NASA Logo, National Aeronautics and Space Administration

National Aeronautics and Space Administration

Goddard Space Flight Center

Astrophysics Science Division | Sciences and Exploration

This website is kept for archival purposes only and is no longer updated.

Skip to content

- Welcome -


Press Release








The Goddard ISOMAX experiment was a state-of-the art superconducting magnetic mass spectrometer constructed for the purpose of measuring the abundance of isotopes in the cosmic radiation. Cosmic radiation is the term used for high energy particles coming from the Sun, the Galaxy, and beyond.

This enabled the balloon-borne instrument, which was first flown in August '98, to put constraints on the typical travel times of cosmic rays and the density of the propagated medium -- hence on the question how old cosmic rays really are and much time they spend traveling outside the galactic disk.

Secondary nuclei in the cosmic radiation, which are produced in the process of propagation and nuclear fragmentation of primary particles through the interstellar medium, can be used to gain information on the propagation mechanism, and the details of the cosmic ray diffusion and the gas distribution in the galaxy.

If the production of isotopes in these fragmentation processes is understood, then the measurement of the ratios of these isotopes as they arrive on earth (especially ratios of the isotopes of Beryllium, 7Be, 9Be and the radioactive 10Be, which has a half-life of 1.6 Myrs) at energies around 1GeV/nucleon can be used to decide between different models of cosmic ray production and propagation.