It was hard to miss this week’s test launch of the SpaceX Falcon Heavy. The Tuesday launch certainly received more attention than any space-related story since the Space Shuttle was retired in 2011. And to be honest, this unmanned test launch garnered a lot more eyeballs than many manned launches in the past.
So … why? What was the big deal about a rocket that is, at its most basic level, just three of the boosters Space X has already been launching for years strapped side by side?
Sure, it lifts more, and that’s nice for several reasons. The previous “most powerful operating rocket” was the Launch Alliance Delta IV. Capable of taking 29 metric tons to orbit, the Delta IV has been a workhorse, especially when it comes to it’s primary mission — launching US military reconnaissance satellites. At least eleven of these eyes-in-the-sky have gone up on Delta IVs. The Delta IV has been around since 2002, and has flown 36 times, but only 9 of those flights have been of the “heavy” configuration. Most have been of the Delta IV Medium, which is capable of taking between 11 and 15 tons to orbit.
The Medium and Medium+ configurations of the Delta IV actually have less capacity than SpaceX’s Falcon 9, which can loft 22 tons. In fact, by most measures, the Falcon 9 itself is a heavy rocket — in the same range as the biggest machines available from other sources.
The Delta IV uses the RS-68 engine, which is important in that it was the first new rocket engine created in the United States after the design of the Space Shuttle main engine, which was designed thirty years earlier. Unfortunately, while the RS-68 was designed to be cheaper to build than the Shuttle engine, getting there meant some significant losses in efficiency. Still, the 8’ throat of the RS-68 puts out 700,000 pounds of thrust. Which is a bunch. And a Delta IV Heavy carries three of them.
But as nice as that Delta IV is, and it’s an impressive machine, it’s a whole different animal from either the Falcon 9 or the Falcon Heavy.