Galileo mission planning for Low Gain Antenna based operations

The Galileo mission operations concept is undergoing substantial redesign, necessitated by the deployment failure of the High Gain Antenna, while the spacecraft is on its way to Jupiter. The new design applies state-of-the-art technology and processes to increase the telemetry rate available through the Low Gain Antenna and to increase the information density of the telemetry. This paper describes the mission planning process being developed as part of this redesign. Principal topics include a brief description of the new mission concept and anticipated science return (these have been covered more extensively in earlier papers), identification of key drivers on the mission planning process, a description of the process and its implementation schedule, a discussion of the application of automated mission planning tool to the process, and a status report on mission planning work to date. Galileo enhancements include extensive reprogramming of on-board computers and substantial hard ware and software upgrades for the Deep Space Network (DSN). The principal mode of operation will be onboard recording of science data followed by extended playback periods. A variety of techniques will be used to compress and edit the data both before recording and during playback. A highly-compressed real-time science data stream will also be important. The telemetry rate will be increased using advanced coding techniques and advanced receivers. Galileo mission planning for orbital operations now involves partitioning of several scarce resources. Particularly difficult are division of the telemetry among the many users (eleven instruments, radio science, engineering monitoring, and navigation) and allocation of space on the tape recorder at each of the ten satellite encounters. The planning process is complicated by uncertainty in forecast performance of the DSN modifications and the non-deterministic nature of the new data compression schemes. Key mission planning steps include quantifying resource or capabilities to be allocated, prioritizing science observations and estimating resource needs for each, working inter-and intra-orbit trades of these resources among the Project elements, and planning real-time science activity. The first major mission planning activity, a high level, orbit-by-orbit allocation of resources among science objectives, has already been completed; and results are illustrated in the paper. To make efficient use of limited resources, Galileo mission planning will rely on automated mission planning tools capable of dealing with interactions among time-varying downlink capability, real-time science and engineering data transmission, and playback of recorded data. A new generic mission planning tool is being adapted for this purpose

Epithelial-to-mesenchymal transition leads to disease-stage differences in circulating tumor cell detection and metastasis in pre-clinical models of prostate cancer

Metastasis is the cause of most prostate cancer (PCa) deaths and has been associated with circulating tumor cells (CTCs). The presence of \u3e= 5 CTCs/7.5mL of blood is a poor prognosis indicator in metastatic PCa when assessed by the CellSearch (R) system, the gold standard clinical platform. However, similar to 35% of metastatic PCa patients assessed by CellSearch (R) have undetectable CTCs. We hypothesize that this is due to epithelial-to-mesenchymal transition (EMT) and subsequent loss of necessary CTC detection markers, with important implications for PCa metastasis. Two pre-clinical assays were developed to assess human CTCs in xenograft models; one comparable to CellSearch (R) (EpCAM-based) and one detecting CTCs semi-independent of EMT status via combined staining with EpCAM/HLA (human leukocyte antigen). In vivo differences in CTC generation, kinetics, metastasis and EMT status were determined using 4 PCa models with progressive epithelial (LNCaP, LNCaP-C42B) to mesenchymal (PC-3, PC-3M) phenotypes. Assay validation demonstrated that the CellSearch (R)-based assay failed to detect a significant number (similar to 40-50%) of mesenchymal CTCs. In vivo, PCa with an increasingly mesenchymal phenotype shed greater numbers of CTCs more quickly and with greater metastatic capacity than PCa with an epithelial phenotype. Notably, the CellSearch (R)-based assay captured the majority of CTCs shed during early-stage disease in vivo, and only after establishment of metastases were a significant number of undetectable CTCs present. This study provides important insight into the influence of EMT on CTC generation and subsequent metastasis, and highlights that novel technologies aimed at capturing mesenchymal CTCs may only be useful in the setting of advanced metastatic disease

