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Bhushan

Jun 17
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Robert Frost
Passed the citizenship test3y
Why can't the US moon landing be easily confirmed with a current picture of the landing site with today's telescopes?
I previously answered a question about whether a telescope in 1969 could have seen the Apollo astronauts on the Moon. Let’s start there.

he best telescope in the world, at the time of the Apollo program, was the Hale Telescope at Mount Palomar. It has a massive 200 inch (5.1 meter) mirror. In a vacuum, the angular resolution that that telescope could theoretically achieve is 0.02 arc seconds. It isn’t in a vacuum, though. Its resolution is limited by the turbulence in the atmosphere. That gives it a peak resolution of about 0.5 arc seconds.

A rule of thumb is that angular size of an object, in radians, is its diameter divided by the distance to it. So, let’s imagine that Buzz Aldrin decided to lie down on the lunar surface and play snow angels. Buzz would have a diameter of about 2 meters and would be about 384,400,000 meters from the Hale Telescope. 2 meters divided by 384,400,000 meters gives an angular size of 0.0000000052 radians. That is equivalent to about 0.001 arc seconds.

Buzz was way too small for the telescope to resolve him. He would have had to have been 500 times bigger. The smallest object that the Hale Telescope could have resolved, on the lunar surface, was about 1 kilometer in diameter.

To the best of my recollection, the largest optical telescope, today (in 2020), is the Large Binocular Telescope (LBT) at Mount Graham in Arizona. That telescope has two 330 inch (8.4 meter) mirrors that work together to gather the same amount of light as a single 464 inch (11.8 meter) mirror and with adaptive optics has the resolution of a 891 inch (22.65 meter) mirror. That’s fricking huge. That enables it to produce images with a resolution of 0.005 arc seconds in visible light. That’s still 5 times too low a resolution to see Buzz doing his snow angels.

At about 240,000 miles (384,400 km) away, an Apollo spacecraft is just too small to resolve as anything other than a pixel reflecting light.

For now, you will have to settle with photographs taken by spacecraft orbiting the Moon. About ten years ago, NASA's Lunar Reconnaissance Orbiter (LRO) got its orbit down to about 13 miles (21 km) above the surface and captured images like this one, showing the Apollo 17 descent stage, the lunar rover vehicle, its tracks and a couple of payloads: