His hands flew over the control panel's switches, levers and dials as he begun to croon out a haunting Venusian aria in a deep baritone. So he didn't notice when the TARDIS slipped into an alternate field and away from where the Doctor was originally headed (which was a side step from the destination the Brigadier had given him).
With a thunk and a sudden power suspension, the TARDIS landed and the Doctor felt that something wasn't right. Of course, it went unheeded as those feelings often did. Instead of worrying, he simplyed flicked the switch that opened the doors and stepped out in a twirl of opera cape and crushed velvet.
...but this wasn't what he was expecting. He was supposed to have landed on one of Jupiter's moons during a month long celebration of children, relationships and marriage. It was supposed to be colourful and jolly, not dark, dank and pungent. However, as he turned back to re-check the coordinates on the TARDIS, it began to dematerialise right before him. With him outside!
"What are you doing?" he asked as the blue police box faded from view. "Come back!" but it was no use. The TARDIS continued to disappear and no amount of shouting was going to bring it back.
The Doctor ran a hand through his silver curls and tried to think of a way he could get the TARDIS back. He had his screw driver, of course but he'd need a stronger power source to boost its connection to his ship so that he could pull it back to him from out of the Space Time Vortex.