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The Question

(Submitted April 07, 1998)

From recent publications in the mass media I understand that the face of Mars seems to appear as nothing more than "some hill". From listening to alternative media I understand that the recent pictures were taken in poor resolution. My question is why did NASA use poor resolution when it is capable of taking better pictures?

The Answer

That is a very good question, and unfortunately it doesn't get the detailed attention it may deserve in the popular or alternative press.

The recent scan of the area containing the "face on Mars" is of a much higher resolution than any taken before. The Viking 1 image had a resolution of 43 meters/pixel, while the Mars Global Surveyor resolution was 4.3 meters/pixel, a factor of 10 increase.

I would look at: http://antwrp.gsfc.nasa.gov/apod/ap980407.html

http://mars.jpl.nasa.gov/mgs/target/CYD1/index.html

http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mars.html#controversy

for good links comparing the two images.

Since the Global Surveyor hasn't reached its final orbit yet, which will be closer to the surface than the altitude at which it took these images, the resolution will increase a bit at that time, not because of the instrumentation as much as the decreased distance to that point. In other words, the 1998 April pictures were taken at the best resolution possible at the moment. When the Global Surveyor reaches its final orbit in 1999 March, it will start the detailed mapping of all Martian surfaces in unprecedented details. The Cydonia region will be photographed again at an even higher resolution in the course of this mapping phase.

It is also important to remember that the first released images were not "poor resolution" but RAW data. It was basically a data dump --- no cleaning, no processing, just formatting into a TIFF file. This allows the so-inclined to perform their own analyses and draw their own supportable or insupportable conclusions. JPL released its cleaned images about 5 hours later. This was an attempt to show that NASA is not hiding any information from the public on this issue.

Now you may ask why the CLEANED data looks so much different than the RAW data. Data cleaning is a bit like tuning your television to remove the static and make sure the picture is the right color and centered on the screen. Every image has some signal and much noise, and cleaning helps remove the noise so the signal (the accurate picture of what is there) stands out more clearly.

The JPL web site listed above gives a "recipe" for what steps were taken to refine and clean the image - you can perform these same steps using a personal computer and some commercially available software. Try it, and see what you think.

To answer the other part of your question, I believe that the alternative media have a very big financial stake in keeping any controversy they can in the public consciousness, just like the mass media have their own agenda. It is often important to keep this in mind when reading any second (or third) hand accounting of a situation. One of us (Mike) found after living in Africa for 2 years that any popular news report he saw on the situation over there was so oversimplified as to be erroneous on many specific issues.

NASA (and the American taxpayers) did not send this mission to Mars to look at the 'face' but to map out the entire surface, to gather geologic information, and in preparation for future missions to the planet. However, as any public agency, it tries to be accountable to the people who pay for it, and hence attempts to answer questions that are important to the American people.

If you have further questions on the Mars Global Surveyor mission please check out the JPL web pages at: http://mars.jpl.nasa.gov/mgs/

Hope this helps,

Mike Arida, Mark Kowitt, Pat Tyler, Sandy Antunes, and Gail Rohrbach
for Ask an Astrophysicist

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