NASA Mars Reconnaissance Orbiter Context Camera P-10 Context Camera (CTX) Observations

MRO CTX Release No. CTX-5, 13 April 2006

Mars Reconnaissance Orbiter (MRO) reached the red planet on
10 March 2006. During its tenth close approach to
Mars—its 10th periapsis—the MRO spacecraft
turned its cameras to view the planet’s surface. Although the images acquired
were over a factor of 10 lower in resolution than will ultimately be
obtained when the spacecraft and its payload are in their final orbit,
these test images provide important confirmation of the performance
of the cameras and the spacecraft. Note that, because these
are initial, test images, there is some linear striping in
the images—this results from incomplete removal of pixel
to pixel variations in the CTX detector by the present
calibration software.

The first picture (CTX-5a) shows a color view cropped from a
Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global map
acquired on the same day as the MRO observations. The MOC map shows
the planet as if every part could be imaged
at some time between 1 and 3 PM, that is, with early
afternoon illumination.
MRO, conversely, imaged the planet during the morning hours.
The MOC view was obtained about 4 hours later in the day than
the MRO data. Inserted into the MOC daily
global map are the two grayscale CTX views. This shows that CTX
first began imaging when it was over the southernmost portion of
the chaotic terrain at the east end of the Valles Marineris.
A second image was acquired several
minutes later, as MRO orbited southward towards the west side
of the large Argyre impact basin. The top of each of the
two CTX images were obtained about 13 minutes apart.

The second figure (CTX-5b) is a comparison of a MGS MOC
full resolution red wide angle (WA) image (left)
and the first CTX image (right). The MOC image was taken
about 6.2 hours after the CTX image, at a local solar time of 13:42;
the CTX image was taken at roughly 07:32 local time. The third
figure (CTX-5c) shows the full resolution view of the first CTX image
ever acquired of Mars. The image has a scale of about
87 meters (285 feet) per pixel, which is 14.5
times lower resolution than will be acquired when MRO is in
its final mapping orbit. In other words, typical CTX images
acquired during the primary science phase of the mission
will have a resolution of 6 meters (~20 feet) per pixel,
and will cover an area ~30 km (~18.6 miles) wide.

The second image obtained by CTX (CTX-5d) was much longer
than the first: 260 kilometers (~162 miles) at its widest point
and about 122 kilometers (~76 miles) at its narrowest,
some 1,590 kilometers (~988 miles) to the south. It covers an
area of about 40,000 km²; the change in width
reflects the change in altitude of the MRO spacecraft as it descended
towards periapsis (the closest point to the planet on each
orbit) over the south polar region. Because it is large,
the picture is shown here at one-third its original
size.

The final picture (CTX-5e) contains the northernmost
portion of the second CTX image, reproduced at one-half its
original scale (because of its large file size). The white box outlines
the location of the
first HiRISE image
released to the public late last month. The CTX and HiRISE images
were acquired simultaneously. As with the CTX, the first HiRISE image
was of a much lower resolution than will be obtained during the
primary science phase of the MRO mission, owing to the higher altitude
during this test. This figure illustrates one of the key roles
that CTX will play during the MRO mission—acquiring
context images for the other science instruments aboard MRO.

Tips for Media Use

Malin Space Science Systems built the
Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and operates
the camera from its facilities in San Diego, California.
The Jet Propulsion Laboratory operates the MRO spacecraft with
its industrial partner, Lockheed Martin Space Systems Company, from facilities
in Pasadena, California, and Denver, Colorado.