Hink said the team found in their cosmic ray collection that this decay process had already run its course. This means that Ni-59, formed in one supernova explosion, sat decaying for over a 100,000 years before another supernova blast wave came along and propelled it into the surrounding galaxy at cosmic ray energies. Hink said that once an atom of Ni-59 is accelerated to cosmic ray energies and loses its electrons, it is relatively stable and invulnerable to decay, as long as it keeps moving. Dr. Mark Wiedenbeck of NASA's Jet Propulsion Laboratory, a member of the CRIS team, said their results rule out the possibility of the cosmic ray seed particles being fresh supernova ejecta. Instead, the results support theories for the origin of cosmic rays to be old stellar or interstellar material.
Results are also consistent with the superbubble theory, put forth last year.
CRIS was developed by the California Institute of Technology, Washington University in St. Louis, Goddard Space Flight Center, and the Jet Propulsion Laboratory. The instrument is one of nine aboard ACE, launched by NASA in 1997 to collect and analyze matter from the sun, from the space between planets and from the Milky Way galaxy beyond our solar system.