Question

clearing out junk in space
1
\dont forget to take out the garbage!\ many teenagers hear this familiar parental reminder on a daily or weekly basis, depending on where they live. disposing of common household trash is a fairly simple task. but on spacecraft, astronauts must use a more sophisticated method for clearing out junk.
2
during u.s. space shuttle missions from 1981 to 2011, astronauts had to perform many tasks, including cleaning windows, doing dishes, and taking out the trash. once they filled their allotted waste bins, crews moved the garbage to an area separate from their living quarters. there, the trash remained until the shuttle returned to earth. to eliminate odors from decaying refuse, astronauts used a special vacuum to vent foul smells into space.
3
today, the international space station (iss) uses a different process for trash disposal. since astronauts reside there for up to six months at a time, a large quantity of garbage accumulates. astronauts need to avoid a stockpile because some waste can grow microbes that pose health risks. to remove trash, a garbage truck of sorts visits the spacecraft periodically. this unmanned spaceship arrives with food, equipment, and other supplies. then, it is launched back to earth carrying hazardous waste like used batteries and medical supplies, as well as harmless trash—discarded food tubes and dirty clothes. upon reaching earths atmosphere, the cargo and craft incinerate. using expendable vehicles keeps manned crews safe by limiting their exposure to noxious substances, including chemical and radioactive waste.
4
one of the biggest problems with garbage in space is not the garbage
what is the main purpose of the passage?

1. to promote a plan to reduce space junk
2. to inform about the threat of space junk
3. to question methods used to track space junk
4. to challenge the idea that space junk is a problem

Explanation:

The passage describes how astronauts on spacecraft (like space shuttles and the ISS) deal with junk, including methods of disposal and reasons for certain processes (e.g., avoiding microbe growth, protecting crews). Option 1 is incorrect as no plan to reduce space junk is promoted; the passage focuses on disposal methods, not reduction plans. Option 3 is wrong as the passage doesn't question tracking methods. Option 4 is incorrect as it doesn't challenge the idea that space junk is a problem. Option 2 is correct because the passage informs about the threat (e.g., health risks from microbes, need for special disposal) and how it's managed, which relates to the threat of space junk.

Answer:

1. to inform about the threat of space junk