Images from ground-based telescopes are invariably distorted by the Earth's atmosphere. Orbiting space telescopes, however, operating above Earth's at...

GMAT Critical Reasoning : (CR) Questions

Source: Official Guide

Critical Reasoning

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Images from ground-based telescopes are invariably distorted by the Earth's atmosphere. Orbiting space telescopes, however, operating above Earth's atmosphere, should provide superbly detailed images. Therefore, ground-based telescopes will soon become obsolete for advanced astronomical research purposes.

Which of the following statements, if true, would cast the most doubt on the conclusion drawn above?

An orbiting space telescope due to be launched this year is far behind schedule and over budget, whereas the largest ground-based telescope was both within budget and on schedule.

Ground-based telescopes located on mountain summits are not subject to the kinds of atmospheric distortion which, at low altitudes, make stars appear to twinkle.

By careful choice of observatory location, it is possible for large-aperture telescopes to avoid most of the kind of wind turbulence that can distort image quality.

When large-aperture telescopes are located at high altitudes near the equator, they permit the best Earth-based observations of the center of the Milky Way Galaxy, a prime target of astronomical research.

Detailed spectral analyses, upon which astronomers rely for determining the chemical composition and evolutionary history of stars, require telescopes with more light-gathering capacity than space telescopes can provide.

Solution

Passage Analysis:

Text from Passage	Analysis
Images from ground-based telescopes are invariably distorted by the Earth's atmosphere.	What it says: Ground-based telescopes always produce distorted images because of Earth's atmosphere What it does: Sets up a problem with current telescope technology What it is: Author's claim about existing limitations
Orbiting space telescopes, however, operating above Earth's atmosphere, should provide superbly detailed images.	What it says: Space telescopes should give much better, clearer images since they're above the atmosphere What it does: Presents a solution that contrasts with the ground-based telescope problem What it is: Author's claim about space telescope advantages Visualization: Ground telescopes (distorted images) vs Space telescopes (crystal clear images)
Therefore, ground-based telescopes will soon become obsolete for advanced astronomical research purposes.	What it says: Ground-based telescopes will become useless for serious astronomy research What it does: Draws a conclusion by combining the atmosphere problem with space telescope advantages What it is: Author's main conclusion

Argument Flow:

The argument starts by identifying a fundamental problem with ground-based telescopes (atmospheric distortion), then presents space telescopes as a superior alternative that avoids this problem, and finally concludes that this superiority will make ground-based telescopes obsolete.

Main Conclusion:

Ground-based telescopes will soon become obsolete for advanced astronomical research purposes.

Logical Structure:

The argument uses a simple comparison structure: if ground-based telescopes have a major flaw (atmospheric distortion) and space telescopes don't have this flaw (operating above atmosphere), then the superior technology (space telescopes) will replace the inferior one (ground-based telescopes). The logic assumes that image quality is the only important factor in determining telescope usefulness.

Prethinking:

Question type:

Weaken - We need to find information that would reduce our belief in the conclusion that ground-based telescopes will become obsolete for advanced astronomical research

Precision of Claims

The conclusion makes a strong claim about future obsolescence ('will soon become obsolete') and specifies the scope ('for advanced astronomical research purposes'). The argument assumes space telescopes are clearly superior based solely on image quality.

Strategy

To weaken this conclusion, we need to find scenarios that show ground-based telescopes might still have value for advanced research despite their atmospheric distortion problem. We can't deny the facts that atmosphere distorts ground images or that space telescopes provide clearer images, but we can question whether image clarity is the only factor that matters for research purposes.

Answer Choices Explained

An orbiting space telescope due to be launched this year is far behind schedule and over budget, whereas the largest ground-based telescope was both within budget and on schedule.

This choice focuses on scheduling and budget issues with one specific space telescope project. While this might delay the adoption of space telescopes, it doesn't address the fundamental argument about whether space telescopes are actually superior for research purposes. The author's conclusion is based on technological superiority, not project management efficiency. A temporary delay doesn't mean ground-based telescopes won't eventually become obsolete when space telescopes are finally deployed.

Ground-based telescopes located on mountain summits are not subject to the kinds of atmospheric distortion which, at low altitudes, make stars appear to twinkle.

This partially challenges the premise by suggesting that atmospheric distortion can be minimized at high altitudes. However, it doesn't completely eliminate the atmosphere problem - it just reduces it. The author's argument would still hold because space telescopes would still provide superior image quality compared to even the best mountain-based ground telescopes. This doesn't give ground-based telescopes a compelling advantage.

By careful choice of observatory location, it is possible for large-aperture telescopes to avoid most of the kind of wind turbulence that can distort image quality.

Similar to choice B, this suggests that careful positioning can reduce (but not eliminate) some atmospheric interference from wind turbulence. However, this only addresses one type of atmospheric distortion and still leaves space telescopes with the fundamental advantage of operating completely above the atmosphere. The conclusion about obsolescence could still stand.

This mentions that ground-based telescopes at certain locations can provide good observations of specific targets like the Milky Way center. While this shows ground telescopes have some capabilities, it doesn't establish that they have advantages that space telescopes lack. Space telescopes could presumably observe the same targets with even better image quality.

This introduces a completely new factor that the argument failed to consider - light-gathering capacity. The choice states that detailed spectral analyses, which are essential for advanced astronomical research (determining chemical composition and evolutionary history of stars), require more light-gathering capacity than space telescopes can provide. This directly contradicts the conclusion by showing that ground-based telescopes have a crucial advantage for specific types of advanced research that space telescopes cannot match, regardless of image quality.

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