NASA has awarded $20 million to a University of Arizona team that is building a small space telescope specializing in detecting polarization in ultraviolet light from distant stars. From its vantage point in low-Earth orbit, the instrument – dubbed PUFFINS – will stare at about 70 stars to analyze how their light has been altered by interstellar dust on its journey to Earth.
PUFFINS is the second Pioneers mission led by the U of A since NASA kicked off the Astrophysics Pioneers program in 2020. U of A is leading Aspera and contributed significantly to Pandora , both first-generation Astrophysics Pioneers missions. Pandora was launched in January of this year, and Aspera is set to be launched in early next year. PUFFINS is a joint effort between the U of A, McDonald Observatory at The University of Texas at Austin and an international network of early-career and senior scientists .
"PUFFINS will change how we understand the dust between stars," said Ramya Anche, an assistant research professor at Steward Observatory who serves as the mission's principal investigator. "Understanding these tiny grains is essential to building a complete picture of how interstellar dust forms, evolves over time and ultimately ends up incorporated into new stars and planets."
By measuring a property of light called polarization, which describes the orientation of the starlight, PUFFINS will reveal new details about what the smallest interstellar dust grains are made of, how they form, and how they behave in some of the most extreme environments in our galaxy. Polarimetry takes advantage of the fact that interstellar dust grains made of silicates, when spun up, align with the galaxy's magnetic field, turning them into a polarizing filter for the starlight that passes through them.
At the heart of PUFFINS (short for Polarimetry in the Ultraviolet to Find Features in INterStellar dust) is a specialized telescope just 10 inches across – the size of a large dinner plate – that captures ultraviolet light from distant stars. PUFFINS will measure the polarization properties of starlight across a range of ultraviolet wavelengths using a technique called spectropolarimetry, which has not been deployed in space in nearly three decades.
"To me, PUFFINS represents the culmination of more than a decade of instrument-building work in polarimetry, and it will be the first instrument I helped design that will actually be built and launched into space," Anche said.
PUFFINS can probe the smallest grain sizes – those smaller than about 50 nanometers, or roughly the size of the common cold virus – which are invisible to optical and infrared telescopes.
"We’ll be working on fully solving what for 50-plus years was the second-longest-standing mystery of interstellar medium physics," said B-G Andersson, PUFFINS Science PI and assistant director for research at McDonald Observatory at The University of Texas at Austin, who has spent more than 20 years studying interstellar dust grain alignment. "The origin of interstellar polarization – dust grains – was discovered in 1949, and we're finally beginning to understand it. That, to me, is really cool."
The effects of interstellar dust ripple through nearly every corner of astrophysics, despite making up only about 1% of the visible mass in the Milky Way. By observing stars at different distances and in different environments – nearby stellar nurseries, reflection nebulae and even our closest extra-galactic neighbors, the Magellanic Clouds – the mission will build a detailed map of how interstellar dust varies across the sky.
Kyle Van Gorkom, an early-career faculty member at Steward Observatory who serves as deputy principal investigator and leads the spacecraft interface work, brings to the project space engineering expertise alongside Anche's ground- and space-based instrumentation background.
"We're very excited to start from conceptualizing a space telescope, and then to see it all the way through from build to launch to operating in orbit," he said.
PUFFINS is currently in its early design phase, with a launch target of 2030. PUFFINS will serve as a critical bridge to NASA's Habitable Worlds Observatory, or HWO, the agency's next flagship space telescope currently in development for the 2040s. HWO mission may carry a UV spectropolarimeter instrument in one of its ports, and PUFFINS data can help define what science that instrument can accomplish.
Anche and Van Gorkom have been deliberate about designing PUFFINS as a training ground as much as a science mission, with graduate students and undergraduate researchers embedded in the instrument development effort from the start.
"Ramya Anche led her winning proposal to NASA while still a postdoctoral researcher at Steward Observatory," said Buell Jannuzi, director of Steward Observatory. "I am proud to be part of an institution that allows and enables talented early career scientists to lead major programs or missions – this is not common, and our willingness to support our most junior scientists so well helps us attract many of the very best early career scientists."
While the PUFFINS payload is being designed and assembled, the PUFFINS science team, will be busy acquiring spectro-polarimetry data of the mission's target stars in visible and infrared light, using U of A telescopes and other facilities throughout the world, that will enhance the data PUFFINS will collect and allow a more complete analysis and interpretation.
"PUFFINS continues the U of A's long track record of excellence in space missions," said Erika Hamden, a professor of astrophysics at Steward Observatory who leads the Arizona Space Institute, or ASI. "ASI was set up to enable exactly these types of missions, and it was such an honor to work with Ramya and the team to provide support and expertise while they developed their winning proposal. They have a great science idea, and we are so excited to help and support the development of the mission."
"The U of A has emerged as the only university leading multiple missions in the NASA Astrophysics Pioneers program – Aspera launching early next year and PUFFINS selected for 2030," added Senior Vice President for Research and Partnerships Tomás Díaz de la Rubia. "Plus, our team is running mission operations for Pandora. We are thrilled NASA continues to entrust us with work that will change our understanding of the universe."
The U of A team includes Carlos Vargas, Erika Hamden, Ewan Douglas, Haeun Chung, Meredith Kupinski, Grant Williams, Victor Gasho, Hannah Tanquary, Manny Montoya, Olivier Durney, Grant West, Dan Vargas, Hiram Olivas, Ruby Huie, Eli Zervigon, Hyukmo Kang; postdoctoral researchers Kelian Sommer and Jaegun Yoo; and graduate students William Melby, Harrison Bradley, Amelia Roosen and Donovan Myrick.
Corporate mission partners are Tucson-based Ascending Node Technologies and SFL Missions Inc. in Toronto, Canada.