Free-Flight Experiments in LISA Pathfinder

The LISA Pathfinder mission will demonstrate the technology of drag-free test masses for use as inertial references in future space-based gravitational wave detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free flight about a test mass while measuring the acceleration of this primary test mass relative to a second reference test mass. Because the reference test mass is contained within the same spacecraft, it is necessary to apply forces on it to maintain its position and attitude relative to the spacecraft. These forces are a potential source of acceleration noise in the LISA Pathfinder system that are not present in the full LISA configuration. While LISA Pathfinder has been designed to meet it's primary mission requirements in the presence of this noise, recent estimates suggest that the on-orbit performance may be limited by this 'suspension noise'. The drift-mode or free-flight experiments provide an opportunity to mitigate this noise source and further characterize the underlying disturbances that are of interest to the designers of LISA-like instruments. This article provides a high-level overview of these experiments and the methods under development to analyze the resulting data

LISA Pathfinder closed-loop analysis: a model breakdown of the in-loop observables

This paper describes a methodology to analyze, in the frequency domain, the steady-state control performances of the LISA Pathfinder mission. In particular, it provides a technical framework to give a comprehensive understanding of the spectra of all the degrees of freedom by breaking them down into their various physical origins, hence bringing out the major contributions of the control residuals. A reconstruction of the measured in-loop output, extracted from a model of the closed-loop system, is shown as an instance to illustrate the potential of such a model breakdown of the data

Beyond the required LISA free-fall performance: new LISA pathfinder results down to 20 μHz

In the months since the publication of the first results, the noise performance of LISA Pathfinder has improved because of reduced Brownian noise due to the continued decrease in pressure around the test masses, from a better correction of noninertial effects, and from a better calibration of the electrostatic force actuation. In addition, the availability of numerous long noise measurement runs, during which no perturbation is purposely applied to the test masses, has allowed the measurement of noise with good statistics down to 20  μHz. The Letter presents the measured differential acceleration noise figure, which is at (1.74±0.05)  fm s^{-2}/sqrt[Hz] above 2 mHz and (6±1)×10  fm s^{-2}/sqrt[Hz] at 20  μHz, and discusses the physical sources for the measured noise. This performance provides an experimental benchmark demonstrating the ability to realize the low-frequency science potential of the LISA mission, recently selected by the European Space Agency

Involvement of the exomer complex in the polarized transport of Ena1 required for Saccharomyces cerevisiae survival against toxic cations

