"Did we really land on the Moon?" - Part 2 - Dr Martin Hendry - Science Week 2010 lecture


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Transcript:
Science Week 2010 Lecture Series from Discover Science & Engineering, Ireland 2010
"Did we really land on the Moon?" Dr Martin Hendry, School of Physics and Astronomy,
University of Glasgow.
Part 2 of 3
If you want to see the Moon and the stars at the same time, what you need is a long
exposure photograph. [Slide changes] Here's one that I and my colleagues took down in
Cornwall, in the south west of the UK, and you can see that the Moon is elongated in
shape that's because we needed to take a long exposure in order to bring out the detail
of the stars which appear as little trails because during the photographic exposure the
Earth is actually tuned a little bit.
As a consequence both the Moon and indeed the street lights of Penzance are horribly
over exposed. So the photographs taken by the astronauts, I would allege don't show
any stars for the very simple reason that they're short exposure photos and the background
light from the Moon surface itself is illuminating the scene far more greatly than the stars
themselves.
Although curiously if you actually go and have a look at the NASA archives where many
of these images are stored, [Slide changes] what you find is that downloading the images,
increasing the contrast and inverting the colours, maybe it's a little hard to see,
but does reveal some little black dots in the photograph. Now for all I know they could
be defects in the photographic film, but they might be stars. I guess my main point is that
these are simple experiments and investigations that people can carry out for them self. But
I think it's an interesting topic, the absence of stars, to really get you thinking about
how photographs work and how the physics of photography influences this question.
Now time is short so as I say there's many of these topics that I greatly encourage you
to go away and have a look at for yourself, but I am going to jump ahead a little bit
now and I am going to talk to you about dust problems.
I want to talk about this one because there is some very good science here and some quite
fun experiments that we enjoyed putting together and many of the schools with whom I have worked
in the UK, they have done some wonderful project work on this topic for themselves.
Let's have a listen to what the TV show says first
[Video commences]
Voiceover on video: In the end there is one set of evidence that is irrefutable and that
is that there are footprints, boot prints still on the lunar surface.
Second voice on video: But conspiracy theorists say that the footprints themselves are suspicious.
Astronaut on video: There's what appears to be very fine grains as you get close to it,
it's almost like a powder.
Bill Kaysing on video: To have a powerful rocket engine blast the surface of the Moon,
blasting away all of the dust and then find footprints surrounding the lunar lander that
to me would be impossibility.
Voiceover on video: Photo after photo reveals that the lunar surface surrounding the lander
is covered with footprints.
[Video ends]
Dr Martin Hendry: Bill Kaysing is having us believe that the powerful rocket engine on
the Apollo 11 in the later missions would have blown away so much dust that you couldn't
have any footprints and moreover that you should have had a major blast crater underneath
the lunar module.
Well to try and address that one lets first of all have a brief look at the final descent
of Apollo 11. Long before the time of many people in the audience, I was only about 18
months old myself. [Video commences in the background] But this is where Neil Armstrong
and Buzz Aldrin are piloting the Eagle, Apollo 11 lunar module down onto the Moon surface.
And the main thing to note here is that they are not really descending very rapidly. They
are going mainly sideways in fact, and the reason for that was very important. There
was real concern that they might end up landing on a sizeable boulder which would tip over
the lunar module and end the mission very fast.
So they were in the business of trying to slow their descent as best they could in order
to ensure a safe landing. So this notion of a powerful rocket engine decelerating [Video
ends and slide appears] very quickly, as was alleged by Bill Kaysing, doesn't really seem
to add up. And again don't take my word for it. If you think about the effect of what
a rocket engine would be, if it was indeed blasting away at the Moon's surface, then
conspiracy theorists would claim that that would make this large crater as well as blowing
away all of the dust around.
But here is what an engineer from NASA has to say about it.
