The Pioneers Program is a new program started in 2020 which is intended to do compelling astrophysics science at a lower cost using smaller hardware than missions in the Explorers Program. Missions will include SmallSats, major Balloon payloads, and modest payloads attached to the International Space Station with a $20M cost cap.
Below are four concepts chosen for further study in January 2021. After additional definition, these four concept studies will undergo a concept study review before being approved for flight.
- 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.
- Pandora is a SmallSat that will study 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.
- 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 would 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 would find up to 10 every year. The principal investigator is Daniel Kocevski of NASA Marshall Space Flight Center.
- PUEO is a balloon mission designed to launch from Antarctica that will 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 would be the most sensitive survey of cosmic ultra-high energy neutrinos ever conducted. The principal investigator is Abigail Vieregg of the University of Chicago.