The mission plan calls for a Starship launch vehicle to launch a Starship HLS into Earth orbit, where it will be refueled by multiple Starship tanker spacecraft before boosting itself into a lunar near-rectilinear halo orbit (NRHO). There, it will rendezvous with a crewed Orion spacecraft that will be launched from Earth by a NASA Space Launch System (SLS) launcher. A crew of two astronauts will transfer from Orion to HLS, which will then descend to the lunar surface for a stay of approximately 7 days, including at least five EVAs. It will then return the crew to Orion in NRHO.
In the third phase of its HLS procurement process NASA awarded SpaceX a contract in April 2021 to develop, produce, and demonstrate Starship HLS. An uncrewed test flight is planned for 2025 to demonstrate a successful landing on the Moon. Following that test, a crewed flight is expected to occur as part of the Artemis 3 mission, no earlier than September 2026.[2] NASA later contracted for an upgraded version of Starship HLS to be used on the Artemis 4 mission.[3]
Design
Starship HLS is a variant of SpaceX's Starship spacecraft optimized to operate on and around the Moon.[4] Unlike the standard Starship Spacecraft, Starship HLS will never re-enter an atmosphere, so it does not have a heat shield or flight control surfaces.[4] This reduces its mass,[4] as well as the number of tanker Starship launches needed for refueling.[4] In contrast to earlier HLS designs that proposed multiple stages, the entire spacecraft functions as both an ascent and descent stage. Like other Starship variants, Starship HLS has six Raptor engines mounted at the tail, which are used during launch and the majority of landing and ascent.[4] When within 100 meters of the lunar surface, the variant will utilize high‑thrust RCS thrusters located mid‑body to avoid plume impingement with the lunar regolith,[5] though these thrusters may not be needed.[6] The thrusters burn gaseous oxygen and methane instead of the liquid oxygen and methane used by the Raptors.[5][7]: 50:30 Electrical power is supplied by a band of solar panels around the circumference of the vehicle.[8][9] HLS has the capability to loiter in lunar orbit for 100 days.[8]
According to NASA, minimizing changes in vehicle configuration and making the design and development of Starship HLS as common as possible will benefit future Starship HLS builds by eliminating the need for additional testing, evaluation, and verification of different vehicle designs.[4] NASA added this will also allow SpaceX to accelerate vehicle builds to help ensure availability and on time delivery for mission integration.[4]
NASA astronauts tested the elevator concept of Starship HLS in December 2023.[10] In February 2024, it was reported that SpaceX had fully tested the Life Support System.[11]
Mission Profile
Prior to the launch of the HLS vehicle from Earth, a Starship configured as a propellant depot would be launched into an Earth orbit and then partially or fully filled by between four and fourteen[b] Starship tanker flights carrying propellant.[12] In November 2023 NASA said that the number of launches required for the mission would be "in the high teens", and that the launches would need to be in "rapid succession", because of the loss of liquid cryogenic propellants due to boiloff.[13] In January 2024, SpaceX vice president of customer operations estimated that the number of launches would be "10-ish", and subject to change.[2] The Starship HLS vehicle would then launch and rendezvous with the already-loaded propellant depot and refuel before transiting from Earth orbit to Lunar orbit.[14]
Artemis 3 Concept of Operations infographic
Once HLS is in a near-rectilinear halo orbit around the moon, an Orion spacecraft would be launched by a Space Launch System rocket and dock with the waiting Starship HLS lander.[14][15]: 4, 5 After two to four of the crew had transferred into the HLS, it would depart and descend to the lunar surface.[15]: 4, 5 After lunar surface operations, Starship HLS will lift-off from the Moon and return to lunar orbit to rendezvous with Orion.[15]: 4, 5 The crew then transfers back to Orion and departs for Earth. Although not confirmed yet, Starship HLS could, in theory, be refueled in orbit to carry more crews and cargo to the surface.[16][17]
History
Starship HLS builds on the SpaceX Starship system by adding a new spacecraft variant called Starship HLS.[16] This spacecraft will be used in conjunction with the Starship booster (called Super Heavy) and two additional Starship spacecraft variants, "tanker" and "depot", that were already planned prior to the HLS contract.[citation needed]
The SpaceXStarship concept was initially conceived in the early 2010s as a spacecraft that would be principally built for the Mars colonization effort that Musk has advocated since 2011,[18] with the first colonists arriving no earlier than the middle of the 2020s.[19]
By 2016, the scope became somewhat broader, enabling landings on planets with and without an atmosphere.[20] Lunar destination flights, however, were not generally emphasized by Musk, and he specifically stated that the Moon was not a necessary step on the path to Mars.[21][22]
By late 2018, SpaceX had specified the primary construction material for Starship to be stainless steel[23] – after approximately a year of building manufacturing pathfinder hardware out of carbon composite materials—and manufacture of the initial test article including pressure vessel construction for the liquid methane and liquid oxygen tanks began in early 2019.[24]
