PHALANX: Expendable Projectile Sensor Networks for Planetary Exploration

Technologies enabling long-term, wide-ranging measurement in hard-to-reach areas are a critical need for planetary science inquiry. Phenomena of interest include flows or variations in volatiles, gas composition or concentration, particulate density, or even simply temperature. Improved measurement of these processes enables understanding of exotic geologies and distributions or correlating indicators of trapped water or biological activity. However, such data is often needed in unsafe areas such as caves, lava tubes, or steep ravines not easily reached by current spacecraft and planetary robots. To address this capability gap, we have developed miniaturized, expendable sensors which can be ballistically lobbed from a robotic rover or static lander - or even dropped during a flyover. These projectiles can perform sensing during flight and after anchoring to terrain features. By augmenting exploration systems with these sensors, we can extend situational awareness, perform long-duration monitoring, and reduce utilization of primary mobility resources, all of which are crucial in surface missions. We call the integrated payload that includes a cold gas launcher, smart projectiles, planning software, network discovery, and science sensing: PHALANX. In this paper, we introduce the mission architecture for PHALANX and describe an exploration concept that pairs projectile sensors with a rover mothership. Science use cases explored include reconnaissance using ballistic cameras, volatiles detection, and building timelapse maps of temperature and illumination conditions. Strategies to autonomously coordinate constellations of deployed sensors to self-discover and localize with peer ranging (i.e. a local GPS) are summarized, thus providing communications infrastructure beyond-line-of-sight (BLOS) of the rover. Capabilities were demonstrated through both simulation and physical testing with a terrestrial prototype. The approach to developing a terrestrial prototype is discussed, including design of the launching mechanism, projectile optimization, micro-electronics fabrication, and sensor selection. Results from early testing and characterization of commercial-off-the-shelf (COTS) components are reported. Nodes were subjected to successful burn-in tests over 48 hours at full logging duty cycle. Integrated field tests were conducted in the Roverscape, a half-acre planetary analog environment at NASA Ames, where we tested up to 10 sensor nodes simultaneously coordinating with an exploration rover. Ranging accuracy has been demonstrated to be within +/-10cm over 20m using commodity radios when compared to high-resolution laser scanner ground truthing. Evolution of the design, including progressive miniaturization of the electronics and iterated modifications of the enclosure housing for streamlining and optimized radio performance are described. Finally, lessons learned to date, gaps toward eventual flight mission implementation, and continuing future development plans are discussed

Substituted dipyridophenazine complexes of Cr(III): synthesis, enantiomeric resolution and binding interactions with calf thymus DNA

[Cr(phen)2(X2dppz)]3+ {X = H, Me, or F} have been synthesised, characterised, and chromatographically resolved into their constituent Δ and Λ enantiomers. The DNA-binding interactions of each of the racemic complexes were investigated, with the results of linear dichroism, thermal denaturation, and emission quenching studies indicative of intercalative binding to CT-DNA with a significant electrostatic contribution. UV/Vis absorption titrations suggest strong DNA binding by each of the racemic complexes, with the methylated analogue [Cr(phen)2(Me 2dppz)]3+ exhibiting the largest equilibrium binding constant. Emission quenching and UV-Vis titrations of the enantiomers of [Cr(phen)2(dppz)]3+ imply similar binding affinities for the Δ and Λ isomers, although significant differences between the circular dichroism spectra of the enantiomers in the presence of DNA connote differences in binding orientation and/or conformation between the two

The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. VII. Ophiuchus Observed with MIPS

We present maps of 14.4 deg^2 of the Ophiuchus dark clouds observed by the Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS). These high-quality maps depict both numerous point sources and extended dust emission within the star-forming and non–star-forming portions of these clouds. Using PSF-fitting photometry, we detect 5779 sources at 24 μm and 81 sources at 70 μm at the 10 σ level of significance. Three hundred twenty-three candidate young stellar objects (YSOs) were identified according to their positions on the MIPS/2MASS K versus color-magnitude diagrams, as compared to 24 μm detections in the SWIRE extragalactic survey. We find that more than half of the YSO candidates, and almost all those with protostellar Class I spectral energy distributions, are confined to the known cluster and aggregates

