Of course there are stars!

Originally posted by ProudBird
reply to post by GaryN

 

Please explain why, during the Apollo missions, there would be any emphasis, at all, on taking pictures of the Sun?

This makes no sense, whatsoever.

From thread: www.abovetopsecret.com...

reply to post by Foxe


Your 'point' about crepuscular rays is well taken....(even if one-off)......but, in the conversation, MY point was that the main emphasis during the Moon missions (Apollo missions) was not the Sun....it was the Moon.

reply to post by ProudBird


Oh my, sorry. I missread your post.

I thought you were saying "please explain why there wouldn't be an emphasis." Rather than "why would there be."

This is what happens when you speed-read posts at work. My sincerest apologies. You are correct, there really is no point to bother with the sun on a lunar mission.

reply to post by Foxe


It's all good!!



( )

Of course there are stars. Ancients have been viewing them even before we had technology to possibly fake it. Some people come up with some ridiculous claims and us really not having a universe or sky is one of them.

Unless were in the matrix of course.

I need some help here. I'm trying to find out what the brightest light levels were for the astronauts on the Lunar surface. I am told the stars could not be seen because the surface was too bright to allow the stars to be seen, but from all the info I have been able to find, the brightest light they worked under was equivalent to the light level 15 minutes after sunset in Texas in July. How bright is that? This document talks about the limitations due to low light levels, but does not mention the times when the surface would have been blindingly bright. Anyone have any further info?
www.lpi.usra.edu...

Originally posted by GaryN
I need some help here. I'm trying to find out what the brightest light levels were for the astronauts on the Lunar surface. I am told the stars could not be seen because the surface was too bright to allow the stars to be seen, but from all the info I have been able to find, the brightest light they worked under was equivalent to the light level 15 minutes after sunset in Texas in July. How bright is that? This document talks about the limitations due to low light levels, but does not mention the times when the surface would have been blindingly bright. Anyone have any further info?
www.lpi.usra.edu...

Perhaps I don't understand your question, but the report you linked was talking about light levels due to Earthshine (light reflect from the Earth and onto the moon) on the Moon's near side during the lunar night, when there is no Sun shining on the near side of the moon. I underlined and emphasized the pertinent text in this excerpt:

ABSTRACT
An investigation into the levels of ambient lighting on the lunar surface indicates
that for most nearside locations, illumination will be adequate throughout most of the
lunar night to conduct extravehicular activities (EVAs) with only minor artificial illumination.
The maximum lighting available during the lunar night from Earthshine will be
similar to the light level on a July evening at approximately 8:00 p.m. in the southern
United States (approximately 15 minutes after sunset). Because of the captured rotation
of the Moon about the Earth, the location of the Earth will remain approximately constant
throughout the lunar night, with consequent constant shadow length and angle.
Variations in the level of Earthshine illumination will be solely a function of Earth phase
angle. Experience during the Apollo Program suggests that EVA activities conducted
during the period around the lunar noon may be difficult due to lack of surface definition
caused by elimination of shadows.

This states that because of the Earthshine, the near side of the moon on a lunar night could sometimes be about as bright as it is on Earth a little after sunset.

If astronauts were to spend extended periods of time on the moon (more than a few days at a time) they may need to contend with the darkness of the lunar night.

reply to post by Soylent Green Is People

Thanks SGIP, but I'm still confused. The diagrams towards the end of that document show the allowed landing window times, starting just after Lunar sunrise, and into early Lunar morning, with a low Sun angle. But this pdf about training for landing at those times shows that they used Neutral Density fitted goggles to simulate the lighting conditions at those times, and that the brightest they allowed for was only equivalent to 2.9% of the light levels at the site of the training and testing site. So, unless I am indeed 'thick', even in the Sun, it was very dim. How would you interpret this?
www.lpi.usra.edu...

reply to post by GaryN


Again, it seems this study involves determining the minimum lighhting levels under which an LEM could be landed. The tests done were to determine whether and what level of darkness (using Earthshine alone) a successful landing should be attempted:

from page 1:

The Apollo lunar excursion module (LEM) is presently scheduled for lunar landing in sunshine conditions. However, several operational constraints presently impose severe penalties on the Apollo mission launch window. The extension of the LEM landing capability to include certain earthshine conditions provides additional latitude where these constraint6 are concerned.

From page 11:

The results of this study indicate that lunar earthshine landing operations should not be attempted at or below 0.009 ft-L. The percentage of unsuccessful approaches (fig. 9) and observer comments (table 111) indicate that LEM operations in brightness levels between 0.009 ft-L and 0.04 ft-L could endanger crew safety. Observer coments indicate that a high level of confidence did not occur until a brightness level of 0.06 ft-L was obtained.

