Wednesday, January 13, 2016

Rocket reusability and holy grails

Reusability is the holy grail of rocketry.

How often have you heard that? Lots, no doubt. Everybody from journalists to space analysts to space company presidents toss out that one when the talk gets around to reusing rockets. By now somebody has probably taught a parrot to squawk it.

If you got a dollar every time a news article said that reusability is the holy grail of rocketry, you’d need a wheelbarrow to move the money. (Keep in mind that Canada has a one dollar coin instead of a paper bill.)

For example, Blue Origin, the space company owned by Amazon.com billionaire Jeff Bezos, successfully landed their New Shepard rocket in November. In a Seattle Times article, Bezos says Blue Origin landing achieves ‘Holy Grail of rocketry’, Mr. Bezos referred to reusability as “the holy grail of rocketry.” In all fairness, despite the headline, he didn’t say Blue Origin had achieved it, but that reusability would make make spaceflight less expensive.

Recently SpaceX, the company owned by billionaire Elon Musk, landed a first stage booster on a landing pad, as seen in this YouTube video. In an earlier undated video interview that Mr. Musk did for the website Space.com, he also used the term holy grail in reference to rocket reusability.

Yes, they say that reusability will lower the cost of launching payloads by allowing launch companies to reuse the booster rather than building a new one from scratch.

There’s only one teeny weeny problem with that idea: nobody has proven it yet.

Jean-Yves Le Gall, President of the French space agency Centre national d'├ętudes spatiales (CNES) said in an article at Space Daily, SpaceX landing is a 'feat', but not a game-changer, that the SpaceX landing was a “technological feat” but nothing more. He went on to say that questions about the cost of refurbishing a used rocket remain. He didn’t dismiss the possible advantages of reusability but he noted that it hadn’t been proven yet.

And please don’t point out that the writer said “game-changer.” One rant at a time.

Another perspective about the difficulties of reusability is outlined in an article at the website The Conversation.com, Explainer: why reusable rockets are so hard to make. The author, an expert in advanced propulsion systems at Southampton University in England, talks about the problems of balancing propellant, vehicle and payload mass. He talks about the importance of keeping the refurbishing costs down as well.

(A side note: he also used the term holy grail. It must be some kind of virus going around.)

Salvatore “Tory” Bruno, President of American launch company United Launch Alliance (ULA) and SpaceX’s main competitor, has talked about his company’s plans to incorporate reusability into their rockets.

In an article at Spaceflight Now, ULA plans to introduce new rocket one piece at a time, Mr. Bruno said ULA will try a more conservative approach to reusability by recycling parts rather than the entire booster. Mr. Bruno also said that an internal ULA study showed it would take 15 flights before a refurbished booster would save money over single-use boosters.

Until a number of successful launches are made with a reusable booster and people get a chance to analyze the numbers, we won’t know if reusability really will bring down the cost of launching rockets, or if it’s just overhyped wishful thinking.

In the mean time, maybe people can ease up on that holy grail squawk. Right now the only holy grails are a religious symbol and a Monty Python movie. Time will tell if there’s a third.