Early on the morning of March 12th, the Cassini spacecraft relayed information that it had successfully swapped to a backup set of propulsion thrusters late Wednesday.
The swap was performed due to degradation in the performance of the primary thrusters, which had been in use since Cassini‘s launch in 1997. This is only the second time in Cassini’s 11 years of flight that the engineering teams have gone to a backup system. The thrusters are used for making small corrections to the spacecraft’s course, for some attitude control functions, and for making angular momentum adjustments in the reaction wheels, which also are used for attitude control. The redundant set is an identical set of eight thrusters. Almost all Cassini engineering subsystems have redundant backup capability. Cassini has successfully completed its original four-year planned tour of Saturn and is now in extended mission operations.
And back on January 22nd, the second image captured by Cassini reveals the huge Odysseus Crater clearly illuminated by the sun on the western limb of Tethys — Saturn shining from the right makes the smaller craters on the eastern part of the moon also visible. The ancient Odysseus Crater is 450 kilometers, or 280 miles, across and covers a sizable chunk of the moon. North on Tethys (1062 kilometers, or 660 miles across) is up and rotated 31 degrees to the left. This view looks toward the Saturn-facing side of the moon. The image was taken in visible light with the Cassini spacecraft narrow-angle camera and was acquired at a distance of approximately 793,000 kilometers (493,000 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 112 degrees. Image scale is 5 kilometers (3 miles) per pixel. (Credit: NASA/JPL/Space Science Institute).
