Frequently Asked Questions (FAQ)
Thank you for visiting the Photojournal. We welcome your questions and comments about our website. In an attempt to provide immediate response to as many users as possible, we've compiled this list of Frequently Asked Questions. Hopefully, the answer to your question is here. If it isn't, please feel free to e-mail us at firstname.lastname@example.org.
If this is your first visit to the Photojournal and you can't wait to get started,
the easiest way to begin is by going to the Photojournal home page and clicking
on the Latest Images link found at the far left of the top navigation bar. When selected, this link will present you with all of the images and related products that have been released during the last seven days. The "Latest Images" link appears in the same location at the top of most of the Photojournal pages. For a more detailed explanation of how the Photojournal works, go to our Introduction page.
You can also view our Sitemap and click on any of the links to get acquainted with the Photojournal
and its related sites. Please enjoy your visit!
The NASA Image Exchange (NIX)
The National Space Science Data Center (NSSDC)
(Also see the NSSDC main home page for information on astrophysics, space physics, and solar physics:
(Also see the following page for information about NASA space missions:
NASA Solar System Exploration
The Space Telescope Science Institute
Hubble's Entire Image Collection
There were three press releases by Malin Space Science Systems detailing the Mars Global Surveyor observations of the Cydonia region on Mars. These are available on the MSSS web site at:
Malin Space Science Systems
MGS MOC Images of Cydonia
The NASA Education site provides a wealth of information including availability of and acquisition of lithographs, posters, and videos, classroom activities and lesson plans that can be downloaded, and links to other online resources.
NASA Education Home Page
The images in the Photojournal are governed by the Jet Propulsion Laboratory's "Image Use Policy." For details see:
There is also a general NASA policy covering the use of images from other NASA sites. This policy is explained here:
JPL Image Use Policy
Using NASA Imagery and Linking to NASA Web Sites
All the images in the Photojournal are released with the maximum (or fullest) resolution available which is largely determined by the maximum resolution captured by the camera aboard any given spacecraft. The TIFF images are the highest resolution images made available to the Photojournal. All images are downloadable, with the TIFF file providing the fullest resolution. We cannot provide you with a higher resolution image than that which appears in the Photojournal. However, am image file manipulation program may allow you to change the print size of an image to conform to your requirements (keep in mind that the larger the print size required, the more pixelated the print will become, although there are some tricks which will allow you to "add" more pixels). We cannot answer any questions you might have about the image manipulation program you choose, however, here is a simple formula to help you determine what dpi will produce your desired print size:
Spatial resolution (width and height) / dpi = print size
To find a specific image in the Photojournal using an image number or feature name, click on the "Photojournal Search" link on the
Photojournal home page, or any other page on the far right of the brown navigation bar. This will take you to a page where you can narrow down your search for images in the Photojournal.
If you wish to search for a particular feature, enter the name of that feature in the blank under "Search for Images in the JPL Photojournal" and hit return.
From this page, you can also search for all the images returned by a specific spacecraft, or all the images entered into the system since a given date.
There is really very little difference between displaying an image and downloading it to your computer. Whenever you display an image (or
any HTML page for that matter) from the World Wide Web on your computer, you have already downloaded it. However, unless you intentionally save the image, it will only reside on your computer temporarily. The image is stored in what is called "memory cache"; this space can be written over as soon as the computer needs it for something else.
The method you use to download and save a file varies depending on which browser and which kind of computer you are using. Often, the easiest way to save a file is to display it first, and then use your browser's "Save Image As..." option to write it to a file. In most web browsers, this option is found under the "File" menu. On certain platforms, right-clicking on the computer mouse while viewing an image, will also bring up an option menu for downloading the file.
We post only those images delivered to us via the mission or JPL's Media Relations Office which have been approved for release.
No image is updated/replaced unless we are notified by the mission or
JPL's Media Relations Office that errors have been found in the posted
image. Any updated caption will also retain the original caption with the
following words appearing on the catalog page "Updated Caption: (View
Original Caption)." Clicking on "View Original Caption" will allow you to
see the caption originally released with the image.
Images are not deleted from the Photojournal unless one or more duplicates have been inadvertently posted, or a significant error has been found in the posted image after release.
Typically, the purpose of false color images is to enhance subtle differences in color. These differences are sometimes so small in a true color image that a person looking at them cannot distinguish the differences. In the case of Mars Exploration Rover (MER) images, as an example, false color allows scientists to more easily assess color differences, which may indicate differences in the types of materials making up rocks and soils, or differences in their physical properties.
Sometimes, false color images are generated because we do not receive enough information to reconstruct an approximate true color image. If, for instance, we used some combination of filters outside the visible range (for example, ultraviolet or infrared wavelengths), then we do not have information about how something looks at the red, green, and blue wavelengths of light associated with human vision. In such an instance, an image might be generated that maps an ultraviolet filtered image to blue (B), a green filtered to green (G), and an infrared filtered image to red (R). The resultant RGB image is not indicative of what the scene would look like if you saw it with your own eyes. However, the image does contain useful information about the differences and magnitudes amongst these particular spectral components in a visibly discernable manner.