COLORADO SPRINGS, Colo. — Despite an influx of money being invested in space companies in recent years, investors and analysts warned that there is no guarantee this growth will continue in the coming years.

“We’re in a great spot right now in terms of the way investment dollars are flowing. I don’t think anybody I talk to in this sector takes that for granted,” said Will Porteous, general partner and chief operating officer of investment firm RRE Ventures, during a panel at the 32nd Space Symposium here April 13.

Porteous cautioned that the investment climate can change quickly depending on the overall economic picture as well as industry-specific events. He didn’t name any specific threats, but his comments come among recent concerns that there is a “bubble” of investment in technology firms in general that could soon burst.

“We counsel all of our companies in this sector to brace themselves for the potential for that,” he said. “You read about these private space companies doing big rounds, but they’re probably not spending a lot of that capital. They’re storing it away for the potential of winter.”

For now, however, there’s little sign of a slowdown in space investment. A report published earlier this year by The Tauri Group concluded that there was a record $2.3 billion invested in space companies in 2015. Of that total, $1.8 billion was venture capital funding, more than the previous 15 years combined.

“The influx of venture capital into space is very important because it reflects an increasing number of financial investors have evaluated space opportunities,” said Carissa Christensen, managing partner of The Tauri Group. According to an unnamed venture capitalist quoted in the report, about 10 percent of established funds have evaluated space companies now, up from one percent just a few years ago.

There’s also growing interest among so-called “angel” investors, individuals who often provide the initial funding for startup companies. Chad Anderson, managing director of Space Angels Network, a group of angel investors, said his group’s membership has grown from about 20 people in 2012 to more than 160 today.

Those members are continuing to invest in space companies. “It shows no signs of slowing,” he said. “The data we’ve seen so far in the first quarter is already outpacing 2015.”

There is a slowdown, however, at the opposite end of the investment spectrum, among those companies that are going public. Chris Quilty, senior vice president of Raymond James and Associates, said that only seven companies have gone public in the U.S. market overall this year to date.

“The picture is not so great,” he said, adding that 71 percent of the companies that went public in 2015 are currently trading at below their initial price. “What we’re seeing is a pretty strong downturn.”

Despite his cautionary note about the future, Porteous remained optimistic about investment in space companies. RRE Ventures has invested in several, including Accion Systems, Spaceflight Industries and Spire. He felt there was still significant growth possible in space investment, thanks to developments ranging from improvements in space access to the use of open standards in the design of spacecraft.

“Markets generally break later and faster than you think they’re going to,” he said. “We tend to overestimate how soon things are going to happen, and then when it happens, it tends to happen faster.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...