The idea was to churn out 500 such supersonic aircraft between 2000 and 2015, racking up $200 billion in sales for U.S. industry and creating 140,000 new jobs in the United States.
It didn't turn out that way, largely due to the problem of making supersonic transportation affordable.
"If it doesn't make money it doesn't fly," said Bob van der Linden, curator of transportation at the Smithsonian's National Air and Space Museum in Washington, D.C.
The U.S. government in the late 1960s had the option to develop a supersonic jet but decided against it in the face of environmental concerns.
The Europeans went ahead and built 20 Concordes and wound up flying 13 of them.
The former Soviet Union in the 1960s and the 1970s also developed its own supersonic, the TU-144, that briefly flew between Moscow and Kazakhstan. Today, NASA rents a TU-144 for supersonic research.
But regardless of who flies or makes supersonics, three big obstacles -- fuel costs, pollution and noise -- have stood in the way of making any of them profitable.
"A supersonic transport is a tool to make money and until you can make them economical enough that the average person can fly them, you're not going to see them in this country," van der Linden said. "It's a huge problem that has not been solved yet. And frankly it doesn't look like it's going to happen anytime soon."
Boeing certainly had that in mind in the late 1990s when it balked at HSCT's development cost -- about $18 billion. The Seattle-based aerospace giant, which by then had swallowed McDonnell Douglas, has said it may look at the project again in 2020.
After Boeing backed out, NASA killed the program in February 1999 in order to add $600 million to the budget for the International Space Station. The extra money was needed as part of a $2 billion, five-year safety net to back up Russian delays on the station.
Other problems besides economics stood in the way of developing the HSCT.
Because it flies high in the stratosphere and into Earth's thin ozone layer, the engines on a supersonic jet must burn much more cleanly than those on a typical jet for purposes of pollution control.
"We had the pollutants problem pretty well in hand and we had developed engines that were meeting the [emissions] requirements," said Rodney Ricketts, who was a technology manager on supersonic research at NASA's Langley Research Center in Hampton, Virginia.
"But somebody had been raising the chinning bar on us when it came to noise. We were starting under one set of standards and the engines on the subsonics were getting quieter. So even though we made significant strides on that, we were chasing a moving target," Ricketts said.
Noise restrictions also limited supersonics to transoceanic flights since their sonic booms can crack windows and disrupt lives along a flight path over land.
Despite the program's end, much of the HSCT research has been transferred to other NASA programs.
Metallic and composite materials designed for its airframe are being used in research into new ways to get to space. Some of the materials can withstand temperatures up to 350 degrees Fahrenheit (177 degrees Celsius) for 60,000 hours of flight -- the equivalent of 20 years.
Clean-burning engines and lightweight cockpits are finding a home in research labs to make today's airliners safer.
And sophisticated computer codes developed to optimize airflow on the wings and body of the HSCT now are used to improve the performance of Boeing's supersonic Joint Strike Fighter aircraft.
"We're trying to find where these technologies can apply," said Terry Hertz, director of research and technology at NASA's office of aerospace technology.
"High-speed research was pushing the state of the art, but there needed to be an outlet for it," Hertz said. "Unless there's an industry that's in a moneymaking role to pick it up...it's very tough."
advertisement