Prediction of Room-Temperature Electric Field Reversal of Magnetization in the Family of A4B3A_4B_3O9_9 Layered Oxides

The promise of a strong magnetoelectric (ME) coupling in a multiferroic (MF) material is not only of fundamental interest, but also forms the basis of next generation memory devices where the direction of magnetization can be reversed by an external electric field. Using group-theory led first-principles calculations, we determine the ME properties of a relatively understudied family of layered oxides with the general formula $A_4B_3$O$_9$. We show how the tetrahedral rotations in these oxides can lead to a variety of hitherto unknown structural phases with different symmetries. In particular, a polar phase in the $Cmc2_1$ space group has been identified where a weak ferromagnetic mode arises spontaneously via a canting of the antiferromagnetically ordered $B$-site spins. In this polar phase, the polar mode couples to the magnetic modes through a rare $\Gamma$-point ME-MF coupling scheme such that the net magnetization can be directly reversed by an electric field switching of the polar mode. Moreover, in agreement with previous experimental observations, we predict room-temperature magnetism in $A_4B_3$O$_9$ layered oxides which is supported by our calculations of the magnetic exchange interaction parameters, further indicating the potential of these compounds in practical technological applications

Multidecadal ocean variability and NW European ice sheet surges during the last deglaciation

A multiproxy paleoceanographic record from the Atlantic margin off the British Isles reveals in unprecedented detail discharges of icebergs and meltwater in response to sea surface temperature increases across the last deglaciation. We observe the earliest signal of deglaciation as a moderate elevation of sea surface temperatures that commenced with a weakly developed thermocline and the presence of highly ventilated intermediate waters in the Rockall Trough. This warming pulse triggered a series of multidecadal ice-rafted debris peaks that culminated with a major meltwater discharge at 17,500 years before present related to ice sheet disintegration across the NW European region. The impact of meltwater caused a progressive reduction in deep water ventilation and a sea surface cooling phase that preceded the collapse of the Laurentide Ice Sheet during Heinrich event 1 by 500-1000 years. A similar sequence of rapid ocean-ice sheet interaction across the European continental margin is identified during the Bølling-Allerød to Younger Dryas transition. The strategic location of our sediment core suggests a sensitive and rapid response of ice sheets in NW Europe to transient increases in thermohaline heat transport

Access to the scientific literature in India

This paper uses an evidence-based approach to assess the difficulties faced by developing country scientists in accessing the scientific literature. I compare backward citations patterns of Swiss and Indian scientists in a database of 43'150 scientific papers published by scientists from either country in 2007. Controlling for fields and quality with citing journal fixed effects, I find that Indian scientists (1) have shorter references lists (2) are more likely to cite articles from open access journals and (3) are less likely to cite articles from expensive journals. The magnitude of the effects is small which can be explained by informal file sharing practices among scientists

Neuropsychological functioning in college students who misuse prescription stimulants

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137497/1/ajad12551.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137497/2/ajad12551_am.pd

Non-contact computer vision enables analysis of the dynamic performance of naphthalene diimide electrochromic films †

Napthalene diimide-based films show effective electrochromic behaviour, with the ability to undergo a reversible transparent-to-dark colour change following the application of an electrical potential. The response of these materials is typically measured using absorption spectroscopy, however this method can be limited, especially with strongly absorbing materials. As an alternative, described herein is the application of the Kineticolor computer vision software platform for the camera-enabled analysis of electrochromic behaviour. Beyond monitoring of the bulk colour change of the films, studying uniformity of colour, stability, and electrochemical reversibility of film response was also undertaken. The findings illustrate an expansion of the modalities avaliable for the analysis of chromic films through a non-contact, economical and more readily deployable method than traditional spectroscopic methods