SH53C-01 INVITED 13:45h
Space Radiation Hazards on Human Missions to the Moon and Mars
One of the most significant health risks for humans exploring Earth's moon and Mars is exposure to the harsh space radiation environment. Crews on these exploration missions will be exposed to a complex mixture of very energetic particles. Chronic exposures to the ever-present background galactic cosmic ray (GCR) spectrum consisting of various fluxes of all naturally - occurring chemical elements are combined with infrequent, possibly acute exposures to large fluxes of solar energetic particles, consisting of protons and heavier particles. The GCR environment is primarily a concern for stochastic effects, such as the induction of cancer, with subsequent mortality in many cases, and late deterministic effects, such as cataracts and possible damage to the central nervous system. An acute radiation syndrome response ("radiation sickness") is not possible from the GCR environment since the organ doses are well below levels of concern. Unfortunately, the actual risks of cancer induction and mortality for the very important high-energy heavy ion component of the GCR spectrum are essentially unknown. The sporadic occurrence of extremely large solar energetic particle events, usually associated with intense solar activity, is also a major concern for Lunar and Mars missions because of the possible manifestation of acute effects from the accompanying high doses of such radiations, especially acute radiation syndrome effects such as nausea, emesis, hemorrhaging or possibly even death. Large solar energetic particle events can also contribute significantly to crew risks from cancer mortality. In this presentation an overview of current estimates of critical organ doses and equivalent doses for crews of Lunar and Mars bases and on those on transits between Earth and Mars is presented. Possible methods of mitigating these radiation exposures by shielding, thereby reducing the associated health risks to crews, are also described.
SH53C-02 14:05h
The Human Exploration Initiative: Space Radiation Measurement Needs
NASA's Space Exploration Initiative envisions human exploration missions to the Moon and Mars. To accomplish these missions safely, they must be designed and planned to limit the acute and long term health risks posed by ionizing radiation. This requires knowledge of the relevant components of the ionizing radiation environment in deep space, on the Moon and on Mars. In this talk we will identify what must be known about the ionizing radiation environment, discuss what knowledge already exists and suggest what new measurements may be needed before manned missions can be conducted safely.
SH53C-03 INVITED 14:20h
Operational Support Issues for the new NASA Exploration Initiative
The recent proposal for NASA to fly astronauts to the Moon and Mars is both very exciting and, at the same time, daunting. Any flight away from the protection of the Earth's magnetic field poses special problems for space weather operational support providers such as NOAA's Space Environment Center. Since the Apollo flights in the 1960's, SEC has provided forecasts and warnings of important space weather to NASA at Johnson Space Center. The NASA Space Radiation Analysis Group (SRAG) receives SEC products and services to aid them in their function of safeguarding the astronaut's health and safety. But to travel away from the Geo-magnetosphere and then the Sun-Earth line, new services will be necessary to insure the warning of imminent solar energetic particle (SEP) events, a severe threat to astronaut safety. Currently SEP forecasts are marginally accurate and must be improved. These SEP add to perhaps the most serious threat to safety, the constant bombardment of Galactic Cosmic Rays (GCR). Fortunately, the GCR behavior, though variable, is well understood. The presentation will consist first of a status report on the state of the predictive art for the near-Earth environment. That report will include both data and models currently used at SEC, as well as prediction verification statistics. Following that, there will be a look into future time on issues related to a lunar flight and a stay on the moon. Lastly some thoughts will be given on what may be required to provide adequate operational support for a flight to and from, and habitation on Mars.
SH53C-04 14:40h
Effects of Solar Energetic Particle Events on the Martian Surface and Atmosphere
Characterization of the Martian radiation environment is a major objective identified by MEPAG in preparation for human exploration of Mars, and includes both determination of the ionizing radiation environment at the surface, and the shielding properties of the Martian atmosphere. Solar energetic charged particles (SEPs) provide an important component of ionizing radiation at Mars, especially during periods of high solar activity. Further, SEP events affect the Martian atmosphere at all altitudes, contributing to increased levels of atmospheric heating and loss. In this work we trace trajectories of test particles subject to interaction with Mars' neutral atmosphere and crustal magnetic fields. We show the penetration depth through the Martian atmosphere as a function of energy and incidence angle for energetic protons, and show that crustal magnetic fields affect SEP energy deposition in the atmosphere. We will provide estimates of the primary proton surface flux and energy deposition for a single large SEP event, such as the one observed in late October of 2003, showing that SEP surface effects exceed those from galactic cosmic rays by an order of magnitude or more during this event. Finally, we will discuss intriguing observations by the electron reflectometer (ER) on the Mars Global Surveyor Spacecraft (MGS) that show a geographic dependence of high energy particles observed during SEP events.
SH53C-05 14:55h
Space Environment Forecasting for the Exploration Initiative with the Space Weather Modeling Framework
Robotic and human exploration of the solar system poses the challenge to model and eventually forecast the plasma and energetic particle environment throughout the inner heliosphere. This talk will describe the recently developed Space Weather Modeling Framework (SWMF) that combines numerical models of the solar corona (the global structure is determined by synoptic magnetograms), magnetically driven solar eruptions, the inner heliosphere out to Saturn's orbit, solar energetic particles, the global magnetosphere, the particle drift physics controlled inner magnetosphere, the radiation belts, the ionospheric electrodynamics and the upper atmosphere and ionosphere into a high performance coupled simulation. This powerful simulation tool is presently capable of running faster than real-time from the Sun to Earth and it will be further developed into a space weather forecasting tool for the Exploration initiative. Particular attention will be paid to predicting solar energetic particle spectra and fluxes throughout the inner heliosphere. The SWMF is capable of simulating the acceleration and transport of energetic particles together with a self-consistent description of interplanetary transients that generate and accelerate the SEP population.
http://csem.engin.umich.edu
SH53C-06 15:10h
On the Creation of Predictive Space Weather Models for the Exploration Initiative
Human exploration of Moon and Mars exposes astronauts and robotic missions to radiation hazards in space. Radiation hazards arise primarily from three sources: radiation belt particles in the inner magnetosphere of the Earth, cosmic rays, and solar energetic particles that are accelerated near the solar surface or in the inner heliosphere. In the event of space travel, long term forcasts of these radiation sources are essential for the health and safety of humans and robotic missions underway or residing on the surface of Moon and Mars. To-date, however, most ingredients of a suitable forecast system are missing, due to a combined lack of physical insight, modeling capabilities, and observations. As a result, the required forecasts are either impossible to-date, or fraught with substantial inaccuracies. In this presentation, we will outline the steps necessary to develop the predictive capability needed to execute safe space travel. We will describe all aspects of a combined campaign that is based on basic research, model development and validation, and on the creation of essential data sources for assimilation and model input.
SH53C-07 15:25h
The Living with a Star (LWS) Sentinels Mission
NASA has recently formed a Science and Technology Definition Team (STDT) to define the Sentinels mission, the heliospheric element of the integrated LWS program. The objective of the Sentinels is to discover, understand and model the connection between solar events such as flares and coronal mass ejections (CMEs) and heliospheric and magnetospheric events, such as Solar Particle Events (SPEs), that can adversely impact life and society. Moreover, Sentinels is also relevant for the new NASA exploration initiative to the Moon and beyond. The primary objective of Sentinels is to provide the observations necessary for an understanding of the physics of the Sun/inner heliosphere processes that affect the solar system, so the requirements for eventual predictive capability can be defined. I will describe the preliminary scientific planning to implement the Sentinels mission.