Today around the world much of the astronomical community is profoundly moved by the impending death of the Cassini spacecraft https://www.nasa.gov/press-release/cassini-spacecraft-makes-its-final-approach-to-saturn. Twitter abounds in Tweets about the intrepid explorer that has been in space almost 20 years and in orbit around Saturn and its moons for 13 years. I am quite sure there are a few wet eyes behind those Tweets for what NASA is calling the Grand Finale https://saturn.jpl.nasa.gov/mission/grand-finale/overview/ .
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| In this computer generated visual Saturn looms ever larger to the Cassini spacecraft as it begins its final plunge into Saturn. CREDIT: NASA |
At approximately 7:55 a.m. EDT, September 15, 2017, NASA expects to lose contact with Cassini as the spacecraft hits the upper atmosphere of the ringed planet at a blistering 70,000 miles per hour https://youtu.be/AbOf91x2_fs . An explorer to the very end, Cassini will be live streaming its last moments and gathering data with 8 of its 12 science instruments until the thrusters cannot overcome the aerodynamic forces and Cassini starts to tumble, break apart and finally be consumed like a shooting star in the atmosphere of Saturn.
It will take 83 minutes for Cassini’s final data transmission to reach Earth traveling at the speed of light - 186,000 miles per second. Almost a billion miles away Saturn and its moons will once again be solitary in their orbit around the Sun. Gone will be the amazing spacecraft that took thousands of photographs, collected Terabytes of data, sent the ESA’s Huygens lander to Titan https://saturn.jpl.nasa.gov/mission/spacecraft/huygens-probe/ and discovered a large global ocean under the thick ice at Enceladus https://saturn.jpl.nasa.gov/science/enceladus/ .
As stated by NASA,“the final set of views from Cassini's imaging cameras is scheduled to be taken and transmitted to Earth on Thursday, Sept. 14. If all goes as planned, images will be posted to the Cassini mission website beginning around 11 p.m. EDT (8 p.m. PDT). The unprocessed images will be available at: https://saturn.jpl.nasa.gov/galleries/raw-images .”
“Live mission commentary and video from JPL Mission Control will air on NASA Television and the agency’s website from 7 to 8:30 a.m. EDT (4 a.m. to 5:30 a.m. PDT) on Sept. 15. A post-mission news briefing from JPL is currently scheduled for 9:30 a.m. EDT (6:30 a.m. PDT), also on NASA TV.”
“A new NASA e-book, The Saturn System Through the Eyes of Cassini, showcasing compelling images and key science discoveries from the mission, is available for free download in multiple formats at: https://www.nasa.gov/ebooks .”
Bright Saturn is in the southwest sky after dark. Tonight look at Saturn and say farewell to Cassini. And when ‘The Grand Finale” for Cassini is finally over take some comfort as will I in knowing that the atoms that were Cassini are now part of Saturn.
Voyagers
Two NASA spacecraft - Voyager 1 and Voyager 2 https://voyager.jpl.nasa.gov/ - made world-wide headlines recently by celebrating their 40th anniversaries in space. Voyager 1 is about 13 billion miles from Earth and is cruising interstellar space while Voyager 2 is 11 billion miles distant. The spacecraft are healthy and continue to send data back to Earth. They will finally go silent years from now when their radioactive fuel supply is spent.
These twins opened up the outer solar system of gas giant planets - Jupiter, Saturn, Uranus and Neptune - as we had never seen them before https://www.jpl.nasa.gov/news/news.php?release=2017-203 . With their respective flybys the Voyagers transformed these giants from what could be obtained through telescopes to up close and mesmerizing personal views. The science obtained filled volumes and the photographs we saw transformed these worlds into actual worlds we had been to.
The Voyagers have become cultural icons due in part to their longevity, discoveries and perhaps most importantly of all, the “Golden Record” https://voyager.jpl.nasa.gov/golden-record/ that each of them carries. The late Dr. Carl Sagan was the primary mover in getting these artifacts of Earth and humanity placed on the Voyagers. He also convinced NASA to take the first ever portrait of the solar system which included our Earth https://photojournal.jpl.nasa.gov/catalog/PIA00451 .
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| SOLAR SYTEM PORTRAIT NASA |
The famous “Pale Blue Dot” photograph became the subject of a wonderful book by Dr. Sagan. Much of what he wrote is even more meaningful today https://www.goodreads.com/work/quotes/1816628-pale-blue-dot-a-vision-of-the-human-future-in-space . I highly recommend reading it as well as Sagan’s other books.
The Voyagers may very possibly outlive humanity as they could roam the Milky Way Galaxy for hundreds of millions of years. Unless they collide with something in space they will be a lasting testament to a species who reached for the stars - and put a Golden Record out amongst them to say, ‘Hello’.
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