Stats: Atlas 5 and Delta 4 histories and backlogs (updated April 20)

Failure struck Russia’s troubled space program for the second time in three weeks Saturday, when a Proton rocket carrying a high-tech satellite for Mexico’s new $1.6 billion space-based communications network crashed shortly after liftoff.

Two ion-driven communications satellites launched from Cape Canaveral on March 1 have begun novel maneuvers using electric propulsion to reach operating posts 22,300 miles over the equator.

SpaceX’s launch team ran through a traditional preflight test Monday, putting a Falcon 9 rocket through a mock countdown, loading it with propellant and briefly firing its nine engines on a launch pad in California ahead of this weekend’s liftoff with a U.S.-European oceanography satellite.