difficulties with instruments, spacecraft, and communications do not threaten mission success and human lives. Working Group F addressed these issues.
The meeting description that introduced Working Group F stated: “Solar activity can affect instrumentation, spacecraft and communications in several ways. The solar energetic particle radiation has been found to degrade the performance of solar cells. This radiation may affect the electronics in all kinds of instrumentation primarily by causing single event effects. It can also interfere with various kinds of sensors both by direct ionization and by activation of the sensor or surrounding materials. For example, direct ionization can interfere with the imagery obtained using solid state cameras and may degrade optical and thermal control surfaces. Activation can interfere with gamma ray spectrometers used for scientific investigations. This group will discuss the effects of solar activity on these systems and identify approaches to avoid or mitigate these effects.”
Space weather effects on instruments and spacecraft have received much attention in the near-Earth space environment. Among the space environment effects that are of concern for instruments, spacecraft, and communications are these: single-event effects in electronics and sensors, total radiation dose to components, radiation damage to sensors and solar cells, and electrostatic charging. All of these effects are of concern for missions to the Moon and Mars. The working group discussed topics that ranged from test facilities needed for electronic components and systems, to the role of environmental models, to the needs for forecasting and specifying space weather conditions. These topics are discussed below. In addition, the group recognized the value of collecting, preserving, and accessing long-term space weather data sets for design, modeling, and operations activities.
Instruments and equipment that will be used on missions to the Moon and Mars need to be tested for their suitability and robustness in a variety of space environments. These environments include diverse regimes that range from conditions near Earth to interplanetary space, to the Moon and Mars. Instruments and equipment will be exposed to a broad range of particle energies and composition from sources such as galactic cosmic rays, solar energetic particle events, and trapped radiation environments. There is also an expectation that commercial off-the-shelf parts and systems such as personal computers and video-cameras will be heavily utilized and will need testing to ensure performance in the disparate environments. Therefore, there is a need for the availability of and access to adequate high-energy particle beams at accelerators for testing and related performance measurements to simulate the space radiation environment under controlled conditions.
NASA engineers have been using various accelerators around the country, but one facility exists where beams of all relevant cosmic ray energies and particle species are available. This is the NASA Space Radiation Laboratory at the Brookhaven National Laboratory. For Vision for Space Exploration projects to gain access to this facility, there is a need for a Memorandum of Understanding between the facility and the VSE program so that proposal-evaluation procedures for using the facility are responsive to VSE engineering activities as well as science investigations. In addition to the need for testing before launch, the group also described the value and importance of on-orbit testing for critical system tests and model validation.
Space environment modeling plays a vital enabling role for missions to the Moon and Mars. At Earth, 1970s vintage, static trapped radiation belt models such as AE8 and AP8 that predict electron and proton flux spectra in Earth’s radiation belts are inadequate and outdated. Even the more recent, 1990s Combined Release and Radiation Effects Satellite models are limited because they were based on a very brief interval (about 1 year of data). Updated models that are dynamic, taking into account current solar wind and magnetospheric conditions, are needed to provide the history of variations on timescales that range from solar cycles to minutes.
If Mars mission architecture includes parking a transit vehicle at geosynchronous orbit, it will be necessary to better understand the spacecraft charging environment, including short-term variations at