We need to keep track of the telescope to 1 mm precision
From a university workshop in Kingston, Ontario, a generation of students is reaching toward the stratosphere with a question that has never been answered: can a telescope floating 33 kilometers above the Earth be woven into the same web of observation as instruments anchored to the ground? Funded by the Canadian Space Agency and led by physicist Laura Fissel, the BVEX project represents both a technical frontier and a quiet reminder that the most consequential experiments are sometimes built by people still learning their craft. Scheduled to launch from Brazil in 2027, the project asks whether the boundary between Earth and sky might itself become a tool for seeing deeper into the universe.
- The sharpest radio wavelengths are swallowed by Earth's atmosphere, leaving ground-based telescopes permanently blind to some of the universe's most revealing light.
- A 100-kilogram telescope must be engineered to survive extreme cold, battery-only power, and remote operation at the edge of space — all by undergraduate and graduate students.
- The experiment's most unforgiving demand is positional accuracy: the drifting balloon must be tracked to within a single millimeter for interferometry to function at all.
- No one has ever successfully linked a balloon-borne telescope with ground-based observatories in a working interferometric array — BVEX is the first attempt.
- If the 2027 launch succeeds, the path opens toward stratospheric telescope arrays that could image supermassive black holes and distant galaxies with resolution currently impossible from any point on the ground.
Laura Fissel occupies a rare position — a physicist who studies how stars and planets form while simultaneously building the instruments needed to see what ordinary telescopes cannot. At Queen's University, she leads a team of undergraduates and graduate students in constructing something that sounds improbable: a radio telescope the size of a small car, destined to float 33 kilometers above Earth aboard a balloon the size of a football field.
The project is called BVEX — the Balloon-Borne Very Large Baseline Interferometry Experiment. It began as an idea in 2021 and has since grown into a funded, scheduled mission. The Canadian Space Agency has committed $291,000 toward a launch from Palmas, Brazil, in late summer 2027. By then, more than twenty students will have invested thousands of hours in the instrument — for many, the closest they will come to actual space exploration.
The scientific problem BVEX addresses is elegant in its logic. To resolve fine structures in the sky — the environment around a supermassive black hole, the birth of a distant galaxy — astronomers need enormous effective apertures. Since no single telescope can span a continent, they instead combine data from multiple observatories pointing at the same target, a technique called interferometry. Processed together, the signals produce images as sharp as those a planet-sized telescope would make. But every telescope in every existing interferometric network sits on the ground.
Fissel's team is testing whether one node in that network could instead drift in the stratosphere. The shortest, most information-rich radio wavelengths are absorbed by the atmosphere before reaching the ground. Lift a telescope above 99.5 percent of the air, and those wavelengths become accessible. Combine that data with ground-based observations, and the resulting images exceed what either platform could achieve alone.
The engineering demands are severe. The instrument must function in extreme cold, run on batteries, and be controlled remotely — all while the balloon drifts on stratospheric winds. Most critically, interferometry requires knowing the balloon's position to within one-tenth of a wavelength, which for BVEX means millimeter-level accuracy on a platform in constant motion. No one has achieved this before.
What distinguishes BVEX is not only its ambition but its authorship. These are not simulations — they are real instruments that will collect real data to be combined with observations from professional observatories across North America and Europe. If the experiment succeeds, it demonstrates that stratospheric platforms can join the global interferometric network, eventually enabling arrays that span both the planet and the sky, producing images of the cosmos sharper than anything currently possible.
Laura Fissel stands at the intersection of two worlds: the physics of how stars and planets form, and the practical challenge of building instruments that can see what ground-based telescopes cannot. At Queen's University, she leads a team of undergraduates and graduate students through an experiment that sounds like it belongs in a science fiction novel but is, in fact, happening in labs and workshops across campus right now. By the summer of 2027, they will launch a radio telescope the size of a small car into the stratosphere aboard a balloon the size of a football field.
The Balloon-Borne Very Large Baseline Interferometry Experiment—BVEX, for short—began in 2021 as an idea. Five years later, it has become real enough to attract serious funding. The Canadian Space Agency awarded the project $291,000 through its Flights and Fieldwork for the Advancement of Science and Technology program, money that will pay for the launch itself, scheduled for late summer 2027 from Palmas, Brazil. By that point, 17 undergraduate students and four graduate students will have poured thousands of hours into designing and building the instrument. For many of them, this will be the closest they ever come to actual space exploration.
