Cosmic-ray detector installed in Bolivia strengthens global space weather network

July 15, 2026

A $600 cosmic-ray detector carried from Atlanta to the Andes makes Bolivia the newest node in a worldwide network watching the particles that guard life on Earth

High above La Paz, where the Bolivian Andes brush the edge of the breathable world, a team of physicists has planted a new sentinel against the violence of space. On 31 March 2026, researchers from Georgia State University (GSU) and Bolivia’s Universidad Mayor de San Andrés (UMSA) installed a compact cosmic-ray detector at the historic Chacaltaya high-altitude observatory, making Bolivia the newest member of the worldwide gLOWCOST network.

An invisible shield and its hidden weaknesses

From the ground, the sky looks like a calm blue void. It is not. Earth sits inside a magnetic cocoon that deflects a relentless rain of high-energy particles streaming through space, called Galactic Cosmic Radiation (GCR), mostly protons forged in the explosive deaths of stars. The contrast with Mars is stark: Earth’s strong magnetic field and thick atmosphere keep the planet alive, while the Martian surface, at roughly 0.006 bar of pressure (about 0.6% of Earth’s pressure), is a radiation-scoured desert where liquid water boils away instantly.

The shield is strong but not impenetrable. In 1859, the Carrington Event – the most intense geomagnetic storm on record – lit auroras as far south as the Caribbean and turned telegraph wires into fire hazards. A comparable storm today could inflict an estimated $600 bn to $2.6 tr in damage in the United States alone. A smaller modern preview came in 1989, when a geomagnetic storm collapsed Québec’s entire power grid in seconds. Monitoring these shifts, the researchers argue, is no longer just science – it is planetary defence.

Chasing the muon, nature’s cosmic messenger

Because primary protons rarely reach the ground intact, we track their ‘ghosts’ instead: muons. A muon is a heavy, short-lived cousin of the electron, born 15-20 km up when cosmic rays slam into air molecules and set off a cascade of particles. By the time the shower reaches the surface, more than 80% of the survivors are muons. They are also living proof of Einstein’s special relativity: with a lifetime of just 2.1 microseconds, they ought to decay before landing, but moving near light speed slows their internal clocks – time dilation – enough to finish the trip to a detector.

Cosmic rays have driven discovery since Victor Hess proved in 1912 that radiation rises with altitude – work that earned the 1936 Nobel Prize and showed the threat comes from above, not below.

A laboratory the size of a microwave

To catch these messengers, an interdisciplinary GSU group spanning nuclear physics, computer science, and solar physics built the GSU Cosmic Muon Telescope. It stacks three 20×20 cm plastic scintillator tiles, spaced a precise 13 cm apart, so that simultaneous flashes in different layers reveal both a muon’s passage and the direction it came from.

The radical part is the price. A science satellite can cost anywhere from millions to billions of dollars; one gLOWCOST detector costs about $600, not including tariffs imposed by governments. That affordability is what makes a dense, ground-based ‘eyes-on-the-sky’ network feasible – and what lets the team hand the same instrument to a research university or a middle-school classroom.

A flight that doubled as an experiment

Getting to Bolivia was itself a data set. Carrying a smaller detector, a prototype of a CubeSat, from Atlanta to La Paz in late March, we logged radiation in real time during the entire flight. At a cruising altitude near 11,000 m, muon counts ran more than 40 times higher than at the Atlanta airport. A layover in Lima brought a sharp dip, and, as the plane neared the equator, the flux fell again – the ‘Equator Effect’, in which Earth’s magnetic field behaves as a high-pass filter, admitting only the hardest, highest-energy particles.

Bolivia’s extreme geography is the whole point. La Paz sits near 3,600 m, El Alto higher still, and Chacaltaya above 5,200 m. Thinner air overhead means more secondary particles survive to the ground, turning the country into a natural laboratory that sea-level sites cannot match. The team’s measurements climbed step by step across those altitudes, and two detectors of different sizes tracked the same flux variations – evidence, validated independently, that the trends are real and that a larger detector resolves them best.

Science anyone can watch

The project is also a teaching tool. Detectors already sit in classrooms from Frederick Douglass High School in Atlanta to Skyview Middle School in Massachusetts, where students track subatomic particles in real time. Anyone can visit cosmic.gsu.edu to see daily updated plots – how muon flux shifts with the seasons, or tracks changing atmospheric pressure and temperature. The detector technology grew out of nuclear physics work at Brookhaven National Laboratory and the U.S. Department of Energy, and the broader effort is backed by GSU’s RISE initiative.

Look ahead

With Bolivia aboard, the collaboration is eyeing further nodes, including an east-west detector arrangement to study how particle arrival depends on direction. Future plans extend the work skyward as well, toward radiation monitoring in flight and a cosmic-ray CubeSat.