Rate the following argument fragment on its writing, argument, and language skills:
Evidence: These differences in speed mean that sometimes we are closer to Mars and other times to Venus because Venus is sometimes right around the corner-in space terms-humans have sent numerous spacecraft to land on this cloud draped world. Each previous missions was unmanned, and for good reason, since no spacecraft survived the landing for more than a few hours. This issue explains why not a single spaceship had landed on Venus and numerous factors contribute to Venus's reputation as a challenging planet for humans to study.

Score: 1