When inspiration fails to inspire: A change of strategy for the US space program

A pressing issue facing the US space program is the projected shortfall in the skilled aerospace workforce, as the number of students in space-related fields wanes. This has prompted many to emphasize the rhetoric of inspiration that prevailed during the Cold War, at the expense of concrete arguments for space that are thought to be lackluster and insufficient. This essay argues that the logic of inspiration fails to consider the changed context and attitudes of this younger public. Instead, such an approach proves counterproductive in attracting generations compelled by a host of ideas, some incompatible with the rhetoric of competition and prestige that prevailed before. Arguments that draw attention to the pragmatic elements of space, and that successfully align space with the notions that make sense now, may in turn prove to be the solution to draw the best and the brightest to the space program.     

Direct dark matter searches with CDMS and XENON

The cryogenic dark matter search (CDMS) and XENON experiments aim to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering on the target nuclei. The experiments use different techniques to suppress background event rates to the minimum, and at the same time, to achieve a high WIMP detection rate. The operation of cryogenic Ge and Si crystals of the CDMS-II experiment in the Soudan mine reported spectrum-weighted exposures of 34 (12) kg-d for the Ge (Si) targets after cuts, over the recoil energies 10–100 keV for a WIMP mass of 60 GeV/c². It gives an upper limit (90% C.L.) of spin-independent WIMP-nucleon cross-section at 1.6 × 10⁻⁴³ cm² for a WIMP mass of 60 GeV/c², starting to constrain predications in supersymmetry models. The two-phase xenon detector of the XENON10 experiment is currently taking data in the Gran Sasso underground lab and promising preliminary results were recently reported. Both experiments are expected to increase their WIMP sensitivity by a one order of magnitude in the scheduled science runs for 2007.     

Effects of Communication Methods on Communication Patterns and Performance in a Remote Spatial Orientation Task

Abstract

An experiment was conducted to examine the impact of communication methods (text-only, audio-only, and audio-plus-video) on communication patterns and effectiveness in a 2-person remote spatial orientation task. The task required a pair of participants to figure out the cardinal direction of a target object by communicating spatial information and perspectives. Results showed that overall effectiveness in the audio-only condition was better than the text-only and audio-plus-video conditions, and communication patterns were more predictive of errors than individual differences in spatial abilities. Discourse analysis showed that participants in the audio-plus-video condition performed less mental transformation of spatial information when communicating, which led to more interpretation errors by the listener. Participants in the text-only conditions performed less confirmation and made more errors by misreading their own display. Results suggested that speakers in the audio-plus-video condition minimized effort by communicating spatial information based on their own perspective but speakers in the audio-only and text-only conditions would more likely communicate transformed spatial information. Analysis of gestures in the audio-plus-video condition confirmed that iconic gestures tended to co-occur with spatial transformation. Iconic gesture rates were negatively correlated with transformation errors, indicating that iconic gestures more likely co-occurred with successful communication of spatial transformation. Results show that when visual interactive feedback is available, speakers tend to adopt egocentric spatial perspectives to minimize effort in mental transformation and rely on the feedback to ensure that the hearer correctly interprets the information. When visual interactive feedback is not available, speakers will put more effort in transforming spatial information to help the hearer to understand the information. The current result demonstrated that allowing two persons to see and communicate with each other during a remote spatial reasoning task can lead to more errors because of the use of a suboptimal communication strategy.     

The Morphologies and Kinematics of Supernova Remnants

We review the major advances in understanding the morphologies and kinematics of supernova remnants (SNRs). Simulations of SN explosions have improved dramatically over the last few years, and SNRs can be used to test models through comparison of predictions with SNRs’ observed large-scale compositional and morphological properties as well as the three-dimensional kinematics of ejecta material. In particular, Cassiopeia A—the youngest known core-collapse SNR in the Milky Way—offers an up-close view of the complexity of these explosive events that cannot be resolved in distant, extragalactic sources. We summarize the progress in tying SNRs to their progenitors’ explosions through imaging and spectroscopic observations, and we discuss exciting future prospects for SNR studies, such as X-ray microcalorimeters.     

Sino-Latin American space cooperation: A smart move

Sino-Latin American space cooperation has grown in the past several years, contributing to debates over China’s rising influence in the region. Much of what has been written about this phenomenon is overly simplistic and denotes a lack of understanding of the interplay between the domestic and the international when decisions of international cooperation are taken. This paper argues that calculations of both domestic and international interest are important in Sino-Latin space relationships, with the former of particular importance to Latin American countries. It explores these interests as demonstrated in the cooperative programs of four Latin American countries. It concludes that, while the US relationship is not a major factor in their decisions to cooperate or not with China, the USA could benefit from a greater understanding of this phenomenon to expand its relationships with the emerging space nations of the region to its benefit.     

Impact disruption and recovery of the deep subsurface biosphere

Although a large fraction of the world's biomass resides in the subsurface, there has been no study of the effects of catastrophic disturbance on the deep biosphere and the rate of its subsequent recovery. We carried out an investigation of the microbiology of a 1.76 km drill core obtained from the ～35 million-year-old Chesapeake Bay impact structure, USA, with robust contamination control. Microbial enumerations displayed a logarithmic downward decline, but the different gradient, when compared to previously studied sites, and the scatter of the data are consistent with a microbiota influenced by the geological disturbances caused by the impact. Microbial abundance is low in buried crater-fill, ocean-resurge, and avalanche deposits despite the presence of redox couples for growth. Coupled with the low hydraulic conductivity, the data suggest the microbial community has not yet recovered from the impact ～35 million years ago. Microbial enumerations, molecular analysis of microbial enrichment cultures, and geochemical analysis showed recolonization of a deep region of impact-fractured rock that was heated to above the upper temperature limit for life at the time of impact. These results show how, by fracturing subsurface rocks, impacts can extend the depth of the biosphere. This phenomenon would have provided deep refugia for life on the more heavily bombarded early Earth, and it shows that the deeply fractured regions of impact craters are promising targets to study the past and present habitability of Mars.     

Un effet de temperature a l'origine du contraste UV dans les nuages de Venus

Un nouveau me´canisme susceptible d'expliquer une partie du contraste UV dans les nuages de Ve´nus est pre´sente´. La section efficace d'absorption de SO₂ de´pend de la tempe´rature, pre´cise´ment dans la re´gion spectrale ou`l'absorption par SO<sub>2</sub> domine l'albedo de Ve´nus. L'effet de variation de tempe´rature est simule´au niveau des nuagesa`l'aide d'un mode`le de transfert de rayonnement et des fluctuations de l'ordre de 20 K produisent un contraste de l'ordre de 10 %, les structures UV brillantese´tant associe´es aux zones chaudes et inversement.