Artemis I


Artemis I, formerly Exploration Mission-1, was an uncrewed Moon-orbiting mission that was launched in November 2022. As the first major spaceflight of NASA's Artemis program, Artemis I marked the agency's return to lunar exploration after the conclusion of the Apollo program five decades earlier. It was the first integrated flight test of the Orion spacecraft and Space Launch System rocket, and its main objective was to test the Orion spacecraft, especially its heat shield, in preparation for subsequent Artemis missions. These missions seek to reestablish a human presence on the Moon and demonstrate technologies and business approaches needed for future scientific studies, including exploration of Mars.
The Orion spacecraft for Artemis I was stacked on October 20, 2021, and on August 17, 2022, the fully stacked vehicle was rolled out for launch after a series of delays caused by difficulties in pre-flight testing. The first two launch attempts were canceled due to a faulty engine temperature reading on August 29, 2022, and a hydrogen leak during fueling on September 3, 2022. Artemis I was launched on November 16, 2022, at 06:47:44 UTC.
Artemis I was launched from Launch Complex 39B at the Kennedy Space Center. After reaching Earth orbit, the upper stage carrying the Orion spacecraft separated and performed a trans-lunar injection before releasing Orion and deploying ten CubeSat satellites. Orion completed one flyby of the Moon on November 21, entered a distant retrograde orbit for six days, and completed a second flyby of the Moon on December 5.
The Orion spacecraft then returned and reentered the Earth's atmosphere with the protection of its heat shield, splashing down in the Pacific Ocean on December 11. The mission aims to certify Orion and the Space Launch System for crewed flights beginning with Artemis II, which is scheduled to perform a crewed lunar flyby no earlier than February 2026 until no later than April 2026. After Artemis II, Artemis III will involve a crewed lunar landing, the first since Apollo 17 in 1972.

Mission profile

Artemis I was launched on the Block 1 variant of the Space Launch System. The Block 1 vehicle consisted of a core stage, two five-segment solid rocket boosters and an upper stage. The core stage used four RS-25D engines, all of which had previously flown on Space Shuttle missions. The core and boosters together produced, or about 4,000 metric tons of thrust at liftoff. The upper stage, known as the Interim Cryogenic Propulsion Stage, was based on the Delta Cryogenic Second Stage and was powered by a single RL10B-2 engine on the Artemis I mission.
Once in orbit, the ICPS fired its engine to perform a trans-lunar injection burn, which placed the Orion spacecraft and 10 CubeSats on a trajectory to the Moon. Orion then separated from the ICPS and continued its coast into lunar space. Following Orion separation, the ICPS Stage Adapter deployed ten CubeSats for conducting scientific research and performing technology demonstrations.
The Orion spacecraft spent approximately three weeks in space, including six days in a distant retrograde orbit around the Moon. It came within approximately of the lunar surface and achieved a maximum distance from Earth of.

Mission profile animation

Background

Artemis I was outlined by NASA as Exploration Mission 1 in 2012, at which point it was set to launch in 2017 as the first planned flight of the Space Launch System and the second uncrewed test flight of the Orion Multi-Purpose Crew Vehicle. The initial plans for EM-1 called for a circumlunar trajectory during a seven-day mission.
In January 2013, it was announced that the Orion spacecraft's service module was to be built by the European Space Agency and named the European Service Module. In mid-November 2014, construction of the SLS core stage began at NASA's Michoud Assembly Facility. In January 2015, NASA and Lockheed Martin announced that the primary structure in the Orion spacecraft used on Artemis I would be up to 25% lighter compared to the previous one. This would be achieved by reducing the number of cone panels from six to three, reducing the total number of welds from 19 to 7 and saving the additional mass of the weld material. Other savings would be due to revising its various components and wiring. For Artemis I, the Orion spacecraft was to be outfitted with a complete life support system and crew seats but would be left uncrewed.
In February 2017, NASA began investigating the feasibility of a crewed launch as the first SLS flight. It would have had a crew of two astronauts and the flight time would have been shorter than the uncrewed version. However, after a months-long feasibility study, NASA rejected the proposal, citing cost as the primary issue, and continued with the plan to fly the first SLS mission uncrewed.
In March 2019, then-NASA administrator Jim Bridenstine proposed moving the Orion spacecraft from SLS to commercial rockets, either the Falcon Heavy or Delta IV Heavy, to comply with the schedule. The mission would require two launches: one to place the Orion spacecraft into orbit around the Earth, and a second carrying an upper stage. The two would then dock while in Earth orbit, and the upper stage would ignite to send Orion to the Moon. The idea was eventually scrapped. One challenge with this option would be carrying out that docking, as Orion is not planned to carry a docking mechanism until Artemis III. The concept was shelved in mid-2019, due to another study's conclusion that it would further delay the mission.

