Question

clearing out junk in space
\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.
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.
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 with 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.
one of the biggest problems with garbage in space is not the garbage
which sentence best expresses the central idea of the passage?

1. spacecraft can maneuver to avoid colliding with space junk.
2. collisions in space increase the amount of junk that is in orbit.
3. reducing space junk is important to the success of future space missions.
4. astronauts use a sophisticated system to dispose of used batteries and supplies.

Explanation:

The passage focuses on the issue of space junk disposal, including the tasks astronauts perform to deal with garbage in space and the methods used for trash disposal at the International Space Station. It emphasizes that space junk is a problem and reducing it is crucial for future space missions.

Answer:

1. Reducing space junk is important to the success of future space missions.