SETI and the law: what if the search succeeds?

If the search for extra-terrestrial intelligence succeeds on detecting evidence of it, it will have immense repercussions. Two documents consider what should be done to validate and announce the evidence, and to consider a reply if the evidence is in radio form. What legal status should such materials be given? The author argues that it is not too early to consider formulating a treaty.     

Trapped particle energy spectrum in shuttle middeck

We describe the differential energy spectrum of trapped particles measured by a solid-state charged particle telescope in the mid-deck of the Space Shuttle during the period of solar maximum. The telescope was flown in two high altitude flights at 28.5° and 57° inclination. Assuming, as is normally done, that the variations of Shuttle orientation during the missions lead to average isotropic incident spectra, the observed spectrum disagrees significantly from AP8 model calculations. This indicates the need to take into consideration the variations of solid-angle direction relative to the magnetic field. The measurements show that there is a very significant flux of secondary light ions. The energy spectra of these ions does not agree with the production spectrum from radiation transport calculations based on omni-directional AP8 Max model as an input energy spectrum.

We also describe measurements of linear energy transfer spectra using a tissue equivalent proportional counter (TEPC) flown both in the mid-deck and the payload bay of the Space Shuttle. Comparisons are made between linear energy transfer spectral measurements AP8 model-based radiation transport predictions, and thermoluminescent dosimeter (TLD) measurements. The absorbed dose-rate measurements using TLD's are roughly 25% lower than the TEPC-measured dose rate measurements.     

Measuring performance: Moving NASA Earth science products into the mainstream user community

Demonstrating performance of the applications of Earth observation satellite-based science data products and services is increasingly a requirement of government research agencies. We present efforts from the NASA-funded Earth Observing System Data and Information System's Synergy Project to measure performance in the development of applications from NASA research and development projects. We summarize challenges in monitoring performance and share our experience in evolving metrics over a 5-year project life. We demonstrate how to adapt project management processes and metrics from the information technology (IT) industry to Earth observation applications research and development. A roadmap for adapting IT processes and developing metrics and examples of quantitative and qualitative metrics are provided. Our findings suggest that designing and implementing these IT metrics will enhance project success, as defined by the degree of penetration of NASA products into the user community and level of non-NASA funding secured.     

维修技术人员短缺状况或将持续恶化

随着劳动人口老龄化加剧,未来10年维修技术人员的短缺将持续加剧。尤其是亚洲将首当其冲。再者,欧洲地区受人口整体规模下降的影响,形势也不容乐观。全球各区域面临的挑战美国据奥纬咨询公司(Oliver Wyman)预测,到2022年维修技术人员的供求差距将会持续扩大,到2027年将达到9%的峰值。据美国联邦航空局(FAA)的民用航空从业人员统计数据显示,2018年只有2.4%的机械工程师和5.2%的维修技术人员是女性。     

On the validity of the aluminum equivalent approximation in space radiation shielding applications

The origin of the aluminum equivalent shield approximation in space radiation analysis can be traced back to its roots in the early years of the NASA space programs (Mercury, Gemini and Apollo) wherein the primary radiobiological concern was the intense sources of ionizing radiation causing short term effects which was thought to jeopardize the safety of the crew and hence the mission. Herein, it is shown that the aluminum equivalent shield approximation, although reasonably well suited for that time period and to the application for which it was developed, is of questionable usefulness to the radiobiological concerns of routine space operations of the 21st century which will include long stays onboard the International Space Station (ISS) and perhaps the moon. This is especially true for a risk based protection system, as appears imminent for deep space exploration where the long-term effects of Galactic Cosmic Ray (GCR) exposure is of primary concern. The present analysis demonstrates that sufficiently large errors in the interior particle environment of a spacecraft result from the use of the aluminum equivalent approximation, and such approximations should be avoided in future astronaut risk estimates. In this study, the aluminum equivalent approximation is evaluated as a means for estimating the particle environment within a spacecraft structure induced by the GCR radiation field. For comparison, the two extremes of the GCR environment, the 1977 solar minimum and the 2001 solar maximum, are considered. These environments are coupled to the Langley Research Center (LaRC) deterministic ionized particle transport code High charge (Z) and Energy TRaNsport (HZETRN), which propagates the GCR spectra for elements with charges (Z) in the range 1 ? Z ? 28 (H–Ni) and secondary neutrons through selected target materials. The coupling of the GCR extremes to HZETRN allows for the examination of the induced environment within the interior of an idealized spacecraft as approximated by a spherical shell shield, and the effects of the aluminum equivalent approximation for a good polymeric shield material such as generic polyethylene (PE). The shield thickness is represented by a 25 g/cm² spherical shell. Although, one could imagine the progression to greater thickness, the current range will be sufficient to evaluate the qualitative usefulness of the aluminum equivalent approximation. Upon establishing the inaccuracies of the aluminum equivalent approximation through numerical simulations of the GCR radiation field attenuation for PE and aluminum equivalent PE spherical shells, we further present results for a limited set of commercially available, hydrogen rich, multifunctional polymeric constituents to assess the effect of the aluminum equivalent approximation on their radiation attenuation response as compared to the generic PE.     

