Images from ground-based telescopes are invariably distorted by the Ea

I have one doubt-: Option E just states that Space telescopes have some adversaries . But It doesn't mean that Ground telescope have these benefits . Thats why i chose A over E. Can someone please explain me this?

saby1410, aritrar4, mk96, enigma1504 - Missed some tags to this question. Here is a detailed analysis. Hope you find it useful.

Images from ground-based telescopes are invariably distorted by the Earth's atmosphere (in some way, whether winds, dust etc)

Orbiting space telescopes (above Earth's atmosphere) should provide superbly detailed images. Note the use of "should" - presumably because Earth's atmosphere does not interfere in their working. Does it actually happen, we don't know.

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

We need to weaken that ground based telescopes will become obsolete. They may have a disadvantage to space telescope but they may have some advantage too. Let's look at the options.

(A) 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.

Irrelevant. There is no implication here that orbiting telescopes are far more expensive and difficult to launch. We are just told about this year's project is lagging while the project of ground telescope was on time and budget. We don't know what budget was allocated to each project.

(B) 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.

So one kind of atmospheric distortion (which makes stars appear to twinkle) can be taken care of by placing the ground based telescopes on mountain summits. But does this take care of all atmospheric distortions? Does it make ground based telescopes relevant? We don't know. So will ground based telescopes become obsolete? Can't say.

(C) 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.

So another kind of issue can be taken care of by carefully choosing location. So again, does this mean ground based telescope will stay relevant? Cannot say.

(D) 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.

How we get the best "Earth based observations" is irrelevant.

(E) 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.

A certain method which is used by astronomers to find data about stars requires telescope with more light gathering capacity than space telescopes. For at least this application then, ground telescopes will remain relevant. It is a method used by astronomers so it is reasonable to assume that ground based telescopes provide this facility. Else, how do the astronomers use detailed spectral analyses? After all, astronomers rely on it for determining the history of stars.
Hence it weakens that ground based telescopes will soon become obsolete for advanced astronomical research purposes.

Answer (E)

VeritasKarishma ChiranjeevSingh GMATNinja


To reject D, can we also say that it talks about astronomical research, whereas the conclusion talks about advanced astronomical research.

Milky way galaxy may be a target of astronomical research but may not be of advanced astronomical research.

Thank you in advance!

saby1410, aritrar4, mk96, enigma1504 - Missed some tags to this question. Here is a detailed analysis. Hope you find it useful.

Images from ground-based telescopes are invariably distorted by the Earth's atmosphere (in some way, whether winds, dust etc)

Orbiting space telescopes (above Earth's atmosphere) should provide superbly detailed images. Note the use of "should" - presumably because Earth's atmosphere does not interfere in their working. Does it actually happen, we don't know.

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

We need to weaken that ground based telescopes will become obsolete. They may have a disadvantage to space telescope but they may have some advantage too. Let's look at the options.

(A) 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.

Irrelevant. There is no implication here that orbiting telescopes are far more expensive and difficult to launch. We are just told about this year's project is lagging while the project of ground telescope was on time and budget. We don't know what budget was allocated to each project.

(B) 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.

So one kind of atmospheric distortion (which makes stars appear to twinkle) can be taken care of by placing the ground based telescopes on mountain summits. But does this take care of all atmospheric distortions? Does it make ground based telescopes relevant? We don't know. So will ground based telescopes become obsolete? Can't say.

(C) 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.

So another kind of issue can be taken care of by carefully choosing location. So again, does this mean ground based telescope will stay relevant? Cannot say.

(D) 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.

How we get the best "Earth based observations" is irrelevant.

(E) 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.

A certain method which is used by astronomers to find data about stars requires telescope with more light gathering capacity than space telescopes. For at least this application then, ground telescopes will remain relevant. It is a method used by astronomers so it is reasonable to assume that ground based telescopes provide this facility. Else, how do the astronomers use detailed spectral analyses? After all, astronomers rely on it for determining the history of stars.
Hence it weakens that ground based telescopes will soon become obsolete for advanced astronomical research purposes.

Answer (E)

Option E . How is it correct?

It is highlighting the limitation Space Telescope but no where mentioned that the GBT has no such limitation or GBT is better than Space Telescope.

Regards

Hi Vibha6,

Let's put some of the information given in the stimulus and in option E down:

1. Astronomers rely on DSA. This means that astronomers are already using DSA to determine the chemical composition and evolutionary history of stars.
2. Space telescopes cannot provide DSA; DSA can be provided only by telescopes with more light-gathering capacity than space telescopes can provide. So DSA needs non-space telescopes.

Because astronomers are already using DSA, and space telescopes can't do DSA, astronomers must be using telescopes that are not space telescopes. Such telescopes must be terrestrial (the opposite of space). Hence E is quite solid as an answer choice.

Wouldn't you agree - B DOES cast doubt on the conclusion, at least a bit ? Here is how

Answer B only compares two types of ground-based telescopes -- it only tells us that some ground telescopes are better than others. It doesn't give us any reason to think that ground telescopes will be more useful, in some cases, than space telescopes, so it doesn't weaken the conclusion.

We already know as a factual premise from the stem that ground telescopes (whether placed on mountains or placed in canyons) are subject to distortion from the atmosphere, while space telescopes are not. Answer B just says that some ground telescopes experience less distortion than others, which still doesn't give us any reason to prefer ground telescopes to space telescopes, no matter where we put the ground telescope.

- Blackberry phones invariably weigh heavier
- Average blackberry phone weight is 2 pounds
- Apple phones weigh 1.5 pounds

Conclusion : Blackberry phones are too heavy for folks who want light pockets

I would think this version of option B would be a weakener
Option B) When it comes to blackberry phones specifically – you can remove the physical keyboard from the phone completely – dropping the blackberry phone’s weight to 1.6 pounds

This will weaken because perhaps folks are okay with a 1.6 pound phone in their pockets BUT not a 2 pound phone in their pockets.

Other than ground-based telescopes and space telescopes -- how do you know there is not a 3rd type of telescope

Hi avigutman – I don’t know because if was to create the following analogy when it comes to option B