Atlas V
Atlas V is an expendable launch system and the fifth major version in the Atlas launch vehicle family. It was developed by Lockheed Martin and has been operated by United Launch Alliance since 2006. Primarily used to launch payloads for the United States Department of Defense, NASA, and commercial customers, Atlas V is the longest-serving active rocket in the United States.
Each Atlas V vehicle consists of two main stages. The first stage is powered by a single Russian-made RD-180 engine that burns kerosene and liquid oxygen. The Centaur upper stage uses one or two American-made Aerojet Rocketdyne RL10 engines that burn liquid hydrogen and liquid oxygen. Strap-on solid rocket boosters are used in several configurations. Originally equipped with AJ-60A SRBs, the vehicle switched to Graphite-Epoxy Motor boosters beginning in November 2020, except for flights in the Boeing Starliner program. Standard payload fairings measure either or in diameter, with multiple available lengths.
In August 2021, ULA announced that Atlas V would be retired and all remaining launches had been sold., 10 launches remain. Production of the rocket ended in 2024. Future ULA missions will use the Vulcan Centaur launch vehicle, which was designed in part to comply with a Congressional mandate to phase out use of the Russian-made RD-180 engine.
Vehicle description
The Atlas V was developed by Lockheed Martin Commercial Launch Services as part of the U.S. Air Force Evolved Expendable Launch Vehicle program and made its inaugural flight on August 21, 2002. The vehicle operates from SLC-41 at Cape Canaveral Space Force Station. It also operated from SLC-3E at Vandenberg Space Force Base until 2022. LMCLS continued to market the Atlas V to commercial customers worldwide until January 2018, when United Launch Alliance assumed control of commercial marketing and sales.Atlas V first stage
The Atlas V first stage, the Common Core Booster, is in diameter and in length. It is powered by one Russian NPO Energomash RD-180 main engine burning of liquid oxygen and RP-1. The booster operates for about four minutes, providing about of thrust. Thrust can be augmented with up to five Aerojet AJ-60A or Northrop Grumman GEM 63 strap-on solid rocket boosters, each providing an additional of thrust for 94 seconds.The main differences between the Atlas V and earlier Atlas I and II family launch vehicles are:
- The first stage tanks no longer use stainless steel monocoque pressure stabilized "balloon" construction. The tanks are isogrid aluminum and are structurally stable when unpressurized.
- Accommodation points for parallel stages, both smaller solids and identical liquids, are built into first-stage structures.
- The "1.5 staging" technique is no longer used, having been discontinued on the Atlas III with the introduction of the Russian RD-180 engine.
- The main-stage diameter increased from.
Centaur III upper stage
When the Atlas V was introduced, the Centaur III was alternatively called the Common Centaur, reflecting its use on both the Atlas III and V., the Centaur III had the highest proportion of burnable propellant relative to total mass of any modern hydrogen upper stage and hence can deliver substantial payloads to a high-energy state.
Payload fairing
Atlas V payload fairings are available in two diameters, depending on satellite requirements. The diameter fairing, originally designed for the Atlas II booster, comes in three different lengths: the original version and extended versions, first flown respectively on the AV-008/Astra 1KR and AV-004/Inmarsat-4 F1 missions. Fairings of up to diameter and length have been considered but were never implemented.A diameter fairing, with an internally usable diameter of, was developed and built by RUAG Space in Switzerland. The RUAG fairing uses carbon fiber composite construction and is based on a similar flight-proven fairing for the Ariane 5. Three configurations are manufactured to support the Atlas V:,, and long. While the classic fairing covers only the payload, the RUAG fairing is much longer and fully encloses both the Centaur upper stage and the payload.
