Mastodawn

AkaSci 🛰️Jun 3, 2023

The JWST team recently released this image of Saturn's moon Enceladus, showing water plumes extending out 10,000 km, 20 times the size of the moon itself, which creates a fuzzy torus of water particles around the orbit of Enceladus.
The inset shows a mosaic of Enceladus and its water jets, based on images taken by the Cassini orbiter in 2009.
Let's learn more about Enceladus and examine why the JWST image is so low-res and pixelated.
https://www.nasa.gov/feature/goddard/2023/webb-maps-surprisingly-large-plume-jetting-from-saturn-s-moon-enceladus
#Enceladus #JWST #Science
1/n

Webb Maps Large Plume Jetting From Saturn’s Moon Enceladus

A water vapor plume from Saturn’s moon Enceladus spanning more than 6,000 miles – nearly the distance from Los Angeles, California to Buenos Aires, Argentina – has been detected by researchers using NASA’s James Webb Space Telescope.

NASA

AkaSci 🛰️Jun 3, 2023

This graphic shows the spectrum of one of the pixels in the area around Enceladus, collected using JWST's NIRSpec instrument in IFU mode in Nov 2022. The spectrum data indicated water molecules as far as 20x times the moon's diameter.
The NIRSpec IDU captures spectrum for each pixel in a 30x30 pixel area.
The graphic also shows an artist's conception of the resulting water torus around Saturn.
https://webbtelescope.org/contents/media/images/2023/112/01H084K8BGF2D8B887J0T580ND?news=true
#Enceladus #JWST
2/n

AkaSci 🛰️Jun 3, 2023

Why is the JWST image of Enceladus so low-res and pixelated? Here is an explanation -
Enceladus diameter: 505 km
Distance: ~1.458 billion km on Nov 9, 2022
Angle subtended at JWST: 0.00002° = 0.07" (1" = 1 arcsec = 1/3600th of a degree)
JWST NIRSpec detector pixel Field of View: 0.1"
Hence, Enceladus is less than 1 pixel wide in the NIRSpec image! A pixel covers 707 km at that distance.
The full 30x30 pixel image covers 3"x3", i.e., 42 times the size of Enceladus.
#Enceladus #JWST
3/n

AkaSci 🛰️Jun 3, 2023

This spectacular image of Enceladus and its water jets was taken by the Narrow Angle Camera (NAC) onboard the Cassini spacecraft from a distance of ~14,000 km on Nov. 21, 2009.
Image size: 1580 x 977 pixels (136 x 84 km)
Resolution: ~85 meters (!) per pixel.
The NAC had a 1k x 1k detector with a Field of View of 0.35°.

Distance matters. That's why we need inter-planetary missions.

https://www.jpl.nasa.gov/images/pia11688-bursting-at-the-seams-the-geyser-basin-of-enceladus
#Enceladus #JWST #Cassini
4/n

Bursting at the Seams: the Geyser Basin of Enceladus

NASA's Cassini spacecraft captured dramatic plumes, both large and small, spray water ice out from many locations along the famed 'tiger stripes' near the south pole of Saturn's moon Enceladus.

NASA Jet Propulsion Laboratory (JPL)

AkaSci 🛰️Jun 4, 2023

Here is a mosaic of 21 images of the fractured and cratered icy surface of Enceladus taken by Cassini's narrow-angle camera, as it swooped past the south pole of the moon on July 14, 2005.

Resolution = 67 to 350 meters per pixel
Distance = 11,100 to 61,300 km
Color = false-color with colors assigned to various wavelengths from UV to infrared used during imaging.

https://photojournal.jpl.nasa.gov/catalog/PIA06254
#Enceladus #JWST #Cassini
5/n

Catalog Page for PIA06254

AkaSci 🛰️Jun 4, 2023

This mosaic is a grey-scale image of Enceladus taken by Cassini.
The images were obtained in visible light with the Cassini spacecraft narrow-angle camera on Nov. 21, 2009. The images were acquired at distances of approximately 3,200 to 23,000 km.
See https://photojournal.jpl.nasa.gov/catalog/PIA11685 for a hi-res zoomable image.
@danedeasy
#Enceladus #JWST #Cassini
6/n

Catalog Page for PIA11685

AkaSci 🛰️Jun 4, 2023

Note that properties of Saturn's E ring, its torus shape, its composition and Enceladus being the source of its material have been known since the Voyager and Cassini days.
https://solarsystem.nasa.gov/news/13021/put-a-ring-on-it/
From https://www.sciencedirect.com/science/article/abs/pii/0273117784900206 (1984) - "Optical properties of the ring suggest a collection of micron-sized spheroids whose composition is generally supposed to be water ice in accordance with the assumed Enceladus source."
Also https://articles.adsabs.harvard.edu/pdf/1984LPI....15..361H
#Enceladus #JWST #Cassini
7/n

Put a Ring On It

Saturn's E ring origin was a decades-long mystery until Cassini came along.

