Question

nasa, which continues to research the effects of space travel on humans, has a lot more work to do to make it safe for humans to travel to mars. until then, pillownauts will continue to lie down on the job. reread the underlined sentence in the passage. what does it tell you about humans and mars? travel to mars is currently unsafe for humans. faster spaceships are needed to carry humans to mars. nasas attempts to send humans to mars are unsuccessful. nasa is doing research with humans on mars.

Explanation:

The underlined sentence mentions that NASA has more work to do to make human travel to Mars safe. This implies that currently, it is not safe. There is no mention of faster spaceships, unsuccessful attempts (just that more work is needed, not that past attempts failed), or research on Mars with humans (research is on space - travel effects, not on Mars itself).

Answer:

Travel to Mars is currently unsafe for humans.