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.
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:
The equation for the distance of the L2 point from the mean radius of the Moon is given by:
The numbers used for the above results are: