Enhanced color image of Saturn's rings, from NASA's Cassini Space Mission.
(Image Source: NASA)
By Glenn A. Walsh
Reporting for SpaceWatchtower
Friday morning (2017 September 15), NASA and the Jet Propulsion Laboratory (JPL) at the California Institute of Technology (Cal Tech) will monitor the Cassini Spacecraft as it ends its mission by diving into the clouds of Saturn. NASA-TV and NASA and JPL Internet web-sites will provide live steaming coverage as scientists monitor Cassini's “Grand Finale,” as well as news conferences before (Thursday afternoon) and after (Friday morning) the event (Links to NASA and JPL Internet-streaming coverage at end of this blog-post.)
Launched on 1997 October 15, the Cassini mission will end exactly one month shy of 20 years. The spacecraft entered orbit around Saturn on 2004 July 1, after swinging around Venus, Earth, and Jupiter for gravity-assist maneuvers. Cassini was a joint project of the American space agency, NASA, the European Space Agency (ESA), and the Italian space agency (ASI). It was the fourth space probe to visit Saturn, and the first to enter orbit around Saturn.
Carried with the Cassini Spacecraft was the Huygens space probe, an ESA project which landed on Titan, Saturn's largest moon, on 2005 January 14. To date, this is the only landing of a space probe on an object in the Outer Solar System, the only landing on a Moon (other than Earth's Moon), and the furthest from Earth a space probe has landed.
After 13 years in orbit of Saturn, following 7 years to travel from Earth to Saturn, the Cassini Spacecraft is now low in rocket fuel, used to adjust its course in orbit. After the discoveries that 2 of Saturn's moons (Enceladus and Titan) have the potential to harbor some type of life (or could develop life sometime in the future), scientists had a difficult decision to make.
Once Cassini's fuel is completely depleted, they could no longer control the spacecraft. Hence, there is a possibility that the spacecraft could crash-land on one of those moons. If this happened, Earth microbes, which may be on the spacecraft, could infect the moon's environment. Hence, the decision was made to have the Cassini Spacecraft dive into the clouds of Saturn, which are unlikely to be contaminated with Earth microbes.
The NASA / JPL scientists currently predict that, as Cassini dives into the clouds of Saturn, they will lose all radio communication with the spacecraft on Friday Morning, 2017 September 15 at 7:55 a.m. Eastern Daylight Saving Time (EDT) / 11:55 Coordinated Universal Time (UTC). Loss of signal could occur a few minutes later, if drag on the spacecraft caused by the Saturn atmosphere slows down the spacecraft's descent.
However, due to the great distance between Earth and Saturn at this time, there is still an 83-minute radio delay. So, whenever the radio signal is lost, the event causing the signal-loss would have actually occurred 83 minutes earlier.
Live coverage from NASA and from JPL, streamed live on their Internet web-sites, will occur on Friday, September 15 from 7:00 to 8:30 a.m. EDT / 11:00 to 12:30 UTC. This will be followed by a Cassini post-mission news conference on Friday, September 15 at 9:30 a.m. EDT / 13:30 UTC. There will also be a pre-event question-and-answer session with project scientists and engineers on Thursday Afternoon, September 14 at 4:00 p.m. EDT / 20:00 UTC.
Internet Web-Sites for Live-Streamed Coverage of Saturn "Grand Finale" ---
NASA-TV: Link >>> http://www.ustream.tv/nasahdtv
JPL / YouTube: Link >>> https://www.youtube.com/nasajpl/live
Most recent Cassini images of Saturn:
Link >>> http://go.nasa.gov/cassiniraw
Internet Links to Additional Information ---
Cassini - Huygens Space Mission:
Link 1 >>> https://www.jpl.nasa.gov/missions/cassini-huygens/
Link 2 >>> https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens
Cassini Spacecraft "Grand Finale":
Link 1 >>> https://saturn.jpl.nasa.gov/mission/grand-finale/overview/
Link 2 >>> https://saturn.jpl.nasa.gov/
Link 3 >>> https://en.wikipedia.org/wiki/Cassini_retirement
Photograph of Cassini Spacecraft:
Link >>> http://spacewatchtower.blogspot.com/2017/09/astronomical-calendar-2017-september.html
"'Our Saturn years'," Cassini's epic journey to the ringed planet, told by the people who helped make it happen."
Link >>> http://www.bbc.co.uk/news/resources/idt-sh/cassini_huygens_saturn
Astronomer Giovanni Domenico Cassini - 1625 June 8 to 1712 September 14 -
Today, 2017 September 14, is the 305th anniversary of the death of Astronomer Cassini:
Link >>> https://en.wikipedia.org/wiki/Giovanni_Domenico_Cassini
Allegheny Observatory (Pittsburgh) Astronomer James E. Keeler, who discovered that the rings of Saturn are made of individual particles, each in its own orbit around the planet. He also discovered a minor division in Saturn’s rings that became known as Keeler’s Gap:
Link >>> http://johnbrashear.tripod.com/bio/KeelerJ.htm
Related Blog Posts ---
"Cassini Probe Shows Colorful Storm at Saturn's North Pole." 2013 Dec. 5.
"Backlit View of Saturn & Rings: Cassini Spacecraft." 2012 Dec. 19.
"New, dramatic Saturn video created from Voyager and Cassini spacecraft images." 2012 April 25.
Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
2017 September 14.
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