This poster outlines the major mission highlights of the Interstellar Boundary Explorer (IBEX) mission, a Small Explorer Earth-orbiting spacecraft that is designed to map the distant boundary between the solar wind from our Sun and the interstellar medium. This poster supports a full-length planetarium show about the IBEX mission and the boundary of the Solar System. Each short activity/product helps to build awareness and engagement in the science and engineering aspects of the mission that are reinforced as visitors choose to participate in more activities, including viewing the show and mission website.

Michelle Nichols

English

Digital Library for Earth System Education

National Aeronautics and Space Administration
IBEX: Interstellar Boundary Explorer
The IBEX spacecraft orbits the Earth and collects data 
to map the solar system's boundary for the first time. 
Maps created by IBEX teach us about the shape and 
nature of the heliosphere, the invisible bubble that 
surrounds the solar system. 
IBEX’s orbital path takes it 5/6 of the 
distance to the Moon’s orbit.  Each 
orbit takes 8 days. Even though this 
orbit is high, it is still incredibly far 
from the boundary it is measuring.
IBEX collects data about particles that 
come from the solar system’s boundary. 
Every six months, the sensors detect 
enough particles to create a picture of 
the boundary across the entire sky.
IBEX communicates by using antennae 
on its surface to send radio signals to a 
network of receivers on Earth.
xploring The Edge Of Our Solar System
E
www.nasa.gov
NW-2008-06-066-GSFC 
National Aeronautics and Space Administration
What is IBEX?
IBEX is a NASA-funded Small Explorer satellite mission to orbit Earth and map the boundary of the Solar 
System.  The acronym IBEX stands for Interstellar Boundary Explorer. 
The boundary of our Solar System is created by the interaction between particles from the Sun that are 
streaming outward, called the solar wind, and material between the stars, called the interstellar 
medium (ISM). The solar wind streams out into space and carves out a protective bubble, called the 
heliosphere, in the ISM around our Solar System.  The outer edge of the boundary of the heliosphere is 
called the heliopause, and the inner edge is called the termination shock.  The interactions between 
the solar wind particles and ISM particles create energetic neutral atoms (ENAs), which are particles 
with no charge that move very fast.  IBEX collects some of the ENAs which stream inward toward Earth. 
The mass, location, direction of origin, and energy of these particles provide information about the Solar 
System’s boundary.
.
An artist’s rendition of the parts of the heliosphere (not to scale) Credit:  NASA/Walt Feimer.
www.nasa.gov
National Aeronautics and Space Administration
What came before IBEX?
In the late 1970s and 1980s, the Voyager spacecraft expanded our knowledge of the outer Solar System. 
Voyagers 1 and 2 both explored the planets Jupiter and Saturn, and Voyager 2 explored Uranus and 
Neptune.  After their planetary observations, both spacecraft continued outward in different directions.  
The Voyagers were only supposed to last a few years, but they have continued to operate for over 30 
years, well past their designed lifetimes.  Today, both Voyagers are taking direct measurements of the 
magnetic field strength and the speed of the solar wind plasma in the boundary region.  These data will 
be combined with IBEX’s data, allowing scientists to create a more complete model of the boundary of 
our Solar System. 
An artist’s rendition of the parts of the heliosphere, as well as the directions of travel & approximate locations of the Voyager 
spacecraft. (not to scale) Credit:  NASA/Walt Feimer.
www.nasa.gov
National Aeronautics and Space Administration
What will we learn from IBEX?
By analyzing the maps created from 
IBEX data, scientists can determine 
what the interaction of the solar wind 
and the interstellar medium is like in all 
areas of the heliopause.  For example, 
scientists are trying to find out if there 
are some areas where the interstellar 
medium quickly slows the progress of 
the solar wind or other places where a 
gradual stop of the solar wind may 
occur.  Also, scientists are trying to 
determine the overall shape of the 
bubble.
An artist’s rendition of the IBEX spacecraft.  Credit: IBEX Team.
www.nasa.gov
National Aeronautics and Space Administration
How does IBEX get into space?  Where does IBEX orbit?
Artist’s rendition of the L1011 aircraft and Pegasus rocket.  Credit: The Adler Planetarium.
IBEX uses a Pegasus rocket to launch into space. This is an inexpensive launch option, especially for 
smaller spacecraft.  
IBEX begins its ride during a launch from Kwajalein Island, Marshall Islands in the middle of the Pacific 
Ocean.  An L-1011 airplane takes the Pegasus rocket and the attached IBEX spacecraft to a high 
altitude.  Then, the Pegasus fires its own rockets to propel it and IBEX into space. 
The satellite has its own small rocket engine that will allow it to climb into an orbit that takes it 5/6 of the 
distance to the Moon’s orbit, or around 200,000 miles (325,000 km) away.  Even though this orbit is high, 
it is still very far from the Solar System boundary that it is measuring.  The distance to the near edge of 
the heliosphere is around 9 billion miles (14 billion km) from the Earth, or about 90 times the distance 
between the Earth and the Sun.  
www.nasa.gov
National Aeronautics and Space Administration
How does IBEX collect data?
IBEX uses two sensors to collect ENAs 
made from solar wind particles. Solar wind 
particles are usually charged, meaning 
they have lost electrons.  Another name for 
a particle that has lost one or more elec-
