Read the sentences.

Some scientists are for a manned mission to Mars. Some scientists are against a manned mission to Mars. There is a lot for people to think about.

What is the best way to revise the sentences for fluency and word choice?

Some scientists are for a manned mission to Mars, while others are against a manned mission to Mars. People should think about it.
Since scientists have stated both pros and cons for a manned mission to Mars, there are a number of factors for people to consider.
There are pros for a manned mission to Mars. There are cons for a manned mission to Mars. There is a lot for people to think about a manned mission to Mars.
When it comes to a manned mission to Mars, people should take some time to think about it because some scientists feel there are pros, while other scientists feel there are cons.