Starship HLS

Starship HLS (Human Landing System) is a lunar lander variant of the Starship spacecraft that is slated to transfer astronauts from a lunar orbit to the surface of the Moon and back. It is being designed and built by SpaceX under the Human Landing System contract to NASA as a critical element of NASA's Artemis program to land a crew of astronauts on the Moon. The mission plan calls for a Super Heavy booster 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 (or more) astronauts will transfer from Orion to HLS, which will then descend to the lunar surface for a stay of approximately seven 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 planned for 2025 to demonstrate a successful landing on the Moon has since been delayed. Following that test, a crewed lunar landing with either Starship HLS or Blue Moon is expected as part of the Artemis IV mission, now scheduled for early 2028. Starship itself has been in privately funded development by SpaceX since the mid-2010s, but development of the HLS variant is being funded under NASA's Human Landing System contracts.

Description

Starship Human Landing System The Starship Human Landing System program includes the development and operational use of several Starship spacecraft variants by SpaceX, including the Starship HLS ship—optimized to operate on and in the vicinity of the Moon—as well as a Starship depot that will store propellant in Earth orbit, and the Starship tanker designed to fly multiple trips to orbit from Earth's surface to transport the necessary fuel and oxygen to the on-orbit depot. The concept of operations for a single lunar human landing mission will involve all three ship variants, as well as docking with another NASA-supplied spacecraft in near-rectilinear halo orbit (NRHO) around the Moon. Unlike the standard Starship spacecraft, both the Starship HLS and Starship depot ships do not re-enter Earth's atmosphere, which allows for the removal of the spacecraft's atmospheric heat shield and flight control surfaces (fins). This reduction in mass allows for a smaller number of Starship tanker launches required for refueling once the spacecraft is in orbit. Like other Starship variants, Starship HLS and Starship depot are equipped with six Raptor engines, which are used during launch and the majority of the landing and ascent phases. When within 100 meters of the lunar surface, the HLS variant is planned to use high‑thrust landing engines located in the mid‑body section of the spacecraft to avoid plume impingement with the lunar regolith, though these engines may not be needed. The landing engines burn gaseous oxygen and methane instead of the liquid oxygen and methane used by the Raptors. Electrical power is supplied by a band of solar panels around the circumference of the vehicle. HLS has the capability to loiter in lunar orbit for 100 days. 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. NASA added this will also allow SpaceX to accelerate vehicle builds to help ensure availability and on-time delivery for mission integration. Both the Starship HLS ship and the Starship depot—propellant depot that will remain in Earth orbit and collect/store the requisite propellant to refill the HLS ship before departure on a trans-lunar trajectory—will use a special purpose insulating tile that will provide micrometeoroid and orbital debris protection as well as insulate the depot from solar and Earth-thermal radiation in order to retain the cryogenic liquid oxygen and liquid methane for long-duration orbital storage. These in-space insulation tiles are different from the ceramic tiles used on Starships that must reenter Earth's atmosphere, such as the tiles on the Starship propellant tankers that will transport fuel/oxidizer cargo to fill the Starship depot.

Cargo variant In April 2024, NASA reported that work was underway on the cargo specific variant of the lander. NASA expects this variant to be ready and in service by Artemis VII. The cargo variant will be referred to by NASA as Human-class Delivery Landers and represent, as of June 2024, the highest capacity landers available to NASA under the current lunar exploration push.

Mission profiles

Propellant transfer test campaign A Starship Propellant Transfer Demonstration remains optimistically scheduled for 2026. On-orbit refueling and storage learnings from LOXSAT may play a major role.

Lunar missions 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 be partially or fully filled by between four to fourteen Starship tanker flights carrying propellant. As such, this spacecraft will be used in conjunction with the Starship booster (called Super Heavy) and two additional Starship spacecraft variants, "tanker" and "propellant depot", that were already planned prior to the NASA HLS contract.

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