If God sends asteroids to destroy the earth, then nothing can be done to stop the destruction.
Even to a non determinist, you would think they would admt God wont permit such a thing against His will.
And as Christians, we should know this earth is marked out for destruction, we look forward to a new heaven and a new earth where there is no more evil. The old ones are dissolved in fire.
2 Peter 3
The Day of the Lord
10 But the day of the Lord will come as a thief in the night, in which the heavens will pass away with a great noise, and the elements will melt with fervent heat; both the earth and the works that are in it will be [d]burned up. 11 Therefore, since all these things will be dissolved, what manner of persons ought you to be in holy conduct and godliness, 12 looking for and hastening the coming of the day of God, because of which the heavens will be dissolved, being on fire, and the elements will melt with fervent heat? 13 Nevertheless we, according to His promise, look for new heavens and a new earth in which righteousness dwells.
For the world, this destruction comes as a thief in the night so unexpectedly, no warning system is going to work.