Of external tanks and Starships

Iconic orange Space Shuttle External Tanks and shiny SpaceX Starships are uncannily close in scale. I was fortunate to be on the team in the 1990s that checked out and prepared the External Tanks and then on the team that filled and launched them. I could not have guessed that 23 years into my career at NASA, I would also be on a team studying refilling propellant tanks in space (my contribution being to connect the new technology with NASA budgets). Refueling in space is now the challenge that awaits the SpaceX Starship and NASA.

I often crawled around inside the Space Shuttle’s External Tanks (and sometimes orbiters, and once inside a solid rocket motor – filled with propellant). I took the picture below inside a tank, in the “intertank,” the space between the forward liquid oxygen tank and the aft liquid hydrogen tank. I recall the particular picture well for the care I had to have inside the tank that day. This was not because I was inside a multi-million-dollar piece of flight hardware, and not watching my step could easily cause some damage. Not at all. Being inside flight hardware was by then a familiar and always conscious affair. Instead, my trepidation was because of the particular camera I held that day – one of the first-ever digital cameras, and naturally being NASA, we spared no expense.

In look and feel, the camera was similar to a modern DSLR with a long lens – except this was 1991 and such things then were from the future. It was $100,000 worth of technology from the future. Except as is visible from the photo, it has about the quality anyone gets today on a cell phone. That is from a cell phone that comes free with the monthly plan. The low end cell phone. With the least expensive plan.

Flash forward and it’s now nearly the tenth anniversary of the NASA Propellant Depot Study. The SpaceX Starship and refueling in space are (barring protests) poised to help lead the way to deep space exploration. Perhaps soon, we will see more of what is inside the Starships, apart from figures of the basic layout of liquid oxygen or liquid methane tanks and some feedlines. Perhaps we will see the diffusers, slosh baffles, crawl spaces, vent valves, and more. Perhaps we will also see that like that $100,000-dollar digital camera, things have improved.

Pictures above, left to right, (1) The scale of the Space Shuttle external tank, (2) inside an external tank (with annotations about leak checks), (3) rear of prior photo, (4) atop the Space Shuttle LOX storage sphere at Pad A in 1996 (a beautiful day for a walk down!) and (5) a screen capture of the launch computer while loading the external tank September 12, 1992, for STS-47 at Pad B with Endeavour (first launch attempt). Credits: Edgar Zapata, zapatatalksnasa.com