NASA Deploys PUEO and GAPS Balloon Missions from Antarctica for Astrophysics Research

The National Aeronautics and Space Administration's Scientific Balloon Program has initiated its 2025 long-duration scientific balloon campaign in Antarctica. Launches are scheduled for early December from a specialized facility near the U.S. National Science Foundation's McMurdo Station on the Ross Ice Shelf. This deployment supports two distinct astrophysics investigations: the Payload for Ultrahigh Energy Observations (PUEO) and the General AntiParticle Spectrometer (GAPS).

The GAPS experiment is designed to investigate the nature of dark matter, which constitutes over 80 percent of the universe's matter content. The mission focuses on precisely measuring low-energy cosmic-ray antinuclei, specifically antideuterons, which are theorized to serve as a clear signature of dark matter decay or annihilation. GAPS employs a detection methodology involving exotic atom formation, where an incoming antiparticle is captured by a target nucleus, leading to the emission of characteristic X-rays and secondary particles from annihilation.

The GAPS team plans for a sequence of at least three long-duration balloon flights from McMurdo Station, building upon earlier prototype tests conducted in Japan in 2005 and a 2012 balloon test. In contrast, the PUEO mission, the inaugural flight under NASA's Astrophysics Pioneers program, utilizes the Antarctic ice sheet as a large-scale radio detector. PUEO is engineered to achieve high sensitivity to ultra-high energy neutrinos, particles that carry data about energetic astrophysical events such as black hole formation and neutron star mergers.

The PUEO instrument array detects radio emissions generated when these high-energy neutrinos interact with the ice via the Askaryan Effect. This mission advances the technology of its predecessor, the Antarctic Impulsive Transient Antenna (ANITA), by incorporating a phased array trigger and doubling the number of channels to 108 dual-polarization quad-ridge antennas, resulting in an order of magnitude improvement in sensitivity. The Astrophysics Pioneers program, established in 2020 with a $20 million cost cap, supports compelling astrophysics science, often using smaller platforms like balloon payloads.

Zero-pressure balloons enable these long-duration missions to remain aloft for extended periods by achieving equilibrium with the atmosphere, capitalizing on the continuous daylight and stable circumpolar wind patterns of the Antarctic summer. PUEO is led by Principal Investigator Abigail Vieregg of the University of Chicago. The combined efforts of PUEO and GAPS represent a cost-effective approach to probing fundamental questions concerning the universe's composition and extreme physical processes.