Photos: Atlas 5 on the pad for X-37B launch

The twin 177-foot-tall solid-fueled boosters for the first flight of NASA’s Space Launch System have been stacked inside the Vehicle Assembly Building at the Kennedy Space Center to await arrival of the rocket’s cryogenic core stage, which is set for a second engine test on a firing stand in Mississippi later this month.

America’s next Mars rover, a $2.1 billion nuclear-powered vehicle to search for evidence that life once existed there, will be launched to the Red Planet in the summer of 2020 by a powerful Atlas 5 rocket.

The 27 Kuiper satellites will head to low Earth orbit on an Atlas 5 rocket flying in a 551 configuration, using five solid rocket boosters. ULA has not announced a new launch date following the scrub.