Hello! You’ll noticed that I skipped Astronomy Pictures of the Week on Wednesday. That… was on purpose.
Today was Cassini’s last day alive. This morning, Cassini plunged into Saturn, sending back some amazing data, but, in the process, ending its life.
Cassini was launched on October 15th, 1997. For two decades, Cassini revealed the wonders of the greatest planet and planetary system in our solar system to us. We learned so much.
But, now, it’s over…
Here’s a timeline of what went down this morning and when:
1:08 am EDT – High above Saturn, Cassini crosses the orbital distance of Enceladus for the last time
3:14 am EDT – Spacecraft begins a 5-minute roll to point instrument (INMS) that will sample Saturn’s atmosphere and reconfigures systems for real-time data transmission at 27 kilobits per second (3.4 kilobytes per second). Final, real-time relay of data begins (transmission received on Earth at 4:37 am EDT)
3:22 am EDT – High above Saturn, Cassini crosses the orbital distance of the F ring (outermost of the main rings) for the last time
6:31 am EDT – Atmospheric entry begins; thrusters firing at 10% of capacity (transmission received on Earth at 7:54 am EDT)
6:32 am EDT – Thrusters at 100% of capacity; high-gain antenna begins to point away from Earth, leading to loss of signal (transmission received on Earth at 7:55 am EDT)
Cassini in the environmental test chamber, 25′ Space Simulator in building 150 at NASA’s Jet Propulsion Laboratory.
Goodbye, Cassini. We’re going to miss you.
And I can’t end this without thanking you, Cassini, for what I truly believe is one of the greatest space images ever taken. This has appeared in my APotW series already… in fact, it was the very first one I posted here…
Saturn eclipses the sun, as seen by Cassini.
What is the jet-fan looking thing the satellite is sitting on, I wonder?
Once nice thing about rocket science(tm) is that you can always assume that anything that’s done is expensive, and therefore nothing is done without a reason. Therefore I conclude the jet-fan thing is very important because someone had to design it, and build it, probably out of something exotic and expensive.
The picture of Saturn is amazing. I remember one day when I was playing Elite and got a ringed gas giant in a similar pose and it looked almost exactly like that and I was hopping up and down with joy so much I forgot to hit a screenshot.
https://www.nps.gov/parkhistory/online_books/butowsky4/space20.htm says “The walls and floor are lined with thermally opaque aluminum cryogenic shrouds controlled over a temperature range of -320° to +200°F by liquid or gaseous nitrogen.”
To get a sense of scale, here’s the same room with a rover and human standing in it. http://www.caltech.edu/news/whatever-happened-space-simulator-jpl-23640 . Cassini was huge!
There is no fan-looking floor in that shot. https://archive.org/details/nasa_techdoc_19680010042 says “The floor shroud shall be covered with a removable structural floor made from aluminum honeycomb panels designed for a live load of 100 lb/ft . A 12-ft-diameter , separately removable center section shall be provided in the floor to accommodate an exciter installation.”
Andrew Dalke@#2:
Holy crap! That’s so cool. 133 2kw lamps. Um. Um.
I wonder if the tardigrades survive in there.
Vale Cassini, one amazing little robot explorer that has brought us so much jaw-dropping wonder, joy and good science -and thankyou to all those who brought it to us, all those who designed, built and made her fly and function -- and there were thousands of people who made that happen and millions globe wide who enjoyed and willbenefit and loved what she brought everyone.
A few good links :
https://saturn.jpl.nasa.gov/news/3120/cassinis-final-images/
Cassini’s final images via JPL / NASA webpage.
https://www.youtube.com/watch?v=7AbLq1nDuR8
Some highlights here from just one Cassini instrument.
Oh & this :
https://www.newscientist.com/article/2147520-tears-for-cassini-why-its-ok-to-well-up-over-a-lump-of-metal/
too. Unashamed to admit that my eyes weren’t dry when Cassini became part of the butterscotch planet she orbited so long and studied and imaged so well.