Going To The Far Side Of The Moon?

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Mentioned in today’s AIAA Daily Launch, Lockheed Martin is proposing a mission to the far side of the Moon.

Space.com (11/23, David) reports, “Lockheed Martin has begun pitching” a mission to the far side of the moon using its Orion spacecraft, arguing that it “could sharpen skills and technologies needed for a trip to an asteroid – as well as showcase techniques useful for exploring Mars by teleoperation as astronauts orbit the red planet,” two “stated goals under the new direction for NASA outlined by President Obama.” Operating robots on the moon’s surface, astronauts would collect “rock specimens for return to Earth from the moon’s South Pole-Aitken basin” and “deploy a radio telescope array on the farside.” However, “NASA would have to develop a new moon lander” for the robots, “since plans for the Altair human moon lander under the Constellation program were axed.”

Popular Science (11/23, Dillow) reports, “The idea is to park an Orion space capsule at the L2 Lagrange point about 40,000 miles above the moon’s far side, where the combined gravity from the Earth and the moon would allow the spacecraft to essentially hover in one place in sync with the moon.” UPI (11/23) also covers this story.

The idea of parking at the L2 Point, one of the Earth-Moon co-linear Lagrange points, is interesting. Lagrange points are points where the gravitational attraction of, in this case, the Earth and the Moon exactly equals the centripetal force felt by a spacecraft. The L2 point is dynamically unstable, unlike the L4 and L5 points, so small departures from positional equilibrium will grow exponentially. That means the L2 point does have a station-keeping fuel penalty. The distance of the L2 point is about 64,135 km above the Moon’s surface, a greater than 52% distance the orbit of geostationary satellites above the Earth’s surface. Still, that is 64,135 km above the far side of the Moon, a place that none have observed for extended periods of time, remotely or otherwise.

The mission suggested by Lockheed Martin is interesting and would further humankind’s knowledge of our sister body.

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For a full treatment on Lagrange Points, check out Fraser Thomson’s A Study of Lagrange Points.

For those who wish to find these numbers for themselves, the equation for the distance of the L2 point from the Earth-Moon barycenter is given by:

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The equation for the distance of the L2 point from the mean radius of the Moon is given by:

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The numbers used for the above results are:

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2 comments to Going To The Far Side Of The Moon?

  • starman

    Technically credible, but totally driven by the current artificially imposed political limitations. If the goal is robotic exploration of the farside, this is better and more cheaply accomplished with relay satellites in lunar orbit and remote control of rovers from Earth. Time lag you say? Drive slowly, the lag is a few seconds. Good practice for manned missions? Only in the current (specious I believe, billion$ to focus on visiting the few reachable NEO 20 meter rocks when a large world next door and 3 days away awaits exploration and settlement) context of an asteroid mission, or if a follow-on goal was crewed missions to the farside or a base at the south lunar pole. As a corollary, Orion-class vehicles are uncomfortably small tin cans for long-term missions.

    • Yes, this mission is absolutely in response to the distorted political picture we are presently in. Despite the language of Congress’ 2010 NASA Authorization Act, specifically directing that cislunar space, which Congressional language notes includes the surface of the Moon, is the next target for beyond-Earth orbit, NASA does not seem on-board.

      In light of NASA’s near-sightedness, I think LockMart’s proposal is interesting and it would further our knowledge, however less than landing humans would. But more to the point, when either the NASA Administrator or Deputy Administrator testify that a cislunar mission is under consideration but not yet decided, LockMart’s proposal adds pressure to NASA’s leadership to explore the Moon.

      Yes, this mission could be done without sending an Orion spacecraft with 4 astronauts to the L2 Lagrange point. But imagine how captivating it would be to have those astronauts there for a week or two? Imagine how much we would learn not only about the far-side of the Moon, but about cislunar space, which we have not visited since the early 70’s?