Cassini EOM

How are you feeling today?


This has been a bittersweet week, watching as my Cassini colleagues gather for the final time to watch the end of this 20-year journey.  This heroic spacecraft has done everything we’ve ever asked of it, even fighting with it’s last moments to deliver new scientific insights back to Earth.  So although I’m sad that Cassini’s exploration will now be a part of the history books,  I think we can be proud of everything that this mission has accomplished.  It just shows what wonders can be achieved when 27 nations work together.

Cassini CIRS team members at their last team meeting with a working spacecraft - June 2017

What will you be looking for in the last set of images to come down from the spacecraft - especially the final one of the spot where it will plunge into the cloud tops?

Those last final looks around the Saturn system will be heart-wrenching, as our last chance to witness new photos of these environments for a generation or more.  Combined with all our recent close encounters in 2017, the resolution of the last images of Saturn’s individual swirling clouds will be revealing the meteorological complexity underlying the usual serene appearance.  But Cassini will meet its fate high in the atmosphere, so the cloud-top meteorology might have little impact on what Cassini is able to measure in its final moments.

And CIRS is going to be on until the bitter end, right? What sorts of insights are you hoping to squeeze out of those final minutes of data?

Oh yes - along with some of the other instruments, CIRS will be fighting to deliver science until the very end of the journey.  These won’t be your typical data - CIRS is used to measuring spectra slowly and returning them to Earth hours later.  In real time, we’ll be getting housekeeping data (i.e., the instrument temperatures, voltages, etc.) and looking for any spikes in our measured interferograms, particularly as the CIRS field of view sweeps over the rings in the last 20 minutes or so.  We expect measurable heating about 25 minutes before loss of signal.  But, as we’ve never done this before, we’re waiting for (and expecting!) surprises!

At one of our team meetings, it was noted that CIRS’ scan platform has travelled 106 miles in tiny 2-cm chunks to assemble its interferograms - in all, more than 170 million interferograms have been acquired.  That legacy will keep scientists going for decades.