NASA has officially approved the Aspera mission for development and launch in late 2026, a specialized satellite designed to study how galaxies form and evolve by examining the nearly invisible gas surrounding them in what astronomers call the circumgalactic medium.
The mission, led by principal investigator Dr. Carlos Vargas of the University of Arizona, will use ultraviolet spectroscopy to observe and analyze the vast, diffuse gas clouds that exist in the space between galaxies—material that plays a crucial role in galactic formation but has been notoriously difficult to study.
Exploring the Galactic Frontier
"Aspera will help us answer fundamental questions about how galaxies form, grow, and evolve," explained Dr. Vargas during the mission approval announcement. "The circumgalactic medium is essentially the reservoir of material that feeds star formation in galaxies, yet we know surprisingly little about its composition and behavior."
The mission's name, Aspera, comes from the Latin phrase "per aspera ad astra" meaning "through hardships to the stars"—a fitting title for a mission designed to study the challenging-to-observe medium between stars and galaxies.
The spacecraft will carry a specialized ultraviolet spectrograph capable of detecting the faint emission from highly ionized oxygen, carbon, and other elements in the circumgalactic medium of nearby galaxies. These observations will reveal how gas flows in and out of galaxies, a process critical to understanding star formation and galactic evolution.
Innovative Technology
Aspera represents a significant technological achievement, packing advanced capabilities into a relatively small and cost-effective package. The mission will utilize a CubeSat platform approximately the size of a microwave oven, demonstrating how increasingly sophisticated science can be conducted with smaller spacecraft.
"This mission showcases how we can do transformative science with smaller, more focused missions," said Dr. Thomas Zurbuchen, NASA's associate administrator for science. "Aspera will provide unique data that complements our larger observatories like Hubble and Webb, giving us a more complete picture of galactic evolution."
The spacecraft's ultraviolet spectrograph has been designed with significantly improved sensitivity compared to previous instruments, allowing it to detect the extremely faint emission from the tenuous gas in the circumgalactic medium.
Scientific Goals
Aspera will focus on observing approximately 30 nearby galaxies across different masses, types, and environments to understand how the circumgalactic medium varies and influences galactic development.
"One of our primary questions is how the circumgalactic medium differs between galaxies that are actively forming stars versus those that have stopped," said Dr. Jessica Rivera, project scientist for the mission. "This could help us understand what causes some galaxies to cease star formation while others continue to produce new stars."
The mission will also investigate how galaxies recycle material, with gas flowing out from supernovae and other energetic events, then potentially falling back to fuel new generations of stars.
International Collaboration
While NASA is leading the mission, Aspera involves international collaboration with scientists from the European Space Agency and the Japanese Aerospace Exploration Agency contributing to data analysis and theoretical modeling.
"Understanding galaxy formation is a global scientific endeavor," noted Dr. Vargas. "The data from Aspera will be made available to the international scientific community, maximizing the scientific return from this mission."
The mission is scheduled to operate for at least two years after launch, with the possibility of extension based on spacecraft performance and scientific results.