[EN] Exomer is an adaptor complex required for the direct transport of a selected number of cargoes from the trans-Golgi network (TGN) to the plasma membrane in Saccharomyces cerevisiae However, exomer mutants are highly sensitive to increased concentrations of alkali metal cations, a situation that remains unexplained by the lack of transport of any known cargoes. Here we identify several HAL genes that act as multicopy suppressors of this sensitivity and are connected to the reduced function of the sodium ATPase Ena1. Furthermore, we find that Ena1 is dependent on exomer function. Even though Ena1 can reach the plasma membrane independently of exomer, polarized delivery of Ena1 to the bud requires functional exomer. Moreover, exomer is required for full induction of Ena1 expression after cationic stress by facilitating the plasma membrane recruitment of the molecular machinery involved in Rim101 processing and activation of the RIM101 pathway in response to stress. Both the defective localization and the reduced levels of Ena1 contribute to the sensitivity of exomer mutants to alkali metal cations. Our work thus expands the spectrum of exomer-dependent proteins and provides a link to a more general role of exomer in TGN organization.We acknowledge Emma Keck for English language revision. We also thank members of the Translucent group, J. Arino, J. Ramos, and L. Yenush, for many useful discussions throughout this work and especially L. Yenush for her generous gift of strains and reagents. The help of O. Vincent was essential for developing the work involving RIM101. We also thank R. Valle for her technical assistance at the CR Laboratory. M. Trautwein is acknowledged for data acquisition and discussions during the early stages of the project. C.A. is supported by a USAL predoctoral fellowship. Work at the Spang laboratory was supported by the University of Basel and the Swiss National Science Foundation (31003A-141207 and 310030B-163480). C.R. was supported by grant SA073U14 from the Regional Government of Castilla y Leon and by grant BFU2013-48582-C2-1-P from the CICYT/FEDER Spanish program. J.M.M. acknowledges the financial support from Universitat Politecnica de Valencia project PAID-06-10-1496.Anton, C.; Zanolari, B.; Arcones, I.; Wang, C.; Mulet, JM.; Spang, A.; Roncero, C. (2017). Involvement of the exomer complex in the polarized transport of Ena1 required for Saccharomyces cerevisiae survival against toxic cations. Molecular Biology of the Cell. 28(25):3672-3685. https://doi.org/10.1091/mbc.E17-09-0549S367236852825Ariño, J., Ramos, J., & Sychrová, H. (2010). Alkali Metal Cation Transport and Homeostasis in Yeasts. Microbiology and Molecular Biology Reviews, 74(1), 95-120. doi:10.1128/mmbr.00042-09Bard, F., & Malhotra, V. (2006). The Formation of TGN-to-Plasma-Membrane Transport Carriers. Annual Review of Cell and Developmental Biology, 22(1), 439-455. doi:10.1146/annurev.cellbio.21.012704.133126Barfield, R. M., Fromme, J. C., & Schekman, R. (2009). The Exomer Coat Complex Transports Fus1p to the Plasma Membrane via a Novel Plasma Membrane Sorting Signal in Yeast. Molecular Biology of the Cell, 20(23), 4985-4996. doi:10.1091/mbc.e09-04-0324Bonifacino, J. S. (2014). Adaptor proteins involved in polarized sorting. Journal of Cell Biology, 204(1), 7-17. doi:10.1083/jcb.201310021Bonifacino, J. S., & Glick, B. S. (2004). The Mechanisms of Vesicle Budding and Fusion. Cell, 116(2), 153-166. doi:10.1016/s0092-8674(03)01079-1Bonifacino, J. S., & Lippincott-Schwartz, J. (2003). Coat proteins: shaping membrane transport. Nature Reviews Molecular Cell Biology, 4(5), 409-414. doi:10.1038/nrm1099Carlson, M., & Botstein, D. (1982). Two differentially regulated mRNAs with different 5′ ends encode secreted and intracellular forms of yeast invertase. Cell, 28(1), 145-154. doi:10.1016/0092-8674(82)90384-1Costanzo, M., Baryshnikova, A., Bellay, J., Kim, Y., Spear, E. D., Sevier, C. S., … Mostafavi, S. (2010). The Genetic Landscape of a Cell. Science, 327(5964), 425-431. doi:10.1126/science.1180823De