I think the key part of this research is that this adds significantly to the evidence that there's liquid water deep in the crust of Mars. We know that there is water in the form of ice in lots of places on Mars but the idea of subsurface liquid water is exciting because there might be life in there! If it's gushing up to the surface periodically, we might even be able to sample it and see if there's signs of life! There's been previous evidence of these streaks before - but researchers had generally thought that was due to ice melting during the planet's warm season. Now they've found "streaks near the equator, including in the gargantuan Valles Marineris canyon". Any subsurface ice here would likely have sublimated. So it's looking pretty likely that this is subsurface liquid water that is leaking out from time to time. An alternative explanation - dust avalanches - was offered when the same scientists unveiled their initial results back in 2011. With the observation of so many streaks at the equator now the simplest explanation appears to be groundwater welling up to the surface. Similar streaks on Antarctica are known to be caused by water.