The European Space Agency’s (ESA) Rosetta comet chaser will swing by Earth November 13 to pick up orbital energy and begin the final leg of its 10-year journey to the outer solar system. Several observations of the Earth-Moon system are planned before the spacecraft heads out to study comet 67/P Churyumov-Gerasimenko.
This will be the third Earth swing-by, the last of Rosetta’s four planetary gravity assists. The swing-by will provide exactly the boost Rosetta needs to continue into the outer solar system. The craft is scheduled for a close encounter with asteroid 21 Lutetia in July next year.
Rosetta is expected to arrive at its final destination May 2014. There, it will release the Philae lander for in-situ studies on the surface. The spacecraft will then escort the comet on its journey toward the Sun, studying it closely for up to 2 years.
As it closes in on Earth next month, Rosetta will have traveled almost 2.8 billion miles (4.5 billion kilometers) since launch. It will speed past Earth at 496 miles per minute (798 kilometers per minute), passing above the Indian Ocean at 109° E, 8° S, just south of the Indonesian island of Java. The gravity-assist will increase the spacecraft’s speed by 3.6 km/s with respect to the Sun.
Instruments in Action
While the swing-by is critical for achieving the velocity required to reach its ultimate destination, the close encounter also will be used to study the Earth-Moon system from Rosetta’s unique perspective.
Several instruments that usually hibernate during the long trek will be turned on in the week before the swing-by.
Critical Swing-by Events
Closest approach is scheduled for 2:45 EST (08:45 CET) November 13, but mission operators will perform a number of critical actions before and after the swing-by to ensure that Rosetta is on the right trajectory.
One of the most important will be a trajectory correction maneuver (TCM), scheduled for October 22 at 8:30 EST (14:30 CET). Results of this maneuver will be analyzed to determine whether additional TCMs are required to achieve the correct approach trajectory.