Matteis, M. A., & Luini, A. (2008). Exiting the Golgi complex. Nature Reviews Molecular Cell Biology, 9(4), 273-284. doi:10.1038/nrm2378De Nadal, E., Clotet, J., Posas, F., Serrano, R., Gomez, N., & Arino, J. (1998). The yeast halotolerance determinant Hal3p is an inhibitory subunit of the Ppz1p Ser/Thr protein phosphatase. Proceedings of the National Academy of Sciences, 95(13), 7357-7362. doi:10.1073/pnas.95.13.7357Drubin, D. G., & Nelson, W. J. (1996). Origins of Cell Polarity. Cell, 84(3), 335-344. doi:10.1016/s0092-8674(00)81278-7Fell, G. L., Munson, A. M., Croston, M. A., & Rosenwald, A. G. (2011). Identification of Yeast Genes Involved in K+Homeostasis: Loss of Membrane Traffic Genes Affects K+Uptake. G3: Genes|Genomes|Genetics, 1(1), 43-56. doi:10.1534/g3.111.000166Ferrando, A., Kron, S. J., Rios, G., Fink, G. R., & Serrano, R. (1995). Regulation of cation transport in Saccharomyces cerevisiae by the salt tolerance gene HAL3. Molecular and Cellular Biology, 15(10), 5470-5481. doi:10.1128/mcb.15.10.5470Forsmark, A., Rossi, G., Wadskog, I., Brennwald, P., Warringer, J., & Adler, L. (2011). Quantitative Proteomics of Yeast Post-Golgi Vesicles Reveals a Discriminating Role for Sro7p in Protein Secretion. Traffic, 12(6), 740-753. doi:10.1111/j.1600-0854.2011.01186.xGaber, R. F., Styles, C. A., & Fink, G. R. (1988). TRK1 encodes a plasma membrane protein required for high-affinity potassium transport in Saccharomyces cerevisiae. Molecular and Cellular Biology, 8(7), 2848-2859. doi:10.1128/mcb.8.7.2848Galindo, A., Calcagno-Pizarelli, A. M., Arst, H. N., & Penalva, M. A. (2012). An ordered pathway for the assembly of fungal ESCRT-containing ambient pH signalling complexes at the plasma membrane. Journal of Cell Science, 125(7), 1784-1795. doi:10.1242/jcs.098897Goldstein, A. L., & McCusker, J. H. (1999). Three new dominant drug resistance cassettes for gene disruption inSaccharomyces cerevisiae. Yeast, 15(14), 1541-1553. doi:10.1002/(sici)1097-0061(199910)15:143.0.co;2-kHayashi, M., Fukuzawa, T., Sorimachi, H., & Maeda, T. (2005). Constitutive Activation of the pH-Responsive Rim101 Pathway in Yeast Mutants Defective in Late Steps of the MVB/ESCRT Pathway. Molecular and Cellular Biology, 25(21), 9478-9490. doi:10.1128/mcb.25.21.9478-9490.2005Herrador, A., Herranz, S., Lara, D., & Vincent, O. (2009). Recruitment of the ESCRT Machinery to a Putative Seven-Transmembrane-Domain Receptor Is Mediated by an Arrestin-Related Protein. Molecular and Cellular Biology, 30(4), 897-907. doi:10.1128/mcb.00132-09Herrador, A., Livas, D., Soletto, L., Becuwe, M., Léon, S., & Vincent, O. (2015). Casein kinase 1 controls the activation threshold of an α-arrestin by multisite phosphorylation of the interdomain hinge. Molecular Biology of the Cell, 26(11), 2128-2138. doi:10.1091/mbc.e14-11-1552Herranz, S., Rodriguez, J. M., Bussink, H.-J., Sanchez-Ferrero, J. C., Arst, H. N., Penalva, M. A., & Vincent, O. (2005). Arrestin-related proteins mediate pH signaling in fungi. Proceedings of the National Academy of Sciences, 102(34), 12141-12146. doi:10.1073/pnas.0504776102Hoya, M., Yanguas, F., Moro, S., Prescianotto-Baschong, C., Doncel, C., de León, N., … Valdivieso, M.-H. (2016). Traffic Through theTrans-Golgi Network and the Endosomal System Requires Collaboration Between Exomer and Clathrin Adaptors in Fission Yeast. Genetics, 205(2), 673-690. doi:10.1534/genetics.116.193458Huranova, M., Muruganandam, G., Weiss, M., & Spang, A. (2016). Dynamic assembly of the exomer secretory vesicle cargo adaptor subunits. EMBO reports, 17(2), 202-219. doi:10.15252/embr.201540795Kung, L. F., Pagant, S., Futai, E., D’Arcangelo, J. G., Buchanan, R., Dittmar, J. C., … Miller, E. A. (2011). Sec24p and Sec16p cooperate to regulate the GTP cycle of the COPII coat. The EMBO Journal, 31(4), 1014-1027. doi:10.1038/emboj.2011.444Lamb, T. M., & Mitchell, A. P. (2003). The Transcription Factor Rim101p Governs Ion Tolerance and Cell Differentiation by Direct Repression of the Regulatory Genes NRG1 and SMP1 in Saccharomyces cerevisiae. Molecular and Cellular