Nasa Apollo 15 Sleep Ambience - No music, no distractions , just the real sound of space missions. Tapes 548 / 549 / 550 ~ Hours 45–54 GET | July 28, 1971 | Day 3 of the Mission Translunar Coast — Approximately 158,000–170,000 nautical miles from Earth Tape 548-AAA (~Hours 45–47) The crew is still deep in their rest period, which began at around 39:58 GET. Mission Control is running a quiet watch, monitoring systems and giving hourly status updates to the media. There are no calls to or from the crew. The spacecraft is in Passive Thermal Control (the "barbecue roll"), rotating slowly at about 3 revolutions per hour to distribute solar heating evenly. The PAO is giving out range and velocity updates: the ship is around 158,000–160,000 nautical miles out, traveling at roughly 3,600 feet per second - slowing noticeably as Earth's gravity still has its grip. Flight Director Glynn Lunney and his Black Team are wrapping up their shift. The atmosphere in Mission Control is quiet and routine. Tape 549-AAA (~Hours 47–49) This is where the notable handover happens. At 47 hours GET, Mission Control announces that Flight Director Glynn Lunney is going off-shift and is being replaced by Flight Director Gerald "Gerry" Griffin and his Gold Team. The CapCom on the incoming shift is astronaut Joe Allen. A change-of-shift press briefing is anticipated, to be held at the MSC News Center briefing room in about an hour. At this point, there is about 1 hour remaining in the crew's rest period, however, Mission Control notes that if the crew wants to sleep an extra hour, they will allow it. No wake-up call will be made at the scheduled time unless the crew calls first. By around 47:57 GET, the handover is complete. Gerry Griffin goes over the day's activities with controllers at each console. Glynn Lunney heads off to hold the change-of-shift press briefing. The spacecraft is now around 160,800 nautical miles from Earth, velocity down to about 3,553 feet per second. Shortly after 49:00 GET, the first communication with the crew occurs at 49:04:11 GET — the crew is up. They get a leisurely start, having taken the opportunity to sleep in slightly. Tape 550-AAA (~Hours 49–54) The day gets going properly now. The crew has breakfast and Joe Allen serves as the voice from Mission Control. Around 50:23 GET, the crew is in the middle of their morning meal. Apollo 15 is now 165,733 nautical miles from Earth, traveling at 3,440 feet per second. At 51:08 GET, Mission Control checks in again. The crew is preparing for the day's main science highlight. At 51:37:31 GET — the Light Flash Experiment begins. This was a formal DTO (Developmental Test Objective) unique to Apollo 15. Apollo 15 was the first mission to use special light-tight eye shades to provide a uniform and reproducible degree of darkness for the experiment, with the crew verbally calling out each flash as they occurred to Mission Control during a one-hour observation period. Ninfinger All three crewmen - Dave Scott, Al Worden, and Jim Irwin - put on their blackout eye shades and sit in the darkened cabin. Each time they see a flash of light (caused by cosmic ray particles passing through the fluid of their eyes or directly stimulating the optic nerve), they call it out to Joe Allen, describing its character - whether it was a streak, a spot, a diffuse glow, its perceived location in the visual field, and which eye it appeared in. At around 51:50 GET, Scott calls "Mark CDR." At 51:52, Irwin reports: "Mark LMP. And this one did have a streak nature to it. Like it went from 8 o'clock over to the plus X position." The flashes come in clusters - one or two per minute at times, then a dearth of events for six minutes or more. Around 52:19, Allen checks in: "15, Houston. Are you still with us?" - suggesting a quiet patch. At 52:33 GET, Allen wraps up the formal observation period: "Dave. We're coming up on 60 minutes here too. And I think that's certainly an adequate period."
