NASA's Dawn spacecraft,designed and built by Orbital ATK,has gotten a second mission extension to further explore dwarf planet Ceres.The new orbit will enable its closest approach to the celestial body located in the asteroid belt between Mars and Jupiter,to within 120 miles/200 km of the surface.Its previous closest approach had been 240 miles/385 km.The orbit will also become Dawn's permanent home once it runs out of hydrazine fuel,which will probably be in late 2018.The Dawn mission team doesn't want the spacecraft to contaminate Ceres by landing on it or crashing into it.*
In the new orbit,Dawn will study the composition of Ceres' upper layer with its gamma ray and neutron spectrometer.Of particular interest is the amount of ice that may be present on and near the surface.Dawn's camera will also take visible light images of Ceres' surface geology,while its visible and infrared mapping spectrometer will take measurements of Ceres' mineralogy.Another highlight will be Dawn's presence during Ceres' perihelion,or closest approach to the Sun,in April 2018.Ice on and near Ceres' surface may turn to water vapor or even the weak transient atmosphere previous observations by ESA's Herschel Space Observatory have documented.Ground-based observatories will also be tapped for this study of Ceres' perihelion behaviour.The prime cause of the fleeting atmosphere,which lasts about a week per occurrence,is currently suspected to be solar wind protons bombarding Ceres in the course of the solar cycle and interacting with ice on and in its outer layer,irrespective of Ceres' distance from the Sun.*
Managed by the NASA Jet Propulsion Laboratory,Dawn's mission science is headed by UCLA.International partners on the mission include The German Aerospace Center;the Max Planck Institue for Solar System Research;the Italian Space Agency;and the Italian National Astrophysical Institute.*
Orbital ATK Inc (OA)
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