Between July 2019 and July 2021, seven Starship prototype vehicles, each with different vehicle design configurations and varied test objectives, flew a total of eight atmospheric test flights, all launched from the SpaceX South Texas launch site at Boca Chica, Texas.[25] In 2023, flight testing of complete Starship vehicles began.[26] As of January 2024, the first two test flights have ended in failure, with a third test flight scheduled for February 2024.[27]
Initial Artemis 3 contract ("Option A")
Mission profile for Artemis 3, with Orion and Starship HLS.[15]: 4
Starship itself has been in privately funded development by SpaceX since the mid-2010s, but the HLS variant is being developed under NASA's Human Landing System contracts.[28] The initial contracted design work started in May 2020, with selection and funding for full-development occurring in April 2021, when Starship HLS was selected by NASA to land "the first woman and the next man" on the Moon for the Artemis 3 mission.[28]
Selection of the Starship lunar lander
In 2021, NASA entered into a fixed-price contract with SpaceX valued at US$2.89 billion. The contract involves the development and manufacturing of Starship HLS,[28] as well as the execution of two flights: an uncrewed demonstration mission and a crewed lunar landing.[29][14]
Starship HLS is intended to dock in a lunar near-rectilinear halo orbit with either the NASA Orion spacecraft or NASA lunar Gatewayspace station, in order to take on passengers before descending to the lunar surface and return them after ascent.[15]
Starship HLS[a] was first made public when it was initially selected by the NASA in April 2020 for a design study as part of their Artemis program, which aims to land humans on the Moon. SpaceX was one of three teams selected to develop competing lunar lander designs for the Artemis program over a year-long[30] period starting in May 2020.[30] The other landers in consideration were Dynetics HLS, developed by aerospace manufacturer Dynetics, and the Integrated Lander Vehicle, developed by a team led by Blue Origin.[16] NASA intended to later select and fund at most two of these landers to continue to perform initial demonstration flights.[31][17]
On 16 April 2021, NASA selected only Starship HLS for crewed lunar lander development[28] plus two lunar demonstration flights – one uncrewed and one crewed – no earlier than 2024. The contract is valued at US$2.89 billion over a number of years.[29][14] Two NASA Artemis astronauts are to land on the first crewed Starship HLS landing.[32] NASA had previously stated that it preferred to fund development of multiple Human Landing System proposals with dissimilar capabilities; however, "only one design was selected for an initial uncrewed demonstration and the first crewed landing, due to significant budget constraints" for the human landing system program imposed by US Congress.[14] NASA stated that the unselected proposals – Dynetics HLS and Blue Origin Integrated Lander Vehicle – as well as landers from other companies would be eligible for later lunar landing contracts.[14]
On 26 April 2021, Blue Origin and Dynetics separately protested the award to SpaceX at the US Government Accountability Office (GAO).[33] On 30 July 2021, the GAO rejected the protests and found that "NASA did not violate procurement law" in awarding the contract to SpaceX, who bid a much lower cost and more capable human and cargo lunar landing capability for NASA Artemis.[33][34] Soon after GAO rejected the appeal, NASA made the initial $300 million contract payment to SpaceX.[35] The protest action delayed NASA from authorizing work on the contract, and thus delayed the start of work by SpaceX for 95 days.[36] Blue Origin produced infographic posters that highlight the complexity of Starship HLS, for example the fact that on orbit refuelling with cryogenic fuels like that Starship HLS uses has never been demonstrated, while stating that its design uses "proven technology".[37]
On 13 August 2021,[38]Blue Origin filed a lawsuit in the US Court of Federal Claims challenging "NASA's unlawful and improper evaluation of proposals".[36][39] Blue Origin asked the court for an injunction to halt further spending by NASA on the existing contract with SpaceX,[40] and NASA stopped work on the contract on 19 August, after SpaceX had been allowed to work on the NASA-specific parts of Starship HLS for just three weeks since the work had been previously halted in April.[38] Reactions to the lawsuit were negative, with many criticizing Blue Origin for causing unnecessary delays to the Artemis program.[41][42][43]
SpaceX On 4 November, the court granted the federal government's motion to dismiss the case,[44][45][46] and NASA announced that it would resume work with SpaceX as soon as possible.[47]
Artemis 4 contract ("Option B")
On 23 March 2022, NASA announced it would be exercising "option B", an option under the initial SpaceX HLS contract that would allow a second-generation Starship HLS design to conduct a demonstration mission after Artemis 3.[48]
On 15 November 2022, NASA announced the Option B award of US$1.15 billion, and announced that this crewed landing is to occur as part of Artemis 4.[3] The flight will include docking with the Gateway.[3] The Option B HLS will meet NASA's requirements for a "sustainable" HLS. These include the ability to support four crew members and delivering more mass to the surface.[3]
Subsequent contracts
After NASA awarded the Option A contract to SpaceX, congress directed NASA to award a second HLS contract. NASA responded by creating "Appendix P" for a non-SpaceX sustainable HLS. This lander will be used for Artemis 5 as its crewed demonstration flight. In May 2023, Blue Origin was awarded $3.4 billion by NASA to develop their Blue Moon lunar lander.[49][50] NASA intends to allow Starship HLS option B and the Blue Moon lander to compete for Artemis missions after Artemis 5.
