Under the current Administration, NASA has been tasked with returning American astronauts to the Moon as quickly as possible. The Artemis program would launch a crewed mission to our nearest celestial neighbor as soon as 2024, and establish a system for sustainable exploration and habitation by 2028. It’s an extremely aggressive timeline, to put it mildly.
To have any chance of meeting these goals, NASA will have to enlist the help of not only its international partners, but private industry. There simply isn’t enough time for the agency to design, build, and test all of the hardware that will eventually be required for any sort of sustained presence on or around the Moon. By awarding a series of contracts, NASA plans to offload some of the logistical components of the Artemis program to qualified companies and agencies.
For anyone who’s been following the New Space race these last few years, it should come as no surprise to hear that SpaceX has already been awarded one of these lucrative logistics contracts. They’ve been selected as the first commercial provider for cargo deliveries to Gateway, a small space station that NASA intendeds to operate in lunar orbit. Considering SpaceX already has a contract to resupply the International Space Station, they were the ideal candidate to offer similar services for a future lunar outpost.
But that certainly doesn’t mean it will be easy. The so-called “Gateway Logistics Services” contract stipulates that providers must be able to deliver at least 3,400 kilograms (7,500 pounds) of pressurized cargo and 1,000 kilograms (2,200 pounds) of unpressurized cargo to lunar orbit. That’s beyond the capabilities of SpaceX’s Dragon spacecraft, which was only designed to service low Earth orbit.
To complete this new mission, the company is proposing a new vehicle they’re calling the Dragon XL that would ride to orbit on the Falcon Heavy booster. But even for this New Space darling, there’s not a lot of time to design, test, and build a brand-new spacecraft. To get the Dragon XL flying as quickly as possible, SpaceX is going to need to strip the craft down to the bare minimum.
So far we only have a single artist’s rendering of the Dragon XL to go by, but that’s already enough to learn a lot about how SpaceX is approaching this new lunar cargo craft. For one thing, it’s immediately obvious that the design is vastly different from either the original Dragon or its Crew Dragon counterpart. If anything, it looks far closer to Japan’s H-II Transfer Vehicle (HTV) or Northrop Grumman’s Cygnus.
Which of course makes perfect sense. Like the HTV and Cygnus, Dragon XL isn’t designed to fly in the atmosphere. Traditional space capsules get their conical shape from the fact that they’re mounted at the tip of the booster on ascent, and essentially act as the rocket’s nosecone. But Dragon XL will be riding to space inside the cargo fairing of the Falcon Heavy, which means there’s no reason for it to have an aerodynamic shape.
While on the subject of shape, the keen observer may notice that the fuselage for the Dragon XL appears to be the same diameter of the Falcon Heavy second stage that’s releasing it. While it’s nothing more than conjecture at this point, some have theorized that the Dragon XL may in fact be a repurposed Falcon second stage with a propellant tank serving as a pressurized cargo compartment. This would save SpaceX the trouble of building new tooling for Dragon XL, and isn’t without precedent; Skylab was built from the upper stage of the Saturn V rocket.
Keeping it Simple
We can also see that the Dragon XL has no primary rocket engine, meaning the second stage of the Falcon Heavy will need to provide the energy for the trans-lunar injection (TLI) maneuver that will put it on course toward the Moon. Once the TLI burn has been completed, the Dragon XL can be released, and the smaller reaction control system (RCS) thrusters dotting the periphery of the craft would be used to eventually slow the craft down for its rendezvous with Gateway.
That’s not the only major component that’s missing. Since the Dragon XL won’t be landing back on Earth, it doesn’t need a heat shield or parachutes. It’s unclear what will actually happen to this spacecraft once its cargo mission is complete, though the Gateway Logistics Services contract does mention the possibility of returning cargo to Earth orbit. This could mean a stop at the International Space Station for offloading, after which it would presumably be commanded to reenter the Earth’s atmosphere in such a way that it will safely burn up over the ocean.
Deleting the engine, heat shield, and parachutes from the craft obviously saves mass, which in turn increases the amount of usable cargo Dragon XL can bring to Gateway. But more than that, it also greatly reduces the amount of time and effort it will take to design and test the spacecraft. With avionics and an RCS system pulled from the standard Dragon, and a fuselage which may be a spare Falcon upper stage, the majority of craft’s hardware can be pulled from SpaceX’s existing production line.
Ample Trunk Space
The current Dragon is capable of carrying bulky cargo in an unpressurized “trunk” that sits between the capsule and upper stage of the Falcon 9 booster. This is ideal for components which don’t need to be brought inside, such as antenna arrays or experiments that will be exposed to open space.
This capability has been used to bring several large components to the International Space Station, such as the Bigelow Expandable Activity Module (BEAM) and the International Docking Adapter (IDA). It’s only natural that NASA would want the same capability of vehicles applying for a Gateway Logistics Services contract, as having multiple craft capable of transporting station components will expedite the assembly process.
So we know Dragon XL has a “trunk” of its own, but where is it? On a standard Dragon, we’d see an open cargo bay when looking at it from the rear, but in its place appears to be a docking port. From this we can surmise that the Dragon XL arrangement is likely opposite that of the standard Dragon: instead of a docking port in the front and trunk in the rear, the trunk must be located in the front of the spacecraft where it can’t be seen in the promotional render.
Given how large the payload fairing is on the Falcon Heavy, this arrangement could potentially allow for the Dragon XL to carry long objects that actually extend outside of the unpressurized bay. As long as the RCS system can compensate for the change in the center of mass, there’s no reason that this new spacecraft couldn’t act as a “tug” for large sections of Gateway.
So when will Dragon XL fly? As with many of the elements involved in NASA’s return to the Moon, it’s a moving target. According to the current timeline the core module for Gateway is supposed to be launched late in 2022, which would then be followed by several launches carrying additional modules. The first crewed mission to Gateway could theoretically happen by 2024, and at that point, NASA is going to need to start flying resupply missions for consumables.
Assuming NASA sticks to this schedule (which is far from certain), Dragon XL could be called into action by 2025 or so. This gives SpaceX just about as much time as they had to get the original Dragon ready after it was selected for the Commercial Orbital Transportation Services contract in 2006. Given the experience they’ve gained in the intervening years, and the fact that they can literally borrow components from the mainline Dragon, there should be no technical problems standing in the way of having this new vehicle ready to greet the first group of astronauts to call Gateway home.