Source: Revised GRE PDF 2nd Ed. Section 3; #2 (p. 51)


Most spacecraft are still at little risk

Most spacecraft are still at little risk of collision with space debris during their operational lifetimes, but given the numbers of new satellites launched each year, the orbital environment in the future is likely to be less _________. crowded, invulnerable, protected, polluted, benign

7 Explanations


Abhishek Gupta

Protected and Invulnerable are wrong as it is used in reference to orbital environment. Do we protect satellites or orbital environment ? The same goes with the invulnerable -> what is vulnerable satellite or the environment ?.
Clearly crowded and polluted are wrong.
So, we are left with benign. (An environment can be friendly not the a satellite..right usage.)

Sep 11, 2020 • Comment

Adam Lyons, Magoosh Tutor

You got it!

Sep 14, 2020 • Reply


Ujjwal Prazapati

Can I take it as that it's the environment initially which has less debris and that's why safe for aircrafts but if we increase the number of spacecrafts launch then chances of collision will increase and environment may become harmful

Sep 16, 2019 • Comment

Sam Kinsman

Yes that's right!

Sep 18, 2019 • Reply



Hi, I read the above replies but no one asked about "invulnerable". "Invulnerable" is a synonym of safe, so why don't "invulnerable" work here?

Jul 4, 2018 • Comment

Sam Kinsman

The word "invulnerable" means "immune to attack" and "impossible to damage." So if we choose this word, the sentence will say that the orbital environment will be less impossible to damage (i.e. more possible to damage). That's not what we are trying to say! Instead, we are trying to say that the orbital environment will be less safe for spacecrafts.

Jul 5, 2018 • Reply


Does this mean that if we change the subject to spacecraft, "invulnerable" will be the answer?

Aug 28, 2019 • Reply

David Recine, Magoosh Tutor

Shu-- yes, if we replace the word "environment" with "spacecraft," then "invulnerable" could work. In that case, though, "protected" would also work. :)

Sep 13, 2019 • Reply



Hi chris, i'm little bit baffle about to be "less polluted" means safe. when i solved that problem, i am also came of same word "safe". that's why i choose pollute, and also tempting with environment. Could you explain me.please

Aug 31, 2016 • Comment

Sam Kinsman

The first sentence explains that spacecrafts run the risk of crashing into space debris. If the orbital environment will be "less polluted" in the future, it means that there will be fewer space debris that a spacecraft could crash into. This would make the orbital environment safer for spacecrafts.

Sep 2, 2016 • Reply


swapnil asawa

Hi Chris i am confused on this one. less invulnerable (less immune to attack) also seems to fit the meaning....could you please throw some time.

Dec 29, 2014 • Comment

Jonathan , Magoosh Tutor

Hi! The problem with "less invulnerable" is that the blank is describing the orbital environment. It's not the environment that's less invulnerable/more vulnerable. It's the SPACECRAFT that is likely to be less invulnerable.

The blank needs to refer to ENVIRONMENT and mean that the ENVIRONMENT is less safe. That's why only "benign" works.

Because the environment will be less benign, the spacecraft in the environment will be more vulnerable.

I hope that helps!

Jan 3, 2015 • Reply

KiranMayee Maddi

great!! got it!

Sep 24, 2017 • Reply

Ruth Wen


Aug 25, 2019 • Reply


Dharini Narayanan

I still dont get it as to why the answer is not protected! is it that something else is needed to protect the enviromnent?and hence it cannot equate safe?

Jul 18, 2014 • Comment

, Magoosh Tutor

You are really close here! I can tell that you understand the sentence and the ideas discussed, but "protected" doesn't work here.

You probably think that we need a word opposite of "risk" and that means that we have an environment that is more protected. But what is doing the protecting here? Nothing in the sentence indicates that anything is going to be protecting the satellites.

By choosing "protected" your skipping over the main idea in the second part of the sentence, specifically that things will be less "safe." We need to choose a word that is synonymous with "safe" and although protection leads to safety, this is not the relationship outlined in the passage.

Does that make sense? I hope I was able to help a little. :D

Jul 22, 2014 • Reply


Gravatar Chris Lele, Magoosh Tutor

Sep 20, 2012 • Comment

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