Mass Value Report for June 2024

Can we compare the Falcon 9 meaningfully to the Saturn V? How does the current performance of SpaceX measure up to the historical performance of the Apollo program?

The underlying idea behind these reports is the use of mass as a universal performance metric. This month I want to demonstrate how this works by getting into the details of how to compare mission to Earth orbit with lunar missions, using specific historical examples and mission proposals, in order to support the underlying mathematical point.

In last months report I said:

To put this into perspective, during the peak of the Apollo program NASA launched 5 Saturn V rockets between December 1968 and November 1969. Their nominal LEO payload together was 700 metric tonnes - although using mass value is better for comparing a Moon rocket to a LEO launch vehicle which bumps the 5 Saturn Vs up to approximately 1000 metric tonnes equivalent. Falcon 9 has already beat that by a factor of 3, and may end up beating it by a factor of 5.

I want to provide some justification for my use of mass value here, using current flight data.

Falcon Cadence

This month saw 10 Falcon 9 flights and a Falcon Heavy flight; a reduction in cadence, but still on track for 134 flights this year.

Even if SpaceX does not meet their target of 148 launches, 134 would still represent an increase of 40% over the previous year, continuing a trend of doubling roughly every 2 years.

For the purposes of this months analysis, though, we are more interested in total mass to orbit. This has been following a slightly different trajectory because payload per flight is changing as more RTLS (Return to Launch Site) recoveries are used, and because of incremental upgrades to the Falcon 9 payload.

The overall picture looks like this:

The projection for this year is 2275 metric tonnes, compared to the above quoted 750 tonnes for the Apollo program during its peak. At three times this rate, nobody is being flown to the Moon on Falcon 9 launches. Is this mass comparison relevant then?

Building Spaceships

Using a single massive launch vehicle to send humans to the Moon hasn’t always been the default approach. Going back to the early work of von Braun in the 1950s, the plan was to assemble spacecraft in Earth orbit and then send them to the Moon (known as an Earth Orbit Rendezvous mission profile)

Colliers Magazine cover from 1952

When serious planning for the Moon began in the early sixties, a single large booster was considered the option with fewest technological challenges. In fact, the original Apollo mission was to be a direct ascent to the Moon and back using a booster even larger than the Saturn V, but it was realised (after a famous intervention by engineer John Houbolt) that this rocket was too difficult and that a Lunar Orbit Rendezvous mission was better. But this was not the end of Earth Orbit Rendezvous.