Interstellar medium image

Interstellar Medium

Exploring Outside the Solar System

The space between the stars, just beyond our solar system, is filled with gas, plasma, dust, cosmic rays, and magnetic fields. The interstellar medium offers exciting clues to how neighboring stars and the Sun interact.

Some 11 billion miles from the Sun, at the edge of the solar system, is the interstellar medium, a vast region of space filled with the dust and gas that gives rise to stars and planets and the cosmic rays that massive stars release in their last, explosive breath. APL is committed to understanding how our solar system interacts with this region, building one of the instruments on Voyager that revealed where the edge of the solar system lies, as well as managing and operating NASA missions to describe the dynamics and interactions of our Sun’s protective heliosphere with matter that lies between the stars.

Related Areas of Impact

Mission Area

Missions

APL has designed, built, and operated more than 70 innovative spacecraft over its six decades of spaceflight experience. Click below to learn about some of the missions that made revolutionary discoveries, and spacecraft that will push the boundaries of exploration and investigate outstanding scientific mysteries.

IMAP Spacecraft rendering

IMAP Interstellar Medium

NASA’s Interstellar Mapping and Acceleration Probe (IMAP) mission, which APL built in partnership with Principal Investigator David McComas of Princeton University, will study the boundary of our heliosphere, decoding the messages in particles from the Sun and beyond our cosmic shield.
Learn more about IMAP
NASA's Galactic/Extragalactic ULDB Spectroscopic Terahertz Observatory (GUSTO) mission launches from Antarctica on Dec. 31, 2023. (Credit: NASA/Scott Battaion)

Balloon Programs Interstellar Medium

APL balloon missions and instruments observe planetary targets and the interstellar medium, and conduct other space science investigations.
Learn more about Balloon Programs

Initiatives

While APL may be known for engaging is space-firsts and building first-of-its-kind spacecraft that deflect asteroids or touch the sun, it also has a deep knowledge base of science and engineering experts who provide critical contributions to critical challenges. Through initiatives like Planetary Defense, Heliophysics and Space Weather, and Cislunar Operations, APL is able to deliver game-changing impacts for civil and national security.

Neptune Rendering

Ice Giant Research and Exploration Giant Planets

In the decades since NASA’s Voyager 2 spacecraft explored the solar system’s ice giants, Uranus and Neptune, APL has made concerted efforts to underscore the scientific value of these planets and provide innovative conceptual missions to return to their azure skies. Through research, workshops, and seminars, APL researchers and engineers are helping establish a framework and community that will maximize the scientific returns of a potential future mission.
Learn more about Ice Giant Research and Exploration

Instruments

Scientists and engineers at APL have designed, built, and operated more than 300 novel space instruments and methods to conduct cutting-edge research and make groundbreaking discoveries. Click below to learn about some of these instruments and their role in shaping our understanding of space and the solar system.

Rendering of the IMAP spacecraft

IMAP-Ultra Interstellar Medium

Advancing designs built to study energetic particles around Earth and Saturn, IMAP-Ultra will image energetic particles from the edge of the solar system, providing detailed visuals of what happens when the Sun’s solar wind meets interstellar space. IMAP-Ultra is one of 10 instruments that will be included on the spacecraft.
Learn more about IMAP-Ultra
Voyager spacecraft

LECP Sun and Solar Wind

The Low-Energy Charged Particle (LECP) detectors have measured ions and electrons in the outer solar system and beyond.
Learn more about LECP

Related News

A SpaceX Falcon 9 rocket with NASA’s Interstellar Mapping and Acceleration Probe (IMAP) and two other spacecraft launches from NASA’s Kennedy Space Center in Florida.

NASA Launches IMAP Mission to Study the Heliosphere and Better Understand Space Weather Sep 24, 2025

NASA’s Interstellar Mapping and Acceleration Probe (IMAP) lifted off aboard a SpaceX Falcon 9 rocket from the agency’s Kennedy Space Center in Florida at 7:30 a.m. EDT.
Listen
The Interstellar Mapping and Acceleration Probe (IMAP) is shown after installation in the X-Ray and Cryogenic Facility chamber at NASA’s Marshall Space Flight Center in Huntsville, Alabama. (Credit: NASA/Johns Hopkins APL/Princeton/Ed Whitman)

NASA’s IMAP Mission Passes Major Prelaunch Milestone Sep 19, 2025

NASA’s Interstellar Mapping and Acceleration Probe (IMAP) completed its Flight Readiness Review on Sept. 18, which certifies its readiness to initiate final launch preparation activities.
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Emory Toomey and Tyler Radomsky prepare to lift NASA’s Interstellar Mapping and Acceleration Probe for testing

International Team Readies the Interstellar Mapping and Acceleration Probe for Launch Feb 4, 2025

Most people hear “spacecraft” and envision rockets blasting into space, but they’re often not aware of the meticulous integration and testing campaigns to get a spacecraft like IMAP ready for the launchpad.
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Matina Gkioulidou, IMAP-Ultra instrument lead, left, and Alexandra Dupont, Ultra lead engineer, work on the Ultra instrument at Johns Hopkins APL.

Johns Hopkins APL Team Readies Advanced Imager for Integration Onto NASA’s Interstellar Mapping and Acceleration Probe Mar 18, 2024

Another instrument planned for flight aboard NASA’s Interstellar Mapping and Acceleration Probe (IMAP) is ready for installation on the spacecraft.
Read More
The GUSTO telescope hangs from the hangar crane

GUSTO Mission Breaks NASA Record for Longest Flight by Heavy Lift Balloon Feb 24, 2024

NASA’s balloon mission GUSTO broke the record for the longest flight time by a heavy lift, long-duration balloon on Feb. 24, topping the previous record holder, which lasted for 55 days, 1 hour and 34 minutes. The new record is 57 days, 7 hours.
Read More