Enceladus is a small icy moon, seemingly similar in chemical makeup tocomets,[3] with jets orgeysers of water erupting from its surface that might be connected to activehydrothermal vents at its subsurface water ocean floor,[4][5][6][7][8] where the moon's ocean meets the underlying rock, a prime habitat forlife.[9][10] The geysers could provide easy access for sampling the moon's subsurface ocean, and if there ismicrobial life in it, ice particles from the sea could contain the evidence astrobiologists need to identify them.[11] Anorganic-rich world,Titan has amethane cycle comparable in atmospheric and geological processes to Earth's water cycle.
Enceladus's south pole - Geysers spray water from many locations along the 'tiger stripes' feature.
The JET orbiter mission concept was proposed in 2011 by theJet Propulsion Laboratory to NASA'sDiscovery Program Mission #13.[12] During the orbiter's one-year mission, it would perform high-resolutionmass spectroscopy mapping that would determine what processes have shaped and are shaping the moons, and it would permit assessment of thehabitability potential of Enceladus and Titan.[8][12]
In order to meet the $450 million cost cap, the orbiter would carry only two instruments. It would orbitSaturn and make a total of 16 flybys of Enceladus and Titan, the closest ones at 900 km from Titan's surface.[12] In June 2015 NASA announced a list of five finalists for the current competition, but theJourney to Enceladus and Titan proposal was not selected.Lucy was selected on January 4, 2017, and was launched in October 2021.[1][2][13]
Titan's mystery cloudsNear-infrared radiation from the Sun reflecting offTitan's hydrocarbon seas.
The three goals of the mission are to determine the processes that have shaped and are shaping Enceladus and Titan, to assess theirastrobiological potential, and to investigate their formation and evolution.[12][14]
At Enceladus, the mission will determine composition and flux of material in the plume, and will produce temperature maps of the faults, tectonics and interior dynamics.[14] At Titan, it will characterize of the organic molecules in the upper atmosphere at different altitudes (> 900 km) and latitudes, and will produce high-resolution images for detailed study of features forming at different time-scales.[14]
The orbiter payload consists of two instruments:[12][14]
Infrared camera: 'Titan Imaging and Geology, Enceladus Reconnaissance' (TIGER) – This high-heritagethermographic camera exploits infrared wavelengths to image through Titan's thick atmosphere and would image the heat of Enceladus's fractures known as 'tiger stripes', permitting a detailed thermal modeling. It would provide 10× better imaging resolution of Titan's surface thanCassini, yielding 50 m/pix images of 15% of Titan's surface.
Mass spectrometer: 'Spectrometer for Titan and Enceladus Astrobiology Mission' (STEAM) – It would characterizeelements and molecules, including complexorganic molecules with 100× higher resolution, and 1000× better sensitivity thanCassini. STEAM is theRosetta flight-spare.
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