I'm going to tell you that I have a very low threshold for scary things. So if I say that a book freaked me out you can take it with a grain of salt. That said, The Last Astronaut, which was a bit of Alien, a bit of The Martian and some Major Tom vibes thrown in, made me read with one eye closed for the latter half of the book as the creeping dread of the unknown grew.
The last astronaut of the story is Sally Jensen. Jensen was in charge of a mission to Mars years ago (prologue of the book) that went disastrously and fatally wrong. After that mission debacle NASA lost most of its funding and Jensen was "retired". She's since built a life and has mostly been able to leave her dreams of space behind. But that could change. Scientists have detected a massive object heading towards earth and not only is it very, very large, it has suddenly increased speed. So clearly it's not just another asteroid and Sally's quiet retirement is disrupted when she's called back into service to lead a new team to investigate the object.
I won't tell you too much more as I don't want to spoil anything, but I will tell you that I read this one cover to cover and the slow build to the climax was a thrill ride.