ATLANTA — Space and air-breathing propulsion is at a “critical crossroads” in the face of shrinking budgets and fewer new program opportunities, NASA Acting Associate Administrator Robert Lightfoot says.

Speaking at the Joint Propulsion Conference here, Lightfoot says that to help counter these trends, the wider industry needs to be reminded about the criticality of propulsion technology as a whole.

“Here’s my challenge: make propulsion relevant again. I think propulsion is being taken for granted. A lot of people don’t realize how important it is in our daily lives. More than ever before, the propulsion is at a critical crossroads as we ask how we go forward.”

Lightfoot also urges the propulsion industry to “look beyond technology to more of a systems-level approach. Propulsion for aviation and space cuts across several sectors of our economy. During these tight fiscal times, the industry needs to ask what should government’s role be in enabling the next develop in propulsion?”

Lightfoot says the industry needs to be considering bigger-picture questions about trades in affordability. “Do we quit chasing the last second of ISP [specific impulse, a measure of rocket performance] for cost?” Other questions need asking about the levels of risk tolerance and securing the industrial base “two to three layers down.”

Beyond this, Lightfoot says, the U.S. propulsion business needs to address the growth of international partnerships, particularly in space.

“We’re not going to get there without international partnerships. We’re working with DOD on how we’re going to do that.”

Top challenges for NASA remain improving access to space at lower cost and enhanced reliability. “So where does that lead rocket propulsion?” Lightfoot asks. “It remains a critical national requirement, but the industry is shrinking and the fact there are no major new development programs makes it hard to stay relevant. But this is our chance to have a group that looks at propulsion issues across the nation.”

Lightfoot has championed the formation of the National Institute for Rocket Propulsion Systems, which brings together industry, government and academic bodies to help shape space policy, and will meet at the Joint Propulsion Conference.

For NASA’s longer-term goals of going beyond low Earth orbit, key propulsion-related projects are among the more than 1,000 individual technology development studies being undertaken. Top propulsion priorities include programs now under way in cryogenic propulsion storage and transfer, solar electric propulsion, the hypersonic inflatable aerodynamic decelerator, nuclear cryogenic propulsion stages, composite cryotanks and solar sails. “Those are the kind of things we’re looking at first,” Lightfoot says.

Many of the programs are already at a test stage, says Lightfoot, who referenced the recent flight from Wallops Island, Va., of an inflatable heat shield. The unit survived to return intact. “I think we showed you can use a large inflatable re-entry shell,” he says.

Additionally, in June NASA completed a second round of robotic refueling demonstrations at the International Space Station, an asset that continues to provide a focus for propulsion development, both for longer-term, exploration-related research and for the raft of commercial companies striving to support cargo and human missions.