The Ever-Changing Edge of the Solar System

Categories: Outer solar system

NASA Mission Shows Evolution of Conditions at Edge of Solar System

Artist’s impression of IBEX exploring the edge of our solar system. Credit: NASA GSFC

New data from NASA’s Interstellar Boundary Explorer, or IBEX, spacecraft, reveal that conditions at the edge of our solar system may be much more dynamic than previously thought. Future exploration missions will benefit in design and mission objectives from a better understanding of the changing conditions in this outer region of our solar system.

The IBEX has produced a new set of “all-sky” maps of our solar system’s interaction with the galaxy, allowing researchers to continue viewing and studying the interaction between our galaxy and Sun. The new maps reveal changing conditions in the region that separates the nearest reaches of our galaxy, called the local interstellar medium, from our heliosphere — a protective bubble that shields and protects our solar system.

In October 2009, scientists announced that the first map data produced by IBEX revealed an unpredicted bright ribbon of energetic neutral atoms emanating toward the Sun from the edge of the solar system. This discovery was unexpected to scientists, because the ribbon of bright emissions did not resemble any previous theoretical models of the region.

The IBEX spacecraft creates sky maps by measuring and counting particles referred to as energetic neutral atoms that are created in an area of our solar system known as the interstellar boundary region.

The IBEX science team compares maps to reveal whether there are time variations in the ribbon or the more distributed emissions around the ribbon. Credit: IBEX Science Team/Goddard Space Flight Center

This imaging technique is required since this region emits no light that can be collected by conventional telescopes. This interstellar boundary is where charged particles from the Sun, called the solar wind, flow outward far beyond the orbits of the planets and collide with material between stars. These collisions cause energetic neutral atoms to travel inward toward the Sun from interstellar space at velocities ranging from 100,000 mph to more than 2.4 million mph.

This second set of all-sky maps, created using data collected during six months of observations, show the evolution of the interstellar boundary region. The maps help delineate the interstellar boundary region, the area at the edge of our solar system that shields it from most of the dangerous galactic cosmic radiation that would otherwise enter from interstellar space. The new findings were published this week in the Journal of Geophysical Research – Space Physics, a publication of the American Geophysical Union.

One of the clear features visible in the IBEX maps is an apparent knot in the ribbon. Scientists were anxious to see how this structure would change with time. The second map showed that the knot in the ribbon somehow spread out. It is as if the knot in the ribbon was literally untangled over only six months. This visualization shows a close-up of the ribbon (green and red) superimposed on the stars and constellations in the nighttime sky. Credit: IBEX Science Team/Goddard Scientific Visualization Studio/ESA

“Our discovery of changes over six months in the IBEX ribbon and other neutral atoms propagating in from the edge of our solar system show that the interaction of our Sun and the galaxy is amazingly dynamic,” said David J. McComas, IBEX principal investigator and assistant vice president of the Space Science and Engineering Division at Southwest Research Institute in San Antonio. “These variations are taking place on remarkably short timescales.”

The IBEX spacecraft was launched in October 2008. Its science objective was to discover the nature of the interactions between the solar wind and the interstellar medium at the edge of our solar system.

“This situational awareness provided by IBEX shows our place in space is not constant,” said Dick Fisher, director of the Heliophysics Division in NASA’s Science Mission Directorate at the agency’s Headquarters in Washington. “Better understanding of the dynamic environment of space is vital for successful planning for future exploration.” The goal of the Heliophysics Division is to understand the Sun and its interactions with Earth and the solar system.

The research is also important for astrobiologists. Our solar system supports the only known habitat for life as we know it – our home planet Earth. In order to search for habitable worlds around distant stars, astrobiologists must fully understand the conditions in our system that have allowed Earth to become habitable.