Thanks to Yvonne Brill, who invented the propulsion system that keeps communication satellites from falling out of orbit, we can confidently go about our everyday business and keep in touch with the rest of the world.


Brill developed the concept for a new rocket engine called a “hydrazine resistojet” (resistojet is a method of spacecraft propulsion that provides thrust by heating a non-reactive fluid). This form of propulsion was first applied on a Radio Corporation of America (RCA) spacecraft in 1983. Since then, it has become a satellite industry standard.


Brill also contributed to the propulsion system of the first upper-atmosphere satellite (Explorer 32) and the first weather satellite (Tiros). In addition, she assisted with a series of rocket designs for Nova’s moon missions, the Mars Observer, and the rocket motor for NASA’s space shuttle.


Brill invented a rocket thruster that allowed satellites to carry less fuel and stay in space longer. The multiple thrust systems used on spacecrafts before her invention enabled the crew on the ground to correct errors and execute new orders. However, this thrust method was heavy because each system had separate fuel types and needed different tanks.


What Brill did was to introduce a single type of propellant for all functions, instead of a number of different systems. This is how her hydrazine resistojet works:


A liquid propellant (hydrazine) is distributed through a manifold (a pipe brunching into several openings) feeding into a series of thrusters. One set of thrusters is designed for more powerful thrusts, the other for less powerful ones. The system is pressurized by nitrogen. The gas supply is monitored by a pressure transducer, while the propellant flow is adjusted by a pressure regulator. The propellant flow is delivered into a catalyst bed by perforated pipes impregnated with a catalyst material. The hydrazine decomposes as soon as it comes in contact with the catalyst at very high temperatures, resulting in expansion, which creates thrust. The pressure can be modified for specific levels of power manually by the crew on the ground.


How did Brill become such an outstanding rocket scientist, and what made her pursue her dream when most women of her generation didn’t even go to college?



Yvonne Brill (née Claeys) was born near Winnipeg, in the Canadian province of Manitoba, on December 30, 1924. She and her two siblings were first generation Canadians (both her parents emigrated from Belgium). Yvonne was the first one in her family to go to college. Her high school science teacher told her that a woman wouldn’t get anywhere in science. Her father wanted her to open up a little shop in town. She didn’t listen to either of them and, with a scholarship, entered the University of Manitoba. A few years later, she graduated with a degree in science (initially, she wanted to study engineering, but the university denied her admission because they couldn’t accommodate women).


In 1945, after graduation, she accepted a job offer from the Douglas Aircraft Company in California and moved to the United States. She wanted to get a master’s degree in chemistry, and she decided to attend evening classes at the University of Southern California. This is where she met her future husband, William Brill. They married within a year and moved to the East Coast, first to Connecticut, then to New Jersey.


Yvonne managed to balance her family life and her career. She followed her husband (who was a research chemist) to wherever his job would take them, ending up in Princeton, New Jersey. She always managed to get job offers in a field dominated by men. In the beginning, she worked part-time jobs so that she could care for their three young children.


Brill is believed to be the only woman in the United Stated who was researching into rocket science in the mid-1940s. She encountered her fare share of prejudice, but she never felt any bitterness: ”It’s just nothing I ever thought about,” she remarked when recalling that she was paid a salary below that of men.


For the last twenty years of her life, Yvonne Brill promoted other women scientists’ work, nominating them for various prizes that she thought they deserved.


Bril and President Obama

In 2011, at a White House ceremony, President Obama awarded Brill the National Medal of Technology and Innovation, the nation’s highest honor for engineers and innovators. When she was asked how she succeeded against all odds and became a pioneer in her field, she replied: “I just had the drive to do it!”


Sadly, Yvonne Brill died last month, on March 27, 2013, in Princeton, New Jersey.

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