NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header




The objective of the Advanced Composition Explorer (ACE) is to collect observations of particles of solar, interplanetary, interstellar, and galactic origins, spanning the energy range from that of KeV solar wind ions to galactic cosmic ray nuclei up to 600 MeV/nucleon. Definitive studies will be made of the abundances of essentially all isotopes from H to Zn (Z = 1-30), with exploratory isotope studies extending to Zr (Z = 40). The ACE payload includes six high resolution spectrometers, each designed to provide the optimum charge, mass, or charge-state resolution in its particular energy range. Each spectrometer has a geometry factor optimized for the expected flux levels, so as to provide a collecting power greater by a factor of 10-1000 times that of previous or planned experiments. The payload also includes three additional instruments of standard design to monitor energetic electrons, H and He ions, and a magnetometer. The ACE spacecraft is based on the design of the Charge Composition Explorer, built at JHU/APL for the Active Magnetospheric Particle Tracer Explorer (AMPTE) program. The spacecraft spin axis is pointed towards the Sun to within +/- 20 degrees, and it occupies a halo orbit about the L1 Earth-Sun libration point. Powered by solar cells, the spacecraft has a design life of at least five years, and it returns data in daily tape recorder dumps, received through NASA JPL's Deep Space Network and initially processed at NASA-GSFC. The average data telemetry rate is 6.7 Kbs.

Alternate Names

  • 24912
  • Advanced Composition Explorer
  • Explorer 71

Facts in Brief

Launch Date: 1997-08-25
Launch Vehicle: Delta II 7920
Launch Site: Cape Canaveral, United States
Mass: 596 kg
Nominal Power: 464 W

Funding Agency

  • NASA-Office of Space Science (United States)


  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. John F. Cooper



NameRoleOriginal AffiliationE-mail
Prof. Edward C. Stone, Jr.Mission Principal InvestigatorCalifornia Institute of
Dr. W. Vernon JonesProgram ManagerNASA
Dr. Jonathan F. OrmesProject ScientistNASA Goddard Space Flight
Dr. John LintottProgram ManagerNASA Headquarters
Dr. W. Vernon JonesProgram ScientistNASA
Mr. Frank E. SnowMission Operations ManagerNASA Goddard Space Flight
Mr. Donald L. MargoliesProject ManagerNASA Goddard Space Flight

Other ACE Data/Information at NSSDCA


SPDF Anonymous FTP (HDF and ASCII data)
SSCWeb (SSC ephemeris plots and data)

Archiving Status

Date Coverage Chart for ACE Data Sets at NSSDCA and on CDAWeb

Press Releases

ACE arrives at KSC (06/13/97)

Other Sources of ACE Data/Information

ACE Science Center Data
ACE Fact Sheet

[] NASA Logo -