 Movement by the astronauts was detected by the spacecraft 's inertial measurement unit and the astronaut 's biomedical sensors , and also indicated by increases in oxygen spacesuit flow , and sounds from Grissom 's stuck @-@ open microphone . There was no evidence to identify the movement , or whether it was related to the fire . The stuck microphone was part of a problem with the communications loop connecting the crew , the Operations and Checkout Building , and the Complex 34 blockhouse control room . The poor communications led Grissom to remark : " How are we going to get to the Moon if we can 't talk between two or three buildings ? " The simulated countdown was held again at 5 : 40 pm while attempts were made to troubleshoot the communications problem . All countdown functions up to the simulated internal power transfer had been successfully completed by 6 : 20 pm , but at 6 : 30 the count remained on hold at T minus 10 minutes . 
