Falcon 9 in the context of "Explorers Program"

The process of assembling the International Space Station (ISS) has been under way since the 1990s. Zarya, the first ISS module, was launched by a Proton rocket on 20 November 1998. The STS-88 Space Shuttle mission followed two weeks after Zarya was launched, bringing Unity, the first of three node modules, and connecting it to Zarya. This bare 2-module core of the ISS remained uncrewed for the next one and a half years, until in July 2000 the Russian module Zvezda was launched by a Proton rocket, allowing a maximum crew of three astronauts or cosmonauts to be on the ISS permanently.

The ISS has a pressurized volume of approximately 1,000 cubic metres (35,000 cu ft), a mass of approximately 410,000 kilograms (900,000 lb), approximately 100 kilowatts of power output, a truss 108.4 metres (356 ft) long, modules 74 metres (243 ft) long, and a crew of seven. Building the complete station required more than 40 assembly flights. As of 2020, 36 Space Shuttle flights delivered ISS elements. Other assembly flights consisted of modules lifted by the Falcon 9, Russian Proton rocket or, in the case of Pirs and Poisk, the Soyuz-U rocket.

Gimbaled thrust is the system of thrust vectoring used in most rockets, including the Space Shuttle, the Saturn V lunar rockets, and the Falcon 9.

Space Exploration Technologies Corp., commonly known as SpaceX, is a private American aerospace company and space transportation company headquartered at the Starbase development site in Starbase, Texas. Since its founding in 2002, the company has made numerous advances in rocket propulsion, reusable launch vehicles, human spaceflight and satellite constellation technology. As of 2025, SpaceX is the world's dominant space launch provider, its launch cadence eclipsing all others, including private competitors and national programs like the Chinese space program. SpaceX, NASA, and the United States Armed Forces work closely together by means of governmental contracts.

SpaceX was founded by Elon Musk in 2002 with a vision of decreasing the costs of space launches, paving the way to a self-sustaining colony on Mars. In 2008, Falcon 1 successfully launched into orbit after three failed launch attempts. The company then moved towards the development of the larger Falcon 9 rocket and the Dragon 1 capsule to satisfy NASA's COTS contracts for deliveries to the International Space Station. By 2012, SpaceX finished all COTS test flights and began delivering Commercial Resupply Services missions to the International Space Station. Also around that time, SpaceX started developing hardware to make the Falcon 9 first stage reusable. The company demonstrated the first successful first-stage landing in 2015 and re-launch of the first stage in 2017. Falcon Heavy, built from three Falcon 9 boosters, first flew in 2018 after a more than decade-long development process. As of May 2025, the company's Falcon 9 rockets have landed and flown again more than 450 times, reaching 1–3 launches a week.

Falcon 9 v1.1 was the second version of SpaceX's Falcon 9 orbital launch vehicle. The rocket was developed in 2011–2013, made its maiden launch in September 2013, and its final flight in January 2016. The Falcon 9 rocket was fully designed, manufactured, and operated by SpaceX. Following the second Commercial Resupply Services (CRS) launch, the initial version Falcon 9 v1.0 was retired from use and replaced by the v1.1 version.

Falcon 9 v1.1 was a significant evolution from Falcon 9 v1.0, with 60 percent more thrust and weight. Its maiden flight carried out a demonstration mission with the CASSIOPE satellite on 29 September 2013, the sixth overall launch of any Falcon 9.

A reusable launch vehicle has parts that can be recovered and reflown, while carrying payloads from the surface to outer space. Rocket stages are the most common launch vehicle parts aimed for reuse. Smaller parts such as fairings, boosters or rocket engines can also be reused, though reusable spacecraft may be launched on top of an expendable launch vehicle. Reusable launch vehicles do not need to make these parts for each launch, therefore reducing its launch cost significantly. However, these benefits are diminished by the cost of recovery and refurbishment.

Reusable launch vehicles may contain additional avionics and propellant, making them heavier than their expendable counterparts. Reused parts may need to enter the atmosphere and navigate through it, so they are often equipped with heat shields, grid fins, and other flight control surfaces. By modifying their shape, spaceplanes can leverage aviation mechanics to aid in its recovery, such as gliding or lift. In the atmosphere, parachutes or retrorockets may also be needed to slow it down further. Reusable parts may also need specialized recovery facilities such as runways or autonomous spaceport drone ships. Some concepts rely on ground infrastructures such as mass drivers to accelerate the launch vehicle beforehand.

The Boeing X-37, also known as the Orbital Test Vehicle (OTV), is a reusable robotic spacecraft. It is boosted into space by a launch vehicle, re-enters Earth's atmosphere, and lands as a spaceplane. The X-37 is operated by the Department of the Air Force Rapid Capabilities Office, in collaboration with the United States Space Force, for orbital spaceflight missions intended to demonstrate reusable space technologies. It is a 120-percent-scaled derivative of the earlier Boeing X-40. The X-37 began as a NASA project in 1999, before being transferred to the United States Department of Defense in 2004. Until 2019, the program was managed by Air Force Space Command.

An X-37 first flew during a drop test in 2006; its first orbital mission was launched in April 2010 on an Atlas V rocket, and returned to Earth in December 2010. Subsequent flights gradually extended the mission duration, reaching 780 days in orbit for the fifth mission, the first to launch on a Falcon 9 rocket. The sixth mission launched on an Atlas V on 17 May 2020 and concluded on 12 November 2022, reaching 908 days in orbit. The seventh mission launched on 28 December 2023 on a Falcon Heavy rocket, entering a highly elliptical high Earth orbit, landing in March 2025 after 434 days in orbit.

Falcon Heavy is a super heavy-lift launch vehicle with partial reusability that can carry cargo into Earth orbit and beyond. It is designed, manufactured and launched by American aerospace company SpaceX.

The rocket consists of a center core on which two Falcon 9 boosters are attached, and a second stage on top of the center core. Falcon Heavy has the second highest payload capacity of any currently operational launch vehicle behind NASA's Space Launch System (SLS), and the fourth-highest capacity of any rocket to reach orbit, trailing behind the SLS, Energia and the Saturn V.