Astronauts could also use the rover to deploy an array of antennas for a radio telescope. Shielded by the moon from Earth-generated radio interference and ionospheric distortion, the far-side telescope could examine the formation of the first stars, 85 million to 250 million years after the Big Bang.
The Burns team envisions a month-long L2 mission, limited in part by concerns about galactic cosmic rays, high-energy particles from outside the solar system. The effects of cosmic rays on human tissue are neither beneficial nor well understood, and radiation is currently a show-stopper for expeditions to Mars. An L2 mission offers opportunities to study the hazards of radiation without risking a lethal dose. “Six months to a year is the limit,” says Lockheed Martin’s Hopkins. “The best way to avoid the effects of radiation is not to stay out in space too long.”
Month-long Gateway missions could be done with Orion alone. Beyond a month, “you need an outpost,” Hopkins said during a recent briefing to a National Research Council panel on technologies for human spaceflight. According to Hopkins, Lockheed and other “major space industry players” from around the world have been meeting to discuss future exploration plans and “talk about what could we do together”—an informal parallel to the official planning exercises at the national space agencies. “L2 outposts and lunar surface mission support popped out as a logical thing to do for a couple of reasons,” Hopkins told the NRC. “One is that because L2 is easy to get to, it’s something that other countries can contribute to, using the assets they already have…. The other reason was that there’s a lot of different things you can do from L2, so you don’t have to agree on why we’re going before you go there.”
If the Gateway outpost were to grow, the Burns group has thought about placing a storage depot there, “something modest, stocked with consumables,” he says. Astronauts would have extra lab space and “more room to maneuver,” he adds. Orion could dock with the depot and have a small, reusable lunar lander berthed there. Burns says the depot would most likely use modules similar to those on the space station.
With this infrastructure or something more elaborate, astronauts, at least in theory, could also use L2 as an orbiting tank farm, mining ice robotically from the lunar poles or taking water extracted from asteroids and converting it to hydrogen and oxygen—the basic components of rocket fuel. NASA has said nothing specific about mining ice, but “as we push out, we’re going to try to take advantage of whatever resources are there,” Gerstenmaier says. “If it’s there, we’re going to figure out a way to do it, it makes sense.”
The L2 Gateway idea has its critics. Some can’t accept a spot in empty space as a legitimate destination. Lunar expert Paul Spudis, a staff scientist for the Lunar and Planetary Institute in Houston (and Air & Space blogger), worries that sending astronauts to L2 will do nothing to build a durable human presence in deep space. He characterizes the mission as a NASA “one-off,” with little value beyond “getting people to L2 and figuring out something for them to do.”
Long an advocate of harvesting lunar water to fuel a transportation system in the Earth-moon neighborhood, Spudis regards NASA’s failure to emphasize that goal as evidence of the agency’s shortsightedness: “If you want to build a space system, you have to learn how to extract resources from the moon,” he says. “There is water ice on the moon and it can be accessed, but the [L2] mission is not long-term. It is configured as a place for Orion to go, not as a place to build a capability.”
Hopkins agrees that L2 is a short-term mission, but doesn’t see that as a negative. “We don’t envision a long-term commitment to infrastructure at L2,” he told the NRC panel. “We would envision a series of missions to do a few things, then move on to the next destination.”
As to whether any of this will actually happen, NASA can’t be sure. In January, when a reporter asked Gerstenmaier where he’d like to send Orion after its initial tests, he smiled and answered like a diplomat: “In terms of my own personal preference, I really don’t have one…. I try to lay out the data and let them [Washington officials] decide.”
All he can say for sure is that next year, a Delta 4 rocket is slated to fire an unmanned Orion 3,600 miles into space, then after two orbits bring it back at 20,000 mph to see if its heat shield can endure 4,000-degree Fahrenheit reentry temperatures. A second unmanned launch of Orion, aboard the Space Launch System, is planned for 2017, and a crewed mission is scheduled for four years after that. Gerstenmaier says the 2021 flight will travel to “the vicinity of the moon,” which includes several possibilities: going into lunar orbit, traveling straight to L2 and returning, or going to L2 and perhaps sliding to L1, on the near side of the moon. (Travel between Lagrange points is easy, requiring little more than a nudge in the right direction.)