16Hit1600
Expression of IdeasVery hardRhetorical synthesis: framing a result as contrary to expectation

Expression of Ideas practice question

While researching a topic, a student has taken the following notes: • In 2020, NASA's OSIRIS-REx spacecraft briefly touched the surface of the asteroid Bennu to collect a sample. • Models developed before the mission predicted that Bennu's surface consisted of tightly packed rubble firm enough to support the spacecraft's weight. • Instead, images and force data showed that the spacecraft sank about half a meter into the surface before its thrusters fired to push it away. • Analysis led by planetary scientist Kevin Walsh concluded that the surface is so loosely packed that it behaves much like a pit of plastic balls. • Walsh's team estimates that Bennu's surface is roughly 50 to 60 percent empty space.

The student wants to explain why the spacecraft's behavior during the sampling maneuver surprised the mission's scientists. Which choice most effectively uses relevant information from the notes to accomplish this goal?

  1. A. In 2020, NASA's OSIRIS-REx spacecraft briefly touched down on the asteroid Bennu, sinking about half a meter into the surface before firing its thrusters to back away.
  2. B. Although models developed before the mission had predicted a surface of tightly packed rubble firm enough to support the spacecraft, OSIRIS-REx sank about half a meter into Bennu before its thrusters fired.Correct
  3. C. Walsh's team concluded that Bennu's surface is roughly 50 to 60 percent empty space, so loosely packed that it behaves much like a pit of plastic balls.
  4. D. Models developed before the mission predicted that Bennu's surface consisted of tightly packed rubble that would support the weight of a spacecraft.

Answer: B. Although models developed before the mission had predicted a surface of tightly packed rubble firm enough to support the spacecraft, OSIRIS-REx sank about half a meter into Bennu before its thrusters fired.

A result can be shown to be surprising only by juxtaposing it with what was expected, and B does exactly that: prediction (firm, packed rubble) versus observation (sinking half a meter). (A) narrates the event accurately but omits the prior prediction, so nothing marks it as unexpected — the error of reporting the outcome alone. (D) supplies only the prediction, with no observation to contradict it — the mirror-image error. (C) is the strongest trap: it explains why the spacecraft sank (a nearly empty, loosely packed surface), but a physical cause is not the same as a violated expectation, so it explains the sinking rather than the surprise.

Why the other answers are wrong

A. In 2020, NASA's OSIRIS-REx spacecraft briefly touched down on the asteroid Bennu, sinking about half a meter into the surface before firing its thrusters to back away.
This accurately reports the sinking, but with no mention of what scientists had predicted, there's nothing to make the outcome surprising — surprise requires the expectation alongside the result.
C. Walsh's team concluded that Bennu's surface is roughly 50 to 60 percent empty space, so loosely packed that it behaves much like a pit of plastic balls.
This explains *why* the spacecraft sank (a surface that's 50-60 percent empty space), but a physical cause isn't a violated expectation; you need the pre-mission prediction to show why scientists were caught off guard.
D. Models developed before the mission predicted that Bennu's surface consisted of tightly packed rubble that would support the weight of a spacecraft.
This gives only the prediction with no observation to contradict it — the mirror image of stating the outcome alone. A surprise needs both halves.

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