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16 votes

Is there an anomalous variation of distance between Earth-Moon during a lunar eclipse?

The deviation in the Moon's position due to the reduced light pressure during a lunar eclipse is too small to measure, even with Lunar Laser Ranging (LLR). However, the reduced surface temperature may ...
PM 2Ring's user avatar
  • 2,614
9 votes
Accepted

How do ultra-stable oscillators for spacecraft work?

The material depended on the mission but was usually quartz, and the stability is insane. The development of Ultra-Stable Oscillators (USOs) is ongoing (see here and here). NASA/the ESA have used ...
Michael Stachowsky's user avatar
8 votes
Accepted

Is there an anomalous variation of distance between Earth-Moon during a lunar eclipse?

The LLR experiment data can be downloaded from Paris Observatory Lunar Analysis Center. Comparing this with NASA Lunar Eclipse catalogs shows that the experiment has been active on the same date as a ...
jpa's user avatar
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6 votes
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How soon after "The Eagle" landed did they first attempt to bounce a laser off the Moon? When did it first succeed?

Apollo 11 retro reflector was placed on the Moon on 21 July 1969, the first successful use of the reflector was on August 1 and 3 by the Lick Observatory. Returns were observed on August 20, ...
Uwe's user avatar
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5 votes
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How did LADEE and LDRC measure it's distance from Lunar orbit to Earth to 1 centimeter accuracy using optical communications?

In case of optical communication we don't deal with electromagnetic waves that are collected in an antenna at a ridiculously low power level, are amplified by many orders of magnitude and then need to ...
asdfex's user avatar
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4 votes
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When they shoot lasers at the Moon for ranging, what is the shape of the beam?

Thanks to @astrosnapper's comment I've looked at section 3.2.1. of Murphy et al. 2007 APOLLO: the Apache Point Observatory Lunar Laser-ranging Operation: Instrument Description and First Detections. ...
uhoh's user avatar
  • 149k
3 votes

How soon after "The Eagle" landed did they first attempt to bounce a laser off the Moon? When did it first succeed?

The first use of LIDAR to measure the distance to the moon was in 1962, around seven years before Apollo 11. https://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment#Overview http://adsabs....
Solomon Slow's user avatar
1 vote
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How to get an initial setting of the range gate for a Lunar Laser Ranging using a new Retro Reflector for the first time?

NASA had not only radar data with a precision of about one km. The unified S Band system used for the communication from Earth ground to both the Command Module and the Lunar Module transmitted voice,...
Uwe's user avatar
  • 49k
1 vote

How to get an initial setting of the range gate for a Lunar Laser Ranging using a new Retro Reflector for the first time?

Almost for sure initial ranging was done by radar. As radar became more advanced following WW2, the Moon loomed large in the sky as a giant target, who could resist? In 1946 a modified military radar ...
uhoh's user avatar
  • 149k

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