Speeds and fluences of hydrogen and helium ejecta from the 2003 Halloween Solar Storm preserved by NASA Genesis samples

Abstract The Halloween solar storms of 2003 and associated coronal mass ejections (CMEs) hurled one of the most intense interplanetary CMEs (ICMEs) during the space age toward Earth. The ICMEs forced many operating spacecraft into “safe mode” and spacecraft that were not “safed” were pushed to their observational limits. In contrast, although the electronics of the NASA Genesis spacecraft were safed, the solar wind (SW) collector array designed to sample CMEs remained deployed. The sample collection arrays were returned to Earth, enabling quantification of the hydrogen and helium particles of the ICMEs by depth profiling. During the entire period of collection by the Genesis spacecraft, the SW was monitored in situ continuously by the Advanced Composition Explorer (ACE). The Genesis results demonstrate that the hydrogen and helium fluences of ICMEs during the Halloween solar storms of 2003 were significantly greater than inferred by the in situ plasma instruments of ACE. In contrast, Genesis and ACE results were shown to be identical within uncertainties except for the period during the Halloween solar storms of 2003. The Genesis returned samples provide a means to investigate intense ICMEs in laboratories using Genesis data as a standard reference.