[U] Cassini Saturnian Ring Plunge No. 12 Completed — Signal Acquired! Underway Right Now

We are now more than halfway — to the dramatic death-burn, and vanishing, in silence — of September 15, 2017.

This is the midpoint of orbit 12 — of 22, in this ever tightening orbit series — each a foreshadowing of the noose, of sorts. On that September morning, local time — at the end point of orbit 22, twisty copper colored Cassini will be vaporized as she skims and glides, out of fuel — deeper and deeper — into Saturn’s atmosphere. . . a somewhat melancholy notion, indeed. . . .

But on this glorious summer’s morning, she is still performing revolutionary (pun intended!) gas giant planetary science. Here is the overview, from NASA’s mission logs:

. . . .During this orbit, Cassini’s Ultraviolet Imaging Spectrograph (UVIS) stares at the star Kappa Canis Majoris, as parts of the C ring and A ring pass between the spacecraft and the star. The spacecraft’s Composite Infrared Spectrometer (CIRS) observes the occultation as well.

Cassini’s imaging cameras, the Imaging Science Subsystem (ISS), observes some of Saturn’s known ring propeller features, then targets the border region of the F ring and A ring to study ring dynamics there.

Cassini’s UVIS instrument also studies small-scale structures in the rings.

During this orbit’s ring-plane crossing, the spacecraft is oriented such that its high-gain antenna (the big dish) faces forward (called “HGA to RAM”) to help shield the spacecraft from ring particles.

Also during ring-plane crossing, in the brief period in which impacts are most likely, the Radio and Plasma Wave Science (RPWS) instrument “listens” for the impacts of ring particles, which produce detectable plasma clouds when they strike the spacecraft. The antenna protrudes several meters beyond the protection of the high-gain antenna and so still detects impacts. . . .

During this orbit, Cassini gets within 2,320 miles (3,730 kilometers) of Saturn’s 1-bar level. Cassini also passes within 2,470 miles (3,980 kilometers) of the inner edge of Saturn’s D ring. . . .

Now you know — and [UPDATED!] we have seen (thus the new masthead!) should see a signal acquisition ping, from the beautifully twisting lil’ shepherded moon-let, as she moves with truly unwasted grace (conserving fuel all the while) — after midnight local, tonight. . . that will indicate she is safe, sound, hale and whole — and still sprinting about the planet. . . preparing ultimately for her. . . fiery demise.

Onward, on a gorgeous July morning — in a ferociously gleaming city. Smile.



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