Earth's earliest biosphere-a proposal to develop a collection of curated archean geologic reference materials

The discovery of evidence indicative of life in a Martian meteorite has led to an increase in interest in astrobiology. As a result of this discovery, and the ensuing controversy, it has become apparent that our knowledge of the early development of life on Earth is limited. Archean stratigraphic successions containing evidence of Earth's early biosphere are well preserved in the Pilbara Craton of Western Australia. The craton includes part of a protocontinent consisting of granitoid complexes that were emplaced into, and overlain by, a 3.51-2.94 Ga volcanigenic carapace - the Pilbara Supergroup. The craton is overlain by younger supracrustal basins that form a time series recording Earth history from approximately 2.8 Ga to approximately 1.9 Ga. It is proposed that a well-documented suite of these ancient rocks be collected as reference material for Archean and astrobiological research. All samples would be collected in a well-defined geological context in order to build a framework to test models for the early evolution of life on Earth and to develop protocols for the search for life on other planets.     

Impact craters as biospheric microenvironments, Lawn Hill Structure, Northern Australia

Impact craters on Mars act as traps for eolian sediment and in the past may have provided suitable microenvironments that could have supported and preserved a stressed biosphere. If this is so, terrestrial impact structures such as the 18-km-diameter Lawn Hill Structure, in northern Australia, may prove useful as martian analogs. We sampled outcrop and drill core from the carbonate fill of the Lawn Hill Structure and recorded its gamma-log signature. Facies data along with whole rock geochemistry and stable isotope signatures show that the crater fill is an outlier of the Georgina Basin and was formed by impact at, or shortly before, approximately 509-506 million years ago. Subsequently, it was rapidly engulfed by the Middle Cambrian marine transgression, which filled it with shallow marine carbonates and evaporites. The crater formed a protected but restricted microenvironment in which sediments four times the thickness of the nearby basinal succession accumulated. Similar structures, common on the martian surface, may well have acted as biospheric refuges as the planet's water resources declined. Low-pH aqueous environments on Earth similar to those on Mars, while extreme, support diverse ecologies. The architecture of the eolian crater fill would have been defined by long-term ground water cycles resulting from intermittent precipitation in an extremely arid climate. Nutrient recycling, critical to a closed lacustrine sub-ice biosphere, could be provided by eolian transport onto the frozen water surface.     

Validation of the new trapped environment AE9/AP9/SPM at low Earth orbit

The completion of the international space station (ISS) in 2011 has provided the space research community an ideal proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the validation of radiation environmental models, nuclear transport codes and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) provided vital information impacting both the environmental models and the nuclear transport code developments by indicating the need for an improved dynamic model of the low Earth orbit (LEO) trapped environment. Additional studies using thermo-luminescent detector (TLD), tissue equivalent proportional counter (TEPC) area monitors, and computer aided design (CAD) model of earlier ISS configurations, confirmed STS observations that, as input, computational dosimetry requires an environmental model with dynamic and directional (anisotropic) behavior, as well as an accurate six degree of freedom (DOF) definition of the vehicle attitude and orientation along the orbit of ISS.