It debuts with a 2 hour premiere in America tonight (Dec 15) but Syfy's 3 day special, Ascension - a murder mystery set in space - is to be aired in the United Kingdom by Sky1 from January 16th. This is the main cable channel in the UK so them picking it up suggests the show is really pretty good.
IGN has given it a great review
words - kindalingers
Sky 1 pick up - http://www.digitalspy.co.uk/tv/news/a616647/sky1-to-air-syfy-series-ascension-in-january
show website with info about the alternate history and setting - http://www.syfy.com/ascension
trailer - https://www.youtube.com/watch?v=AJqQ4OdPcAo