This Rocket Stage Did More Than Get Us to the Moon

The Saturn V rocket was the icon of America’s space program and its third stage, the S-IVB, had the special responsibility of taking Apollo astronauts from the Earth to the Moon. This stage was also used in other roles, such as a retrofitted space station and a makeshift moonquake generator. To help lighten the load, engineers used the lightest, energy-dense fuel they could get their hands on, liquid hydrogen, which was packed into one large tank. To prevent an explosion, engineers installed vents to release excess gas and developed insulation tiles to keep the fuel cold. After testing the S-IVB on uncrewed missions, it was used on Apollo 7 and 8 to send astronauts to the Moon. After the second burn of the engine, the crew popped the Command and Service module off of the S-IVB and continued on their way. The S-IVB used the last of its propellant to redirect itself and avoid a future collision with the people it worked so hard to get out there.

This video is supported by the SciShow Space pin! You can find cool rocket pins at DFTBA.com/SciShow. And the pin this month features the rocket from this video! During Apollo 11 and 12, the S-IVB was intended to slingshot around the Moon and enter a predictable orbit around the Sun. Apollo 11’s plan went as expected, but Apollo 12’s ended up in a wide orbit around Earth that was lost track of in 1971. In 2002, an amateur astronomer located an unidentified object that may be the missing S-IVB. Scientists then came up with a more productive role for S-IVBs to play: intentionally crashing them into the Moon. This was done to measure seismic activity like moonquakes, and to learn what the Moon was made of.

In 1973, one of the remaining three Saturn Vs launched Skylab, the US’ first space station, and its S-IVB was modified to serve as living quarters, working space, and waste tank. The other two S-IVBs are now on display at various museums.

In 2022, the Space Launch System successfully launched an Orion capsule around the Moon and back, but this system does not have a successor to the S-IVB. To celebrate the rockets of the past, SciShow is offering a limited time pin of the S-IVB at DFTBA.com/SciShow. Each month a different rocket pin will be available.