Starship HLS: the new update shows silent progress.
Written by Magnum and Rex.
So close and yet so far.
53 years since humanity last foot step on the Moon, 53 years of innumerable times asking the same question again and again: “Why don’t we go back?”
Maybe it is a financing issue; maybe there is not a necessity of going back; maybe we just can't go back in a better way?
We have the money to go back, we have a imperative necessity of going back but, what about the vehicle that is supposed to allow us to visit our old friend?
SpaceX, among other corporations and space fans, knows that if we go back, we can’t repeat an Apollo situation where we stayed temporarily, like when a grandson visits his grandmother for a few days and then returns to his home. Mars is there, and the Moon acts like a perfect “gas station and rest area.” Why don't we take an advantage?
But, as many families choose a caravan for a long journey, we need a space caravan. It is my pleasure to present to you the Human Landing System, most commonly known as the HLS.
HLS contract.
Back in 2018, NASA was thinking about a crucial question: how would they land the first Artemis astronauts on the Moon? At the time, they were deep in the development of the SLS rocket and Orion capsule, and there were no concrete plans for a lander made by NASA.
That’s when they came up with the idea of turning to the commercial sector, issuing a request for proposals in May 2019, with a deadline by November of the same year.
5 companies submitted proposals by the deadline, and after some evaluation by NASA, 3 of these were selected for further work and initial design funding in April 2020, ahead of a final decision in February 2021, and the companies were:
Blue Origin, which received $579 million for the design of a 3-vehicle architecture, with each vehicle launched by NG or Centaur and responsible for either transfer, descent, or ascent.
Dynetics, which received $253 million for the design of a single-stage concept to be launched by Vulcan or SLS.
SpaceX, which received only $135 million for the design of a Starship variant to be refueled in orbit and used for all the mission, moving between Gateway, Orion, and the Moon.
These companies worked on their design for about a year, until NASA made a decision on April 16th, 2021: the winner was SpaceX. They had evaluated all 3 companies based on 3 criteria, which were technical, management, and bid price: both SpaceX and Blue Origin were found to be acceptable in the technical section, while Dynetics was considered marginal; however, SpaceX stood out with outstanding management (the other 2 were deemed “very good”) and the lowest bid price: $2.94 billion, against $5.99 billion by BO and $9.08 billion by Dynetics! This bid price would cover the design, development, build, test, evaluation, uncrewed landing, and crewed landing.
SpaceX, once chosen, received a $2.89 billion fixed-price contract, slightly cheaper than they had requested, but not everyone was happy: Blue Origin went against NASA and SpaceX, saying that they had been unfairly and poorly chosen, causing a halt to HLS development; however, the issue was solved by the end of the year, with no consequence for SpaceX.
When SpaceX was selected, Starship was still in its early days, with a minimal launch site for suborbital hops, small bays to contain the rockets, and tents to develop them in… they had just come off a streak of 4 10-km hops with the Starship upper stage to test and prove out the capability of descent and propulsive vertical landing… all these 4 tests had resulted in failures to land or be recovered, with the latest one being 2 weeks before the contract was won. However, 20 days later they finally proved this capability on SN15.
This reason is probably why many doubted SpaceX in the first place or even went against it; however, 4.5 years after this contract was won by SpaceX, Starship is one of the most advanced rockets in the world, with a streak of 11 launches that have proved unmatched capabilities in a short time and with a considerably smaller amount of money than any other company could’ve achieved at this scale.
This reason is probably why nobody should doubt SpaceX… and the next section will show you that.
On the shoulders of the giants.
The Saturn V, the biggest and most powerful rocket of his era, allowed us to reach the Moon and take the first steps on the satellite, but only for a very limited time.
With a height of 110.6 meters, a weight of 2970 tons at launch, and a thrust of 34.5 million newtons, this behemoth served its purpose, but as we plan to stay on the Moon for more than just a few days, we need an even bigger rocket, a new spacecraft, a new titan, and that's when the HLS enters the stage, designed and manufactured by Space Exploration Technologies Corp, commonly known as SpaceX.
The Saturn V that launched the Apollo 11 mission lifting off the Launch complex 39.
The Human Landing System is a variant of his Starship core stage vehicle framework, featuring an impressive height of 52.3 meters, a diameter of 9 meters, and roughly 613 m³. When we compare these numbers with the Apollo Lunar Module, we can imagine how much bigger the HLS is, featuring 7 meters and “only” 4.5 m³. The difference is astonishing; to put it into perspective, only one of Starship's dual airlocks has more than double the interior volume of the entire Apollo lander.
Designed for interplanetary transport, HLS takes advantage of the Starship core framework design, providing up to 100 tons of cargo and a unique method of delivering all kinds of cargo, from astronauts to supplies such as equipment, food, or scientific tools up to payloads needed for a permanent and sustainable presence on the Moon.
