Advanced Composition Explorer

Advanced Composition Explorer (ACE)

An artist's concept of ACE
Operator	NASA
Mission type	Orbiter
Launch date	August 25, 1997
Launch vehicle	Delta II
Mission duration	August 25, 1997 to 2024
COSPAR ID	1997-045A
Homepage	Advanced Composition Explorer Home
Mass	596 kilograms (1,313 lb)
Power	44 Watts
Orbital elements
Semimajor axis	2.57
Eccentricity	0.98967
Inclination	28.7°
Apoapsis	1,256,768 kilometers (780,919 mi)
Periapsis	179 kilometers (111 mi)
Orbital period	1,398 hours (58.25 days)

ACE in orbit around the Sun–Earth L₁ point

Advanced Composition Explorer (ACE) is a NASA Explorer program Solar and space exploration mission to study matter comprising energetic particles from the solar wind, the interplanetary medium, and other sources. Real-time data from ACE is used by the Space Weather Prediction Center to improve forecasts and warnings of solar storms. The ACE robotic spacecraft was launched August 25, 1997 and is currently operating in a Lissajous orbit close to the L1 Lagrange point (which lies between the Sun and the Earth at a distance of some 1.5 million km from the latter). The spacecraft is still in generally good condition, and has enough fuel to maintain its orbit until 2024. NASA Goddard Space Flight Center managed the development and integration of the ACE spacecraft.

Instrumentation

Cosmic Ray Isotope Spectrometer (CRIS): CRIS determines the isotope composition of galactic cosmic rays. It is designed to be sensitive enough to detect isotopes up to the range of zinc (Z-30).

ACE Real Time Solar Wind (RTSW):

Solar Wind Ion Mass Spectrometer (SWIMS) and Solar Wind Ion Composition Spectrometer (SWICS): These two instruments are time-of-flight mass spectrometers, each tuned for a different set of measurements. They analyze the chemical and isotopic composition of solar wind and interstellar matter.

Ultra-Low Energy Isotope Spectrometer (ULEIS): ULEIS measures ion flux and is sensitive to a range from helium through nickel to determine the makeup of solar energetic particles and the mechanism by which the particles become charged by the sun.

Solar Energetic Particle Ionic Charge Analyzer (SEPICA): As of 2008, this instrument is no longer functioning due to failed gas valves.

Solar Isotope Spectrometer (SIS):^{[citation needed]}

Solar Wind Electron, Proton and Alpha Monitor (SWEPAM):^{[citation needed]}

Electron, Proton, and Alpha-particle Monitor (EPAM):^{[citation needed]}

Magnetometer (MAG):^{[citation needed]}

See also

• Heliophysics
• Tom Krimigis
• Cassini–Huygens
• Cluster (spacecraft)
• Helios (spacecraft)
• MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging), launched 2004, still operational.
• Solar Dynamics Observatory (SDO), launched 2010, still operational.
• Solar and Heliospheric Observatory (SOHO), launched 1995, still operational.
• Solar Maximum Mission (SMM), launched 1980, decommissioned 1989.
• Solar Orbiter (SOLO), set to launch in 2015.
• Solar Probe Plus, set to launch in 2015.
• STEREO (Solar TErrestrial RElations Observatory), launched 2006, still operational.
• Transition Region and Coronal Explorer (TRACE), launched 1998, decommissioned 2010.
• Ulysses (spacecraft), launched 1990, decommissioned 2009.
• Van Allen Probes

External links

• "Advanced Composition Explorer (ACE) Home Page". ACE Science Center. July 1, 2003. Archived from the original on 5 July 2006. Retrieved June 30, 2006.