Sending a spacecraft beyond the heliopause to begin the exploration of our local galactic neighborhood will be one of the grand scientific enterprises of the next century. Interstellar space is a largely unknown frontier that holds many of the keys to understanding our place in the galaxy.

The rapidly expanding solar atmosphere - the solar wind - creates a bubble called the heliosphere that shields our solar system from the interstellar plasma and magnetic fields, and most of the cosmic rays and dust that comprise the local galactic neighborhood. The proposed Interstellar Probe mission, which will travel to >200 AU in 15 years, is designed to exit this bubble and begin exploring the space between the stars. In the course of this journey, Interstellar Probe will investigate unknown aspects of the outer solar system, explore the boundaries of the heliosphere to reveal how a star interacts with its environment, and directly sample the properties of the nearby interstellar medium. These studies will address key questions about the nature of the primordial solar nebula, the structure and dynamics of our heliosphere, the properties of organic material in the outer solar system, the nature of other stellar systems that may also harbor planets, the chemical evolution of our galaxy, and the origins of matter in the earliest days of the universe.

To carry out these exploratory studies, Interstellar Probe will include a comprehensive suite of sensors designed to measure the detailed properties of the plasma, neutral atoms, energetic particles, magnetic fields, cosmic rays and dust at the heliospheric boundaries and in the nearby interstellar medium. It will explore the "wall" of neutral interstellar hydrogen that lies just beyond the heliopause and determine the large-scale structure of the heliosphere by imaging energetic neutral atoms created in dynamic processes occurring just beyond the termination shock. In addition, Interstellar Probe will map the infrared emission in the outer solar system to determine the distribution of interplanetary dust and reveal the cosmic infrared background radiation.

This great journey requires advanced propulsion, and the 200-kg Interstellar Probe is designed to use a 200-m radius solar sail to achieve a velocity of 14 AU/yr. After exiting the heliosphere within a decade of launch, it will be capable of continuing on to ~400 AU. Interstellar Probe will serve as the first step in a more ambitious program to explore the outer solar system and nearby galactic neighborhood.


Interstellar Medium
Interaction Between the Interstellar Medium and the Solar Wind
The Outer Solar System
Scientific Instruments and Mission Requirements
Table of Contents


For more information regarding this website
and the Interstellar Probe Project,
please contact Dr. Paulett Liewer

This site was last updated:
February 8, 2000.