The lander also features systems and hardware for the astronauts to use in space and on the Moon's surface, such as legs for a soft landing and landing thrusters located on the base of the nose cone for a precise landing while also preventing large amounts of lunar regolith from damaging the base of the lander, and removing specific hardware that is just not needed, such as the characteristic Starship heat shield and the forward and aft flaps.
The interior of the vehicle is thermally optimized to prevent the boil-off of his propellant in the transit and while it stays on the lunar surface.
The HLS lander awaiting its launch at the Space Launch Complex 37.
HLS interior render.
Starship critical feature is the ability of transfer propellant in orbit allowing the HLS to depart to the Moon, the HLS will receive the propellant from the Depot variant.
The depot is a specifically designed variant that will dock with the HLS and refill it taking advantage from its increased tanks volume and specialized equipment such as docking ports and navigation sensors Dragoneye, with proven capabilites thanks to his extensive use in the Dragon spacecraft thanks to multiple dockings to the International Space Station.
SpaceX has also been flying experimental propellant gauging sensors on every recent Starship flight test which use radio frequency measurements to accurately measure propellant levels while in microgravity.
Depot variant render on the SpaceX website.
The depot variant is designed not only to transfer propellant but also to receive it; this is when the Tanker variant emerges.
The tanker is a Starship variant designed to storage propellant and deliver it to the depots or landers; it also mimics the same design as the core Starship vehicle and features docking probes allowing it to link up with other Starships in space.
Tanker variant render on the SpaceX website.
Milestones reached.
As you know by now, SpaceX published a major update on the progress of HLS, likely in response to the latest doubts by the acting administrator of NASA, Sean Duffy, about SpaceX’s capabilities to deliver in time for a mid-2027 launch of Artemis 3. Duffy even went as far as reopening the HLS contract, meaning new companies could apply and even win over SpaceX, which wasn’t obviously pleased with his decision; but instead of answering with lawsuits and rage, they published all the milestones they completed so far, showing how much they’ve already accomplished behind the scenes:
SpaceX stated that they’ve completed 49 HLS milestones, which include:
- Testing of the lunar environmental control, life support, and thermal control systems in the nosecone sitting in the Rocket Garden. Here, they tested the systems’ ability to inject oxygen and nitrogen, manage air distribution and quality, and control humidity and temperature, as well as the acoustics.
- Qualification of the androgynous docking adapter between Starship and Orion, which is based on the flight-proven docking system on Dragon 2.
- Testing of the full-scale landing legs by dropping them onto simulated lunar regolith. Some theories are circulating that this test was conducted in the tarp-covered mysterious structure at McGregor.
- Raptor testing at McGregor, including a throttle test simulating a lunar descent burn and cold start demonstrations to simulate the cold conditions an engine would experience after a prolonged stay in space.
- Testing of MMOD (MicroMeteoroid and Orbital Debris) shielding, insulation, and window panels to identify the perfect combination of materials to protect Starship and its crew.
- Software testing, including landing software, sensors, and radars that will guide Starship down to a precise spot on the Moon, and a whole architecture review to define major software functions. Starship HLS software is based on the DragonEye-2 software from Dragon 2.
- Integrated lunar mission operations plan review between NASA and SpaceX to develop procedures and a highly defined mission plan.
- Depot power module demonstration, testing electrical power generation and distribution systems that will be used on the propellant depot.
- Communication testing with radio frequency communication between both ground and flight systems.
- Elevator and airlock demonstration with NASA and Axiom, testing how the elevator will be used to carry crew and cargo down to the lunar surface and back up to the airlock.
- Medical system demonstration, ensuring the presence of medical systems and telemedicine capability on Starship.
- HITL (Hardware In The Loop) testing for the upcoming propellant transfer flight test.
List of the milestones archieved.
Whats next?
SpaceX has a road map of milestones tied to HLS that need to be met, such as a long-duration mission launched from Starbase, Texas, destined to spend an extended time in orbit gathering data on the propulsion side of the ship and the boil-off phenomenon and validating hardware. This ship will act as the target; the chaser will be a second Starship launched to rendezvous with the first to demonstrate the ship-to-ship propellant transfer demo.
Both of these tests are targeted to take place in 2026; after these, HLS will perform an uncrewed landing demonstration to ensure and validate all the hardware needed for a crewed landing in Artemis 3.
in-space propellant transfer renders.
Moonbase Alpha: SpaceX’s Moon plans.
HLS is just the start of SpaceX’s Moon exploration plans. As of now, they will conduct a minimum of 3 missions to the Moon, which include the uncrewed landing demo followed by the 2 crewed landings during Artemis 3 and 4. But SpaceX’s Moon plans are much bigger, as the plan is to create Moonbase Alpha: a true base on the Moon.
While SpaceX hasn’t said much about it, renders indicate the base is supposed to have the capability of landing and hosting multiple Starship HLS, along with lunar regolith habitats, crewed and uncrewed rovers, and the capacity of carrying tens of people on each vehicle.
So yeah, if you thought that SpaceX only had Mars ambitions, now you know they have eyes for the Moon as well.
SpaceX HLS on the Moon.
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