The Robert Carlyle-fronted sci-fi series was up slightly on last week's episode, which drew 635k (2.9%) over the same period.
Also on the multichannel stations, Dollhouse's latest offering managed 155k (1%) at 10pm, topping last week's season two opener, which logged a lowly 115k (0.7%).
Elsewhere, Holby City won its usual 8pm slot, bringing in 5.87m (24.3%) for BBC One. Its nearest rival, BBC Two's new series James May's Toy Stories, put in 3.54m (14.6%).
ITV1's Who Wants To Be A Millionaire had 3.22m (13.3%), 2.18m (9%) watched How To Look Good Naked on Channel 4, and Five's Nature Shock drew 1.18m (4.9%).
At 9pm, Around The World In 80 Days attracted 4.18m (17.9%) to BBC One, the second episode of 7 Days On The Breadline, which stars Mel B, Keith Allen, and Trinny Woodhall, grabbed 3.5m (15%), and 2.7m (11.5%) watched CSI: Miami on Five.
BBC Two's Horizon grabbed 1.6m (6.8%), and The Force interested 1.32m (5.6%) for Channel 4.
Overall, BBC One dominated Tuesday primetime with an average share of 23.2% to ITV1's 15.6%. BBC two was third with 8.8%, followed by Channel 4 with 6.1% (+1: 0.7%) and Five's 6.6%.
BARB ratings data supplied by Attentional