The film has a clever dodge for avoiding the inevitable silly moment when the aliens are revealed but, in a few too many scenes, this is a bit more snore than awe.

It is a fantasy, but it’s more confrontational than escapist. It doesn’t want us to turn our brains off. It wants us to think.

Other cerebral sci-fi films such as Contact or Arrival may have already answered some of the questions posed here - and with a much higher budget - but this is still an intriguing contemplation.

Consisting mostly of rocket scientist conversations about astrophysics, 'Signal One' is nevertheless far more intriguing than anything in 'Disclosure Day.'