‘CubeSats are not toys.’ Small satellite scientific output could have a big impact | Science

Orbiting several hundred kilometers above the planet, there are two satellites, each about the size of half a loaf of bread, measuring light-speed bursts of electrons that sometimes fall into the atmosphere. When University of New Hampshire (UNH) researchers first launched them in 2015, they hoped the tiny satellites would last 3 months before breaking down. More than 7 years later, they’re still transmitting information about the variations and locations of electron bursts—and the UNH 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 dealing with the activity of charged solar particles and their effects on Earth. Space weather missions using small satellites known as CubeSats have gotten more bang for their buck than NASA’s larger missions, producing more than four times as many publications per dollar, according to a recent study. “CubeSats are not toys,” said Amir Kaspi, a solar astrophysicist at the Southwest Research Institute and an author of the study. “CubeSats are real science vehicles that can achieve real science.”

Like prefabricated homes, CubeSats are similarly constructed from the outside using modular building blocks. Costs are low because many of the components are standardized and because the lightweight satellites can be placed on rockets as “shared rides” along with larger missions. With low costs, researchers can take more risks by using inexpensive consumer-grade electronics rather than specialized parts suitable for use in space. 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.

UNH solar physicist Harlan Spence and his colleagues wanted to quantify the scientific value of CubeSats. They examined science results from FIREBIRD II and four other space-weather CubeSat missions, which cost between $1.2 million and $1.3 million each and weighed an average of 3 kilograms. They compared the CubeSat’s output to that of five larger NASA missions that cost between $72 million and $1.5 billion and weigh hundreds or thousands of kilograms.

Not surprisingly, large missions produce far more science—nearly 86 publications per year since launch—compared to roughly two publications per year for CubeSats. But when science output was weighed against mission cost, CubeSats came out on top, producing 1.6 publications per year from launch per million dollars spent, versus 0.4 for large missions, the researchers report in a preprint published June 7 on arXiv , and has now been accepted for publication in Space time Journal. FIREBIRD II, for example, generates 2.2 posts per year per million dollars spent. NASA’s $600 million Van Allen Probes (VAP) mission, which also studies space weather, produces 0.1 publications per million dollars per year.

The researchers also attempted to calculate the caliber of published research by looking at the impact factors of the journals in which the articles were published compared to the number of articles published per journal. The five CubeSat missions had an estimated average impact factor of 3.8, while the five larger missions averaged 4. For Spence, this shows that “the most successful CubeSat missions are able to handle the big missions.”

In the paper, the authors argue that CubeSats have a vital and cost-effective role in space weather forecasting, which can cause power outages, disrupt GPS systems and expose those on board aircraft to harmful levels of radiation. Cross-referencing data from multiple CubeSats in small fleets helps researchers determine the movement patterns of electron activity occurring in the radiation belts, similar to weather stations, to predict patterns on Earth, says Eftychia Zesta, an astrophysicist at the Goddard Space Flight Center of NASA, which works with both CubeSats and larger missions. “Until there were automated weather stations in every corner of the planet feeding data to large simulation models, we didn’t have good weather forecasting,” she says. “CubeSats can be a very powerful tool for that.” FIREBIRD II, for example, uses two CubeSats in tandem to fill information gaps that VAP’s single satellite was unable to address alone.

But Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who works with both CubeSats and multibillion-dollar missions like the Chandra X-ray Observatory, says CubeSats have their scientific limitations. “There are niches where CubeSats are not only valuable, but absolutely the way to go,” McDowell says. “But I think there are whole classes of investigations where you really need the big flagships, and CubeSats just aren’t going to cut it.”

And Zesta points out some ways the study may have been comparing apples and oranges. For starters, she says, the study highlights university-built CubeSats funded by the National Science Foundation and likely doesn’t include the full engineering salaries of the graduate students who worked on the project as part of the mission’s total cost. NASA CubeSats, like the ones Zesta is working on, are not subsidized in the same way and typically cost between $4 million and $8 million. For Zesta, excluding the students’ labor not only creates an uneven comparison, but also gives the inaccurate impression that CubeSats can be built for just a few million dollars. Caspi admits that calculating the true cost and true output of each mission is complicated, but overall the ratios came out even in the end, he says.

The study also selected only successful, productive CubeSat missions for its analysis. Caspi admits that more than half of CubeSat missions fail to launch and transmit usable data, and only about 25 percent produce data of the caliber of the missions presented in the study. On the other hand, larger missions are more than 90 percent successful, Zesta says.

But for Spence, the fact that CubeSats still have room for improvement is part of what makes them exciting. “CubeSats are still a bit like the Wild West,” says Spence. “It’s a calculated risk, it’s fast moving. To me, it’s just a lot of fun.”

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