Orbiting several hundred kilometers above the planet are two satellites, each the size of a half-loaf of bread, measuring bursts of light-speed electrons that sometimes rain into the atmosphere. When researchers first launched them in 2015, they had hoped the little satellites would last 3 months before they malfunctioned. More than 7 years later, they are still transmitting information about the variation in and location of the electron bursts—and the team has 19 published papers to show for the $1.2 million mission, called FIREBIRD II.
The success of FIREBIRD II and missions like it are changing the way scientists think about studying space weather, the field of space physics concerned with the activity of charged solar particles and their impact on Earth. Space weather missions using small satellites known as CubeSats earned more bang for their buck when compared with larger NASA missions, producing more than four times the number of publications per dollar, according to a recent study. “CubeSats are not toys,” says Amir Caspi, a solar astrophysicist at the Southwest Research Institute and an author of the study. “CubeSats are real scientific vehicles that can achieve real science.”
Like prefabricated homes, CubeSats are constructed similarly on the outside using modular building blocks. Costs are low because many of the components have been standardized and because the lightweight satellites can be slotted onto rockets as “rideshares” alongside bigger missions. With low costs, researchers can take more risks, using cheap, consumer-grade electronics rather than specialized space-qualified parts. With low barriers to entry, CubeSats have democratized space science, but until recently many scientists thought they were little more than trinkets for students to play with.
University of New Hampshire solar physicist Harlan Spence and his colleagues wanted to quantify CubeSats’ scientific value. They examined the scientific output of FIREBIRD II and four other space weather CubeSat missions that cost between $1.2 million and $1.3 million each and weighed an average of 3 kilograms. They compared the CubeSat output with that of five larger NASA missions that cost between $72 million and $1.5 billion and weighed hundreds or thousands of kilograms.
Unsurprisingly, the big missions produced much more science—nearly 86 publications per year since launch— compared with roughly two publications per year for the CubeSats. But when the scientific output was compared with mission cost, the CubeSats came out on top, producing 1.6 publications per year since launch per million dollars spent, versus 0.4 for the big missions, the researchers report in a preprint posted on 7 June on arXiv, and now accepted for publication at the Space Weather Journal. FIREBIRD II, for example, produced 2.2 publications per year per million dollars spent. NASA’s $600 million Van Allen Probes mission (VAP), which also studied space weather, produced 0.1 publications per year per million dollars.
The researchers also attempted to calculate the caliber of the published research by looking at the impact factors of the journals in which the papers were published compared to the number of papers published per journal. The five CubeSat missions had a calculated average impact factor of 3.8, whereas the five larger missions averaged 4. To Spence, this demonstrates that “the most successful CubeSat missions are able to hold their own with the big missions.”
In the paper, the authors argue CubeSats have a vital and cost-effective role to play in predicting space weather, which can cause power outages, interfere with GPS systems, and expose those in airplanes to harmful levels of radiation. Cross-referencing data from multiple CubeSats in small fleets helps researchers pinpoint the movement patterns of electron activity occurring in radiation belts, much like weather stations do to predict patterns on Earth, says Eftyhia Zesta, an astrophysicist at NASA’s Goddard Space Flight Center who works with both CubeSats and larger missions. “Until there were automated weather stations in every corner of the planet transmitting data to big simulative models, we didn’t have good weather prediction,” she says. “CubeSats could be a very powerful tool for that.” FIREBIRD II, for example, used two CubeSats in tandem to fill information gaps VAP’s singular satellite was unable to address on its own.
But Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who works with both CubeSats and multibillion-dollar missions such as the Chandra X-ray Observatory, says CubeSats have their scientific limits. “There are niches where CubeSats are not only valuable, but absolutely the way to go.” McDowell says. “But I think that there are whole classes of investigation where you really need the big flagships and CubeSats are just not going to cut it.”
And Zesta points out some ways in which the study may have been comparing apples and oranges. For starters, she says, the study highlighted university-built CubeSats, funded by the National Science Foundation, and likely did not include the full engineering salaries of graduate students who worked on the project as part of the total mission cost. NASA CubeSats, like the ones Zesta works on, aren’t subsidized in the same way and usually cost between $4 million and $8 million. For Zesta, excluding the labor of grad students not only creates an unequal comparison, but also gives the inaccurate impression that CubeSats can be built for just a few million dollars. Caspi acknowledges that calculating the true cost and the true output of any mission is complicated, but overall the relative ratios came out even in the end, he says.
The study also selected only successful, productive CubeSat missions for its analysis. Caspi acknowledges that more than half of CubeSat missions fail to launch and transmit usable data, and only about 25% produce data of the caliber of the missions represented in the study. Bigger missions on the other hand are over 90% successful, Zesta says.
But for Spence, the fact that CubeSats still have room for improvement is part of what makes them exciting. “CubeSats are a little bit like the Wild West still,” Spence says. “It’s calculated risk, it’s quickly moving. To me, that’s just a lot of fun.”