The Atlas V first stage is the common core booster. This main booster is 107 feet (32.5 meters) long, with a diameter of 12.5 feet (3.8 meters). With the payload on board, the launch vehicle is 188 feet (57.3 meters). Fully fueled, with the spacecraft on top, it weighs about 730,000 pounds (333,000 kilograms).

Thermally stable kerosene fuel (type RP-1) and liquid oxygen will be loaded shortly before launch into cylindrical fuel tanks that make up about half of the total height of the vehicle.

The common core booster can provide thrust of up to about 850,000 pounds (3.8 million newtons) at full throttle. Named for the famous Isaac Newton, a newton is a unit of force required to accelerate a mass of one kilogram, one meter per second... every second!

During this phase, the spacecraft accelerates to supersonic speeds of about 4,500 meters per second (10,000 miles per hour)

Atlas V-401 Launch Vehicle, Stage 2 Centaur: Fuel and oxidizer and the vehicle's "brains"; fires twice, once to insert the vehicle-spacecraft stack into low Earth orbit and then again to accelerate the spacecraft out of Earth orbit and on its way towards Mars.

The Upper Stage contains fuel and oxidizer, and the vehicle's "brains." It fires twice, once to insert the vehicle-spacecraft stack into low Earth orbit and then again to accelerate the spacecraft out of Earth orbit and on its way towards Mars.

Two interstage adapters connect the first stage of the Atlas with its Centaur upper stage. The interstage adapter attached to the Centaur encloses the aft bulkhead carrier while the stages are linked.

The Centaur is 41.7 feet (12.7 meters) long and 10.2 feet (3.1 meters) in diameter. It has a restartable RL-10C engine made by Aerojet Rocketdyne, Sacramento, California.

This engine uses liquid hydrogen and liquid oxygen and can provide up to about 22,890 pounds (101,820 newtons) of thrust. The Centaur can control its orientation precisely, which is important for managing the direction of thrust while its engine is firing. It carries its own flight control computer and can release its payload with the desired attitude and spin rate.

The Centaur's aft bulkhead carrier holds the CubeSat deployment system that contained the two mini-spacecraft called Mars Cube One, or MarCO. During launch, these CubeSats were released after leaving Earth orbit and they flew on their own path to Mars behind InSight.

The spacecraft rides into the sky inside a protective payload fairing atop the Centaur stage. The fairing is 39.4 feet (12 meters) long, with a diameter of 13.8 feet (4.2 meters) at the widest part, tapering to the top of the cone.

The fairing jettisons shortly after ignition of the Centaur's engine, when the vehicle has climbed high enough to have escaped most of Earth's atmosphere.
With the payload fairing on top, the Atlas V 401 ready for launch, will stand approximately 188 feet (57.3 meters) tall.