The solar wind generated by our Sun carves out a protective bubble around the solar system, called the heliosphere. The interstellar medium, consisting of the gas and the dust found between the galaxies, interacts with the solar wind and defines the actual boundary, which is called the termination shock.
NASA has designed a mission to map the boundary of the solar system. The mission is called IBEX (Interstellar Boundary Explorer) and it is ready to launch. The data collected by IBEX will allow scientists to understand the interaction between our Sun and the galaxy for the first time. Understanding this interaction will help us protect future astronauts from the danger of galactic cosmic rays.
In January 2005, the Orbital Science Corporation was selected to develop, build, and launch a small spacecraft for NASAâ€™s IBEX mission. The IBEX spacecraft is based on an already existing bus: the MicroStar satellite. IBEX will be launched by a Pegasus XL rocket, which will be dropped from an aircraft flying over the Pacific Ocean.
Pegasus began its commercial career in April 1990, and since then it has launched more than 80 satellites into space.
Pegasus is a three-stage launching system used to deploy small satellites weighing up to 1,000 pounds into Low Earth Orbit (LEO). An aircraft carries Pegasus to an altitude of 40,000 feet.
The rocket is released and free-falls before igniting its engines. It takes roughly ten minutes for Pegasus to deliver a satellite into orbit.
Pegasus will place IBEX into a 130 mile altitude orbit. An extra solid-fueled rocket will boost the spacecraft from the LEO. IBEXâ€™s final orbit will be a highly elliptical orbit with the perigee at an altitude of 7,000 km and the apogee at 236,000 km. IBEX has to operate in this orbit because any interference from the Earthâ€™s magnetosphere would make it impossible to take accurate measurements with the scientific instruments onboard.
IBEX has a mass of only 83.33 lbs (roughly 38 kg) and is described by NASA as being the size of a bus tire. The instruments onboard IBEX will collect particles called energetic neutral atoms (ENAs). The ENAs are radiated from the termination shock region. The ENA hits recorded by the instruments onboard IBEX will be used to create a map of this region.
The mission is scheduled to launch tomorrow, October 19th, 2008. The spacecraft will be operational for 24 months. You can find out more about the IBEX spacecraft on NASAâ€™s IBEX mission web page.