbit.
- Phasing Maneuver: Changes a spacecraft's position in its orbit.
- Chase Maneuver: Involves one spacecraft adjusting its trajectory to intercept and meet another spacecraft within a specific timeframe.
Hohmann Maneuver
- This transfer is used to move a spacecraft between two orbits of different altitudes around a central body.
- It raises a satellite's orbit from low Earth orbit to geostationary orbit if initial and target orbits are circular and coplanar in an idealized case.
- The Hohmann maneuver involves placing the spacecraft into an elliptical transfer orbit that is tangential to both the initial and target orbits, with two impulsive engine burns to establish and adjust the transfer orbit.
- It requires the least impulse but takes longer compared to higher-impulse transfers.
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