Many branches of science—including Earth science, planetary science, astrophysics, and microgravity science—depend strongly on NASA and its ability to enable experiments in space, or the observation of Earth from space. Every ten years, the U.S. Congress funds the National Academy of Sciences to conduct a survey probing what the scientists as a whole community believe are the next big discoveries. Where’s the edge of their science? What are the questions that need to be answered to push back that edge? The report, called the Decadal Survey, comes back to NASA in the form of recommendations. These in turn provide a road map that determines how the agency will spend its science funds. Some money will go to researchers to utilize existing, but not fully explored, data. Some funds will go toward building instruments to gather more data. Other money will fund rockets to launch those instruments. Each branch of science gets assigned a NASA program manager who decides where the money goes. Periodically, a call will go out to the scientific community inviting proposals for experiments. Researchers who have been thinking about how to better understand Earth’s radiation budget, or crystal growth, or how stars evolve over their lifetimes will propose experiments or measurements that test their hypotheses.

Imagine a Dr. Mary, a young assistant professor of chemistry at the University of Maryland. Mary wants to combine a set of different molecules to form a crystal, one that she believes might offer unparalleled insulating qualities. Her problem is, her Earth-bound laboratory can’t produce the kind of perfect crystal that she needs to prove her hypothesis. Gravity has a tendency to distort the way crystals form. Dr. Mary sees an Announcement of Opportunity (AO) from the NASA Microgravity Program Manager. She decides to propose an experiment in the International Space Station to grow her crystal in zero gravity, with an astronaut taking pictures of the results.

But it’s not enough simply to describe her experiment. She needs to come up with the means to conduct it in space, with equipment that an astronaut can use. What’s more, that equipment has to meet standards beyond normal laboratory devices; for one thing, it has to be able to withstand the forces of a rocket launch. It has to fit into the tiny space allotted in a crowded capsule. And it must work perfectly the first time; no one is going to fix it, and there are no spare parts to fix it with.

In other words, Dr. Mary needs an engineer. She happens to be in a good place. The University of Maryland has an excellent engineering department. NASA’s own Goddard Space Flight Center sits right next door. Essentially, the engineer (or engineers) must agree to invent the equipment on spec. At this point they’re at the proposal stage, and other teams are competing to get their own experiments into space. Engineers at Raytheon, one of the nation’s top aerospace contractors—also nearby in Maryland—agree to take on the speculative job. With their help, Dr. Mary’s proposal gets the Program Director’s approval, and she becomes the proud principal investigator in her crystal experiment. The equipment takes months to build, and an astronaut practices the experiment on the ground for another period of months (along with hundreds of other experiments; astronauts’ schedules in space are packed). Finally, perhaps three years after she first responded to the Announcement of Opportunity, Dr. Mary watches online as a Soyuz rocket bearing a capsule with the astronaut and her experiment launch from the Baikonur Cosmodrome in Kazakhstan. A few weeks later, she gets back the pictures from her experiment: perfect crystals!

Eventually, Dr. Mary gets more funding through the National Nanotechnology Initiative, and she works with engineers and materials scientists to develop a new form of heat shield out of her crystal for industry and aerospace. The shield will someday end up protecting a capsule bearing astronauts and scientists as they hurtle through the Martian atmosphere. And the cycle continues: invention leading to discovery leading to invention.

While it’s appropriate to credit the government for Dr. Mary’s part in it, it’s easy to miss the role of private industry. A significant part of the funding in her chemistry department at the University of Maryland comes from the private sector and foundations. A phalanx of companies helped build the International Space Station—Boeing, Lockheed, Raytheon, Northrop Grumman, Orbital ATK, and others. Still more companies are creating the inventions that will take us to Mars in the 2030s, if we decide to fund NASA properly. In fact, most of the work done for space, while funded by government, isn’t actually performed by government. NASA’s budget provides for about 65,000 jobs, of which only 18,000 are NASA employees.

In short, the invention-discovery cycle is also a public-private cycle.