The rocket standing ready on the pad at Space Launch Complex-3 at Vandenberg Air Force Base in California, is a United Launch Alliance Atlas V 401 configuration. It is the workhorse of the Atlas V fleet, delivering about half of all Atlas V missions to date.
The 401 designation means this rocket has a payload fairing, or nose cone, that is approximately four meters wide, a common core booster with no solid rocket boosters, and a Centaur upper stage with a single engine. Booster propulsion is provided by the RD-180 engine system, a single engine with two thrust chambers. The RD-180 burns Rocket Propellant-1 (RP-1), a highly purified kerosene, along with liquid oxygen, providing 860,200 pounds of thrust at liftoff.
The booster is controlled by the Centaur second stage avionics system, which provides guidance, flight control and vehicle sequencing functions during the booster and Centaur phases of flight. The single-engine Centaur upper stage is a cryogenic vehicle, fueled with liquid hydrogen and liquid oxygen. The two-piece payload fairing that protects the Insight spacecraft tops the vehicle.
The Atlas V 401 rocket stands 188 feet tall, or about as tall as a 19-story building. Fully stacked, with spacecraft, the rocket weighs about 730,000 pounds, or the equivalent of 14 big rigs fully loaded with cargo.