It’s not the first time I cover this authentic natural wonder, including posting a link to a media gallery with some of the best Cassini’s coverage. They are the most beautiful of their kind, at least in the Solar System (we just found out there are exoplanets with their own set of rings (for a really amazing one, have a look at this. J1407 is no slouch). What took me to Saturn’s rings this time was a completely different issue.
Is it difficult flying across them? After all, they are composed of particles ranging in size from 1 centimetre to 10 metres, extending in a multiple set of rings from 7,000 km to 80,000 km above Saturn’s equator. Well, ring-crossing was required to put Cassini-Huygens into orbit. When the probe reached Saturn on 1 July 2004, it passed through a gap in Saturn’s rings on its way around the planet, and then did it again on the way down. And now does it routinely.
“Although the ring gaps appeared empty, they were not. Millions of dust particles were waiting for Cassini-Huygens, and the spacecraft ploughed through them at a relative speed of about 20 kilometres a second. That’s about 70 000 kilometres per hour!” (Here for hearing the sound of the crossing.)
(Credit: Emily Lakdawalla)
Not all rings’ gaps are the same to negotiate. Some are more challenging than others. As Emily Lakdawalla wrote in 2008 on her blogs, “the gap between Saturn and the D ring is only about 3,000 kilometers wide. I suppose for a mission to a place like Mars, 3,000 kilometers of leeway is quite a lot. But Saturn is 120,000 kilometers across, and the main ring system extends another 60,000 kilometers or so above Saturn; Cassini would have to do an orbital maneuver to majorly drop its periapsis (closest approach point) to right in between the planet and its rings, leaping over the main ring system in the process. The idea seems totally crazy.”
I found out that Cassini’s team had given more than a thought about it, since the probe will actually end its mission in 2016 with 22 breathtaking loops passing through the gap between Saturn and its innermost ring (details here). Too bad we won’t be on board, admiring it.
Artist’s impression of the Rings (Credit: NASA/JPL/Univ. of Colorado)
“I have often thought: What a surreal sight this would be if you were flying low across the rings in a shuttle craft. To your eyes, the rings would seem like a gleaming white, scored, gravelly sheet below you, extending nearly to infinity. (…) And as you flew, you would see in the distance a wall of rubble that, eventually, as it neared, you would come to realise towered two miles above your head. There isn’t another sight like it in the Solar System!” (Carolyn Porco, Cassini Imaging Central Laboratory for Operations – CICLOPS).
I look forward to what Cassini can send back in 2016, when doing just that. Not as good as being physically there, but the second best.
In the meantime, just to refresh the memory, a good compilation of the existing imagery of the rings in a video.