Data collected by the Cassini spacecraft during its flybys of Saturn's moon Enceladus reve… — SAT

Data collected by the Cassini spacecraft during its flybys of Saturn's moon Enceladus revealed the presence of silica nanoparticles in the plumes of water vapor erupting from the subsurface ocean. Laboratory simulations indicate that such nanoparticles can only form at temperatures above $90^\circ\text{C}$ in alkaline water that is in direct contact with a rocky core containing specific minerals. Because the surface temperature of Enceladus is constantly below $-180^\circ\text{C}$ , the detection of these nanoparticles in the plumes indicates that Enceladus's subsurface ocean ______.

Which choice most logically completes the text?

must contain areas where liquid water is heated to high temperatures at the boundary of its rocky core.Answer
B
is composed of water that has a uniform temperature matching the freezing surface environment.
C
will eventually evaporate entirely into space due to the constant eruption of water vapor.
D
is heated primarily by solar radiation that easily penetrates the moon's outer ice shell.

Answer

must contain areas where liquid water is heated to high temperatures at the boundary of its rocky core.

The correct option is supported because the passage states that the silica nanoparticles require temperatures above

90^\circ\text{C}

and direct contact with a rocky core containing specific minerals to form. Since these nanoparticles were detected in the plumes erupting from the subsurface ocean, it can be logically inferred that the ocean contains areas where water is heated to high temperatures through contact with the rocky core, despite the freezing surface environment.

Step-by-Step Solution

Identify the conditions required for the formation of the silica nanoparticles.

The nanoparticles only form in alkaline water at temperatures exceeding

90^\circ\text{C}

in direct contact with a rocky core.

This establishes the premise that must be satisfied for the nanoparticles to exist.

Relate these conditions to the observational evidence.

Silica nanoparticles were detected in the water vapor plumes erupting from Enceladus's subsurface ocean.

This indicates that the required formation conditions must exist somewhere within Enceladus.

Draw the logical inference that connects the surface temperature to the subsurface state.

Even though the surface is extremely cold, there must be localized regions at the rocky core where water is heated to at least

90^\circ\text{C}

This is the only way to account for the presence of the nanoparticles in the ocean's plumes without contradicting the given premises.

Key Concept

Drawing logical conclusions based on a set of scientific premises without introducing outside assumptions.

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