Level 2 FreeFlyer Certification Exam Part D

Altitude Raise with a Hohmann Transfer:

You and your team are deploying a satellite into Low Earth Orbit (LEO), and you’ve been tasked with analyzing potential orbit raise maneuvers.

In the diagram below, you see a good depiction of a Hohmann transfer. In part 1 (the green orbit), the satellite is in a "parking orbit" which is a Low Earth Orbit that is achieved shortly after launch. In part 2 (the yellow orbit), a maneuver is performed, increasing the velocity of the satellite until its orbit is an ellipse with an apogee at the target orbit's semi-major axis. This part is called the transfer trajectory. Once the spacecraft reaches the apoapsis of that trajectory, it performs an orbital insertion burn. This increases the velocity, matching the orbit to its target circular orbit.

Since we’re analyzing multiple orbit raise maneuvers, design a Procedure which utilizes the Vis-Viva Equation to calculate everything needed for the Hohmann Transfer. Using the Vis-Viva Equation calculate the parking orbit velocity, then the transfer semi-major axis, the velocity of the transfer, and the ∆v required for the first maneuver. Then, calculate the transfer trajectory velocity at apoapsis, the target orbit velocity, the magnitude of the second ∆v, and the total ∆v.

Finally, to visualize the maneuvers, set up a 3D ViewWindow with the Spacecraft object included. Propagate the Spacecraft for 2 hours in its parking orbit, then apply the first ∆v using an ImpulsiveBurn object. After applying the first maneuver, step the Spacecraft to apoapsis, apply the second maneuver, and propagate for 1 day to see the Spacecraft in its new orbit.

Initial Spacecraft Orbital Elements:

Propagator:

Using a parking orbit Semi-Major Axis of 7,500 km we wish to raise our Semi-Major Axis to 25,000 km.

Electric Propulsion Spiral Out:

You and your team are deploying a satellite into Low Earth Orbit (LEO), and you’ve been tasked with performing an initial analysis comparing potential electric thruster providers to perform a spiral out maneuver to get your satellite into a Geosynchronous altitude (42,164 km). Your satellite only has the capability of performing a maneuver when it is not shadowed by Earth and will be coasting whilst shadowed. The satellite is set to be deployed on Jan 01, 2024 00:00:00.000. Using a continuous FiniteBurn in the velocity direction with a burn duration of 120 seconds, raise the satellite’s Semi-Major Axis analyzing the impact specific thruster configurations has on time of flight and mass.

Initial Spacecraft Orbital Elements:

Propagator:

Tank:

Thruster Configuration: