SEPICA (Solar Energetic Particle Ionic Charge Analyzer) is one of nine instruments on the ACE (Advanced Composition Explorer) satellite. The ACE spacecraft is designed to identify matter that comes near the earth. This matter can come from the sun, the "space" between planets, and the Milky Way galaxy. The particles are identified by their type, energy, and electric charge. These observations will help us to better understand the formation and evolution of the solar system. When reporting space weather, ACE can provide an advanced warning (about one hour) of geomagnetic storms that can overload power grids, disrupt communications, and present a hazard to astronauts.

ACE Facts:

• Launch vehicle: Delta II
• Primary mission: To observe energetic particles within the solar system.
• Mission lifetime: 2 years with a 5 year goal
• Launch date: August 1997
• Orbit: ACE will be in the L ₁ Halo orbit, where the Earth's gravitational pull is equal to that of the sun

A picture of the ACE satellite:

A photo of the actual satellite:

A graph of the range of particles that ACE will measure. The portion labeled SEPICA represents the particles our instrument will deal with:

ACE Links:

• UNH Space Science Home Page
• NASA ACE Home Page
• Science Goals for ACE