[Bell tone]
Launched on October 19th 2008, the Interstellar Boundary
Explorer, or IBEX, spacecraft, is unique in NASA's heliophysics fleet.
IBEX looks at the very edge of the sun's reach, starting at about 8 billion miles away.
This region begins with the termination shock, and ends with the heliopause. Between those two is the heliosheath,
a teardrop-shaped region sculpted by the pressure of the interstellar medium. IBEX is
also different because it makes its images from particles instead of light. Over the course of 6 months,
and many orbits, IBEX can paint a picture of the entire sky in energetic neutral atoms,
or ENAs for short. During its first 5 years, IBEX has made some astounding
discoveries. New narrator: The IBEX mission science
team has used data from the spacecraft to construct the first-ever all-sky map
of the interactions occurring at the edge of the solar system, where the sun's influence
diminishes and interacts with the interstellar medium. The most
startling finding as a result of this map is a bright ribbon of energetic neutral
atoms, emanating toward the sun from the edge of the solar system.
New narrator: New data from NASA's Interstellar
Boundary Explorer, reveal that conditions at the edge our solar system
may be much more dynamic than previously thought. This second
set of all-sky maps show the evolution of the interstellar boundary region.
The mysterious ribbon feature at the nose of the heliosphere
has changed shape, and a knot-like feature has formed.
This variation over time is forcing scientists to try to
understand how the heliosphere can be changing so rapidly.
New narrator: Because IBEX is orbiting Earth, it also can observe
the creation of energetic neutral atoms along the nose of
Earth's magnetosphere. ENAs are created there as solar wind protons
take electrons from hydrogen atoms in the outermost vestiges of our
atmosphere, known as the exosphere. IBEX has also
scanned another nearby world, with surprising results. The moon
has no atmosphere or magnetosphere, so the solar wind slams unimpeded into
its surface. About 10 percent of the impinging solar wind protons
bounce off the lunar surface, becoming ENAs as they do.
New narrator: IBEX has now made the first direct measurements of
hydrogen, oxygen and neon from outside the solar system.
The measurement of these atoms has enabled scientists to get a better grasp on
the environment around our solar system. The speed of the
galactic wind registered around 52,000 miles per hour.
Heavy interstellar atoms show a difference from the solar system and galaxy
as a whole. This puzzle may mean that the sun has moved out of the region
where it formed, or that some of the oxygen has been captured by dust
in interstellar space.
New narrator: New measurements by IBEX have suggested that there is no bow shock to the
heliosphere. The previous understanding of the boundary of the heliosphere was that
outside the influence of the sun, a shockwave was formed by the entire
heliosphere pushing through the interstellar material around it.
New narrator: IBEX recently mapped the boundaries of the solar
system's tail, called the heliotail. If we could look straight down the tail
we would see a shape a little like a four-leaf clover.
The two side leaves are filled with slow-moving particles, and the upper and
lower leaves with fast ones. The entire shape is rotated slightly.
This indicates that as it moves farther away from the sun's magnetic
influence, the charged particles have begun to be pulled into a new
orientation, aligning with the magnetic field of the local galaxy.
New narrator: Recent measurements of the interstellar wind
by IBEX have shown that its direction has changed by about 7 degrees
in only the last 40 years. While the cause of this shift
is unknown, it may be telling us something about the changing conditions as we move
through the Milky Way. New narrator: As IBEX
continues to scan the edge of the sun's influence, who knows what other discoveries it will
make? [Music]
Beeping