When we started thinking about what Collins' digital publishing could look like around Wonders of the Solar System and Wonders of the Universe by Professor Brian Cox, we knew it had to be ambitious, innovative and of course wonderful to look at and use. We began with a "what if" conversation in which the seeds of the final product were sown.

Having first decided to fold both books into one product, we wanted to augment Brian's written narrative with video from the BBC series, something the BBC had not permitted previously. Our vision was then to place this content within a 3D model of the Universe that demonstrated its scale and beauty, from the smallest particle to the edge of the known Universe.

We chose to break down the Universe into seven realms: Sub atomic; Atomic; Solar system; Local stars; Galaxies and Universe. In each realm we would place related Wonders, from the planets and moons of the Solar System to Galactic Red Giants, Nebulae and Pulsar Stars. Content would be pinned to these models, making it tangible in the process, whilst the Universe level would habour the more abstract content around light, time and gravity.

We wanted the user experience to be one of unconstrained discovery so we gave them the option of jetting off on their own through the 3D Universe, to a Black Hole for example, where they could call up related content on arrival. But, if they preferred, they could take Brian Cox's guided tours of the Solar System and the Universe for a more curated experience. For the non-linear approach it would mean chunking up the content and tagging it to the various models we'd create.

This brief was well beyond the capabilities of epub, .iba or KF8, so the product was clearly going to be an app. Though Collins had been a first mover in the app space, publishing the SAS Survival Guide in 2009 and clocking up 150,000 sales to date at £3.99, subsequent commissions have had mixed fortunes, leading us adopt our current app strategy of Fewer, Bigger, Better. We felt confident that this branded and creative proposition would break out and would justify investment. Where other astronomy apps charted planetary positions and orbits, and were limited in scope to the Solar System, Brian Cox's Wonders of the Universe would deliver users a 3D universe at their fingertips underpinned by a contextual rich-media story of its creation and ultimate demise.

We found a development partner brave enough to take on this enterprise in the other media, a London based agency that grasped the brief wholeheartedly and proposed to create a bespoke 3D engine to create the models and enable the user to move smoothly between the seven levels. There were interesting discussions about what exactly a black hole should look like, given it’s a theoretical construct that's never been seen by human eyes, but they heroically created a convincing incarnation sucking down a hapless star. They also built a beautiful reading experience in which users can drag up a page from a thumbnail at the bottom of the screen, incorporating Brian's text, image galleries and BBC video clips, which we had by then reached usage agreement on. As a final flourish the app was optimised for the new iPad's screen resolution, making a drift through the Lagoon Nebula a particularly spectacular experience.

Though as the publisher I'm biased, the final product really is wonderful, a true showcase app that sets a new benchmark for UI, content and production values. With it now completed, the focus shifts to consumer discovery. Our pricing is low initially, just £4.99 for the first few weeks.

Rather than take the fingers crossed approach to sales - do nothing and hope for organic take up - we've liaised with Apple at an early stage to whet their appetite in the hope of iTunes promotion, planned a media campaign spanning social, paid search, and PR and for the first time partnered with a US PR agency to drive take-up in the States, given that our success on other apps had derived primarily from US sales.