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Before a space telescope ever reaches orbit, and long after satellites are up there, NASA has another way to do frontier science: high-altitude scientific balloons. These balloons can loft instruments to roughly 120,000 feet (about 36.6 kilometers) — high in the stratosphere, above most of Earth's atmosphere—at a fraction of the cost and complexity of a space mission, while still enabling serious astrophysics, heliophysics, Earth science, and technology testing.

Antarctica is one of the best places on Earth to fly these missions. NASA's annual Antarctic Long-Duration Balloon campaign operates from a site on the Ross Ice Shelf near the U.S. National Science Foundation's McMurdo Station.

In the austral summer, near-constant sunlight and stable polar wind patterns can support extended-duration flights, allowing payloads to gather data for days to weeks as they circle the continent.

What is it?

NASA's first scientific balloon flight of the 2025 Antarctica Balloon Campaign lifted off from the agency's Antarctic facility at 5:30 a.m. NZST Tuesday, Dec. 16 (11:30 a.m. Monday, Dec. 15 U.S. Eastern Time) and reached float altitude carrying an experiment called GAPS — the General AntiParticle Spectrometer.

Once airborne, NASA reported the balloon was floating at about 120,000 feet (36 kilometers) above Earth's surface.

Where is it?

This image was taken near Antarctica Rubilotta where the balloon launched.

Why is it amazing?

GAPS' goal is to look for rare particles from space called antimatter nuclei, specifically antideuterons, antiprotons, and antihelium. Scientists have never clearly seen antideuterons or antihelium in cosmic rays before. If GAPS detects even a single antideuteron, it could give us important clues about the mysterious substance known as dark matter, which makes up most of the universe but is invisible to us. GAPS uses a time-of-flight system to measure how fast the particles are moving and a tracker system to record the interaction.

Now that the balloon has been launched, the GAPS project is underway, hopefully revealing more about the universe around us in due course.

Want to learn more?

You can learn more about antimatter and dark matter.