Greenbelt (MD) – NASA said it is set to launch a spacecraft to image and map the interstellar boundary regions for the very first time: IBEX is planned to conduct high-altitude orbits above Earth to investigate and capture images of processes taking place at the farthest reaches of the solar system – a region where the solar system meets interstellar space - nine billion miles from the sun.
The Interstellar Boundary Explorer, short IBEX, could be viewed as a result of the fascinating journey of Voyager 1 and Voyager 2 spacecraft that began in 1977. More than 30 years ago, the two Voyagers were sent on a 5-year mission to study Jupiter (reached in March 1979) and Saturn (reached in November 1980) as well as the larger moons of the two planets. As we know today, the spacecraft lasted much longer than expected and flew by Uranus (reached in January 1986) and Neptune (reached in August 1989) as well, capturing fascinating imagery along the way.
Last year, Voyager 1 crossed the border into the heliosheath (the area beyond the termination shock, see our slideshow for illustrations), about 9.7 billion miles from the sun. Voyager 2 was 7.8 billion miles from the sun at the time and was approaching the heliosheath. Both spacecraft are on their way to cross the edge of the heliopause - outermost boundary of the solar wind - within the next ten years. In July of this year, NASA scientists used data sent from Voyager 2 to determine the bubble of solar wind surrounding the solar system is not round, but has a squashed shape.
As the Voyager spacecraft continue their journey and remain the most distant human-made objects in space - carrying famous golden records describing life on Earth - NASA is now ready to create image data from the farthest part of our solar system between the termination shock - where an invisible shock forms as the solar wind piles up against the gas in interstellar space - and the beginnings of the heliosheath. NASA considers the termination shock as our solar system’s final frontier and believes it can use IBEX, a relatively low-cost spacecraft, from far away: IBEX is designed to provide image data of the termination shock and areas beyond by using hits from high-speed atoms that are radiating out of this region. The images promise to provide detailed insight in the global interaction between our sun and the galaxy for the very first time.
“IBEX will let us make the first global observations of the region beyond the termination shock at the very edges of our solar system. This region is critical because it shields out the vast majority of the deadly cosmic rays that would otherwise permeate the space around the Earth and other planets,” said David J. McComas, IBEX Principal Investigator (PI) from the Southwest Research Institute (SwRI) in San Antonio, Texas. “IBEX will let us visualize our home in the galaxy for the first time and explore how it may have evolved over the history of the solar system. Ultimately, by making the first images of the interstellar boundaries neighboring our solar system, IBEX will provide a first step toward exploring the galactic frontier.”
To be able to create images, the spacecraft needs to travel about 200,000 miles away from Earth and leave the magnetosphere, a region controlled by Earth’s magnetic field, behind. According to NASA, the magnetosphere generates radiation and the same high-speed atoms (Energetic Neutral Atoms or ENAs) that IBEX will use to make its pictures. NASA believes that a “spinning” IBEX will have observed the entire sky after six months and will have revealed the global structure of the heliosheath and termination shock for the first time. “The solar system’s frontier is billions of miles away, so it’s difficult for us to go there, but interesting things happen at boundaries, and with IBEX, we will see them for the first time,” said Dr. Robert MacDowall, IBEX Mission Scientist at NASA’s Goddard Space Flight Center in Greenbelt.
The Voyager spacecraft remain the inspiration for the IBERX mission. McComas said that "the Voyager spacecraft are making fascinating observations of the local conditions at two points beyond the termination shock that show totally unexpected results and challenge many of our notions about this important region."
IBEX is scheduled to launch on October 19. The two-year mission will begin from the Kwajalein Atoll, a part of the Marshall Islands in the Pacific Ocean.
The future of Voyager 1 and 2
The Voyager 1 and 2 interstellar mission is still running and is expected to continue for perhaps 20 more years in total, which makes those two spacecraft, which were built, launched and operated during the first five years for $865 million, one of NASA’s best investments. Both craft are currently operated with an annual budget of $30 million and travel about 320 million miles (Voyager 1) and 290 million miles (Voyager 2) per year.
Voyagers 1 and 2 are identical spacecraft equipped with television cameras, infrared and ultraviolet sensors, magnetometers, plasma detectors, and cosmic-ray and charged-particle sensors. Communications are still intact and are planned to be maintained until the Voyagers' nuclear power sources (radioisotope thermoelectric generators) can no longer supply enough electrical energy to power critical subsystems. It is estimated that there is enough power to run these systems until the year 2020 – 2025. Both craft are too are too far from the sun to use solar power and consume just 300 watts, NASA said.
The functionality of the two Voyagers is limited. The cameras on the spacecraft have been turned off several years ago and only five of the original ten science instruments are still in operation. However, both spacecraft are described as healthy and are returning scientific data using NASA's Deep Space Network, a system of antennas around the world. The spacecraft are so distant that commands from Earth, traveling at light speed, take 14 hours one-way to reach Voyager 1 and 12 hours to reach Voyager 2.
NASA said that it is still conducting experiments to study the solar wind, energetic particles, magnetic fields and radio waves as the Voyagers travel farther away from Earth. The spacecraft have also become space-based ultraviolet observatories and their unique location in the universe gives astronomers the best opportunity they have ever had for looking at celestial objects that emit ultraviolet radiation.