Press Release   Home  >   News & Publications  > Press Releases

20 February 1997
For Immediate Release

Advanced Composition Explorer Spacecraft Shipped to Goddard for Prelaunch Testing

The Advanced Composition Explorer (ACE) was shipped today on an air ride van to the NASA Goddard Space Flight Center (GSFC) in Greenbelt, Md., by The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., where it was designed and built. Goddard will now begin final environmental testing in preparation for the spacecraft's scheduled August 21, 1997, launch from Cape Canaveral Air Station in Florida, aboard a Delta II rocket.

Earlier this month the ACE spacecraft was subjected to vibration testing at APL to verify structural integrity. "The tests went smoothly with all systems performing as expected," said Mary Chiu, APL Program Manager for spacecraft development. While at Goddard the spacecraft will undergo acoustic and mass properties testing, which is expected to be completed by mid-April, and thermal vacuum testing, scheduled for completion by mid-May. ACE will then be transported to Cape Canaveral and prepared for launch.

Once launched, ACE will begin a two- to five-year mission studying energetic particles coming from the sun, interplanetary space, and regions beyond, collecting data to help us understand the origin and evolution of our solar system. ACE will also serve as a lookout for geomagnetic storms stirred up by the sun and provide up to an hour's advance warning of conditions that could affect power and communications systems on Earth.

ACE will orbit the L1 point - the point of equilibrium between the Earth and sun's gravitational fields, located approximately 1.5 million kilometers (1 million miles) from the Earth. ACE carries nine particle measuring instruments, which together cover a broad and continuous mass and energy range. Several of these instruments will have collecting powers 10 to 1,000 times greater than any previous mission. With this impressive collecting power, the expansive mass and energy range, and an orbit outside the influence of the Earth's magnetosphere, ACE will be a premier platform for particle studies - much like the Hubble telescope's capabilities for astronomical investigations.

Instruments on the ACE platform include: the Electron, Proton and Alpha Particle Monitor (built by APL); Ultra-Low Energy Isotope Spectrometer (APL and the University of Maryland); a Solar Isotope Spectrometer (California Institute of Technology, GSFC, and JPL); a Cosmic Ray Isotope Spectrometer (Caltech, Washington University, GSFC, and JPL); a Solar Energetic Particle Ionic Charge Analyzer (University of New Hampshire and the Max Planck Institute, Germany); Magnetic Field Monitor (University of Delaware/Bartol Research Institute and the GSFC); Solar Wind Ion Mass Spectrometer and the Solar Wind Ion Composition Spectrometer (University of Maryland and the University of Bern, Switzerland); and the Solar Wind Electron, Proton, and Alpha Monitor (Los Alamos National Laboratory).

The ACE mission is sponsored by the Office of Space Science Mission and Payload Development Division at NASA Headquarters, Washington, D.C., with overall project management by the Explorer Project Office at Goddard. The California Institute of Technology Space Radiation Laboratory in Pasadena, Calif., is responsible for science payload management and the ACE Science Center, which will process and distribute collected science data.

Management for the ACE mission includes Donald L. Margolies, ACE Mission Manager, Explorer Office, GSFC; John R. Thurber, ACE Observatory Manager, Explorer Office, GSFC; Jonathan F. Ormes, ACE Project Scientist, GSFC; W. Vernon Jones, ACE Program Scientist, NASA Headquarters; and Louis J. Demas, ACE Program Senior Executive, NASA Headquarters.

ACE management at APL includes Mary C. Chiu, ACE Spacecraft Program Manager; Ute I. von Mehlem, Spacecraft Systems Engineer; Cliff E. Willey, Structure Lead Engineer; Elliot H. Rodberg, Spacecraft Ground Test System Lead Engineer; and Joseph P. Staiger, Integration and Test Lead Engineer. Stamatios M. Krimigis is Head of the APL Space Department and also Co-Investigator for the EPAM and ULEIS instruments, along with Robert E. Gold.

For more information please contact:

For more information, contact APL Public Information Officer Helen Worth; phone: 240-228-5113 or 410-778-5113.

Jim Sahli, Goddard Space Flight Center Office of Public Affairs,
(301) 286-0697 e-mail:

Photos are available upon request

ACE information can be accessed on the World Wide Web at: