Our Solar System is wrapped in a vast, invisible bubble created by the Sun, a protective region that shields Earth and the planets from much of the radiation that fills our galaxy. But until recently, scientists have only had rough sketches of what this boundary looks like and how it behaves.

In this episode of Planetary Radio, host Sarah Al-Ahmed is joined by David McComas, professor of astrophysical sciences at Princeton University and principal investigator of NASA’s Interstellar Mapping and Acceleration Probe (IMAP) and Interstellar Boundary Explorer (IBEX) missions, along with Matina Gkioulidou, a heliophysicist at Johns Hopkins Applied Physics Laboratory, former IMAP-Ultra instrument lead, and current IMAP project scientist and co-investigator.

Now stationed at the Sun–Earth L1 Lagrange point, IMAP uses 10 instruments to study the heliosphere — the region where the solar wind collides with material from interstellar space. The mission does this by tracking energetic neutral atoms, particles that travel in straight lines from distant regions of the heliosphere, allowing scientists to map areas of space that spacecraft can’t directly sample.

McComas and Gkioulidou explain how IMAP builds on the legacy of Interstellar Boundary Explorer, what makes this mission different, and why understanding the Sun’s influence across space matters not just for fundamental science, but for space-weather forecasting and protecting technology and astronauts closer to home.

Discover more at: https://www.planetary.org/planetary-radio/2026-imap

Our Solar System is wrapped in a vast, invisible bubble created by the Sun, a protective region that shields Earth and the planets from much of the radiation that fills our galaxy. But until recently, scientists have only had rough sketches of what this boundary looks like and how it behaves.
In this episode of Planetary Radio, host Sarah Al-Ahmed is joined by David McComas, professor of astrophysical sciences at Princeton University and principal investigator of NASA&rsquo;s Interstellar Mapping and Acceleration Probe (IMAP) and Interstellar Boundary Explorer (IBEX) missions, along with Matina Gkioulidou, a heliophysicist at Johns Hopkins Applied Physics Laboratory, former IMAP-Ultra instrument lead, and current IMAP project scientist and co-investigator.
Now stationed at the Sun&ndash;Earth L1 Lagrange point, IMAP uses 10 instruments to study the heliosphere &mdash; the region where the solar wind collides with material from interstellar space. The mission does this by tracking energetic neutral atoms, particles that travel in straight lines from distant regions of the heliosphere, allowing scientists to map areas of space that spacecraft can&rsquo;t directly sample.
McComas and Gkioulidou explain how IMAP builds on the legacy of Interstellar Boundary Explorer, what makes this mission different, and why understanding the Sun&rsquo;s influence across space matters not just for fundamental science, but for space-weather forecasting and protecting technology and astronauts closer to home.
Discover more at:&nbsp;<a href="https://www.planetary.org/planetary-radio/2026-imap">https://www.planetary.org/planetary-radio/2026-imap</a>

Planetary Radio brings you the human adventure across our Solar System and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts who are taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye the Science Guy and Bruce Betts as they dive deep into space science and exploration. The monthly Space Policy Edition takes you inside the DC beltway where the future of the US space program hangs in the balance. Visit planetary.org/radio for an episode guide and much more.

Planetary Radio brings you the human adventure across our Solar System and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts who are taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye the Science Guy and Bruce Betts as they dive deep into space science and exploration. The monthly Space Policy Edition takes you inside the DC beltway where the future of the US space program hangs in the balance. Visit planetary.org/radio for an episode guide and much more.

Planetary Radio: Space Exploration, Astronomy and Science

Planetary Radio brings you the human adventure across our solar system and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye, the Science Guy, and Bruce Betts, chief scientist for The Planetary Society, as they dive deep into the latest space news. The monthly Space Policy Edition takes you inside the DC beltway with Casey Dreier and Jack Kiraly to discuss the politics of space exploration in the US and advocacy actions you can take to support the missions that matter. Visit planetary.org/radio for the space trivia contest, an episode guide, and much more.

Planetary Radio brings you the human adventure across our solar system and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye, the Science Guy, and Bruce Betts, chief scientist for The Planetary Society, as they dive deep into the latest space news. The monthly Space Policy Edition takes you inside the DC beltway with Casey Dreier and Jack Kiraly to discuss the politics of space exploration in the US and advocacy actions you can take to support the missions that matter. Visit planetary.org/radio for the space trivia contest, an episode guide, and much more.

Host Sarah Al-Ahmed speaks with David McComas, principal investigator of IMAP and IBEX, and Matina Gkioulidou, IMAP project scientist, about how energetic neutral atoms let us map the heliosphere.