Launched from Antarctica on December 20, 2025, the PUEO mission has successfully completed its 23-day flight and recovered its data.
The Payload for Ultrahigh Energy Observations (PUEO), a NASA Astrophysics Pioneers Program mission, launched on December 20, 2025, from NASA's Long Duration Balloon Facility near McMurdo Station, Antarctica. The launch occurred at 5:56 a.m. NZST, corresponding to 11:56 a.m. U.S. Eastern Time on December 19.
The mission flew at approximately 120,000 feet for 23 days before landing approximately 120 miles (200 km) from the South Pole. The payload, including data drives, has been recovered, and the team is currently analyzing the data.
Mission Objectives
PUEO was designed to detect ultra-high energy neutrinos and cosmic rays by measuring radio signals generated when these particles interact with the Antarctic ice sheet or Earth's atmosphere. The mission aims to study energetic cosmic phenomena, including supermassive black holes and neutron star mergers.
Technology and Design
PUEO builds on the earlier ANITA mission, which conducted four flights from 2006 to 2016, and incorporates several advancements:
- An interferometric phased array trigger that coherently sums signals from multiple antennas in real time, lowering the detection threshold.
- Doubled antenna collecting area for frequencies above 300 MHz compared to ANITA, achieved by increasing the low-frequency cutoff to reduce antenna size.
- A low-frequency instrument (sensitive down to 50 MHz) that deployed after reaching float altitude to improve sensitivity to extensive air showers.
"The interferometric phased array trigger lowers the detection threshold, allowing PUEO to capture signals that were previously beyond reach."
Calibration Efforts
Two additional balloons accompanied the PUEO mission, carrying calibration equipment designed to transmit test signals. These signals are used to verify that the PUEO payload's detection instruments are functioning correctly for real signal acquisition from space.
Project Leadership and Future Applications
Project lead Dr. Abigail Vieregg, David N. Schramm Director of the Kavli Institute for Cosmological Physics and professor at the University of Chicago, is assisted by graduate student Rachel Scrandis. The mission is sponsored by the NASA Astrophysics Division Pioneers Program.
Technology developed for PUEO may be applicable to future missions using lunar regolith as a detector for ultra-high energy cosmic rays.