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  <Observatory>
    <ResourceID>spase://CDPP/Observatory/AMDA/ACE</ResourceID>
    <ResourceHeader>
      <ResourceName>ACE</ResourceName>
      <AlternateName>Advanced Composition Explorer, NASA</AlternateName>
      <AlternateName>1997-045A</AlternateName>
      <AlternateName>Explorer 71</AlternateName>

      <ReleaseDate>2015-12-31T18:19:16Z</ReleaseDate>

      <Description>Advanced Composition Explorer (ACE) observes particles of solar, 
        interplanetary, interstellar, and galactic origins, spanning the energy range 

        from solar wind ions to galactic cosmic ray nuclei.

        The Advanced Composition Explorer (ACE) spacecraft carries six high-resolution 
        sensors and three monitoring instruments that sample low-energy particles of solar
        origin and high-energy galactic particles with a collecting power 10 to 1000 times 
        greater than past or planned experiments. From a vantage point approximately 1/100 of the 
        distance from the Earth to the Sun, ACE performs measurements over a wide range of energy 
        and nuclear mass, under all solar wind flow conditions and during both large and small
        particle events including solar flares.
        
ACE provides near-real-time solar wind information 
over short time periods. When reporting space weather, 
ACE can provide an advance warning (about one hour) of geomagnetic 
storms that can overload power grids, disrupt communications on Earth, 
and present a hazard to astronauts.

The prime objective of ACE is 
to measure and compare the composition of several samples of matter, 
including the solar corona, the solar wind, and other interplanetary particle populations, 
the local interstellar medium (ISM), and galactic matter. While there has been great progress 
addressing these objectives, the changing conditions over the solar cycle present new opportunities. 
In addition, new observations and theoretical advances, new missions, and the evolving goals of NASA 
and the Sun-Solar- System Connection (S3C) Theme have introduced new challenges, including the goal 
of achieving the scientific understanding needed to forecast space weather in the coming years when 
humans will venture beyond Earth's protective magnetosphere.
      </Description>
      <Contact>
        <PersonID>spase://SMWG/Person/Edward.C.Stone.Jr</PersonID>
        <Role>PrincipalInvestigator</Role>
      </Contact>
      <InformationURL>
        <Name>ACE Home Page</Name>
        <URL>http://www.srl.caltech.edu/ACE</URL>
        <Description>ACE mission home page at Caltech with data download</Description>
      </InformationURL>
      <InformationURL>
        <Name>NSSDC's Master Catalog</Name>
        <URL>http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1997-045A</URL>
        <Description>Information about the ACE mission</Description>
      </InformationURL>
      <PriorID>spase://vspo/observatory/2</PriorID>
    </ResourceHeader>
    <Location>
      <ObservatoryRegion>Heliosphere.NearEarth</ObservatoryRegion>
      <ObservatoryRegion>Heliosphere.Inner</ObservatoryRegion>
    </Location>
    <OperatingSpan>
      <StartDate>1997-08-25T00:00:00</StartDate>
      <Note></Note>
    </OperatingSpan>
  </Observatory>
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