While plow trucks across the US northwest pushed around snow this
week, a Mount Everest-size rock near Saturn continued a
centuries-long effort of clearing its own lane in the planet’s
expansive disc of icy rings.
On January 16, the nuclear-powered Cassini spacecraft flew by the
moonlet, called Daphnis, and took the closest-ever photo of the
object. The shot below, which NASA released on
Wednesday, is as pretty as it is incredible.
The image looks down on the 5-mile (8-kilometer) wide space rock
in its 26-mile (42-kilometer) wide lane, called the Keeler Gap,
as it zips on by:
NASA calls Daphnis the “wavemaker moon,” and it’s not hard to see
The passing moonlet stirs up large waves of ring material with
its weak gravitational pull, as well as smaller trails of grit
that it yanks into the gap.
If you look closely, you can see a wisp to the bottom-left of the
These waves aren’t flat, though.
Take a look at the stunning top-down photo by Cassini from August
You can see Daphnis’ gravity “splashing” ring material up and
down, thanks to shadows cast on the rings by the sun:
NASA is trying to squeeze every last photo it can out of Cassini,
since that mission — which launched in October 1997 and has spent
13 years in orbit around Saturn — is scheduled to end this year.
And by “end” we mean plunge into the bottomless clouds of Saturn.
The space agency in late 2016 put Cassini on course for a
“Grand Finale” orbit of the planet and its dozens of moons,
allowing the robot to take in unprecedented views like the one
released this week.
But sometime in late April, Cassini will begin its death spiral.
It will swoop over Saturn’s north pole, slip between the planet
and its rings 22 times, and ultimately “burn up like a meteor,”
according to NASA, on September 15, 2017.
And why, you might ask, end the mission in a flame-out instead of
letting Cassini carry on, like
the Voyager spacecraft, which continue their drawn-out escape
from the solar system?
Because two icy moons of Saturn, Enceladus and Titan, are
dripping with water and thus promising places to
look for life — so
NASA wants to avoid any chance that Cassini would crash into
them and contaminate the worlds with any earthly germs.
from SAI http://ift.tt/2js40bN