Polar Orbit Change and Line of Sight Time

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SUMMARY

The discussion centers on a satellite in a circular polar orbit at an altitude of 240 km, which undergoes an impulsive burn to achieve a polar orbit with an apogee over the North Pole. The satellite's velocity post-burn is recorded at 9.183 km/s, and its altitude when visible from the North Pole is 3670.9 km. The primary focus is on determining the duration of line of sight communication with the satellite, utilizing relevant equations for viewing geometry and central angles. The participant expresses confusion regarding the necessity of the velocity and initial orbit altitude in relation to the line of sight question.

PREREQUISITES
  • Understanding of orbital mechanics, specifically polar orbits
  • Familiarity with Hohmann transfer orbits and delta-v calculations
  • Knowledge of line of sight communication principles
  • Proficiency in trigonometric functions related to angles and distances in space
NEXT STEPS
  • Research the equations governing line of sight communications for satellites
  • Study the geometry of satellite visibility and central angle calculations
  • Learn about the implications of velocity in orbital mechanics
  • Explore the concept of swath width and its relevance to satellite communication
USEFUL FOR

Aerospace engineers, satellite communication specialists, and students studying orbital mechanics will benefit from this discussion, particularly those interested in the practical applications of satellite visibility and communication parameters.

orbitsnerd
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Homework Statement


A satellite is in a circular polar orbit 240 km altitude. When the satellite is over the South Pole the engine is fired to achieve a polar orbit that has apogee directly over the North Pole. After the impulsive burn an observer on the North Pole observes the satellite has a velocity of 9.183 km/s. As the satellite comes over the horizon at the North Pole it is determined to have an altitude of 3670.9 km. How long with the observer be able to communicate with the satellite assuming only line of sight communications with the satellite?


Homework Equations


If Hohmann transfer, those equations.
deltav1=v2-v1
deltav2=v4-v3


The Attempt at a Solution


rp=240km+6378km
ra=3670.9km+6378km
If it is necessary to find e, I can with rp and ra. e=.206
v3=9.183km/s
Possible use of swath angle with Hohmann transfer information?
 
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The question is not asking about Hohmann transfers. It is asking about line of sight communications: How long is the satellite in view? What are the relevant equations for this?

BTW, that velocity is not right for the Earth. This must be some other planet.
 
D H said:
The question is not asking about Hohmann transfers. It is asking about line of sight communications: How long is the satellite in view? What are the relevant equations for this?

BTW, that velocity is not right for the Earth. This must be some other planet.

I have to go off of that it is Earth even though the velocity doesn't seem to make sense I guess. :/

As for the relevant equations for line of sight/viewing geometry I have:
central angle to the horizon=cos angle=re/re+h so at 240 km angle is 15.477 degrees and at 3670.9 km angle is 50.6 degrees.
I can also find the angle from the nadir to the spacecraft by saying cos central angle=sin rho.

Swath width=2re*central angle to the horizon

There are a handful of other equations that define Dh and other angles. I guess my biggest question is: why was I given velocity and the initial orbit altitude if it is only for line of sight?
Thanks!
 

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