Enceladus-3 (March 12, 2008) Options

[Guest_AlexBlackwell_*]

Excerpt from Cassini Significant Events for 02/16/06 - 02/22/06:

"As mentioned in previous weeks, the project has been working on adopting a new reference trajectory in order to raise the minimum Titan flyby altitude for various encounters. Today the project reached a decision to proceed with the 'optocc2' trajectory. Additional work is still to be performed before delivery of the final files. This will include minor tweaks that have been analyzed in other trajectories, adjusting orbit 68 timing, and capture of an Enceladus plume occultation on orbit 28."

For the record, the new reference trajectory will result in an even more spectacular Enceladus-3 flyby [61EN (t) E3] on March 12, 2008.

[volcanopele]

a few notes:

E3 Imaging: Don't expect super high res images. Cassini will be approaching Enceladus while the moon is in high phase and closest approach will occur over the night side. A good amount of the blur in the high res images from July were because we were tracking gamma Orionis, not a point on the surface. If we were targeting the surface and had 5 ms exposures, it's possible the smear would be less, though as Bruce mentioned, you also have to keep the spacecraft point so that the HGA is in the RAM direction to protect the spacecraft from E-ring particles. Unfortunately, to see anything in saturn-shine, as would be possible at closest approach, we would need significantly more than 5 ms exposures to see anything. And that's assuming we had prime pointing. Which as of right now, we don't (INMS does I think). Then, three minutes after C/A, Enceladus goes into eclipse. Plenty of time for CIRS to look for even higher temps, but not good for ISS imaging.

Composition of reservoir: INMS observations of the plume suggest that it isn't pure H2O. Their composition measurements suggest 91% H2O, 3% CO2, 3.3% N2 (though CO is possible), and 1.6% CH4.