|11 Filter Color Sets||Departure Movie 3 Filter Color Sets||Press Release|
Mariner 10's trip to Mercury was a downhill slide. Mercury is the closest
planet to the Sun, so a spacecraft traveling there from Earth can simply
"fall" into the Sun's gravity well - a lot like skiing down a hill.
Gravity does the work; the skier just has to maintain balance and steer.
If you head straight down the hill, you accelerate, but you manage your
speed if you zigzag from side-to-side. By the time Mariner 10 reached
Mercury, its speed relative to the planet was about 11 km/s - it had no
chance of slowing down! Since MESSENGER will go into orbit about Mercury
it can't just slide downhill - its speed and direction have to be very
carefully controlled through a series of six close
The Earth gravity assist helped to aim MESSENGER toward a precise
flyby of Venus for its second gravity assist.
The Mercury Dual Imaging System (MDIS for short) acquired spectacular images of the Earth during the flyby, including a "film" of Earth as it receded in the distance. These images also served important engineering functions: the camera's automatic exposure function was checked on a target with contrast greater than what scientists expect to find on Mercury; pre-launch calibration values were verified, the camera's gimbal pointing was exercised, and stray light tests were performed. All told, the Earth flyby was a fantastic boon to the Mission Operations and Science Teams.
Beyond the critical operations and engineering and calibration value, the MDIS Earth flyby images also reminded us of the spectacular beauty of our own planet.
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