Biology, 23(2), 677-686. doi:10.1128/mcb.23.2.677-686.2003Lamb, T. M., Xu, W., Diamond, A., & Mitchell, A. P. (2000). Alkaline Response Genes ofSaccharomyces cerevisiaeand Their Relationship to theRIM101Pathway. Journal of Biological Chemistry, 276(3), 1850-1856. doi:10.1074/jbc.m008381200Madrid, R., Gómez, M. J., Ramos, J., & Rodrı́guez-Navarro, A. (1998). Ectopic Potassium Uptake intrk1 trk2Mutants ofSaccharomyces cerevisiaeCorrelates with a Highly Hyperpolarized Membrane Potential. Journal of Biological Chemistry, 273(24), 14838-14844. doi:10.1074/jbc.273.24.14838Maresova, L., & Sychrova, H. (2004). Physiological characterization of Saccharomyces cerevisiae kha1 deletion mutants. Molecular Microbiology, 55(2), 588-600. doi:10.1111/j.1365-2958.2004.04410.xMarqués, M. C., Zamarbide-Forés, S., Pedelini, L., Llopis-Torregrosa, V., & Yenush, L. (2015). A functional Rim101 complex is required for proper accumulation of the Ena1 Na+-ATPase protein in response to salt stress in Saccharomyces cerevisiae. FEMS Yeast Research, 15(4). doi:10.1093/femsyr/fov017Mulet, J. M., Leube, M. P., Kron, S. J., Rios, G., Fink, G. R., & Serrano, R. (1999). A Novel Mechanism of Ion Homeostasis and Salt Tolerance in Yeast: the Hal4 and Hal5 Protein Kinases Modulate the Trk1-Trk2 Potassium Transporter. Molecular and Cellular Biology, 19(5), 3328-3337. doi:10.1128/mcb.19.5.3328Mulet, J. M., & Serrano, R. (2002). Simultaneous determination of potassium and rubidium content in yeast. Yeast, 19(15), 1295-1298. doi:10.1002/yea.909Murguía, J. R., Bellés, J. M., & Serrano, R. (1996). The YeastHAL2Nucleotidase Is anin VivoTarget of Salt Toxicity. Journal of Biological Chemistry, 271(46), 29029-29033. doi:10.1074/jbc.271.46.29029Obara, K., & Kihara, A. (2014). Signaling Events of the Rim101 Pathway Occur at the Plasma Membrane in a Ubiquitination-Dependent Manner. Molecular and Cellular Biology, 34(18), 3525-3534. doi:10.1128/mcb.00408-14Paczkowski, J. E., & Fromme, J. C. (2014). Structural Basis for Membrane Binding and Remodeling by the Exomer Secretory Vesicle Cargo Adaptor. Developmental Cell, 30(5), 610-624. doi:10.1016/j.devcel.2014.07.014Paczkowski, J. E., Richardson, B. C., & Fromme, J. C. (2015). Cargo adaptors: structures illuminate mechanisms regulating vesicle biogenesis. Trends in Cell Biology, 25(7), 408-416. doi:10.1016/j.tcb.2015.02.005Paczkowski, J. E., Richardson, B. C., Strassner, A. M., & Fromme, J. C. (2012). The exomer cargo adaptor structure reveals a novel GTPase-binding domain. The EMBO Journal, 31(21), 4191-4203. doi:10.1038/emboj.2012.268Parsons, A. B., Brost, R. L., Ding, H., Li, Z., Zhang, C., Sheikh, B., … Boone, C. (2003). Integration of chemical-genetic and genetic interaction data links bioactive compounds to cellular target pathways. Nature Biotechnology, 22(1), 62-69. doi:10.1038/nbt919Peñalva, M. A., Lucena-Agell, D., & Arst, H. N. (2014). Liaison alcaline: Pals entice non-endosomal ESCRTs to the plasma membrane for pH signaling. Current Opinion in Microbiology, 22, 49-59. doi:10.1016/j.mib.2014.09.005Ríos, G., Cabedo, M., Rull, B., Yenush, L., Serrano, R., & Mulet, J. M. (2013). Role of the yeast multidrug transporter Qdr2 in cation homeostasis and the oxidative stress response. FEMS Yeast Research, 13(1), 97-106. doi:10.1111/1567-1364.12013RIOS, G., FERRANDO, A., & SERRANO, R. (1997). Mechanisms of Salt Tolerance Conferred by Overexpression of theHAL1 Gene inSaccharomyces cerevisiae. Yeast, 13(6), 515-528. doi:10.1002/(sici)1097-0061(199705)13:63.0.co;2-xRitz, A. M., Trautwein, M., Grassinger, F., & Spang, A. (2014). The Prion-like Domain in the Exomer-Dependent Cargo Pin2 Serves as a trans-Golgi Retention Motif. Cell Reports, 7(1), 249-260. doi:10.1016/j.celrep.2014.02.026Rockenbauch, U., Ritz, A. M., Sacristan, C., Roncero, C., & Spang, A. (2012). The complex interactions of Chs5p, the ChAPs, and the cargo Chs3p. Molecular Biology of the Cell, 23(22), 4402-4415. doi:10.1091/mbc.e11-12-1015Roncero, C. (2002). The genetic complexity of chitin synthesis in fungi. Current Genetics, 41(6), 