Return to Europa: Overview of the Jupiter Europa orbiter mission

The use of extra-terrestrial oceans to test ocean acoustics students

“…In addition to the assumption of S ¼ 35 g kg À1 in Eq. (1) (despite the uncertainty as to the ocean's ionic nature 9,13 ) and the assumption that Europa's water and ice were taken to have the properties of standard seawater and sea ice that characterize Earth's oceans (taking, for example, no account of any differences in the crystalline phase on Europa), they were further instructed to model the acoustic propagation as if Europa were a flat world with a constant value of g, and to assume that the signal would have sufficient signal to noise ratio (SNR) to be detected were it to reach the base of the ice pack.…”

“…5,11,12 III. CALCULATION FOR EUROPA For the purpose of providing a tractable examination question, Europa can be assumed to have an outer radius of 1560 km, and an ocean consisting of a depth H ¼ 100 km of water underneath a thickness h ice ¼ 20 km of ice (popular but not uniformly accepted dimensions 13 ). Europa's acceleration due to gravity at its surface is g ¼ 1:31 m s À2 .…”

Use of NanoSIMS to Identify the Lower Limits of Metabolic Activity and Growth by Serratia liquefaciens Exposed to Sub-Zero Temperatures

“…The spatial resolution was~150 nm. The isotopes 12 C, 13 C, 16 O, 18 O, 12 C 14 N, 12 C 15 N, and 32 S were simultaneously collected as negative secondary ions in electron multipliers. The mass resolving power (~7000) was sufficient to resolve any isotopic interferences, including 12 C 1 H and 13 C 14 N. Nitrogen isotopes are analyzed as CN.…”

“…For Mars, different icy terrains have been described such as polar caps, lake deposits, and ground ice; condensation on spacecraft struts; and permafrost. For Europa, an ice shell of 15 to 25 km thickness has been described above a liquid ocean in contact with a metal core likely possessing oceanic hydrothermal features [12,13]. Ice-dominated locations have been suggested as possible refugia of habitable niches that may support biological growth or may contain biosignatures of past or present life [14][15][16][17][18].…”

“…We performed a series of experiments to determine the boundaries of metabolism and growth for the bacterium, Serratia liquefaciens, at freezing and sub-zero temperatures by supplementing the growth medium with three isotopically labeled substrates including 13 C-glucose, ( 15 NH 4 ) 2 SO 4 , and H 2 18 O. The uptake and incorporation into cell biomass were assessed using NanoSIMS by simultaneously measuring the 13 C/ 12 C, 12 C 15 N/ 12 C 14 N, and 18 O/ 16 O ratios in the cells.…”