Cassini finds gap in Saturn’s rings surprisingly empty
The uncertainty of science: The data from Cassini’s first dive through the gap between Saturn and its innermost ring suggests that the space there has much less material than predicted.
Cassini’s Radio and Plasma Wave Science (RPWS) instrument was one of two science instruments with sensors that poke out from the protective shield of the antenna (the other being Cassini’s magnetometer). RPWS detected the hits of hundreds of ring particles per second when it crossed the ring plane just outside of Saturn’s main rings, but only detected a few pings on April 26. When RPWS data are converted to an audio format, dust particles hitting the instrument’s antennas sound like pops and cracks, covering up the usual whistles and squeaks of waves in the charged particle environment that the instrument is designed to detect. The RPWS team expected to hear a lot of pops and cracks on crossing the ring plane inside the gap, but instead, the whistles and squeaks came through surprisingly clearly on April 26.
“It was a bit disorienting — we weren’t hearing what we expected to hear,” said William Kurth, RPWS team lead at the University of Iowa, Iowa City. “I’ve listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.” The team’s analysis suggests Cassini only encountered a few particles as it crossed the gap — none larger than those in smoke (about 1 micron across).
The second dive through the rings will occur tomorrow, with data sent down the next day. Because the gap is emptier than expected, they will not have to protect the spacecraft so thoroughly, and will thus have more instruments gathering data during the fly through.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The uncertainty of science: The data from Cassini’s first dive through the gap between Saturn and its innermost ring suggests that the space there has much less material than predicted.
Cassini’s Radio and Plasma Wave Science (RPWS) instrument was one of two science instruments with sensors that poke out from the protective shield of the antenna (the other being Cassini’s magnetometer). RPWS detected the hits of hundreds of ring particles per second when it crossed the ring plane just outside of Saturn’s main rings, but only detected a few pings on April 26. When RPWS data are converted to an audio format, dust particles hitting the instrument’s antennas sound like pops and cracks, covering up the usual whistles and squeaks of waves in the charged particle environment that the instrument is designed to detect. The RPWS team expected to hear a lot of pops and cracks on crossing the ring plane inside the gap, but instead, the whistles and squeaks came through surprisingly clearly on April 26.
“It was a bit disorienting — we weren’t hearing what we expected to hear,” said William Kurth, RPWS team lead at the University of Iowa, Iowa City. “I’ve listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.” The team’s analysis suggests Cassini only encountered a few particles as it crossed the gap — none larger than those in smoke (about 1 micron across).
The second dive through the rings will occur tomorrow, with data sent down the next day. Because the gap is emptier than expected, they will not have to protect the spacecraft so thoroughly, and will thus have more instruments gathering data during the fly through.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Highly recommend:
“Cassini’s Grand Finale”
NASA-JPL
From 4-4-17
https://youtu.be/G0g4L6a6Ns4
(59:51 –Part presentation & part Q&A)
They spend a bit of time describing the dive through the rings.
Go to
https://youtu.be/G0g4L6a6Ns4?t=940 in the video, for a cool graphic showing the last orbits and how they intend to modify them, depending on what they find.