Tuesday, October 27, 2015

Historic Flyby Through the Plumes of Enceladus

Hey Space Placers!

Ever seen “Old Faithful” or other smaller geysers erupt at beautiful Yellowstone National Park   http://www.nps.gov/yell/planyourvisit/exploreoldfaithful.htm     ? It is quite the sight. Located on a small, ice covered moon around the ringed planet Saturn there is a continuous eruption of huge Yellowstone-like geysers that an intrepid spacecraft will fly through at very close range to further discern their secrets.

On Wednesday morning the Cassini spacecraft http://www.nasa.gov/mission_pages/cassini/main/index.html    that has been exploring the Saturn system for over 11 years will perform its 21st flyby  http://www.jpl.nasa.gov/news/news.php?release=2015-328    of Enceladus, the amazing ice covered moon with a global sub-surface ocean. This daring flyby will be only 30 miles above the South Pole of Enceladus   https://www.youtube.com/watch?v=BZ1KowQXc3Y    and it will be the deepest penetration ever of the fascinating plumes that are located there. Closest approach will be at 11:22 a.m.EDT.

The plumes of Enceladus, originally called fountains,  were discovered  http://saturn.jpl.nasa.gov/science/moons/enceladus/enceladusdiscoverytimeline/      in November 2005 and have been flown through before but at a higher altitude. These earlier flybys showed that the plumes are made up of ice, water vapor and organic molecules and occur continuously only at the South Pole of Enceladus. This deeper plume penetration will allow for the best sampling ever of the particles and complex chemistry contained within.

This artist's rendering showing a cutaway view into the interior of Saturn's moon Enceladus. NASA's Cassini spacecraft discovered the moon has a global ocean and likely hydrothermal activity. A plume of ice particles, water vapor and organic molecules sprays from fractures in the moon's south polar region. Image Credit: NASA/JPL-Caltech

The plumes are believed to be caused by “Yellowstone” like eruptions that originate from the global ocean and hydrothermal heat concentrated at the South Pole. The plumes might be erupting from the “Tiger Stripes” of Enceladus - fractures in the surface ice. The makeup and structure of the plumes is one of the key science objectives of this flyby     http://saturn.jpl.nasa.gov/mission/flybys/enceladus20151028/    .

During a teleconference held on Monday   http://www.ustream.tv/recorded/76308203 , scientists stated that traveling at over 19,000 miles per hour Cassini will spend only a few tenths of a second flying through the plumes. But its instruments have been prepped and tuned specifically for this encounter and are expected to gather data that will help answer a number of questions including “is the Enceladus ocean habitable for simple life?”. The spacecraft can detect complex organic molecules but can’t determine if they are biological in nature.

Cassini will gather data and take pictures inbound and outbound of Enceladus. The North Pole is visible for the first time ever while the South Pole will be illuminated only by the light of Saturn itself. I asked Linda Spilker, Cassini project scientist at the Jet Propulsion Laboratory (JPL), “How bright will the South Pole be during the flyby?”. She responded that, “It will be much, much less than our own Full Moon. Enceladus is very bright and we have done this before.” Dr. Spilker stated that the Cassini science team is “excited and awaiting results”.

Cassini will be flying by so fast that it must take “smeared” pictures which software should be able to convert to regular view. By late afternoon Wednesday the spacecraft is expected to do a call back followed by transmission of data and pictures. It will take a week to process the initial results followed by weeks and months of analysis but we may see the first pictures by late Thursday or Friday morning.

This pioneering close flyby is our first step in exploring other oceans in our solar system. Sniffing, probing and photographing the plumes of Enceladus will reveal much about its hidden global ocean. In turn this may give us another  place in addition to Mars to look for life. Jupiter’s moon Europa  http://www.caltech.edu/news/probing-mysteries-europa-jupiters-cracked-and-crinkled-moon-48593   also has a global liquid ocean and is a target for future exploration. The science and lessons learned by Cassini will go a long way in preparing for future exploration of Europa and Enceladus.

Cassini, described by the scientists during the teleconference as “a perfect mission” has two years left. It will flyby Enceladus one more time in December  http://solarsystem.nasa.gov/finalflybys   , take high resolution pictures of the F-ring of Saturn, fly close to tiny ring moons and in April 2017 hop across the entire ring system to fly in between a gap in the rings - wow.

At its end Cassini will do a death plunge into the atmosphere of Saturn and will have written THE book on the ringed planet and its moons.

I’ll have updates on the flyby and Cassini as they become available.

Sky Guy in VA

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