trons is an “ion.”  Sometimes these solar 
wind ions interact with neutral atoms that 
come from the ISM.  Neutral atoms contain 
equal numbers of protons and electrons. 
The solar wind ions take electrons from 
these neutral ISM atoms and get deflected 
from their original path.  Since the solar 
wind particles are now neutral, they no 
longer react to magnetic fields in the area.  
They travel very quickly in a straight line 
from the spot where the interaction 
occurred.  
The IBEX-Hi sensor, one of two sensors on the IBEX spacecraft 
(IBEX-Hi and IBEX-Lo).  Credit:  IBEX Science Team.
Some of the ENAs happen to get knocked in a straight line in just the right way so that they travel in 
through the Solar System toward the IBEX spacecraft.  This is how the scientists can map the boundary 
– they know the direction of travel of each particle since they did not change direction between the helio-
pause and the IBEX spacecraft.  IBEX’s sensors detect between one particle per hour and a few per 
second. 
To make sure that only ENAs enter IBEX’s collectors, ions are deflected before they even enter the 
collectors. The sensors sort the particles and keep track of the direction of travel of all of the particles,  
the time they entered the sensor, the mass of the particles, and the amount of energy each particle has.  
Though IBEX cannot determine the distance the particles have traveled, an accurate map of the bounary 
can be created from the information IBEX is able to collect.
www.nasa.gov
National Aeronautics and Space Administration
How does IBEX communicate with Earth?
IBEX completes an orbit every eight days. 
During each orbit, there is a period of time 
when the spacecraft is within the Earth’s 
magnetosphere and closer to Earth.  At this 
point, the spacecraft uses antennae that 
are attached to the outside of the spacecraft 
to send radio signals to receivers on Earth.  
Due to the rotation of the Earth each day, 
the IBEX team needs a global network of 
receivers so that no matter how the satellite 
and Earth are lined up, there is a receiver 
available to accept the signal.  IBEX is 
never far from Earth, so it takes a second or 
less for signals to travel between IBEX and 
Earth. 
IBEX communications are slow, but they do 
not need to be on par with DSL connections 
on Earth.  Communication from the satellite 
to the ground is 320,000 bits of information 
per second, and from the ground to the 
satellite is 2,000 bits per second.  Compare 
this to a typical home cable modem connec-
tion, where the download speed is often 6 
million bits per second, and the upload 
speed is about 500,000 bits per second!  
IBEX does not need a high-speed connec-
tion, though, since it only has the opportu-
nity to collect up to a few particles per 
second and does not need to transmit a 
vast amount of information to Earth.  Once 
on Earth, the signal is carried to the IBEX 
Mission Control Center in Dulles, Virginia 
and to the IBEX Science Operations Center 
in San Antonio, Texas. 
IBEX's orbital location is about 200,000 miles (323,000 kilometers) 
from Earth.  IBEX spins but always keeps its solar panels aimed at 
the Sun.  Over the course of a year, IBEX’s sensors will gather 
particles from the entire sky.    Credit:  IBEX Team
www.nasa.gov
National Aeronautics and Space Administration
Why is IBEX’s mission important?
IBEX will be the first spacecraft to map the entire region of the Solar System boundary. Mapping the 
current state of the outer edge of the heliosphere, called the heliopause, will help scientists to determine 
what this important protective boundary is like. The heliopause and the heliosheath are regions that 
protect our Solar System from incoming cosmic rays. Cosmic rays are energetic particles that are often 
made when a star explodes; other cosmic rays come from the Sun or from as far away as other galaxies. 
If cosmic rays impact something, they can do damage to atoms and molecules. If the Solar System did 
not have this boundary, then there would be around 4 times more high-energy cosmic rays that would 
enter our Solar System. 
Life on Earth benefits from two other layers that protect us from cosmic rays – our planet’s magnetic 
field, or magnetosphere, and atmosphere.  If there were a dramatic increase in the number of cosmic 
rays entering the Solar System, such as from a nearby supernova, more cosmic rays might then reach 
the Earth’s surface.  Damage to the Earth’s ozone layer could occur, and cosmic rays could cause 
damage and mutation to DNA. Additionally, when humankind travels to the Moon again or to other loca-
tions in our Solar System, astronauts would be outside of the Earth’s atmosphere and magnetosphere, 
so knowing more about the protective abilities of the heliopause will help us plan for future long-term 
space travel that is safer for humans.
This graph shows a representation of the percentage of cosmic rays that are blocked by the boundary of our 
Solar System in terms of distance from the boundary in astronomical units (1 AU = 93 million miles).  Only about 
1 in 4 cosmic rays reaches the area of the planets.  Credit:  IBEX Science Team. 
www.nasa.gov
National Aeronautics and Space Administration
What is in store for IBEX’s future?
Our star, the Sun, as imaged by the SOHO spacecraft.  Credit: SOHO (ESA and NASA)
IBEX’s primary mission will last for two years. If the spacecraft is healthy in mid-2010, and if NASA’s 
budget permits, then the mission may be extended. From 2008 to 2010, the Sun’s activity level will 
increase, which may push the heliosphere outward and/or change its shape. Because the amount of 
solar wind particles streaming from the Sun depends, in part, on how active the Sun is, scientists are 
eager to make several maps of the heliopause, not just one.
 
