which eventually launched in 2013 on Falcon 9), Swedish Space Corp and US Air Force. Design According to SpaceX, the Falcon 1 was designed to minimize price per launch for low-Earth-orbit satellites, increase reliability, and optimize flight environment and time to launch. It also was used to verify components and structural design concepts that would be reused in the Falcon 9. SpaceX started with the idea that the smallest useful orbital rocket was the minimum viable product (Falcon 1 with about to orbit), instead of building something larger and more complicated, and then running out of money and going bankrupt. First stage The first stage was made from friction-stir-welded 2219 aluminum alloy. It employs a common bulkhead between the LOX and RP-1 tanks, as well as flight pressure stabilization. It can be transported safely without pressurization (like the heavier Delta II isogrid design) but gains additional strength when pressurized for flight (like the Atlas II, which could not be transported unpressurized). The parachute system, built by Irvin Para­chute Corp­oration, uses a high-speed drogue chute and a main chute. For the first two launches, the Falcon 1 used a Merlin 1A engine. An improved version of the Merlin 1A, the Merlin 1B, was supposed to fly on later flights of the Falcon 1, although it was further improved to create the Merlin 1C, which was first flown on the third Falcon 1 flight, and on the first 5 flights of the Falcon 9. The Falcon 1 first stage was powered by a single pump-fed Merlin 1C engine burning RP-1 and liquid oxygen providing of sea-level thrust and a specific impulse of 245 s (vacuum Isp 290 s). The first stage burns to depletion, taking around 169 seconds to do so. Second stage The second stage Falcon 1 tanks were built with a cryogenic-compatible 2014 aluminum alloy, with the plan to move to aluminum-lithium alloy on the Falcon 1e. The helium pressurization system pumps propellant to the engine, supplies heated pressurized gas for the attitude control thrusters, and is used for zero-g propellant accumulation prior to engine restart. The Kestrel engine includes a titanium heat exchanger to pass waste heat to the helium, thereby greatly extending its work capacity. The pressure tanks are composite overwrapped pressure vessels made by Arde corporation with inconel alloy and are the same as those used in the Delta III. The second stage was powered by a