As engineers, we need to avoid getting stuck in the same old mindsets and attempting to solve problems in the same way over and over. Sometimes we need to toss out the old way of doing things and take a fresh approach.
Consider the approach that some of the commercial (privately held) space research companies are taking in doing projects, and compare that to NASA's traditional approach. Rather than lift the whole launch vehicle vertically using powerful rocket engines (high stress over a short time frame), they are using a high-altitude aircraft to lift the launch vehicle to 40,000 to 50,000 feet over a longer period of time -- a kinder, gentler approach.
Aircraft are a more mature technology, and statistically more reliable, more environmentally friendly, and less expensive to operate than rocket boosters.
