Originally posted Dec 3, 2015
An engineering field where the products you’re designing are constantly trying to kill you
The holiday season is here and it’s been a while since I have wandered off topic. I hope you’ll indulge me a little, and trust my promise that this post will bring some insight about the business we’re in, at least by happy contrast.
It’s a good time of the year to reflect on things we’re thankful for, and in this post I’d like to introduce you to a book about a fascinating field of R&D: developing rocket fuel. Compared to work on rocket fuel, our focus on RF technology has at least two major advantages, including longevity and personal safety.
Let’s talk first about safety and the excitement engendered by the lack of it. Robert Goddard is generally credited with the first development and successful launch of a liquid-fueled rocket. Here he is with that rocket, just before its launch in March of 1926.
Robert Goddard stands next to his first liquid-fueled rocket before the successful test flight of March 16, 1926. The combustion chamber is at the top and the fuel tanks are below. The pyramidal structure is the fixed launch frame. (photo by Esther Goddard, from the Great Images in NASA collection)
In my mind, the popular image of Goddard has been primarily that of an experimenter, skewed by the footage we’ve all seen of his launches. In reality, he was also a remarkable theoretician, very early on deriving the fundamental parameters and requirements of atmospheric, lunar, and interplanetary flight.
He also showed good sense in choosing gasoline as his primary rocket fuel, generally with liquid oxygen as the oxidizer. This may seem like a dangerous combination, but it was tame compared to what came just a few years later.
That brings me to the fascinating book about the development of liquid rocket fuels. The author is John D. Clark, a scientist, chemist, science/science-fiction writer, and developer of fuels much more exotic than those Goddard used. The introduction to the book was written by author Isaac Asimov and it describes the danger of these fuels very well:
There are, after all, some chemicals that explode shatteringly, some that flame ravenously, some that corrode hellishly, some that poison sneakily, and some that stink stenchily. As far as I know, though, only liquid rocket fuels have all these delightful properties combined into one delectable whole.
Delectable indeed! And if they don’t get you right away, they’re patient: it’s no surprise that many of these fuels are highly carcinogenic.
The book is titled Ignition! An Informal History of Liquid Rocket Propellants. It was published in 1972 and is long out of print, but a scan is available at the link. Fittingly, the book opens with two pictures of a rocket engine test cell, before and after an event called a “hard start.” Perhaps rocket engineers think the term “massive explosion” is too prejudicial.
For many spacecraft and missiles, the most practical fuels are hypergolic, those that burn instantly on contact, requiring no separate ignition source. Clark describes their benefits and extravagant hazards in the chapter “The Hunting of the Hypergol.” The suit on the technician in this picture and the cautions printed on the tank give some idea of the potential for excitement with these chemicals.
Hydrazine, one part of a hypergolic rocket-fuel pair, is loaded on the Messenger spacecraft. The warnings on the tank note that the fuel is corrosive, flammable, and poisonous. The protective gear on the technician gives some idea of the dangers of this fuel. (NASA image via Wikimedia commons)
Clark is a skilled writer with a delightful sense of humor, and the book is a great read for holiday downtime at home or on the road. However, it is also a little sad to hear that most of the development adventure in this area came to an end many years ago. Clark writes:
This is, in many ways, an auspicious moment for such a book. Liquid propellant research, active during the late’40s, the ’50s, and the first half of the ’60s, has tapered off to a trickle, and the time seems ripe for a summing up, while the people who did the work are still around to answer questions.
So in addition to being thankful that we’re doing research on things that aren’t constantly trying to kill us, we can also be grateful for a degree of career longevity. RF/microwave engineering has been a highly active field for decades and promises to continue for decades more. No moon suits or concrete bunkers required.
Plus, while we give up a certain degree of excitement, we don’t need to wear a moon suit to prepare for tests and we don’t need run them from a concrete bunker.