Advanced Composition Explorer

The Advanced Composition Explorer, or ACE, is a satellite that orbits Earth nearly 1 million miles above the ground. As an ongoing NASA mission, the purpose of ACE is to research the makeup of energetic particles that the solar wind and galactic cosmic rays carry to Earth.
 
Other functions of ACE include:
  • to analyze the composition of the solar corona, the outer atmosphere of the sun
  • to research the structure of the Local Interstellar Medium, visible gaseous matter that makes up the 10 percent of the visible matter in our galaxy.
The ACE carries nine different instruments to scientifically observe, analyze and investigate the materials it gathers. These tools also help ACE investigate the origin and development of galactic matter.
 
Through its analysis and observation, the Advanced Composition Explorer can give researchers some advanced warning of geomagnetic storms that send large amount of ionized particles to Earth. Because these particles can disrupt or even breakdown cell phone networks and other satellite-operated services, having advanced warning is helpful to the companies and people that utilize electronic resources. The warning the ACE provides also helps protect astronauts from injury.

ACE History

Scientists who wanted to gather information on the makeup of galactic cosmic rays and solar rays were the driving forces behind the development of ACE. After a meeting at the University of Maryland in 1983, these scientists proposed a satellite created to glean matter and information from these rays.

However, NASA didn't begin to act on the idea until three years later, when Dr. Vernon Jones resubmitted the proposal under a different name. Two years after Dr. Jones resubmitted the proposal, NASA began exploring the feasibility of such a project.

In April 1991, the California Institute of Technology and NASA signed a contract to begin developing the Advanced Composition Explorer. On Aug. 25, 1997, 14 years after the idea was originally proposed, the ACE launched from the Kennedy Space Center in Florida. By that time, the satellite was about 3 feet tall and almost 3 yards across.

ACE Today

Currently, the Advanced Composition Explorer is still in orbit. However, because its orbiting point is unstable, NASA has to perform about five maneuvers per year to keep the ACE in its proper position. To do this, NASA uses hydrazine-fueled rockets to propel the satellite back into place, which is essential to keeping the ACE's antenna pointing toward Earth so NASA receives all of its transmissions.
 
To run its electronics, the ACE uses a solar array that provides about 500 watts of power. To date, the ACE seems to have enough fuel to keep it in orbit until 2022, barring any unusual maneuvers that will use up more hydrazine than expected. However, the readings and information ACE collects and transmits back to Earth will likely prove to valuable long past then, as researchers use this information to help them determine the origins of our galaxy.
 
Resources
 
Christian, Eric R., and Andrew J. Davis (2007). Advanced Composition Explorer (ACE) Mission Overview. Retrieved February 8, 2008, from the Cal Tech ACE Web site.
 
Nemiroff, Robert, and Jerry Bonnell (2002). Astronomy Picture of the Day. Retrieved February 8, 2008, from the NASA Web site.