Files in This Directory
Notes
How to Use the Search Tool
How to Begin a Search
How to Constrain a Search
How to Use the Results
| bindefs.js | JavaScript functions to define contents of latitude-longitude bins |
| cookies.js | JavaScript functions for managing browser cookie files |
| helpresult.htm, helpsearch.htm, helpzoom.htm |
Help files for each HTML page |
| proddefs.js | JavaScript functions to define product database |
| result.htm | HTML page that displays results of a search |
| search.htm | HTML page that begins a search; start here |
| uistyle.css | Cascading style sheet used by HTML files |
| volumeid.js | JavaScript global variable definition for volume ID |
| zoom.htm | HTML page for constraining a search |
A JavaScript-compatible browser is required to use these pages. They have been tested with Netscape Navigator 4.0 and Internet Explorer 4.0. The tests showed that performance is noticeably slower in the Navigator browser.
Internet Explorer 3.0 and 4.0 browsers use cookies (small temporary files stored locally) to pass information from one page to the next. The cookies files are automatically deleted by the browser software when no longer needed. You may wish to set your browser options to allow all cookies, to avoid being prompted each time a cookie is set.
The global map on the search page is from the MOLA gridded topography data set, with a grid size of 1 degree. It is labeled with east longitude coordinates from -180 to 180. The enlarged 30 by 30 degree maps that appear on subsequent pages are from the Mars Digital Image Model (MDIM) shaded relief data from the Viking mission. They are labeled with west longitude coordinates from 0 to 360. No attempt was made to reproject the MDIMs using an updated Mars control net or new prime meridian. At the scale of the maps on these pages, the difference is only a few pixels.
Colored lines and points are overlain on this map to show the locations of MGS products. The product locations were plotted a little differently for each data set. In some cases products are included in the search database even though they do not appear on the maps due to subsampling or other plotting restrictions. See details below. Also, where multiple products coincide on the map, the underlying ones may be hidden.
MOLA
To show the approximate ground track of MOLA observations, each MOLA orbit was subsampled to every 50th observation, and lines were drawn connecting those points. Obvious discontinuities were eliminated. Therefore it is possible that a search may turn up some MOLA products in the results listing that do not appear on the map.
MOC
The center point of each narrow-angle MOC image was plotted as a point. Wide-angle MOC images are not shown on the map because they are often so wide as to cover the entire area. Wide-angle images do appear in the results listing, however, if their center points occur in the selected area.
TES
To show the approximate ground track of TES observations, the observations from TES detector 2 were subsampled every 0.25 degree, and further restricted to those observations where the spacecraft altitude was less than 1000 km. These locations were plotted as points. However, all TES products are included in the search database. Therefore it is possible that a search may turn up some TES products in the results listing that do not appear on the map.
ACC
The spacecraft ground track was computed using SPICE data for the times during which Accelerometer observations were obtained, and plotted as lines.
MAG/ER
The spacecraft ground track was computed using SPICE data for the times during which MAG and ER data were acquired, limited to times when the spacecraft altitude was less than 350 km, and plotted as lines. The search database is also limited to products acquired at altitudes below 350 km.
RS
The projected surface point of occultation was plotted as a point for each Radio Science observation. These data are from the Radio Science occultation summary files in the RS/OCS subdirectory.
Open the file SEARCH.HTM in a web browser. Begin by choosing the general area for your search. There are two ways to do this:
Click on the map. Notice that the map has a latitude-longitude grid with lines every 30 degrees. When you click on the map, you're selecting one of the 30 by 30 degree areas.
If you have a particular location in mind, then instead of clicking on the map you may enter a latitude and longitude in the boxes above the map. After the longitude coordinate, specify east or west for the longitude direction. (The map is labeled with longitude increasing to the east, but you may enter a west longitude coordinate if you want to.) Now click the button labeled Go to this lat/lon. You're really selecting the 30 by 30 degree area that surrounds the location you entered.
When you have selected a location by clicking either the map or the Go to this lat/lon button, a new page will appear showing an enlargement of the 30 by 30 degree area around the point you selected. This map will also show locations of the MGS products that occur in the area, either as points or ground tracks.
The map is marked with latitude and longitude lines every 5 degrees. It also shows the locations of MGS data products that occur in the area, either as points or ground tracks. The product locations are color-coded by data type according to the legend.
You may limit your search to include only products of a certain type (MOLA and TES products, for example). You may also choose to include only products from a certain orbit range. Use the checkboxes labeled Data products and orbits to set these constraints.
MGS data product types are:
- MOC-NA (Mars Orbiter Narrow-Angle Camera)
- MOC-WA (Mars Orbiter Wide-Angle Camera)
- MOLA (Mars Orbiter Laser Altimeter)
- TES (Thermal Emission Spectrometer)
- MAG (Magnetometer)
- ER (Electron Reflectometer)
- ACC (Accelerometer)
- RS (Radio Science)
MGS pre-mapping mission phases are equivalent to these orbits:
- AB-1 (aerobraking phase 1): 1-201
- SPO-1 (science phasing orbit 1): 202-268
- SPO-2 (science phasing orbit 2): 329-573
- AB-2 (aerobraking phase 2): 574-1284
- Transition to circular mapping orbit: 1285-1683
To complete your search, select a latitude/longitude area in the same way as before, either:
To go back to the beginning and choose a different area of the global map, click the button labeled Start Over.
The result of your search will be a new page listing all the products that fall into the 5 by 5 degree area and that match your criteria for data products and orbits. The listing will include links to the data files so that you can display or download the data. It will also include links to "browse" versions of the data products if they exist.
The table has one row for each data product found. The file name of the product is a link to the data file on one of the DVD-ROM volumes, so that you may use your browser to download the data. In most browsers you do this by right-clicking on the link and choosing "Save As". If the file is on a volume other than the one you are currently using, insert the right volume and then download.
If a browse file is listed for the data product, its name also appears as a link. Browse files are intended to be viewed in your web browser, so you may simply click on the link to see the file. It will open in a new window.
From the Results page, you may go back to the Close-Up Page to change the search criteria or select a different 5 by 5 degree box on the map, or you may go back to the global map to start over completely.