The billionaire flyboys of space tourism get all the attention, but women are developing some of the most promising technologies designed for the final frontier, writes Fortune.

Today, private money is flowing into a range of space-based innovations at light speed. According to BryceTech, a research firm that tracks the sector, $36.7 billion was invested in space startups over the past two decades—with a full 72% of that pot doled out since 2015. This recent uptick in private funding is largely driven by venture capital firms that are betting space is quite literally the next big frontier.

But the adventures of the flyboy founders also cloud the reality of what’s happening in the industry. All three are emphasizing space tourism, which, while exciting, represents just a fraction of the innovation happening in the sector; the tourism market accounts for $1.7 billion of the $366 billion “space economy,” according to BryceTech.

And when it comes to women:

“There’s an unwritten rule [for women in the industry],” she says. “If someone asks you to do something, like speak at a conference, and you can’t do it, suggest another woman.”

One of the women on her “must” list is Hélène Huby, a French-born entrepreneur who lives in Germany Huby represents the next generation of women in the sector—a generation that is expanding the horizons of space tech, fueled by the boom in financing and the lowered barrier to entry as the cost of launching satellites, capsules, and, yes, humans into space falls.

As these women open their networks to me, I’m repeatedly struck by their commonalities. They dream big and bold. They think in decades, not years—you have to, in the space sector. They are hungry for collaboration, and they invest in one another. Also: None of them are billionaires, or financed by billionaires. And, while they might love to blast off into the great beyond, for the moment they are focused on building their companies right here, on Earth.

Read more in an extensive article in Fortune.