1. A few centuries ago people didn’t travel in space. - Past Simple
2. It’s raining heavily now. - 6. Present Continuous
3. Tomorrow at this time they’ll be broadcasting this programme again. - 4. Future Continuous
4. He had finished his essay by 7 p. m. yesterday. - 1. Past Perfect
5. Nobody will read this book. - 5. Future Simple
6. She was cleaning the park with other volunteers all day long. - Past Continuous
7. Tornadoes usually occur in the spring. - 2. Present Simple
8. Present Perfect - похоже лишнее