Schedule delays
In 2021, the NASA Office of Inspector General warned that the HLS development schedule was unrealistic when compared to other major NASA space flight programs.[15]: 14–15 Stating that space flight programs in the prior 15 years had taken on average 8.5 years from contract award to first operational flight, while the HLS Program was attempting to do so in about half that time.[15]: 14–15 By contrast, NASA OIG noted that Apollo Lunar Lander took approximately 6 years from contract award to its launch on the Apollo 11 mission while receiving "substantially higher levels of funding" adjusted for inflation.[15]: 14 Based on the HLS base period contract award date (May 2020) and the average delay for recent major NASA space flight programs, they estimated that the HLS Program could face up to 3.4 years of delays before operational flights.[15]: 16
In November 2023 the United States Government Accountability Office, in their report to Congress, outlined several challenges moving that Starship HLS is facing in development.[51] As of September 2023 the "HLS program has delayed 8 out of 13 key events by at least 6 months",[51] with 2 events being delayed to 2025, "the year the lander is planned to launch".[51]
The GAO also noted that SpaceX had made limited progress maturing the technologies needed for in-orbit refueling and cryogenic propellant storage, a "critical aspect of SpaceX’s plan for landing astronauts on the moon".[51] In 2023 NASA said to have delayed Starship HLS's critical design review until after SpaceX performs a mission demonstrating in-orbit transfer of cryogenic propellants.[52] The GAO concluded in their report to congress that the Artemis 3 crewed lunar landing is unlikely to occur in 2025, and that a launch date in early 2027 is more likely.[51][53] Although SpaceX's considers the technology behind the Raptor engine to be "relatively mature", the HLS development office identified its development as a "top risk" for the program and its 2025 timeline.[51]
NASA's chief of exploration systems development Jim Free, was quoted as saying that the current December 2025 launch date for Artemis 3 was "really concerning" and would likely slip to 2026.[54] He stated that the Starship HLS's critical design review, required before further funds from the contract can be released to SpaceX, has been delayed until SpaceX completes an in orbital refueling demonstration mission.[54] The head of NASA's moon and Mars exploration strategy said that the delay of Artemis 3 from 2025 to 2026 was partly due to "development challenges" with Starship HLS.[55]
In January 2024, NASA and SpaceX confirmed that the uncrewed Starship HLS lunar landing and ascent test was now expected to take place in 2025, with Artemis III being delayed to no earlier than September 2026.[2]
^ abHLS is an initialism for "Human Landing System"
^In the documentation of SpaceX's HLS bid, a conservative figure of 14 tanker flights is used. Musk has stated that with a tanker payload mass of 150 tons, four to eight tanker flights would be necessary, depending on the payload mass on Starship HLS itself and the intended fuel load (since the mission profile may allow for a less than full tank).
^ abCummings, Nick (11 June 2020). Human Landing System: Putting Boots Back on the Moon. American Astronautical Society. Event occurs at 35:00–36:02. Retrieved 12 June 2020 – via YouTube. ... for the terminal descent of Starship, a few tens of meters before we touch down on the lunar surface, we actually use a high-thrust RCS system, so that we don't impinge on the surface of the Moon with the high-thrust Raptor engines. ... uses the same methane and oxygen propellants as Raptor.
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