Enlarge / The Ariane 5 has been a workhorse since 1996 for the European Space Agency. (credit: ESA/Arianespace)

The Ariane 5 rocket has had a long run, with nearly three decades of service launching satellites and spacecraft. Over that time, the iconic rocket, with a liquid hydrogen-fueled core stage and solid rocket boosters, has come to symbolize Europe's guaranteed access to space.

But now, the road is ending for the Ariane 5. As soon as Tuesday evening, the final Ariane 5 rocket will lift off from Kourou, French Guiana, carrying a French military communications satellite and a German communications satellite to geostationary transfer orbit. A 90-minute launch window opens at 5:30 pm ET (21:30 UTC). The launch will be webcast on ESA TV.

And after this? Europe's space agency faces some difficult questions.