Ground testing

The core stage for Artemis I, built at Michoud Assembly Facility in Louisiana by Boeing, had all four engines attached in November 2019 and was declared finished one month later. The core stage left the facility to undergo the Green Run test series at Stennis Space Center, consisting of eight tests of increasing complexity:
  1. Modal testing
  2. Avionics
  3. Fail-safe systems
  4. Propulsion
  5. Thrust vector control system
  6. Launch countdown simulation
  7. Wet dress rehearsal, with propellant
  8. Static fire of the engines for eight minutes
The first test was performed in January 2020, and subsequent Green Run tests proceeded without issue. On January 16, 2021, a year later, the eighth and final test was performed, but the engines shut down after running for one minute. This was caused by pressure in the hydraulic system used for the engines' thrust vector control system dropping below the limits set for the test. However, the limits were conservative – if such an anomaly occurred in launch, the rocket would still fly normally. The static fire test was performed again on March 18, 2021, this time achieving a full-duration eight-minute burn. The core subsequently departed the Stennis Space Center on April 24, 2021, en route to the Kennedy Space Center.

Assembly

SLS/Orion is assembled by stacking its major sub-assemblies atop a mobile launcher platform inside the NASA Vehicle Assembly Building. First, the seven components of each of the two boosters are stacked. The core stage is then stacked and is supported by the boosters. The interstage and upper stage are stacked atop the core, and the Orion spacecraft is then stacked onto the upper stage.
The Interim Cryogenic Propulsion Stage was the first part of the SLS to be delivered to the Kennedy Space Center in July 2017. Three years later, all of the SLS's solid rocket booster segments were shipped by train to the Kennedy Space Center on June 12, 2020, and the SLS launch vehicle stage adapter was delivered by barge one month later on July 29. The assembly of the SLS took place at the Vehicle Assembly Building's High Bay 3, beginning with the placement of the two bottom solid rocket booster segments onto Mobile Launcher-1 on November 23. Assembly of the boosters was temporarily paused due to the core stage Green Run test delays before being resumed on January 7, 2021, and the boosters' stacking was completed by March 2.
The SLS core stage for the mission, CS-1, arrived at the launch site on the Pegasus barge on April 27, 2021, after the successful conclusion of Green Run tests. It was moved to the VAB low bay for refurbishment and stacking preparations on April 29. The stage was then stacked with its boosters on June 12. The stage adapter was stacked on the Core Stage on June 22. The ICPS upper stage was stacked on July 6. Following the completion of umbilical retract testing and integrated modal testing, the Orion stage adapter with ten secondary payloads was stacked atop the upper stage on October 8. This marked the first time a super-heavy-lift vehicle has been stacked inside NASA's VAB since the final Saturn V in 1973.
The Artemis I Orion spacecraft began fueling and pre-launch servicing in the Multi-Payload Processing Facility on January 16, 2021, following a handover to NASA Exploration Ground Systems. On October 20, the Orion spacecraft, encapsulated under the launch abort system and aerodynamic cover, was rolled over to the VAB and stacked atop the SLS rocket, finishing the stacking of the Artemis I vehicle in High Bay 3. During a period of extensive integrated testing and checkouts, one of the four RS-25 engine controllers failed, requiring a replacement and delaying the first rollout of the rocket.

Launch preparations

On March 17, 2022, Artemis I rolled out of High Bay 3 from the Vehicle Assembly Building for the first time to perform a pre-launch wet dress rehearsal. The initial WDR attempt, on April 3, was scrubbed due to a mobile launcher pressurization problem. A second attempt to complete the test was scrubbed on April 4, after problems with supplying gaseous nitrogen to the launch complex, liquid oxygen temperatures, and a vent valve stuck in a closed position.
During preparations for a third attempt, a helium check valve on the ICPS upper stage was kept in a semi-open position by a small piece of rubber originating from one of the mobile launcher's umbilical arms, forcing test conductors to delay fueling the stage until the valve could be replaced in the VAB. The third attempt to finish the test did not include fueling the upper stage. The rocket's liquid oxygen tank started loading successfully. However, during the loading of liquid hydrogen on the core stage, a leak was discovered on the tail service mast umbilical plate, located on the mobile launcher at the base of the rocket, forcing another early end to the test.
NASA rolled the vehicle back to the VAB to repair the hydrogen leak and the ICPS helium check valve while upgrading the nitrogen supply at LC-39B after prolonged outages on the three previous wet dress rehearsals. Artemis I was rolled back to the VAB on April 26. After the repairs and upgrades were complete the Artemis I vehicle rolled out to LC-39B for a second time on June 6 to complete the test.
During the fourth wet dress rehearsal attempt on June 20, the rocket was fully loaded with propellant on both stages. Still, due to a hydrogen leak on the quick-disconnect connection of the tail service mast umbilical, the countdown could not reach the planned T−9.3 seconds mark and was stopped automatically at T−29 seconds. NASA mission managers soon determined they had completed almost all planned test objectives and declared the WDR campaign complete.
On July 2, the Artemis I stack was rolled back to the VAB for final launch preparations and to fix the hydrogen leak on the quick disconnect ahead of a launch targeted in two launch windows: August 29 and September 5. The SLS passed its flight readiness review on August 23, checking out five days before the first launch opportunity.