Director James Gray’s lush new space opera Ad Astra is essentially two parallel films. One is a visually inventive science fiction odyssey that imagines near-future space travel as the new Wild West frontier. The other is a tepid father / son drama that Gray and his co-writer, Ethan Gross, don’t even try to elevate above the most threadbare clichés. The latter film doesn’t entirely drag down the former, although it seems to be trying its ready best.