‘Vehicle traffic’ is the term we use for every spaceship that goes to or leaves the International Space Station. Currently there are four attached to the Station: ATV-4, two Soyuz (one each for each expedition) and one Progress. Every couple of weeks, we have one of those vehicles coming or going. Of course, the most recent arrival was Europe's ATV-4.
Progress 50, which is docked on the bottom side of the International Space Station, will depart this evening at 20:44 GMT. After separation from the Station, the Progress will move down and away from it. The astronauts will take pictures and watch the Progress depart. Progress 50, like all other Progress vehicles, is filled with waste that accumulates over time on board the Station; the crew load all the items to throw away in order to make space for cargo that is delivered by vehicles such as ATV-4.
Once the Progress is far enough away from the Space Station and at the right position in orbit, it will perform a deorbit burn of several minutes at around 23:53 GMT. This will initiate its destructive re-entry into the atmosphere.
The entry into the atmosphere and the burn-up will occur between 00:30 and 00:39 GMT. With a little bit of luck, the astronauts will be able to see the spectacular plasma tree created when they look out of their windows.
The next vehicle to arrive will be Progress 52P, which will dock at the same location as Progress 50P later this week.
“Vehicles leaving and arriving is always a special moment for us. It’s never a routine task. Every resupply ship brings us new work,” says ESA Mission Director Roland Luettgens.