The problem BVEX is trying to solve is ancient and elegant. To see fine detail in the sky—to resolve the structures around a supermassive black hole, say, or to map the birth of a distant galaxy—you need a telescope with an enormous mirror or antenna. But you cannot simply build a single telescope the size of the world. Instead, astronomers have learned to do something cleverer: they point multiple telescopes at the same patch of sky and combine the data they collect. The result, processed by supercomputer, is an image as sharp as if a single telescope the size of the Earth had made the observation. This technique is called interferometry, and it has been the foundation of modern radio astronomy for decades. But it has always relied on one thing: the telescopes stay on the ground.
Fissel and her team are asking a question no one has successfully answered before: what if one of those telescopes was floating in the stratosphere? The advantage is straightforward. Radio telescopes observe light that human eyes cannot see—radio waves with wavelengths far longer than visible light. But the shortest radio wavelengths, the ones that produce the sharpest images, are absorbed by Earth's atmosphere. Fly a telescope 33 kilometers up, above 99.5 percent of the air, and that problem vanishes. The balloon-borne instrument can observe radio waves that ground-based telescopes cannot, and when you combine data from both, you get images with resolution impossible from the ground alone.
The engineering is punishing. The students will build a radio telescope roughly one meter across and weighing 100 kilograms. It needs to work reliably at extreme altitude, in extreme cold, powered by batteries, and controlled remotely from the ground. But there is another challenge that Fissel emphasizes with particular intensity: precision. For interferometry to work between a balloon telescope and ground-based instruments scattered across North America and Europe, the position of the balloon telescope must be known to within one-tenth of a wavelength. For BVEX, that translates to millimeter-level accuracy. The balloon will be drifting in the wind, moving constantly, and the students must track its position to within a single millimeter. No one has ever done this before.
What makes BVEX remarkable is not just the technical ambition but the fact that it is being carried out by students. This is not a simulation or a classroom exercise. These are real instruments that will fly to the edge of space and collect real data that will be combined with observations from professional observatories around the world. If it works—and Fissel is confident it will—it opens a new frontier in astronomy. Future missions could place multiple telescopes in the stratosphere, creating an interferometric array that spans the planet and the sky simultaneously. The images that could produce would be sharper, more detailed, more revealing than anything we can make today. But first, a team of students in Kingston, Ontario, has to prove it is possible.
Notable Quotes
By combining telescopes spread around the globe we synthesize a telescope basically the size of the world. We are now trying to demonstrate that flying telescopes can be part of this effort too.— Laura Fissel, Queen's University
No one has yet done interferometry between a balloon-borne telescope and ground-based telescopes. To successfully demonstrate that balloon telescopes can be used as part of these global interferometry arrays, we need to know the position of our telescope to a tenth of a wavelength.— Laura Fissel
The Hearth Conversation Another angle on the story
Why does it matter that no one has done this before? Isn't interferometry already well understood?
The technique is understood, yes. But it has only ever worked with telescopes bolted to the ground. A balloon moves. It drifts with the wind. Knowing where it is to millimeter precision while it is 33 kilometers up and constantly shifting—that is a different problem entirely. We are not just doing interferometry. We are doing interferometry with a moving target.
And the payoff is better images of space?
Better images of specific things. Radio waves at certain wavelengths cannot penetrate the atmosphere. They get absorbed. So ground-based telescopes are blind to them. But a telescope in the stratosphere can see them clearly. When you combine that data with what ground telescopes observe, you get a much fuller picture. For studying things like supermassive black holes and distant galaxies, that matters enormously.
Why Brazil? Why launch from Palmas?
The balloon needs to fly in a stable wind pattern. The stratospheric winds at that latitude and season are predictable. It gives the mission the best chance of success and the longest possible flight duration.
What happens if the millimeter precision fails? If they lose track of the telescope?
Then the interferometry does not work. The data from the balloon and the ground telescopes cannot be combined meaningfully. The whole experiment fails. That is why Fissel emphasizes it so much. It is the single most difficult technical requirement.
These are undergraduates. How do you teach someone to solve a problem that has never been solved?
You do not teach them the solution. You teach them how to think about the problem. You give them the physics, the engineering principles, the constraints. Then you let them design and build and test. Some approaches will fail. Others will work. That is how you learn.