This article originally appeared in the Dec. 17, 2018 issue of SpaceNews magazine.
“Sometime in 2028 (The plan is now, as VPOTUS Pence has stated it, ‘To have an American woman and an American man on the Moon by 2024 in an American rocket’ 04APR19), competing for attention alongside a presidential election and the return of the Summer Olympics to Los Angeles, NASA will return humans to the surface of the moon.
“A lunar lander will depart the cluster of modules in an elliptical orbit around the moon, called Gateway, and descend. One stage will take the lander to a low lunar orbit and then separate, after which the descent module will handle the rest of the journey to the lunar surface. A crew of up to four will spend days — perhaps up to two weeks — on the surface before boarding the ascent module, which will take them back to the Gateway.
“At least that’s NASA’s plan for now. A year after President Donald Trump formally directed NASA to return humans to the moon in Space Policy Directive (SPD) 1, the agency has developed the outlines of a plan to carry that out, while emphasizing the language in the policy to do so in a “sustainable” manner and with international and commercial partners. But as the agency describes two of the biggest elements of the plan, the Gateway and a “human-class” lunar lander, it’s still struggling to sell the proposal to its various stakeholders, including its own advisers.
Three stages to the moon
“As NASA started to implement SPD-1, it made use of something it had already proposed: a cislunar habitat called the Deep Space Gateway. Under the agency’s previous “Journey to Mars” plans, the Deep Space Gateway was intended to test out technologies needed for future human deep space missions, including expeditions for Mars proposed for the 2030s. After SPD-1 went into effect, the Deep Space Gateway was renamed the rather unwieldy Lunar Orbiting Platform-Gateway, with a focus on supporting robotic and human exploration of the moon. (Today, NASA simply refers to the facility as the Gateway.)
But while the Gateway could be repurposed to support human exploration of the moon, NASA lacked a means of getting to the surface. Internally, the agency started to study concepts for lunar lander designs, and put into motion efforts to solicit proposals from industry to study how to get astronauts from the Gateway to the surface.
“There’s been no shortage of ideas. For example, Lockheed Martin unveiled in October its concept for a large lunar lander, based on designs it had developed earlier for Mars. Its lunar lander was a single-stage vehicle, capable of getting from the Gateway to the moon and back without discarding stages. The company envisioned a propellant depot in the same orbit as the Gateway — eventually using water obtained from lunar ice deposits converted into liquid hydrogen and oxygen — to refuel the lander.
“The Lockheed concept was big: 62 metric tons when fully fueled, and 22 tons when empty. The vehicle would be 14 meters tall, requiring astronauts in the habitat module at the top of the lander to use what the company called a “simple platform elevator” to get down to the surface.
“NASA, though, is moving in a different direction. Even in a best-case scenario, a single-stage lunar lander would weigh about 50 metric tons fully fueled, noted Jason Crusan, director of NASA’s Advanced Exploration Systems division, in a presentation Dec. 7 to the human exploration and operations committee of the NASA Advisory Council (NAC).
“If you did a single-stage lander, there isn’t a launch vehicle that it can fit on,” he said. Even the future Block 1B version of Space Launch System, he said, can place only about 45 metric tons onto a trajectory to the moon…”