MARCI2-1a -- Color Composite of 5 pixels-wide image of Earth (enlarged 5x)|
MARCI2-1b -- Enlarged 5x animated GIF of Earth (left) and Moon (right) passing through MARCI's view.
All images credit: NASA/JPL/Malin Space Science Systems
Three days after the Mars Reconnaissance Orbiter (MRO) launch
(Launch +3), the spacecraft was pointed toward Earth
and the Mars Color Imager (MARCI) was powered up to acquire a
suite of color and ultraviolet images of Earth and the Moon.
When it gets to Mars, MARCI's main objective will be to obtain
daily global color and ultraviolet images of the planet to
observe martian meteorology
by documenting the occurrence of dust storms, clouds, and
ozone. MARCI will also observe how the martian surface changes
over time, including changes in frost patterns and
surface brightness caused by dust storms and dust devils.
The purpose of acquiring an image of Earth and the Moon just 3 days after launch was to help the MARCI science team obtain a measure, in space, of the instrument's sensitivity, as well as to check that no contamination occurred on the camera during launch. Prior to launch, the team determined that, 3 days out from Earth, the planet would only be about 4.77 pixels across, and the Moon would be less than 1 pixel in size, as seen from MARCI's wide angle perspective. If the team waited any longer than 3 days to test the MARCI performance in space, Earth would be too small to obtain meaningful results.
The Earth/Moon images were acquired by turning MRO toward Earth, then slewing the spacecraft so that the Earth and Moon would pass before each of the 5 color and 2 ultraviolet filters of the MARCI system. The acquisition began around 15:12:56 GMT. The distance to the Moon was about 1,440,000 kilometers (~895,000 miles); the range to Earth was about 1,170,000 kilometers (~727,000 miles).
The first image, above, shows a color composite view of the MARCI image of Earth. As expected, it only covers 5 pixels. This color view has been enlarged 5 times. The Sun was illuminating our planet from the left, thus only one quarter of Earth is seen from this perspective. North America was in daylight and facing toward the camera at the time the picture was taken; the data from MARCI were being transmitted in real time to the Deep Space Network antennas in Goldstone, California.
The second image, an animated GIF, shows the passage of Earth and the Moon across the field of view of a single color band of the MARCI system. As the spacecraft slewed to view the two objects, they passed through the camera's field of view. Earth has been saturated white in this image so that both Earth and the Moon can be seen in the same frame. As with the first picture, the Sun was coming from the left, so Earth and the Moon are seen in a quarter phase. Earth is on the left, the Moon appears briefly on the right. The Moon fades in and out; the Moon is only 1 pixel in size, its fading is an artifact of the size and configuration of the light-sensitive pixels of the MARCI charge-coupled device (CCD) detector.
The MARCI ultraviolet images are not shown here. MARCI has two ultraviolet bands, one at 320 nanometers and the other at 260 nanometers. MARCI ultraviolet images are acquired at an 8 times lower spatial resolution, such that Earth would be less than 1 pixel in size, and the Moon would not be visible. Earth only appeared in the 320 nanometer image. Earth did not appear in the 260 nanometer data, which was expected because of the large amount of ozone in our planet's atmosphere.
Malin Space Science Systems built and operates the MARCI onboard MRO at its facilities in San Diego, California. The Jet Propulsion Laboratory operates the Mars Reconnaissance Orbiter spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California and Denver, Colorado.