A satellite powered by 48 AA batteries and a $20 microprocessor demonstrates an inexpensive way to reduce space debris

SBUDNIC, a loaf-sized cube satellite with a Kapton polyimide sheet tow sail designed and built by Brown University students, was launched last May on a SpaceX rocket. Credit: Marco Cross

Common sense suggests that space missions can only be accomplished with multi-million dollar budgets, materials capable of withstanding the unforgiving conditions outside of Earth’s atmosphere, and as a result of the work of highly skilled specialists.

But a team of engineering students at Brown University turned that assumption on its head.

They built a satellite on a minimal budget and using off-the-shelf accessories available at most hardware stores. They even sent the satellite – which is powered by 48 Energizer AA batteries and a $20 microprocessor popular with robot hobbyists – into space and hitchhiked on Elon Musk’s SpaceX rocket about 10 months ago.

Now, a new analysis of Air Force Space Command data shows that the satellite not only operated successfully, but could have far-reaching implications for efforts to stem the growing problem of space debris, which poses a potential hazard to all current and future spacecraft.

According to NASA, more than 27,000 pieces of so-called space debris, or space debris, are currently being tracked by the Department of Defense’s global space surveillance network. Debris in orbit ranges from any man-made objects in Earth orbit that no longer serve a useful function, such as: It also includes defunct satellites that remain in orbit, sometimes decades after completing their mission.

That’s a problem because most satellites stay in orbit for an average of 25 years or more, said Rick Fleeter, an associate professor of engineering at Brown University. When his students got the golden opportunity to design and build their own satellite to be launched into space, they decided to develop a possible solution.

The students added a 3D-printed tow sail made of Kapton polyimide film to the loaf-sized cube satellite they built. When it was deployed at an altitude of around 520 kilometers – well above the orbit of the International Space Station – the sail opened up like an umbrella and, according to initial data, is helping to push the satellite back to Earth earlier. In fact, the satellite is well below the other small devices that have been deployed with it. At the beginning of March, the satellite was about 470 kilometers above the earth, while the other objects were still in an orbit of about 500 kilometers or more.

The graph shows how much lower SBUDNIC’s orbit, represented by the thick blue line, is compared to other devices deployed with it from late May 2022 to early March 2023. Photo credit: Brown University

“You can see in the tracking data that we are visible below everyone else and are accelerating away from them,” Fleeter said. “You can see that our satellite is already descending toward re-entry while the others are still in a nice circular orbit higher up.”

The data suggests the student satellite, dubbed SBUDNIC, will be out of orbit within five years, as opposed to the estimated 25 to 27 years the students have calculated it will be without the towed device.

Fleeter and the Brown students believe their initial analysis of the publicly available tracking data serves as a proof of concept that this type of sail can be part of an effort to reduce the amount of space debris in orbit around Earth. They hope similar sails can be added to other devices of the same size or scaled up for larger projects in the future.

“The theory and physics of how this works is pretty well accepted,” Fleeter said. “What this mission showed was more about how to do it — how to build a mechanism that does that and how to make it so it’s light, small, and affordable.”

The project is the result of a collaboration between researchers from Brown’s School of Engineering and the National Research Council of Italy. It is also supported by D-Orbit, AMSAT-Italy, La Sapienza University of Rome and the NASA Rhode Island Space Grant. The satellite’s name is a nod to Sputnik, the first satellite to orbit the earth, and is also an acronym for the project’s stakeholders.

This is the second small satellite designed and built by Brown students to be sent into orbit in recent years. The previous satellite, EQUiSat, made 14,000 loops around the Earth before ending its mission and burning up upon re-entering the atmosphere in late 2020.

However, SBUDNIC is believed to be the first of its kind to be sent into orbit, made almost entirely of materials not intended for use in space, and at such an astronomically low price compared to other objects in orbit. The total cost of the student-designed cube satellite was about $10,000.

“The large, complex space missions that we hear about in the news are amazing and inspiring, but they also send the message that space is only for these types of specialized initiatives,” Fleeter said. “Here, we’re opening up that opportunity to more people… We’re not breaking down all the barriers, but you have to start somewhere.”

The Kapton polyimide towsail attached to the SBUDNIC satellite helps push the satellite back to Earth sooner. Credit: Marco Cross

Developed by students at Brown

The satellite was designed and built in a year by a group of about 40 students — about half from Brown’s School of Engineering and others from fields as diverse as economics, international relations and sculpture. It started in the ENGN 1760: Design of Space Systems course, which Fleeter taught in Spring 2021.

Italian aerospace company D-Orbit approached with an opening for a satellite on the SpaceX Falcon 9 rocket, which would launch in a year. Fleeter approached his students, who had just attended their first seminars on space systems design, and presented them with the opportunity.

From then on the race continued.

Students began conceptualizing and designing each of the satellite’s subsystems, often working with industry consultants who provided feedback and technical guidance on the feasibility of their proposals. The students then put their plans into action, managing the technical aspects of the satellite and coordinating the administrative parts. The continuous prototyping, testing, and improving that was required was a Herculean effort from the students in terms of hours and brain power.

“The Brown Design Workshop is very quiet at 4 a.m., and I’ve been there more times than I can count during that time,” said Marco Cross, who completed his master’s degree in biomedical engineering at Brown last year and served as the lead engineer for SBUDNIC .

Students purchased materials they needed from local stores and online retail websites. They often had to develop ingenious workarounds for their materials in order for them to survive in space. The approach often meant developing test equipment that reproduced specific environmental conditions in space, like the high vibrations experienced during rocket launch, Cross said. For example, the team used reptilian heating lamps in a vacuum chamber to test the heat shield they created to protect the satellite’s electronics from the sun.

To be cleared for launch, the satellite had to pass qualification tests and meet the strict rules and regulations that SpaceX and NASA follow. “It’s an environment that doesn’t tolerate mistakes,” Cross said. “The team has never wavered.”

Students who worked on SBUDNIC created the majority of their building at the Brown Design Workshop. Credit: Marco Cross

The students got the go-ahead after a series of vacuum, heat and vibration tests. A group then traveled to Cape Canaveral, Florida, to deliver SBUDNIC for use in D-Orbit’s larger launch satellite, which was then placed on the SpaceX rocket.

Students said the project helped them see themselves as creators and innovators, and that experience is ingrained in their lessons that they will use well into the future.

“I applied what I learned in this program to an internship at Lockheed Martin Space,” said Selia Jindal, a senior at Brown and one of the project leaders. “This project has really changed the way I see the world and has had a huge impact on my undergraduate experience. This feeling is not unique to me. Many team members, like myself, came to SBUDNIC with no previous experience in the space industry and left to pursue paths in this space. We have SBUDNIC alumni across the industry – from PhD to engineering at SpaceX.”

In addition to presenting their findings at conferences and submitting their data for publication, the SBUDNIC team is currently planning a series of presentations to schools across Rhode Island. They hope to inspire future innovators and make high school students aware of the opportunities that exist for them in space engineering and design.

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