367-378. doi:10.1007/s00294-002-0318-7Rothfels, K., Tanny, J. C., Molnar, E., Friesen, H., Commisso, C., & Segall, J. (2005). Components of the ESCRT Pathway, DFG16, and YGR122w Are Required for Rim101 To Act as a Corepressor with Nrg1 at the Negative Regulatory Element of the DIT1 Gene of Saccharomyces cerevisiae. Molecular and Cellular Biology, 25(15), 6772-6788. doi:10.1128/mcb.25.15.6772-6788.2005Santos, B., & Snyder, M. (1997). Targeting of Chitin Synthase 3 to Polarized Growth Sites in Yeast Requires Chs5p and Myo2p. Journal of Cell Biology, 136(1), 95-110. doi:10.1083/jcb.136.1.95Sato, M., Dhut, S., & Toda, T. (2005). New drug-resistant cassettes for gene disruption and epitope tagging inSchizosaccharomyces pombe. Yeast, 22(7), 583-591. doi:10.1002/yea.1233Schekman, R., & Orci, L. (1996). Coat Proteins and Vesicle Budding. Science, 271(5255), 1526-1533. doi:10.1126/science.271.5255.1526Sopko, R., Huang, D., Preston, N., Chua, G., Papp, B., Kafadar, K., … Andrews, B. (2006). Mapping Pathways and Phenotypes by Systematic Gene Overexpression. Molecular Cell, 21(3), 319-330. doi:10.1016/j.molcel.2005.12.011Spang, A. (2008). Membrane traffic in the secretory pathway. Cellular and Molecular Life Sciences, 65(18), 2781-2789. doi:10.1007/s00018-008-8349-yStarr, T. L., Pagant, S., Wang, C.-W., & Schekman, R. (2012). Sorting Signals That Mediate Traffic of Chitin Synthase III between the TGN/Endosomes and to the Plasma Membrane in Yeast. PLoS ONE, 7(10), e46386. doi:10.1371/journal.pone.0046386Trautwein, M., Schindler, C., Gauss, R., Dengjel, J., Hartmann, E., & Spang, A. (2006). Arf1p, Chs5p and the ChAPs are required for export of specialized cargo from the Golgi. The EMBO Journal, 25(5), 943-954. doi:10.1038/sj.emboj.7601007Trilla, J. A., Durán, A., & Roncero, C. (1999). Chs7p, a New Protein Involved in the Control of Protein Export from the Endoplasmic Reticulum that Is Specifically Engaged in the Regulation of Chitin Synthesis in Saccharomyces cerevisiae. Journal of Cell Biology, 145(6), 1153-1163. doi:10.1083/jcb.145.6.1153Valdivia, R. H., Baggott, D., Chuang, J. S., & Schekman, R. W. (2002). The Yeast Clathrin Adaptor Protein Complex 1 Is Required for the Efficient Retention of a Subset of Late Golgi Membrane Proteins. Developmental Cell, 2(3), 283-294. doi:10.1016/s1534-5807(02)00127-2Wadskog, I., Forsmark, A., Rossi, G., Konopka, C., Öyen, M., Goksör, M., … Adler, L. (2006). The Yeast Tumor Suppressor Homologue Sro7p Is Required for Targeting of the Sodium Pumping ATPase to the Cell Surface. Molecular Biology of the Cell, 17(12), 4988-5003. doi:10.1091/mbc.e05-08-0798Wang, C.-W., Hamamoto, S., Orci, L., & Schekman, R. (2006). Exomer: a coat complex for transport of select membrane proteins from the trans-Golgi network to the plasma membrane in yeast. Journal of Cell Biology, 174(7), 973-983. doi:10.1083/jcb.200605106Weiskoff, A. M., & Fromme, J. C. (2014). Distinct N-terminal regions of the exomer secretory vesicle cargo Chs3 regulate its trafficking itinerary. Frontiers in Cell and Developmental Biology, 2. doi:10.3389/fcell.2014.00047Yahara, N., Ueda, T., Sato, K., & Nakano, A. (2001). Multiple Roles of Arf1 GTPase in the Yeast Exocytic and Endocytic Pathways. Molecular Biology of the Cell, 12(1), 221-238. doi:10.1091/mbc.12.1.221Yenush, L., Merchan, S., Holmes, J., & Serrano, R. (2005). pH-Responsive, Posttranslational Regulation of the Trk1 Potassium Transporter by the Type 1-Related Ppz1 Phosphatase. Molecular and Cellular Biology, 25(19), 8683-8692. doi:10.1128/mcb.25.19.8683-8692.2005Yenush, L. (2002). The Ppz protein phosphatases are key regulators of K+ and pH homeostasis: implications for salt tolerance, cell wall integrity and cell cycle progression. The EMBO Journal, 21(5), 920-929. doi:10.1093/emboj/21.5.920Zanolari, B., Rockenbauch, U., Trautwein, M., Clay, L., Barral, Y., & Spang, A. (2011). Transport to the plasma membrane is regulated differently early and late in the cell cycle in Saccharomyces cerevisiae. Journal of Cell Science, 124(7), 1055-1066. doi:10.1242/jcs.07237

