"Penetrating Planets Since 2004"
ECE6390 Introduction to Satellite Communications Fall, 2004
 Initial Research
 Introduction
 Project Requirements
 Neptune Facts
 Calculations
 Penetrating Probes
 Introduction
 Design
 Calculations
 Parts & Pricing
 Relay Satellite
 Introduction
 Link with Probe
    Calculations
 Link with Earth
    Calculations
 Parts & Pricing
 Conclusions
 Summary
 Total Cost
 Contact Info
 Home » Initial Research » Neptune Facts

Neptune Facts

 

Neptune is one of the gaseous planets in our solar system.  While it is the smallest of the gas giants, its size and mass compared to the Earth is mind-boggling.  

The mass of Neptune is FormBox[RowBox[{102.43, , 10^24, kg}], TraditionalForm], about 17 times more massive than the Earth.  It's volume covers FormBox[RowBox[{6.254, , 10^13, km^3}], TraditionalForm], 58 times that of the Earth. [1]

The period of a Neptunian sidereal day is 16.11 hours, and it takes 60,189 days (or 165 years) to complete its orbit around the Sun.  Due to the mass and the shortened day, as will be shown later in the report, a geostationary satellite around Neptune will be very far away, traveling very fast.

The shape of Neptune is not entirely spherical, but more like a partially-squashed rubber ball.  It has an equatorial orbit of 24,767 km and a polar orbit of 24,341 km (see Figure 1), yielding an ellipticity of about 0.01708.  This irregular shape will be important in calculating the orbit and trajectory of the relay satellite and probes.

[Graphics:/mathematica/HTMLFiles/index_3.gif]
Figure 1: Polar and Equatorial Radii of Neptune

 

The minimum distance from the Earth to Neptune is FormBox[RowBox[{4.3, , 10^9, km}], TraditionalForm] and the maximum distance is FormBox[RowBox[{4.6, , 10^9, km}], TraditionalForm].  

With any dish antenna pointing towards Neptune, a certain noise temperature will be felt at the receiver.  Figure 2 shows the various frequency-dependant noise temperatures that will be seen by an antenna pointed at Neptune.

 

Figure 2: Noise Temperatures of Neptune at Various Frequencies [2]

 

As a gaseous planet, Neptune's atmosphere is very thick and very dense. However, Neptune does have a core; Figure 3 shows a cutaway sectional of Neptune's composition.

 

Figure 3: Neptune's Composition

 

 

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References:
1. Neptune Fact Sheet (http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html)
2. ECE6390 Home Page (http://www.propagation.gatech.edu/ECE6390), Dr. Greg Durgin

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William W
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