What Was Up With the Starship Stacking Anyway?

As we talked about on Friday, SpaceX transported Starship 20 (S20) to the launch complex and stacked it on top of Booster 4 (B4) for about an hour.  OK, cool.  If it was a fit check or just a gigantic photo opportunity I'm cool with that, but there was nothing even semi-official to judge what was going on.  

Today, we get a couple of interpretations from the two Erics who follow SpaceX (and space exploration) full time: Eric Ralph at Teslarati and Eric Berger at Ars Technica.  Both point out what we really know: for one, brief, shining moment, the tallest rocket in history was standing on the launch pad in Texas.  When it's fired up to launch, it will be the most powerful rocket in history.  

Eric Ralph added a little information I haven't read yet to the picture.

For those that followed the process closely in the days and weeks prior, the fact that Starship’s first full assembly was just a fit check (and, really, more like 50:50 between fit check and photo op) came as no surprise. In the lead-up, it became clear through several reports that CEO Elon Musk had challenged SpaceX to stack Ship 20 and Booster 4 by August 5th and flown in several hundred employees normally stationed elsewhere to accomplish the feat.

SpaceX could have stacked a non-flyable Starship on Booster 3; it's right there on the test stand, close to B4 on the Orbital Launch Pad (OLP).  Instead, they chose the booster and Starship which are the full-up operational prototypes that are expected to fly soon.  

There's still a backlog of things to be done on this pair, what some are calling B4-S20, and they're in line with our speculation in last Friday's post.  Quoting Elon Musk:

4 significant items:

– Final heat shield tiles for ship
– Thermal protection of booster engines
– Ground propellant storage tanks
– QD arm for ship

2 weeks.

— Elon Musk (@elonmusk) August 6, 2021

There's more testing that needs to be done.  S20 is in the high bay waiting for more heat shield tiles, but at some point will be tested as we talked about Friday.  They've never built this configuration of Starship before, with three Raptor Boost and three Raptor Vacuum engines.  That means there's new plumbing and new controls. It's prudent risk reduction to bring S20 back out to the test stand and test it.  Test stand B has been modified specifically for some of these tests:

(Photo Credit: Philip Bottin on Twitter)

The same sort of testing campaign is needed for Booster 4.  The only tests done to a Super Heavy have been the few done on B3; some cryogenic tests and the one brief static firing.  B4 may well be taken down off the OLP and brought to test stand A, but A currently has B3 on it.  Some of the tests can be done on B3, but a static firing of any significant duration isn't happening without a water deluge system and that seems to need the size of the OLP.  Especially if they fire all 29 Raptors!  

The wild card they need to be concerned about isn't in that list: they need the FAA's approval.  Eric Berger over at Ars Technica believes that something that went largely unnoticed by most of us is a poke at the FAA from Musk.  Musk released this photo. 

Berger's theory is that releasing a black and white photo of SpaceX workers building Starship/Super Heavy will cause a nearly reflexive recall of photos like this one:

On Friday, SpaceX founder Elon Musk sent a clear message to the FAA and other federal regulators. One evocative photo, in particular, drove home his message to anyone watching. It showed workers standing beneath Starship, as it was lowered onto the first-stage rocket. In releasing a black-and-white version, Musk knew exactly what he was doing in harkening back to the age of skyscrapers.

The 21st-century skyscrapers are being built right now, the photo screamed, by modern engineers and welders. Such rockets are not to be found in PowerPoints or wooden mockups any longer. They are living, breathing machines nearly ready to breathe fire.

To the FAA, Musk seemed to be saying, federal regulators must do their part to ensure the future arrives on schedule. Just as the 20th-century skyscrapers marked the beginning of a new era and eventually launched America into a prosperous future of finance, communication, marketing, and more, the 21st century now beckons.

By invoking the imagery of building skyscrapers, Musk seems to be saying we're transitioning from the days of building skyscrapers to building Starships. Delaying Starship is the equivalent of delaying the age of skyscrapers and the prosperity that brought.

Clearly, these aren't the earliest days of space programs. For the last 60 years we've been exploring our neighborhood in the solar system, taking our first, tentative steps in the bigger picture. Starship is intended to start extending our presence into the wider solar system and taking the first steps toward building colonies on sterile, uninhabited worlds. Musk is betting that the FAA will want to align with that.  Good luck with that, Elon.