Each semester during the Earth & Moon segment of my astronomy course, I like to show this video for the class of the Apollo 11 liftoff. It gives the students, most too young to have witnessed this, an opportunity to see how the event was covered at the time. Also, it ties in well with the concepts learned in the prior module involving Newton’s Laws of Force. Many of the concepts apply to launches today and this is a good opportunity to break down NASA jargon into comprehensible English.
Working the broadcast that day for CBS was Walter Cronkite and Wally Schirra, who was an astronaut on three space missions including Apollo 7. The description of the video is as follows with the time being for the video rather than launch itself.
0:12 These are the 5 stage one F-1 engines each capable of producing 1.5 million pounds of thrust for a total of 7.5 million pounds of thrust. The Saturn V weight was 5 million pounds at launch. Newton’s third law states for every action, there is an equal and opposite reaction. The excess 2.5 million pounds of thrust is what lifted the Saturn V at launch. The engines were produced by Rocketdyne (dyne is Greek for power) which is now part of GenCorp Inc. Now known as Aerojet Rocketdyne, the company has had some difficult times recently. The center engine is referred to as the inboard engine and the four outer engines as the outboard engines. The outer four gimbal and guide the rocket.
0:30 The steam you see from the Saturn V is boil off from the cryogenically cooled liquid hydrogen and oxygen. Hydrogen boils at – 4230 F. That is only 360 F warmer than absolute zero. Oxygen boils at -2970 F. Venting the boiling liquid hydrogen and oxygen prevents the fuel tanks from being deformed. The black markings on the Saturn V are quarter marks and are used to study the roll of the rocket during launch.
0:43 The fuel tanks are continually pressurized until right before launch as discussed above, liquid hydrogen and oxygen boil at very low temperatures and the boiled off fuel needs to be replenished.
1:53 Walter Cronkite mentions the water deluge on the launch pad. This system could release 45,000 gallons per minute as a sound suppression device to avoid acoustical damage to the Saturn V. A nuclear weapon is the only human made device louder than a Saturn V.
2:21 Ignition of the F-1 engines starts 8.9 seconds before launch. This is the amount of time it takes to build up the required thrust for lift-off.
2:32 Lift-off! The Saturn V is angled 1.25 degrees away from the launch pad to avoid contact. Close up videos of the launch (below) will reveal large chucks of ice vibrating off the rocket. The Saturn V would have 1,200 pounds of ice on its sides created by the very cold liquid hydrogen and oxygen in the fuel tanks.
2:41 Jack King announces the tower is cleared. At this point, control of the flight is transferred from the Kennedy Space Center in Florida to the Johnson Space Center in Houston.
2:43 Neil Armstrong announces the beginning of the roll and pitch program to send the Saturn V over the Atlantic. This is the same direction the Earth rotates. At the Cape, the Earth rotates at 914 mph (1471 km/hr). That is the amount of velocity boost Apollo 11 receives from Earth’s rotation to help attain orbit and that is why all launches are eastward. The closer to the equator, the faster the Earth’s rotational movement is. Launch facilities located near the equator such as ESA’s Guiana Space Center have a competitive advantage of being able to life more payload per amount of thrust.
2:48 Walter Cronkite mentions the building is shaking, a common occurrence during Apollo launches. The press was stationed three miles from the launch pad. One (of many) reason the recent movie Apollo 18 was not realistic, lift-off would have set the entire Cape shaking. It would not be possible to launch a Saturn V there in secret.
3:31 As Apollo 11 approaches the speed of sound, the pressure differences from the shock waves lift water vapor away from the vehicle.
4:06 The region of maximum dynamic pressure, or Max Q, is when the combination of velocity and air pressure is greatest on the Saturn V. Although the velocity will continue to increase, the atmospheric density begins to drop off rapidly after this point. This can be seen by the widening thrust field from the rocket due to the rapid decline in atmospheric pressure.
5:12 Staging, the first stage is released and dropped into the Atlantic Ocean and the second stage ignites. Apollo 11 is now in the stratosphere at an altitude of 42 miles.
5:16 The second stage has 5 J-2 engines. Like the F-1, these are also made by Rocketdyne. At this point in the flight, thrust is less important as the rocket is lighter and burn time takes precedent. The thrust of the J-2 is 230,000 pounds each but the burn time is about 7 minutes.
5:43 Skirt sep refers to the skirt between the first and second stage being separated.
5:58 Mike Collins reports visual is a go. He is referring to the command module launch shield being removed along with the escape vehicle. At this point, the astronauts now have a view out the window.
7:50 Here, many of my younger students express shock at the animation used in the coverage. A common device during the early years of the Space Age as there was not the miniaturization of cameras as there is today which allowed for on-board cameras famously seen on the shuttle launches.
8:45 Fitted between the third stage and the service module was the IBM computer for Saturn V. The computer ring was 3 feet high, 22 feet in diameter, and had 32 kb of memory-about half the size of a blank Word page.
9:20 The water deluge on launch pad 39 to mitigate damage from the lift-off burn. After the Apollo program was complete, this launch pad was converted for use during the Shuttle program. Today, launch pad 39 is leased out to SpaceX for its future space operations.
10:38 This was a very troubled time for American passenger railroads as alluded to by Walter Cronkite. Penn Central would file for bankruptcy less than a year later prompting Congress to form Amtrak in 1971.
Two hours and fifty minutes after launch, Apollo 11 began trans-lunar injection and was on its way to the Moon.
*Top image launch of Apollo 11, July 16, 1969. Photo: NASA.