National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
 By Target   By Name   By Decade 
Search all Missions Between:      and      Search
1950-1959 1960-1969 1970-1979 1980-1989 1990-1999 2000-2009 2010-2019 2020+
ACE Mission to Our Solar System

Goals: The Advanced Composition Explorer's prime objective is to measure and compare the composition of particles that travel to us from the Sun, the space surrounding our solar system, and elsewhere in the Galaxy. The mission also seeks to advance our ability to forecast space weather in the coming years when humans will venture beyond Earth's protective magnetosphere.

Accomplishments: 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.

Key Dates
25 Aug 1997:  Launch (14:39 UT)
21 Jan 1998:  Spacecraft Operational
Status: Extended Mission in Progress
Fast Facts
ACE Facts ACE analyzes particles blown from the sun and from elsewhere in our galaxy.

The particles ACE detects include galactic cosmic rays, which are fragments of atoms from deep in the galaxy, traveling at nearly the speed of light.

ACE helps us understand the sun, its interaction with Earth, and the Solar System's origin and evolution.

ACE provides about a one-hour warning of space-weather events that could harm electronics and future astronauts. It may help us one day to predict hazardous space weather.

ACE orbits the sun at Lagrangian Point 1 (L1), which is about 930,000 miles (1.5 million km) sunward of Earth.

At L1, Earth's gravity counterbalances that of the sun such that ACE remains directly between Earth and the Sun as the planet and spacecraft orbit the sun.
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writers: Courtney O'Connor and Bill Dunford
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> NASA Advisory Council
> Open Government at NASA
Last Updated: 8 Apr 2014