ACE

Advanced Composition Explorer

Active Mission

Designed to collect and analyze particles from near and far, ranging from solar wind ions to galactic cosmic ray nuclei, ACE far exceeded its expected life span of five years, and it continues to provide data on space weather and give advance warning of geomagnetic storms.

Type

Orbiter

Launch

Aug. 25, 1997

Target

Sun-Earth Interaction

Objective

Study spaceborne energetic particles

Experience Earth, our solar system, nearby asteroids, the universe, and the spacecraft exploring them with immersive real-time 3D web-based apps for Mac, PC, and mobile devices.

NASA/JPL-Caltech/VTAD

NASA's Advanced Composition Explorer (ACE) collects and analyzes particles of solar, interplanetary, interstellar, and galactic origins. The data contributes to our understanding of the Sun, its interaction with Earth, and the evolution of the solar system.

ACE continues to provide space weather reports and warnings of geomagnetic storms that can disrupt communications on Earth and harm astronauts in space.
The spacecraft has operated far beyond its expected lifetime.

Nation	United States of America (USA)
Objective(s)	Sun–Earth L1 Lagrange Point
Spacecraft	ACE
Spacecraft Mass	1,658 pound (752 kilograms)
Mission Design and Management	NASA / GSFC
Launch Vehicle	Delta 7920-8 (no. D247)
Launch Date and Time	Aug. 25, 1997 / 14:39 UT
Launch Site	Cape Canaveral, Florida / Launch Complex 17A
Scientific Instruments	1. Solar Wind Ion Mass Spectrometer (SWIMS) 2. Solar Wind Ion Composition Spectrometer (SWICS) 3. Ultra-Low Energy Isotope Spectrometer (ULEIS) 4. Solar Energetic Particle Ionic Charge Analyzer (SEPICA) 5. Solar Isotope Spectrometer (SIS) 6. Cosmic Ray Isotope Spectrometer (CRIS) 7. Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) 8. Electron, Proton, and Alpha-Particle Monitor (EPAM) 9. Magnetometer (MAG)

Key Dates

Aug. 25, 1997: Launch

Jan. 21, 1998: Spacecraft began operations

👁 Image

A Boeing Delta II expendable launch vehicle lifts off with NASA’s Advanced Composition Explorer (ACE) observatory at 10:39 a.m. EDT on Aug. 25, 1997, from Launch Complex 17A, Cape Canaveral Air Station, Florida.

NASA

In Depth: ACE

NASA's Advanced Composition Explorer (ACE) spacecraft was designed to study spaceborne energetic particles from the Sun-Earth L1 Lagrange point, about 870,000 miles (1.4 million kilometers) from Earth.

Specifically, the spacecraft was launched to investigate the matter ejected from the Sun to establish the commonality and interaction between the Sun, Earth, and the Milky Way galaxy.

In addition, ACE also provides real-time space weather data and advanced warning of geomagnetic storms. ACE’s nine instruments have a collecting power that is 10 to 10,000 times greater than anything previously flown.

After launch, the spacecraft’s Delta 2 launch vehicle’s second stage reignited after four hours to insert the satellite into a 110 × 851,000-mile (177 × 1.37 million-kilometer) orbit.

After reaching apogee after launch, ACE inserted itself into its Lissajous orbit around the L1 point. The spacecraft was declared operational Jan. 21, 1998.

As of 2015, it continued to provide near-real-time 24/7 coverage of solar wind parameters and to measure solar energetic particle intensities.

With the exception of the SEPICA instrument (data from which was no longer received after Feb. 4, 2005), all instruments on ACE remain operational.