Astrophysics Pioneers
The Pioneers Program, started in 2020, is intended to carry out compelling astrophysics science, at a lower cost and using smaller hardware than missions in the Explorers Program. Current Pioneers missions include SmallSats, major Balloon payloads, and modest payloads attached to the International Space Station with a $20M cost cap.
There are currently seven Pioneers missions that have been selected, including two which have already launched.
- PUEO (Payload for Ultrahigh Energy Observations) is a balloon mission designed to detect signals from ultra-high energy neutrinos, particles that contain valuable clues about the highest energy astrophysical processes, including the creation of black holes and neutron star mergers. Neutrinos travel across the Universe undisturbed, carrying information about events billions of light years away. PUEO intends to carry out the most sensitive survey of cosmic ultra-high energy neutrinos ever conducted. The principal investigator is Abigail Vieregg of the University of Chicago. PUEO was successfully launched from NASA LDB camp near McMurdo Station, Antarctica on December 20, 2025. The payload reached a float altitude of 35 km and circumnavigated the Antarctic continent for 23 days, using the vast ice sheet below as detection volume for impulsive radio signals of neutrino interaction in the thick ice sheet. The payload landed ~300 km from the Scott-Amundson South Pole Station. Payload and data vaults have been recovered by ground traverse.
- Pandora, launched on January 11th, 2026, is a SmallSat that will study at least 20 stars and their 39 exoplanets in visible and infrared light. It is aimed at disentangling the signals from stars and planetary atmospheres. Understanding how changes in starlight affects measurements of exoplanets is an outstanding problem in the search for habitable planets beyond the solar system. The principal investigator is Elisa Quintana of NASA Goddard Space Flight Center.
- Aspera is a SmallSat that will study galaxy evolution. Through observations in ultraviolet light, it will examine hot gas in the space between galaxies, called the intergalactic medium, and the inflow and outflow of gas from galaxies. The intergalactic medium is a major component of the Universe but is poorly measured; Aspera would close this gap. The principal investigator is Carlos Vargas at the University of Arizona.
- StarBurst is a SmallSat that will detect high-energy gamma rays from events such as the mergers of dense stellar remnants called neutron stars. This will provide valuable insight into such events, which are also detected through gravitational waves by observatories on Earth. These events are where most of the heavy metals in the Universe, such as gold and platinum, are formed. To date, only one such event has been observed simultaneously in gravitational waves and gamma rays; StarBurst, with a target launch date of Summer 2027 (aligned with LIGO's O5 observing run) aims to find up to 10 every year. The principal investigator is Daniel Kocevski of NASA Marshall Space Flight Center.
- The Trans-Iron Galactic Element Recorder on the International Space Station (TIGERISS) is a NASA Astrophysics Pioneers mission, envisioned for the International Space Station. TIGERISS will provide the most comprehensive data yet on ultraheavy Galactic cosmic rays, transforming our understanding of the Galaxy's cycle of matter. It builds on the balloon-borne TIGER and SuperTIGER technology, with improved charge resolution and range, and adjustments to meet ISS payload requirements. The principal investigator is Brian Rauch of Washington University in St. Louis.
- POEMM (Planetary Origins and Evolution Multispectral Monochromator) is a balloon-borne 1.8-m telescope, combined with state-of the-art spectrometers and detectors developed by the POEMM team, to study planet formation and evolution with uniquely powerful far-infrared (FIR) diagnostic tools. The principal investigator is Gordon Stacey, at Cornell University. The payload is scheduled to launch on a Super-Pressure Balloon (SPB) for an ultra-long duration flight around 2028.
- The Landolt mission, named for the late astronomer Arlo Landolt, will put an artificial “star” in orbit around the Earth, allowing scientists to calibrate telescopes and more accurately measure the brightness of stars ranging from those nearby to the distant explosions of supernova in far-off galaxies. By establishing absolute flux calibration, the mission will begin to address several open challenges in astrophysics including the speed and acceleration of the Universe expansion. The principal investigator is Peter Plavchan, of George Mason University.
