There’s a renewed interest in exploring space, but the way we design the rockets and propulsion systems that actually get people to the final frontier is super inefficient and insanely expensive. If mankind really wants to explore deep space, that has to change.
So says Vigor Yang, the William R. T. Oakes Professor and Chair at the Georgia Institute of Technology’s School of Aerospace Engineering. He explained how we need to “rethink” the way we approach this crucial aspect of space exploration during a lecture at the American Institute of Aeronautics and Astronautics’s Space 2016 forum.
In the past, NASA and other agencies have spent up to 75 percent of their recourses on testing and redesigning propulsion systems. To Yang, that’s far too costly and not fast enough. High-fidelity designs — careful and precise planning ahead of the testing stage — and a “defense-in-depth” approach could make more advanced systems a reality.
Consider how engineers tried out pretty much everything when designing the rockets that would eventually propel the Apollo missions to the moon. For instance, the rockets required baffles — dividers used to restrain or direct the flow of gas or fuel. Yang said the scientists tested designs that had numbers of baffles ranging from a modest three to an absurd 81.
“This 81-baffle design is obviously not wonderful, but it shows how desperate they were,” Yang said, noting that President John F. Kennedy had put them on a deadline with his famous 1962 speech.
Yang said that nobody really knows for sure how much NASA spent on this extreme level of trial and error rocket testing, but according to his research, it was around $2.4 billion to make the final F-1 rocket and $1.7 billion on the J-2. In today’s money, that’s $17.85 billion and $12.57 billion, respectively. Developing the engine that moved the space shuttle was similarly costly.
Spending that type of money just isn’t sustainable. Yang quipped that it was “almost a so-called Tom Cruise Mission Impossible.”
Solid and liquid rockets both have their benefits and drawbacks, Yang explained, but it’s “design, not architecture” that will really make the difference. A high-fidelity design strategy could lower the number of possible variations for a rocket’s injectors from a trillion to 120, for starters. He said smart use of 3-D printing and other advanced manufacturing methods could further reduce costs.
Yang did admit that it’s easier to point out problems and make suggestions than it is to implement solutions.
The other aspect of space travel he mentioned, aside from launch propulsion, was in-space propulsion. Solar sails and nuclear propulsion are fledgling technologies, but Yang says it’s performance, rather than cost efficiency, that we need to focus on once we’ve gotten a vehicle in space. Otherwise, a trip to Mars will take “several hundred days,” and getting back will take “years.”