NASA Solar System Exploration

AkaSci 🛰️Jun 4, 2023

This astounding image of Enceladus and its water jets was taken by the Cassini spacecraft on Aug. 13, 2010 from a distance of 59,000 km.
The bottom half of the image contains Saturn, observed from its night side, with its atmosphere backlit by the sun. Enceladus is closer to the spacecraft than Saturn in this image.

https://solarsystem.nasa.gov/resources/168/looming-enceladus/
#Enceladus #JWST #Cassini
9/n

Looming Enceladus | NASA Solar System Exploration

Small water ice particles fly from fissures in the south polar region of Saturn's moon Enceladus in this image taken during the Aug. 13, 2010, flyby of the moon by NASA's Cassini spacecraft.

NASA Solar System Exploration

AkaSci 🛰️Jun 4, 2023

Here is a beautiful colorized version of the image posted above of Enceladus and its water jets. The image was taken by the Cassini spacecraft on Aug. 13, 2010 from a distance of 59,000 km.

Gordan Ugarković colored Saturn's limb backlit by the Sun as it would appear to the human eye.

Also makes a great desktop background image.

Can an earthbound telescope take such images? No.

https://www.flickr.com/photos/ugordan/5931534600
Credit: NASA / JPL / SSI / Gordan Ugarkovic
#Enceladus #JWST #Cassini
10/n

Enceladus and Saturn [colorized]

Flickr

AkaSci 🛰️Jun 4, 2023

Lot more is known about the composition of the plumes of Enceladus besides water.
On March 12, 2008, Cassini collected samples from the plume and analyzed them using its Ion and Neutral Mass Spectrometer. See chart below for the results.
The plumes have traces of molecular N, CO2, NaCl, simple hydrocarbons (methane, propane, acetylene and formaldehyde), benzene, ammonia and even complex organics with large # of C atoms.

https://photojournal.jpl.nasa.gov/catalog/PIA10356
https://en.wikipedia.org/wiki/Enceladus#Composition
#Enceladus #Cassini
11/n

Catalog Page for PIA10356

AkaSci 🛰️Jun 4, 2023

Check out https://solarsystem.nasa.gov/missions/cassini/galleries/images/?page=10&per_page=25&order=created_at+desc&search=&tags=cassini%3Aenceladus&condition_1=1%3Ais_in_resource_list&category=51 for a treasure-trove of fascinating images of Saturn's intriguing icy moon Enceladus.
Image 1: Nov. 21, 2009; 2,000 km distance, scale = 116 m per pixel. https://solarsystem.nasa.gov/resources/145/enceladus-warm-baghdad-sulcus-in-context/
Image 2: "Baghdad Sulcus", Aug 2008; 12 to 30 m per pixel. https://solarsystem.nasa.gov/resources/14680/perspective-view-of-baghdad-sulcus-enceladus/
#Enceladus #Cassini
12/n

Images | Galleries – NASA Solar System Exploration

NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.

NASA Solar System Exploration

The Enceladus Orbilander mission was the 2nd highest priority Flagship mission in the 2023-2032 Planetary Science Decadal Survey, but did not make the cut for funding in this decade.

It would orbit Enceladus and sample its plumes for 1.5 years and then land to study surface material for 2 years, searching for evidence of life or its building blocks.
No drills, uses funnel and scoop.
Cost: $2.56B in FY 2025 dollars
Timeline: see graphic

https://ntrs.nasa.gov/api/citations/20205008712/downloads/enceladusorbilander_2020pmcs.pdf
#Enceladus #Orbilander
13/n

AkaSci 🛰️Jun 5, 2023

Here is a fascinating image of Enceladus lined up in front of its larger sibling Tethys. The image was taken by the Cassini spacecraft on Sep 24, 2015.

The lower graphic shows Saturn's main moons and the location of Saturn's rings. The E ring, formed by the plumes of Enceladus, extends out to Titan, a million km away.

Particles of the E Ring rain and accumulate on moons Tethys, Telesto, Calypso, Helene and Polydeuces!

https://solarsystem.nasa.gov/resources/16284/bulls-eye-moons/
https://photojournal.jpl.nasa.gov/catalog/PIA03550
#Enceladus #Saturn
14/n

Bull's-eye Moons | NASA Solar System Exploration

Like a cosmic bull's-eye, Enceladus and Tethys line up almost perfectly for Cassini's cameras.

NASA Solar System Exploration

AkaSci 🛰️Jun 7, 2023

Enceladus appears around the 1:40 mark in this beautiful video of the Cassini mission and the Grand Finale. Cassini's Grand Finale involved a series of close Saturn passes, diving between the rings, then an entry into Saturn's atmosphere on Sept. 15, 2017, to end the mission.
https://www.youtube.com/watch?v=xrGAQCq9BMU
#Enceladus #Saturn #Cassini
15/n

NASA at Saturn: Cassini's Grand Finale

YouTube

Marshall Eubanks Jun 4, 2023

@AkaSci I would still go for a fast flyby sample return.

Richard Jun 4, 2023

@AkaSci It will be okay. I just emailed the president. This project will move forward on time. I have some matter of influence.

KanaMauna Jun 7, 2023

@AkaSci $2.5 B is chump change for a billionaire. If #BEZOS had any brains, he'd sponsor it to get ahead of #muskrat and #zuckbot