They also go on to say at what altitude the terrain could be discerned under only "Earthshine" lighting (more from page 11):

The acceptable pilot's confidence level appears directly related to the brightness level at which terrain elevation could first be observed. Terrain texture, visible at 0.04 ft-L,was the final factor to cause a change in rate of selection, commitment, and approach times. There were no unsuccessful approaches at or above the brightness level of 0.0325 ft-L. These factors indicate that 0.06 ft-L is definitely an operationally feasible brightness level. It is also apparent that a lower minimum could exist at 0.04 ft-L. Simulators should be used to train the flight crew in initial lunar approaches.

Obviously, when the Moon is being lit by the Sun, the terrain is visible from very high up, such as photos from the apollo missions and satellites. Also, the Apollo photos show us that details can be seen in far-off mountains, so we know the lighting was pretty good in the sunlit areas.. Heck, the Sunlit surface can be seen well from a telescope on Earth. This particular study was done to determine if the terrain can be seen well enough to land in just earthshine.

We all know the moon is bright. A full Moon as seen from Earth 238,000 miles away is bright enough to almost read by. Using logic, I can imagine it would also be bright for an astronaut walking on the surface.

reply to post by Soylent Green Is People

Using logic, I can imagine it would also be bright for an astronaut walking on the surface.

Let's look at some figures. I think I did it right!

10,000–25,000 lux Full daylight (not direct sun)
32,000–130,000 lux Direct sunlight
Conversion gives 930 to 2,323 and 2,973 to 12,077 ft/L respectively.

The 0.06 ft/l they use as a minimum safe level equals 0.65 lux, which is full moon directly overhead at tropical latitudes.Or that is what wiki says anyway.
en.wikipedia.org...
They landed first thing in the Lunar morning, and left while the Sun was still very low in thier sky, the day was still young, so when did it ever get bright?

Moon doesn't have the same kind of morning / evening effect we have. That's because of the angle of the sun entering our athmosphere. No athmosphere = bright as soon as the sun light is direct.

reply to post by PsykoOps

No athmosphere = bright as soon as the sun light is direct.

That seems like a logical conclusion PsykoOps. Plus, there should be all the harsh x-rays, EUV, UV that our atmosphere protects us from.
www.windows2universe.org...
So why did they practice landing in very low light levels, when they knew exactly the window of time they would be landing in? And why were the TV cameras designed to work in very low light levels, and why would they take still cameras with large apertures? And no UV or any other filters at all?
They never measured total solar irradiance on the Lunar surface, and assume it is the same as on Earth as we are at the same distance from the Sun, but without an atmosphere, it should be much higher. No, there is something odd about the lighting on the Moon, and I believe I know what is going on, but unless I can get NASA to take me some pictures from the ISS, I can't prove it.

Feel free to voice your concerns. Also make sure to do your googling and search on ATS too. These kinds of things have popped up and gotten debunked alot.

Originally posted by GaryN
So why did they practice landing in very low light levels, when they knew exactly the window of time they would be landing in?

That answer is in the first paragraph of the study:

The Apollo lunar excursion module (LEM) is presently scheduled for lunar landing in sunshine conditions. However, several operational constraints presently impose severe penalties on the Apollo mission launch window. The extension of the LEM landing capability to include certain earthshine conditions provides additional latitude where these constraints are concerned.

This study was done in 1965, during the early stages of the Apollo program. According to the excerpt above, even though it made more sense to land in sunshine, the launch window for such a landing was very small. They wanted to understand "how big' the maximum launch window could be, and to do so meant studying the possibility of landing in earthshine.

They weren't exactly "practicing" low-light landings. They were doing tests to see what light level (at various shadow-lengths) were adequate for landing.

From the JunoCam, an RGB image, from a device much more like a regular camera. Why no stars?


But in this image, there is the Big Dipper. Go figure.

Cause of exposure? That happens with all cameras.

I'm offering a prize that could be worth millions of dollars to the first person to send me a verifiable image taken from the ISS or any other orbiting vehicle which shows a crescent moon with Earthshine, similar to what we can see from Earth. Good hunting.

reply to post by GaryN


You mean like this? (link)

ETA:

Found another (link)

Originally posted by jra
reply to post by GaryN

 

You mean like this? (link)

ETA:

Found another (link)

edit on 8-9-2012 by jra because: Added more

What will you spend the money on jra

reply to post by wmd_2008


A trip to the Moon!... or just retire early