vendredi 23 septembre 2016
Weekly Recap From the Expedition Lead Scientist, Week of Sept. 12, 2016
ISS - Expedition 49 Mission patch.
Sept. 23, 2016
(Highlights: Week of Sept. 12, 2016) - The week began with moving day and ended with a handful of satellite deployments on the International Space Station.
On Sept. 12, NASA astronaut Kate Rubins disassembled and removed the hardware for the Effects of Microgravity on Stem Cell-Derived Cardiomyocytes (Heart Cells) investigation from the Microgravity Science Glovebox (MSG). Spaceflight can cause a variety of health issues with astronauts, which may become problematic the longer crew members stay in microgravity. The study looked at how human heart muscle tissue contracts, grows and changes genetically in microgravity and how those changes vary between subjects. Understanding how heart muscle cells, or cardiomyocytes, change in space can improve efforts to study disease, screen drugs and conduct cell replacement therapy for future space missions.
Image above: A pair of Planet Lab Dove satellites are ejected into orbit by the NanoRack CubeSat Deployer on the International Space Station. The satellites, each about the size of a shoebox, will take images of Earth. Image Credit: NASA.
Extended stays aboard the station are becoming more common, and future crews will stay in space for even longer periods as they travel on deep-space missions or a journey to Mars. Living without gravity’s influence for long periods can cause negative health effects such as muscle atrophy, including potential atrophy of heart muscle. The Heart Cells investigation cultured heart cells on the station for a month to determine how those muscle cells changed on a cellular and molecular level in space. Scientists hope the results will improve understanding of microgravity’s negative effects. Understanding changes to heart muscle cells could benefit cardiovascular research on Earth, where heart disease is a leading cause of death in many countries.
Rubins cleared out the Heart Cells investigation to make way for an ESA (European Space Agency) study into how molecules in liquid mixtures move in space where buoyancy-driven convection does not mask the more subtle molecular motions. The Selective Optical Diagnostics Instrument (SODI-DCMIX) will observe and measure the diffusion coefficient of liquid mixtures after a temperature gradient is established. Diffusion occurs at the molecular level as opposed to convection which occurs at the bulk level with entire masses, fronts, or regions of a gas or liquid moving somewhat as a unit.
Image above: An image taken from the International Space Station provides a nighttime view looking south at the Mediterranean Sea and the Strait of Gibraltar. A Russian Soyuz spacecraft (left) and Progress spacecraft (right) are in the foreground. Image Credit: NASA.
With convection eliminated in the weightlessness of space, the diffusion coefficient can be more accurately measured. Fluids and gases are never at rest, even if they appear to be when viewed by the naked eye. Molecules are constantly moving and colliding, even though there is no microscope powerful enough to see the phenomenon. SODI-DCMIX will study the Soret effect -- the movement of heat and mass that is caused by a difference in temperature. This is different from convection, where hotter, less dense matter rises upward compared to cooler, denser material.
Creating accurate models of how fluids heat is difficult. Measuring liquid mixtures at rest is not always possible on Earth, because heavier elements in a mixture will follow gravity and sink to the bottom. A mixture on the space station is free from the constraints of gravity, and will not separate. SODI-DCMIX exploits this fact to record temperatures of mixtures in space, using optical techniques to understand how molecules move in liquids. Understanding the fundamentals of thermodiffusion could help oil companies that use computer simulations to model and monitor underground oil reservoirs.
Image above: NASA Astronaut Kate Rubins installs an optical diagnostic instrument in the Microgravity Science Glovebox (MSG) as part of the Selective Optical Diagnostics Instrument (SODI-DCMIX) investigation. Image Credit: NASA.
JAXA (Japan Aerospace Exploration Agency) astronaut Takuya Onishi installed a series of eight Planet Lab-Dove satellites in the NanoRack CubeSat Deployer (NRCSD) using a special airlock in the Japanese Experiment Module (JEM). The NRCSD is a self-contained deployment system on the end of a robotic arm, called the JEM Remote Manipulating System (JRMS), mounted to the exterior of the station. It is a rectangular compartment that "ejects" very small satellites to place them into orbit. It provides a low-cost and frequent flight opportunity for industry and academia to put research satellites into space.
The eight Dove satellites -- each about the size of a shoebox -- were "launched" from the station by ground controllers to capture images of Earth from space. The images have several humanitarian and environmental applications, from monitoring deforestation and urbanization to improving natural disaster relief and agricultural yields in developing nations. The nanosatellite program engages the space community to enhance space-based global communication networks, and to conduct research on our climate and Earth’s atmosphere.
Progress was made on other investigations and facilities this week, including Plant RNA Regulation, Asia Try-Zero G, FLEX-2, Biomolecule Sequencer, Phase Change Heat Exchanger, Manufacturing Device, ELF.
Other human research investigations conducted this week include Dose Tracker, Fine Motor Skills, Habitability, Multi-Omics, and Space Headaches.
Stem Cell-Derived Cardiomyocytes (Heart Cells): http://www.nasa.gov/mission_pages/station/research/experiments/1914.html
NanoRack CubeSat Deployer (NRCSD): http://www.nasa.gov/mission_pages/station/research/experiments/1350.html
Japanese Experiment Module (JEM): https://www.nasa.gov/mission_pages/station/structure/elements/jem.html
Planet Lab-Dove satellites: http://www.nasa.gov/mission_pages/station/research/experiments/1326.html
Plant RNA Regulation: http://www.nasa.gov/mission_pages/station/research/experiments/2019.html
Asia Try-Zero G: http://www.nasa.gov/mission_pages/station/research/experiments/2016.html
Biomolecule Sequencer: http://www.nasa.gov/mission_pages/station/research/experiments/2181.html
Phase Change Heat Exchanger: http://www.nasa.gov/mission_pages/station/research/experiments/2077.html
Manufacturing Device: http://www.nasa.gov/mission_pages/station/research/experiments/2198.html
Dose Tracker: http://www.nasa.gov/mission_pages/station/research/experiments/1933.html
Fine Motor Skills: http://www.nasa.gov/mission_pages/station/research/experiments/1767.html
Space Headaches: http://www.nasa.gov/mission_pages/station/research/experiments/181.html
Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Japan Aerospace Exploration Agency (JAXA): http://global.jaxa.jp/
Images (mentioned), Text, Credits: NASA/Vic Cooley, Lead Increment Scientist Expeditions 49 & 50/Kristine Rainey.
Publié par Orbiter.ch à 12:45