NASA's Advanced Composition Explorer (IMAGE) NASA/Goddard Space Flight Center Caption NASA's Advanced Composition Explorer (ACE) observes a wide array of particles that flow toward Earth from the sun to better understand the great space weather system that connects the sun to our planet. Credit NASA/H. Zell Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.