Groundtrack Layer
From JMARS Wiki
The Groundtrack Layer draws a satellite groundtrack on the maps displayed in the Viewing Window, allowing planetary geologists and mission planners to determine where various Mars-orbiting spacecraft will be at a given times. The Groundtrack Layer is available in all JMARS releases.
[edit] Display a Groundtrack
- Open the Groundtrack Layer: Chose "Add New Layer" -> "Groundtracks"
- Select a Spacecraft: Using the first drop-down box, select either Mars Odyssey (ODY), Mars Global Surveyor (MGS) or Mars Express (MEX).
- Since Mars Global Surveyor is no longer operating, groundtracks can only be drawn for times before December 2006.)
- Select a Start and End Time: Since the positions of the satellites are defined as functions of time, a start and end time for the groundtrack must be given. Any of the many acceptable JMARS Time Formats can be used.
- Select a "Delta Secs": The groundtrack is caluclated at discrete points and the "Delta Secs" option allows users to specify how often along the groundtrack a point should be calculated. The default value is 120 secs, which is optimal for most JMARS functions. At higher values, the groundtrack will start to appear as a series of line segments instead of a smooth curve. At lower values, the groundtrack layer will load slower since JMARS has to calculate the spacecraft position at a larger number of points.
- Select a Ground Track Color: The default color of the groundtrack that will be displayed is "yellow", but if colorized layers are being used a different groundtrack color may be more visable.
- Display the Groundtrack: Once these four parameters have been set, clicking on "Update" will draw the desired groundtrack. Users can return to the "Groundtrack" tab in the Layer Manager at any time to adjust these parameters. A sample of the "Groundtrack" tab is shown below and the accompanying groundtrack is shown in the figure above.
- Using the showtime_themis script discussed in Time Formats, the time range of orbit:25380-orbit:25385 equates to Sep 4, 2007 at 12:40am UTC through Sep 4, 2007 at 10:33am UTC.)
[edit] Related Pages
- Tutorial #3: Finding THEMIS Observation Opportunities
