How did CubeSats evolve from a dumb idea to interplanetary capable missions in just 15 years? Unlike large, expensive spacecraft that rely on proven technology, CubeSats have the flexibility to be riskier and try things that aren't guaranteed to work. This has allowed the industry to learn from mistakes and evolve new technologies quickly.

This is important for agencies like NASA that seek space hardware with a high technology readiness level, or TRL — a metric that assesses the maturity level of a particular technology. NASA supports the CubeSat industry through programs like ELaNA (Educational Launch of Nanosatellites), which helps CubeSat providers find free rides to orbit as secondary rocket payloads. To date, ELaNA has helped 18 groups of CubeSats get to space (including The Planetary Society's LightSail 1).

Another NASA program, SIMPLEx, funds CubeSats to fly on planetary exploration missions. The agency's current SIMPLEx solicitation is looking for SmallSats — which could include CubeSats — to fly on the upcoming Lucy and Psyche missions.

It didn't take long after CubeSats first launched in 2003 for some people to see they could be used in deep space. Robert Staehle, who is now the assistant instruments division manager for advanced concepts at NASA's Jet Propulsion laboratory, attended a Nov. 2010 workshop called GAINSTAM (Government and Industry Nano-Satellite Technology and Mission) in Huntington Beach, California. The Boeing-sponsored event hoped to raise awareness of the potential for small spacecraft.

At GAINSTAM, Staehle said he listened to a presentation by Tomas Svitek, the founder of Stellar Exploration, Inc., on The Planetary Society's LightSail 1 mission. At that point, the spacecraft had passed its critical design review.

LightSail was designed to demonstrate the feasibility of solar sailing for small spacecraft. Its key technology was the ability to package a 32-square-meter Mylar sail, deployment motor and sail booms into a 10-by-10-by-30-centimeter spacecraft — and still have room to spare for batteries, avionics, and cameras. Staehle, who had also taken notice of early JPL efforts to miniaturize spacecraft components, was intrigued. He knew propulsion was a key technology holding CubeSats back from a broader range of usages. Might solar sailing be a key piece of the puzzle?

"I thought, if I scale up what [Svitek] is doing by a little bit, I can get more out of it — a few kilometers per second, per year, maybe," recalled Staehle, referring to the change in velocity gained by solar sailing. "I thought, I bet you can do interplanetary.”

Staehle assembled a team of experts and came up with a reference design for a solar sailing, 6-unit CubeSat measuring 30-by-20-by-10 centimeters. It was just double the size of the diminutive LightSail 1 spacecraft, yet it would be capable of conducting an interplanetary mission. He pitched the idea to Puig-Suari, the CubeSat co-inventor.

"I said, 'We can do this in 6U,' and Jordi's jaw dropped," Staehle said. "He said, 'You're right, we can do this."

The group prepared an abstract for a presentation to be delivered at an upcoming SmallSat conference. They figured it was an easy sell, but to their surprise, the abstract was rejected.

Just two days later, Staehle said, NASA put out a call for proposals for NIAC, the NASA Innovative Advanced Concepts program. NIAC provides seed funding to help mature next-generation technology projects. It was the first NIAC call in years, so the competition was fierce. But Staehle's team turned their SmallSat abstract into a proposal, submitted it for a NIAC grant, and won $100,000 to study CubeSats for interplanetary missions. The team concluded their work with a final report in 2012. Two Planetary Society staff members co-authored the report: Bruce Betts, who is now the Planetary Society's chief scientist, and Louis Friedman, the executive director emeritus.