The family's countdown to blast-off was documented by a BBC Horizon special, which had been following them for the past year.
It beat a BBC2 Horizon special about the hunt for the Higgs particle, which averaged 1.2 million viewers, 4.8% of the audience, including 95,000 on BBC HD.
BBC2 came out on top in the ratings battle of the fast turnaround meteor documentaries, with Horizon Special The Truth about Meteors averaging 3 million viewers and a 12% share in the 9pm hour.
It might have started off looking like a genteel Big Brother, but the BBC's two-part Horizon special How Mad Are You? had a rather more interesting question at its heart than everyone's favourite love-to-hate reality show.
The programme, a Horizon special, plumbed the archives for enlightenment and best practice since the postwar years, the era in which we started to take a bit more interest in our offspring.
Competition on the other main networks included BBC1's Antiques Roadshow (8pm: 5.667 million/21.6%) and Waking the Dead (9pm: 5.228 million/19.2%), and on BBC2 Japan Earthquake: A Horizon Special with Iain Stewart (8pm: 2.338 million/8.9%) and the final episode of professor Brian Cox's Wonders of the Universe (9pm: 2.76 million/10.2%).
On Tuesday night around 2.4m people in the UK tuned into BBC2 to watch a Horizon special on the science of the transit - a respectable audience for a science programme up against the live launch of Big Brother on Channel 5 (which had 2.7m viewers).
Competition at 9pm included BBC1's Silk (4.7 million/19.9%), BBC2's The Transit of Venus: a Horizon special (2.4 million/10.2%, including BBC HD), ITV1's Martin Clunes: the Lemurs of Madagascar (1.7 million/7%) and Channel 4's Jimmy and the Giant Supermarket (1.4 million/5.9%).
What's Killing Our Bees - A Horizon Special, BBC Two, 9pm.
