[X] My Assistant

[As old as Voyage...]

A couple of websites state that Pioneer 11 discovered a new moon of Saturn during its 1979 flyby and nearly collided with it.

http://www.uwgb.edu/DutchS/CosmosNotes/voyagr00.htm

The website says Pioneer 11 missed the previously unknown moon by only a few hundred km.

http://www.uwgb.edu/dutchs/planets/satslid.htm

Apparently the spacecraft inferred the moon's existance by the disturbances it created in Saturn's magnetic field.

Is this right? Did Pioneer 11 nearly end its mission in an unforseen Deep Impact style crash?

[Ian R]

According to the American Geophysical Union's publication entitled Pioneer Saturn, here are the details regarding the object(s) discovered orbiting Saturn by Pioneer 11:

1979 S1 - imaged by the photopolarimeter.
1979 S2 - discovered by the charged-particle experiment.
These were later determined to be the same object, also later observed from Earth and called 1980 S3. This was later named Epimetheus.
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1979 S4 - This is a different object, co-orbital to S1/S2, also later seen from Earth and called 1980 S1. This went on to be offically labelled Janus.
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Some of the information on the page that Phil linked to seems to contradict what I've stated above. However, since the paper in the Pioneer Saturn journal was written by Brian Marsden, I'm pretty confident of its accuracy.

Ian.