Astronauts Andrew Morgan of NASA and Luca Parmitano of the European Space Agency (ESA) will venture outside the International Space Station starting at ~6:50 a.m. EST to continue repairing the Alpha Magnetic Spectrometer (AMS) instrument. This is the third in a series of repair spacewalks – the most complex of this kind since the servicing of the Hubble Space Telescope. AMS is attached to the outside of the space station, where it has been operating since 2011. It is a particle physics experiment working to help us understand dark matter and the origins of the universe.