Upgrades
Many systems on the Atlas V have been the subject of upgrade and enhancement both prior to the first Atlas V flight and since that time. Work on a Fault Tolerant Inertial Navigation Unit started in 2001 to enhance mission reliability for Atlas vehicles by replacing the earlier non-redundant navigation and computing equipment with a fault-tolerant unit. The upgraded FTINU first flew in 2006, and in 2010 a follow-on order for more FTINU units was awarded.In 2015, ULA announced that the Aerojet Rocketdyne-produced AJ-60A solid rocket boosters then in use on Atlas V would be superseded by new GEM 63 boosters produced by Northrop Grumman Innovation Systems. The extended GEM 63XL boosters will also be used on the Vulcan Centaur launch vehicle that will replace the Atlas V. The first Atlas V launch with GEM 63 boosters happened on November 13, 2020.
Human-rating certification
Proposals and design work to human-rate the Atlas V began as early as 2006, with ULA's parent company Lockheed Martin reporting an agreement with Bigelow Aerospace that was intended to lead to commercial private trips to low Earth orbit.Human-rating design and simulation work began in earnest in 2010, with the award of US$6.7 million in the first phase of the NASA Commercial Crew Program to develop an Emergency Detection System.
As of February 2011, ULA had received an extension to April 2011 from NASA and was finishing up work on the EDS.
NASA solicited proposals for CCP phase 2 in October 2010, and ULA proposed to complete design work on the EDS. At the time, NASA's goal was to get astronauts to orbit by 2015. Then-ULA President and CEO Michael Gass stated that a schedule acceleration to 2014 was possible if funded. Other than the addition of the Emergency Detection System, no major changes were expected to the Atlas V rocket, but ground infrastructure modifications were planned. The most likely candidate for the human-rating was the N02 configuration, with no fairing, no solid rocket boosters, and dual RL10 engines on the Centaur upper stage.
On July 18, 2011, NASA and ULA announced an agreement on the possibility of certifying the Atlas V to NASA's standards for human spaceflight. ULA agreed to provide NASA with data on the Atlas V, while NASA would provide ULA with draft human certification requirements. In 2011, the human-rated Atlas V was also still under consideration to carry spaceflight participants to the proposed Bigelow Commercial Space Station.
In 2011, Sierra Nevada Corporation picked the Atlas V to be the booster for its still-under-development Dream Chaser crewed spaceplane. The Dream Chaser was intended to launch on an Atlas V, fly a crew to the ISS, and land horizontally following a lifting-body reentry. However, in late 2014 NASA did not select the Dream Chaser to be one of the two vehicles selected under the Commercial Crew competition.
On August 4, 2011, Boeing announced that it would use the Atlas V as the initial launch vehicle for its CST-100 crew capsule. CST-100 will take NASA astronauts to the International Space Station and was also intended to service the proposed Bigelow Commercial Space Station. A three-flight test program was projected to be completed by 2015, certifying the Atlas V/CST-100 combination for human spaceflight operations. The first flight was expected to include an Atlas V rocket integrated with an uncrewed CST-100 capsule, the second flight an in-flight launch abort system demonstration in the middle of that year, and the third flight a crewed mission carrying two Boeing test-pilot astronauts into LEO and returning them safely at the end of 2015. These plans were delayed by many years and morphed along the way so that in the end, the first orbital test flight with no crew materialized in 2019, but it was a failure and needed to be reflown in 2022, the in-flight launch abort system test flight did not materialize, and the third flight, a crewed orbital test flight with two astronauts materialized in June 2024 as Boeing Crewed Flight Test. The launch abort system was tested in 2019 in the Boeing Pad Abort Test. The spacecraft launched from a test stand, not from an Atlas V.
In 2014, NASA selected the Boeing Starliner CST-100 spacecraft as part of the Commercial Crew Program. Atlas V is the launch vehicle for Starliner. The first launch of an uncrewed Starliner, the Boeing OFT mission, occurred atop a human-rated Atlas V on the morning of December 20, 2019; the mission failed to meet goals due to a spacecraft failure, though the Atlas V launcher performed well. In 2022, an Atlas V launched an uncrewed Starliner capsule for the second time on Boe-OFT 2 mission; the mission was a success.
In June 2024, on Boe-CFT mission, Atlas V carried humans into space for the first time, launching two NASA astronauts to the ISS.