I went with a three. I agree the science is dodgy, but I don't watch Doctor Who for scientific accuracy. I found it enjoyable enough, and I liked the shambolic expedition.
There is a nice big full moon ... in broad daylight. Full moons by definition rise at sundown, it should not have been bright and sunny on that beach.
No, it rises at 6 pm sun-time, which isn't always the same thing. Where I live, at the summer solstice the full moon would have been up for a couple of hours by sunset. It's not entirely clear where that beach was.
Speaking of astronauts, why do they all have British accents?
I suppose for much the same reason that they always have American accents in US shows