Apollo 11's Lunar Module Might Still Be Orbiting The Moon
Apollo 11's Lunar Module Might Still Be Orbiting the Moon
After Neil Armstrong and Buzz Aldrin landed on the Moon 52 years ago today in the Lunar Module (aka Eagle), they rode the ascent stage of the LM back to rendezvous with Michael Collins in the Command Module (aka Columbia). After docking, Eagle was jettisoned and the three astronauts returned to Earth in Columbia. It was presumed that Eagle orbited the Moon until eventually crashing into the surface, but a recent analysis shows that the spacecraft may have entered a stable orbit and is still circling the Moon decades after the end of the mission, a priceless artifact of an historic achievement.
Most spacecraft in lunar orbit suffer from instability in their orbits due to the ‘lumpy’ nature of the lunar gravity which tends to cause the orbits to eventually get so elliptical that they hit the moon.
However, an amateur space fan wanted to narrow down the possible impact location and used orbit modelling software to propagate the orbit forwards in time until it hit the moon. He was surprised to find that it didn’t hit the moon, and remained in a stable orbit for decades, this suggests that the Eagle may still be orbiting the moon over 5 decades after being left there.
The paper detailing the analysis suggests that if Eagle has survived, it should be detectable by radar.
More Posts from Scenesofspace and Others
A vintage NASA-commissioned Rick Guidice painting gives a cutaway view of the inside of a space colony design known as the Stanford torus, a proposed habitat that would house 10,000 to 140,000 permanent residents. The rotating, doughnut-shaped ring could have a diameter of around 2 kilometers, revolving once per minute to give about 1.0g of artificial gravity on the inside of the ring through centripetal force. A massive system of mirrors would provide the sunlight needed for daily activity, agriculture, and so forth. (NASA Ames Research Center)
Actually, Mercury Is Our Closest Planetary Neighbor
If you look at the orbits of the planets adjacent to the Earth’s orbit (Venus & Mars), you’ll see that Venus’s orbit is closest to our own. That is, at its closest approach, Venus gets closer to Earth than any other planet. But what about the average distance?
According to this article in Physics Today by Tom Stockman, Gabriel Monroe, and Samuel Cordner, if you run a simulation and do a proper calculation, you’ll find that Mercury, and not Venus or Mars, is Earth’s closest neighbor on average (and spends more time as Earth’s closest neighbor than any other planet):
Although it feels intuitive that the average distance between every point on two concentric ellipses would be the difference in their radii, in reality that difference determines only the average distance of the ellipses’ closest points. Indeed, when Earth and Venus are at their closest approach, their separation is roughly 0.28 AU – no other planet gets nearer to Earth. But just as often, the two planets are at their most distant, when Venus is on the side of the Sun opposite Earth, 1.72 AU away. We can improve the flawed calculation by averaging the distances of closest and farthest approach (resulting in an average distance of 1 AU between Earth and Venus), but finding the true solution requires a bit more effort.
What the calculation also shows is that Mercury is the closest planetary neighbor to every planet, on average. Also, the authors of the paper don’t explicitly mention this, but the Sun (at 1 AU) is closer on average to the Earth than even Mercury (1.04 AU).
Earth and Moon
To scale, The Last Planet
Sirens of Titan
The South Pole, Jupiter
The Sirens of Titan
February 19, 2010 – The Space Shuttle Endeavour as seen from the ISS after undocking. (NASA)
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