Gateway versus tollbooth
by Jeff Foust
|“The Gateway will also be the jumping-off point for missions further into the solar system,” NASA’s Moore said.|
In presentations at the International Space Development Conference recently in Los Angeles, NASA officials sometimes stumbled over the name, one calling it the “Lunar Orbiting Platform-Gateway” and another the “Lunar Outpost, uh, Platform, Platform-Gateway.” On some slides, it still showed up under its former, and perhaps more eloquent, moniker, the Deep Space Gateway. It’s little wonder, then, that it usually was called just the Gateway throughout the conference.
Whatever you call it, NASA has billed it as the next big step in human spaceflight. “We’re looking at four different tracks on how we could use the Gateway,” said Christopher Moore of NASA’s Advanced Exploration Systems Division during a conference talk May 26. That included, he said, scientific applications, technology demonstrations, and unspecified commercial and international applications.
“The Gateway will also be the jumping-off point for missions further into the solar system,” he added. “It will help us develop some of the capabilities we need for those missions.”
NASA has played down the size of the Gateway in its past discussions of the outpost: a Power and Propulsion Element (PPE), a habitat module, a logistics module, and an airlock. NASA is already ramping up planning for the first element, the PPE: in a procurement update posted last week, NASA said it planned to issue a draft solicitation for the module in June or July, a schedule that would result in final proposals being submitted to NASA in November.
“We have a head start on the Power and Propulsion Element based on work we did with the previous mission, the Asteroid Redirect Mission,” said Ron Ticker, deputy director of the PPE program at NASA Headquarters, in a May 25 presentation at the conference. Like the now-cancelled ARM, the PPE will us electric propulsion to maneuver, while also providing power for the other modules as well as communications services.
NASA plans to procure the PPE through a public-private partnership for a commercial launch in 2022. “NASA intends to release a BAA [Broad Agency Announcement] to award one or more contracts for a NASA-industry partnership for development and demonstration of a PPE,” he said, leaving open the possibility of NASA procuring more than one PPE.
Indeed, NASA officials at the conference had visions of a Gateway that could be significantly larger than the minimalistic concept the agency has been publicly discussing. “We’re looking ahead as to how this initial configuration could evolve,” Moore said, showing an illustration of an expanded Gateway. “This concept shows two habitat elements, one supplied by an international partner and the other the US, and it would include logistics modules, robotic arm, and also have robotic or human landers that would depart from the Gateway and fly to the lunar surface and then return for refueling and reuse.”
“There will be two habitats,” said Paul McConnaughey, associate director, technical, at NASA’s Marshall Space Flight Center, in a separate conference talk May 25. “There will be an international habitat. There will be a US/commercial habitat. There will be a cargo/logistics module, a docking module, a robotic arm.”
But as NASA seeks to expand the Gateway, others at the conference made it clear they would rather not see it built at all. “What we’re going with right now is the worst of all possible plans,” said Robert Zubrin.
Zubrin, best known for his advocacy of human missions to Mars, championed in an ISDC presentation an alternative architecture called Moon Direct. Like his Mars Direct concept from a quarter-century ago, it seeks to make use of in situ resources to lower the mass requirements, and thus cost, of getting humans to the lunar surface. “If you’re going to the Moon,” he said, “take advantage of what’s on the Moon, and design your architecture around that.”
|“If you’re going to the Moon,” Zubrin said, “take advantage of what’s on the Moon, and design your architecture around that.”|
Those lunar resources, not surprisingly, are lunar ice deposits, with that water converted into liquid hydrogen and liquid oxygen propellants. It also makes use of what Zubrin calls a Lunar Exploration Vehicle (LEV), a vehicle that can use those propellants to make long hops across the lunar surface and even achieve orbit or escape velocity.
“The Moon is big, its terrain is rough; there’s no roads, there’s no railways, there’s no rivers,” he said. “If you’re going to travel any distance on the Moon, you’re going to have to fly.”
In the first phase of the plan, large boosters—Zubrin baselines the use of SpaceX’s Falcon Heavy, which can carry at least eight tons to the lunar surface—send elements of the initial base, including equipment needed to extract water ice. As few as two such missions, he said, could deploy the basic elements of a lunar base.
In the second phase, a Falcon Heavy launches cargo lander, including a fully-fueled LEV, into low Earth orbit, where it rendezvouses with a Crew Dragon spacecraft launched on a Falcon 9. Astronauts transfer from the Dragon to the LEV for the trip to the Moon to finish outfitting the base. At the end of their stay, the crew boards the LEV for a trip back to LEO to dock with a Crew Dragon craft for the rest of the trip home.
Once the base is running, and producing propellants, all that is needed for future missions is a single Falcon 9/Crew Dragon launch of crews, who would travel to and from the Moon in the LEV. That LEV could be refueled on the Moon either for excursions elsewhere on the lunar surface or the trip back to LEO.
Zubrin argued that Moon Direct, by making use of lunar propellants and simplified systems, could achieve a lunar base with one-fifth the mass launched into LEO as a similar approach that required the use of the Gateway. That base, he said, could be sustained by flying just a few missions a year (assuming crews spend at least four months at the base) and at a cost he estimated to be as low as $400 million a year.
Whether anyone in power, in the administration or Congress, will pay attention to Zubrin and his Moon Direct alternative remains to be seen. He did, though, offer his own suggestion for the name of the Lunar Orbital Platform-Gateway when noting that mission concepts that had to use it suffered reduced performance compared to those that go directly to the surface. He called it the “lunar orbital tollbooth.”
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