Harnessing functional food strategies for the health challenges of space travel—Fermented soy for astronaut nutrition

Astronauts face numerous health challenges during long-duration space missions, including diminished immunity, bone loss and increased risk of radiation-induced carcinogenesis. Changes in the intestinal flora of astronauts may contribute to these problems. Soy-based fermented food products could provide a nutritional strategy to help alleviate these challenges by incorporating beneficial lactic acid bacteria, while reaping the benefits of soy isoflavones. We carried out strain selection for the development of soy ferments, selecting strains of lactic acid bacteria showing the most effective growth and fermentation ability in soy milk (Streptococcus thermophilus ST5, Bifidobacterium longum R0175 and Lactobacillus helveticus R0052). Immunomodulatory bioactivity of selected ferments was assessed using an in vitro challenge system with human intestinal epithelial and macrophage cell lines, and selected ferments show the ability to down-regulate production of the pro-inflammatory cytokine interleukin-8 following challenge with tumour necrosis factor-alpha. The impact of fermentation on vitamin B1 and B6 levels and on isoflavone biotransformation to agluconic forms was also assessed, with strain variation-dependent biotransformation ability detected. Overall this suggests that probiotic bacteria can be successfully utilized to develop soy-based fermented products targeted against health problems associated with long-term space travel.     

THE DIGITAL WAVE-PROCESSING EXPERIMENT ON CLUSTER

The wide variety of geophysical plasmas that will be investigated by the Cluster mission contain waves with a frequency range from DC to over 100 kHz with both magnetic and electric components. The characteristic duration of these waves extends from a few milliseconds to minutes and a dynamic range of over 90 dB is desired. All of these factors make it essential that the on-board control system for the Wave-Experiment Consortium (WEC) instruments be flexible so as to make effective use of the limited spacecraft resources of power and telemetry-information bandwidth. The Digital Wave Processing Experiment, (DWP), will be flown on Cluster satellites as a component of the WEC. DWP will coordinate WEC measurements as well as perform particle correlations in order to permit the direct study of wave/particle interactions. The DWP instrument employs a novel architecture based on the use of transputers with parallel processing and re-allocatable tasks to provide a high-reliability system. Members of the DWP team are also providing sophisticated electrical ground support equipment, for use during development and testing by the WEC. This is described further in Pedersen et al. (this issue).     

Two new hot white dwarfs in a region of exceptionally low hi density

We report the discovery of two hot white dwarfs which have the lowest line-of-sight neutral hydrogen column densities yet measured. The stars were found independently by the ROSAT EUV, Montreal-Cambridge-Tololo, and Edinburgh-Cape surveys. Follow-up observations made using the Voyager 2 ultraviolet spectrometer reveal strong continua shortward of the 912Å Lyman limit from which we deduce that the neutral hydrogen column densities are 1.3 × 10¹⁷ and 2.0 × 10¹⁷ atoms cm⁻².     

Metrology on-board PROBA-3: The shadow position sensors subsystem

PROBA-3 is an ESA mission aimed at the demonstration of formation flying performance of two satellites that will form a giant coronagraph in space. The first spacecraft will host a telescope imaging the solar corona in visible light, while the second, the external occulter, will produce an artificial eclipse. This instrument is named ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun). To accomplish the payload's scientific tasks, PROBA-3 will ensure sub-millimeter reciprocal positioning of its two satellites using closed-loop on-board metrology. Several metrology systems will be used and the Shadow Position Sensor (SPS) subsystem senses the penumbra around the instrument aperture and returns the 3-D displacement of the coronagraph satellite, with respect to its nominal position, by running a dedicated algorithm. In this paper, we describe how the SPS works and the choices made to accomplish the mission objectives.