Lecture 27: Icy World I

Question 1

why does europa have promise for astrobiologists?

Answer 1

subsurface liquid water ocean beneath icy crust

energy sources to support life as it makes use of tidal heating from jupiters gravity keeping the ocean warm

essential chemical ingredients suggested from spectral data that europas surface contains salts, organics, and possibly sulfur

Question 2

give atleast two lines of evidence for a subsurface ocean on europa

Answer 2

dark patches shown in images is though to be younger warm ice rising to the surface as the solid ice surface pulls apart from a subsurface ocean

images of surface show what we believe to be regions where ice is presumed to have broken away from a liquid ocean surface

europa generates an induced magnetic field allowing us to infer the interior structure, suggesting the presence of a conductive layer beneath the surface

Question 3

what evidence is there for a young surface on the moon?

Answer 3

very few impact craters suggesting surface is renewed regularly

surface features suggest ongoing geological activity as it is covered in ridges, fractures, and chaos terrain

Question 4

what is chaos terrain?

Answer 4

regions where ice is presumed to have broken away from a liquid ocean surface, believed to be analogous to pack-ice break-up

Question 5

why does europa have internal heating?

Answer 5

experiences tidal heating, small but significant, due to its non-circular orbit

surface estimated to distort from each tidal interaction, which is one explanation for its cracked ice surface

Question 6

what are some possible sources of energy and nutrients in europa?

Answer 6

CHNOPS
- from comets, asteroids, and the rocky core

energy
- radiation
- organics
- redox couples
- sunlight

nutrients
- bombardment
- crust connected to ocean

Question 7

what are some comparisons to other galilean moons, and why might callisto and ganymede have oceans?

Answer 7

callisto:
- surface is old and geologically stable, europas is geologically active and renewed regularly, shown by its ridges and fractures

• no tidal heating as too far away from jupiter, unlike europa
• make of rocks and ices, so potential for ocean

ganymede:
- has its own magnetic field, unlike europas induced one

• possibly several oceans between ices as a salty liquid water ocean can conduct electricity, which explains magnetic readings from moon

Question 8

what are the limitations of lo as a habitable environment?

Answer 8

• volcanically active
• complex sulfur cycle
• water-free (dead) world