trajectory meant that if no further burns were performed, Apollo 13 would miss Earth on its return trajectory, rather than intercept it, as with a free return. A free return trajectory could only reach sites near the lunar equator; a hybrid trajectory, which could be started at any point after TLI, allowed sites with higher latitudes, such as Fra Mauro, to be reached. Communications were enlivened when Swigert realized that in the last-minute rush, he had omitted to file his federal income tax return (due April 15), and amid laughter from mission controllers, asked how he could get an extension. He was found to be entitled to a 60-day extension for being out of the country at the deadline. Entry into the LM to test its systems had been scheduled for 58:00:00; when the crew awoke on the third day of the mission, they were informed it had been moved up three hours and was later moved up again by another hour. A television broadcast was scheduled for 55:00:00; Lovell, acting as emcee, showed the audience the interiors of Odyssey and Aquarius. The audience was limited since none of the television networks were carrying the broadcast, forcing Marilyn Lovell (Jim Lovell's wife) to go to the VIP room at Mission Control if she wanted to watch her husband and his crewmates. Accident Approximately six and a half minutes after the TV broadcastapproaching 56:00:00Apollo 13 was about from Earth. Haise was completing the shutdown of the LM after testing its systems while Lovell stowed the TV camera. Jack Lousma, the CAPCOM, sent minor instructions to Swigert, including changing the attitude of the craft to facilitate photography of Comet Bennett. The pressure sensor in one of the SM's oxygen tanks had earlier appeared to be malfunctioning, so Sy Liebergot (the EECOM, in charge of monitoring the CSM's electrical system) requested that the stirring fans in the tanks be activated. Normally this was done once daily; a stir would destratify the contents of the tanks, making the pressure readings more accurate. The Flight Director, Kranz, had Liebergot wait a few minutes for the crew to settle down after the telecast, then Lousma relayed the request to Swigert, who activated the switches controlling the fans, and after a few seconds turned them off again. Ninety-five seconds after Swigert activated those switches, the astronauts heard a "pretty large bang", accompanied by fluctuations in electrical power