A strategy to characterize the LISA-Pathfinder cold gas thruster system

The cold gas micro-propulsion system that will be used during the LISA-Pathfinder mission will be one of the most important component used to ensure the "free-fall" of the enclosed test masses. In this paper we present a possible strategy to characterize the effective direction and amplitude gain of each of the 6 thrusters of this system

The LISA pathfinder mission

ISA Pathfinder (LPF), the second of the European Space Agency's Small Missions for Advanced Research in Technology (SMART), is a dedicated technology validation mission for future spaceborne gravitational wave detectors, such as the proposed eLISA mission. LISA Pathfinder, and its scientific payload - the LISA Technology Package - will test, in flight, the critical technologies required for low frequency gravitational wave detection: it will put two test masses in a near-perfect gravitational free-fall and control and measure their motion with unprecedented accuracy. This is achieved through technology comprising inertial sensors, high precision laser metrology, drag-free control and an ultra-precise micro-Newton propulsion system. LISA Pathfinder is due to be launched in mid-2015, with first results on the performance of the system being available 6 months thereafter. The paper introduces the LISA Pathfinder mission, followed by an explanation of the physical principles of measurement concept and associated hardware. We then provide a detailed discussion of the LISA Technology Package, including both the inertial sensor and interferometric readout. As we approach the launch of the LISA Pathfinder, the focus of the development is shifting towards the science operations and data analysis - this is described in the final section of the paper

Free-flight experiments in LISA Pathfinder

The LISA Pathfinder mission will demonstrate the technology of drag-free test masses for use as inertial references in future space-based gravitational wave detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free flight about a test mass while measuring the acceleration of this primary test mass relative to a second reference test mass. Because the reference test mass is contained within the same spacecraft, it is necessary to apply forces on it to maintain its position and attitude relative to the spacecraft. These forces are a potential source of acceleration noise in the LISA Pathfinder system that are not present in the full LISA configuration. While LISA Pathfinder has been designed to meet it's primary mission requirements in the presence of this noise, recent estimates suggest that the on-orbit performance may be limited by this `suspension noise'. The drift-mode or free-flight experiments provide an opportunity to mitigate this noise source and further characterize the underlying disturbances that are of interest to the designers of LISA-like instruments. This article provides a high-level overview of these experiments and the methods under development to analyze the resulting data.Comment: 13 pages, 5 figures. Accepted to Journal Of Physics, Conference Series. Presented at 10th International LISA Symposium, May 2014, Gainesville, FL, US