www.nasa.gov
National Aeronautics and Space Administration
Activities to do at home:
How big is IBEX? 
IBEX is the size of a bus tire or a large semi 
truck tire. Next time you see one of these tires 
close up, check it out!  As a comparison, the 
cargo bay of the space shuttle is the size of a 
bus.  IBEX is pretty small, but it can accomplish 
a lot!
Scientists work on the IBEX spacecraft. 
Credits: IBEX Team/Orbital Sciences
Sorting Particles
IBEX uses its sensors to sort particles coming 
from the Solar System’s boundary.  Try your 
own sorting activity to see how easy or difficult 
  this might be. 
Next time you are walking among a few trees 
that have lost their leaves, stop and pick up 
some of the leaves.  Sort them by type of leaf if 
they are from different kinds of trees.  Can you 
tell which trees the leaves came from?
In the same way you used your hands and eyes as tools to sort leaves, IBEX sorts particles by direction 
of origin.
Learn More
For more information, to play games, and sign up for monthly mission updates visit: http://ibex.swri.edu
Credit: Images available in the public domain 
through Wikimedia Commons.
www.nasa.gov


Exploring the Edge of Our Solar System: IBEX Mission (Poster)

http://www.ibex.swri.edu/planetaria/IBEX_missionposter.pdf

Exploring the Edge of Our Solar System: IBEX Mission (Poster)

Abstract

Similar works

Full text

Available Versions

Digital Library for Earth System Education