Martian Radiation Environment Experiment (MARIE)

The radiation environment between Earth and Mars and particularly at Mars, must be known prior to sending astronauts on lengthy exploratory missions. In an effort to understand the radiation environment that future astronauts will be exposed to, the Martian Radiation Environment Experiment (MARIE) was sent to Mars aboard the 2001 Odyssey spacecraft. Odyssey left Earth April 7, 2001 and arrived at Mars on October 23, 2001. MARIE collected data from April 2001-August 2001 and from March 2002-October 2003. MARIE is capable of detecting charged nuclei with energies greater than 30 MeV/u, and elements can be distinguished for charges of Z < 11. The average dose at Mars is about twice that measured by instruments aboard the International Space Station. Although the radiation level at Mars is higher than that experienced in low-Earth orbit (LEO), the measured radiation level does not necessarily preclude a manned Mars mission. However, the measurement does conclude that proper shielding materials must be used in the habitation module of any spacecraft and a highly shielded area must be provided as shelter from intense solar particle events (SPE) in order to minimize the total radiation dose received by any exploration crew. The data presented here are the absolute flux measurements of protons and He in Mars orbit in the energy range of 50-240 MeV/u.