voyager.PlotSpeed Class Reference

Detect planetary encounters of Voyager 2 by analyzing its distance from the Earth. More...

Static Public Member Functions
static void	main (String[] args)

Detailed Description

Detect planetary encounters of Voyager 2 by analyzing its distance from the Earth.

In this example, we read a processed data feed that provides averaged hourly readings of various instruments in the spacecraft. We are interested in the date and the relative distance to Earth, expressed in astronomical units (AU). From these two data fields, we compute the average weekly speed (in AU/week), and send the output stream to signal processors that detect peaks (i.e. abrupt variations in the values of a numerical signal). This is shown in a plot.

One can see that the last three peaks correspond precisely to the dates of Voyager's flybys of Jupiter, Saturn, and Neptune:

Planet	Date	Days after 77/1/1
Jupiter	July 9, 1979	918
Saturn	August 25, 1981	1696
Neptune	August 25, 1989	4618

The flyby of Uranus (Jaunary 24, 1986, or Day 3310) does not produce a speed variation large enough to be detected through this method.

About the data files

This example requires you to first download some data files from the Voyager 2 space probe; these files are publicly available on a NASA FTP site:

ftp://spdf.gsfc.nasa.gov/pub/data/voyager/voyager2/merged/

Author

Sylvain Hallé

Definition at line 67 of file PlotSpeed.java.

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The documentation for this class was generated from the following file:

• Source/src/voyager/PlotSpeed.java