Organic Contamination Baseline Study: In NASA JSC Astromaterials Curation Laboratories. Summary Report

In preparation for OSIRIS-REx and other future sample return missions concerned with analyzing organics, we conducted an Organic Contamination Baseline Study for JSC Curation Labsoratories in FY12. For FY12 testing, organic baseline study focused only on molecular organic contamination in JSC curation gloveboxes: presumably future collections (i.e. Lunar, Mars, asteroid missions) would use isolation containment systems over only cleanrooms for primary sample storage. This decision was made due to limit historical data on curation gloveboxes, limited IR&D funds and Genesis routinely monitors organics in their ISO class 4 cleanrooms

The Effects of Statutory Minimum Wages

This discussion will explore the various theories regarding the effects of minimum wages on employment and relative earnings for the low-paid in an economy. Then, we will examine the research to consider which side the data supports—that is, if it does indeed conclusively decide the case one way or the other

The Gender Pay Differential: Choice, Tradition, or Overt Discrimination?

No one disputes that a male-female gender wage differential favoring men exists. This study seeks to unearth not only the sources of this differential but also the relative degrees to which the various sources impact the differential. The theories proposed by current literature suggest three principal causes: differences in human capital, crowding discrimination, and other forms of discrimination. This study estimates separate equations for men and women and then uses the regression results to decompose the gender wage differential into the three aforementioned components. We find, after isolating the effects of differences in individual human capital and choice characteristics as well as differences due to crowding, the residual surprisingly accounts for the largest proportion of the gender wage gap. Because the residual is so large, we believe that basic discrimination models must still be necessary and useful. Moreover, when one considers that the human capital differences that do exist may be reflecting feedback effects, the justification for combating societal stereotyping of gender roles becomes even stronger, to promote not only equity but also efficiency in today\u27s labor market

Benjamin Franklin and Transgenderal Pseudonymity

This article discusses letters written by Benjamin Franklin that were done under various female pseudonyms. These female identities were used to critique the gender stereotypes of the time and to show that women were more virtuous than men

Maximum Sample Temperature for Mars Sample Return: A Historical Perspective

Since the first Mars Sample Return (MSR) report published by the Jet Propulsion Laboratory (JPL) in 1974 [1], a series of panels, reports, and white papers have recognized the importance of sample temperature and offered an informed sample maximum temperature (henceforth SMT) limit for returning martian samples to Earth. The Mars Sample Handling and Requirements Panel (MSHARP, 1999) stated that "[t]he main issue in sample preservation is temperature" [2]. More recently, the Mars Exploration Program Analysis Group (MEPAG)'s "Science Priorities for Mars Sample Return" report (2008), declared that "[s]ignificant loss, particularly to biological studies, occurs if samples reach +50C for three hours", whereby "scientific objectives related to life goals could be seriously compromised" [3]. By contrast, the Mars 2020 mission has adopted a SMT of +60C as spelled out in Beaty et al., 2016 [4]. Samples will be collected and then deposited on the surface in sealed tubes for possible retrieval and return to Earth. Beaty et al. [4] calculates that the samples will experience maximum temperatures of ~+30 to +60C, depending on latitude. At present, there is no mission requirement for the measurement/data logging of sample temperature during this period. We will explore the history of martian SMTs, as they have been recorded since 1974 [1], effectively representing input across multiple generations of Mars scientists. Ten separate publications present SMTs for MSR samples [1-10]. One report [10] is for a mission concept specifically designed to exclude life detection investigations, and recommended an SMT of 50C. Another did not specify a temperature, recommending "Mars ambient temperature" [5]. Of the remaining eight, SMTs are given as: -30C [1], -20C [3], 60C [4], -73 to 41C depending on sample type [6], -40C [7], -43 to 13C depending on type [2,8], and -33C [9]. If we restrict the temperatures to samples highlighted in the Mars 2020 mission goals, i.e. organics-bearing and sedimentary rocks, then the average SMT is -28+/-39C (n=8). Applying a Dixon's Q Test at P=0.05 (two-tailed), the 60C SMT [4] fails with Q=0.602 versus Qcrit=0.526. Excluding the outlier produces an average SMT of -40+/-17C (n=7). Therefore, the average SMT expressed by the Mars science community over the past 44 years (two generations) is a sample temperature no greater than -40C. The difference in chemical reaction rates between this average SMT and Beaty et al [4] can be estimated using the Arrhenius equation. Assuming a generic chemical reaction with an activation energy of 50 kJ/mol and a pre-exponential factor invariant with temperature, this reaction will proceed 2300x faster at 60C than at -40C. To illustrate the effects of the increased reaction rate, consider 10 ppb of alanine in a Mars 2020 cache, and assume that it becomes unmeasurable if it degrades to 1 ppb, as per the Mars 2020 Organic Contamination Panel contamination limits [11]. If we illustrate the effect with an arbitrary degradation rate such that the alanine will become undetectable in ten years at -40C, then the same 10 ppb alanine degrades beyond detectability in only 38 days at 60C. Further research is required to quantify expected analyte losses in the cached samples due to thermal processing