Robotic Probes Scouting Human Gravity Pathways

By Frank Morring, Jr.
Source: Aviation Week & Space Technology

October 15, 2012

Budgets are tight and probably will shrink as the world economy continues whatever tectonic shifting is underway, but the world’s space programs are making their first tentative steps to send humans out of Earth’s gravity well. After extended discussion, the International Space Station partnership has decided to send an astronaut and a cosmonaut to the station for a year to practice the kind of endurance space-travel future crews must undertake to reach an asteroid or cismartian space.

At the 63rd International Astronautical Congress in Naples, Italy, at the beginning of the month, there were indications that serious thought is being given to building a pressurized space habitat that can set off into the Solar System from “EML2,” the second Earth-Moon Lagrangian point (AW&ST Oct. 8, p. 26). NASA human-spaceflight chief William Gerstenmaier, who has a knack for poetry unusual in engineers, says they could follow gravity “rivers” into the unexplored continent beyond Earth orbit. They would start from halo orbit around EML2, riding an Orion capsule linked to a spacecraft so new in concept that it doesn’t really have a name.

“This is potentially our habitation vehicle that is going to be used to go to an asteroid or go to Mars,” Gerstenmaier says, drawing on work underway in Russia, Europe and Japan as well as in his own organization. “We’re just going to place it in a gravity well to learn how it would operate, work on systems development, et cetera, and it may not be the actual [International Space Station] module, but it will be something along those lines. It’s not a destination and it’s not a space station.”

Lagrangian points are appealing because not much delta-v—propulsive change in velocity—is needed to escape them, which means you don’t have to lift as much propellant through Earth’s gravity. Mission planners sending probes to comets and asteroids—and, in the Voyager missions, toward the edge of the Solar System—have combined gravity and low-thrust, high-specific-impulse ion propulsion systems to save weight at liftoff. Now the human explorers are preparing to follow the trails they have blazed.

Read more: Robotic Probes Scouting Human Gravity Pathways — Aviation Week & Space Technology.

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