[Video commences]
Engineer from NASA: The fact that there is no blast crater under the lander is one of
the most conclusive pieces of evidence that I find supporting the hoax
Voiceover on film: In fact, no sign of a blast crater is visible for any of the six lunar
landings. But LEM specialist Paul Fjeld says he can explain whey the lunar module left
no crater when landing on the Moon.
Paul Fjeld on video: The amount of thrust that you need coming out of the bottom of
the descent engine is about 1,500 to 2,000 pounds of thrust and all that does is just
push dust away. There's no burning or anything like that.
[Video ends]
Dr Martin Hendry: He is saying that there is no burning or anything like that. The crucial
thing here is that Paul Fjeld, one of the NASA engineers, actually quotes some numbers.
Science is all about being quantitative; it's all about measuring things. It's about working
things out as best you can rather than just making wild guesses or rather speculative
answers.
We thought we would explore that little bit. In setting up an experiment, again it was
a bit difficult to replicate the exact conditions you would have had on the Moon, but what we
wanted to do was to explore just what the effect of the engine of the lunar module would
have been on the dust on the Moon's surface.
First of all notice that there are some photos that indicate a small crater. A small amount
of dust does indeed appear to have been disturbed immediately below the engine. We'll come back
to that point in a moment.
But first of all let me show you a little experiment that we had great fun doing this.
We got to build our own lunar landscape first of all. [Video commences]. Then populate it
with some dust in the form of some flour, then along comes our lunar module in a moment.
What we are doing is blowing some compressed air through the lunar module, aiming it directly
downwards, to try and simulate the effect of the engine disturbing the dust immediately
below the lunar module but not anywhere else.
Then in a few seconds you will see our brave astronaut coming along and sure enough there
is still plenty of dust around for him to make footprints in our lunar surface. Now
I know it's not exactly very rigorous science but nonetheless what we are trying to explore
here [Video ends] is how the absence of an atmosphere on the Moon would change things
compared with how dust would behave on Earth.
To look further at that, we'll not just think about the effect of the lunar module landing
but also the lunar rover, the Moon buggy, which the Apollo astronauts used a bit later
on. And before we get to the Moon buggy, let's have a watch of a brief video clip of a rally
car racing down here on Earth.
[Video commences]
[Video ends]
Dr Martin Hendry: What we see going on there is that as the rally car races along the dusty
road the wheels are turning very fast. Those wheels are disturbing dust on the road, which
in turn can then transfer some of the energy of the car moving along, to more dust. That
creates this billowing cloud of dust. But there is a very crucial element that makes
that possible which is the air molecules in-between the dust particles.
Now this is a phenomenon which you can study in a variety of different ways, no less a
person than Albert Einstein actually did some of the theory related to this about a hundred
years ago. And the phenomenon is called Brownian motion. The random motion of the dust particles
which bump into the air molecules, which in turn bump into more dust particles. Before
you know it you've got a billowing cloud of dust. Again I could have showed you similar
footage of say a helicopter landing or indeed a spacecraft taking off from the Earth. You
get a billowing cloud of gas and dust produced by such a dramatic event.
What about on the Moon? Well lets have a look at what the lunar rover does on the Moon [video
commences] first of all notice there is no sound this time. But look carefully at what
the dust is doing. The dust is not producing this large billowing cloud, instead it is
indeed being thrown up by the wheels, but it spreads out a little but not nearly so
much. In fact what the dust does is forms a particular form of mathematical curve called
a parabola. Now that parabola is the shape of curve that say if I take a coin and throw
it over here [throws coin] the coin will go up and then it will go down. It will follow
a curving arch. On Earth dust doesn't do that, because dust floats, because of air resistance.
On the Moon, dust will follow a curved path just like a coin or a rock or something much
heavier. In fact it won't follow exactly the same path as it would on Earth because the
gravity is lower. But crucially if you think of the lunar module landing or the lunar rover
chugging along on the Moon's surface. In both cases you don't have the air to help create
the billowing cloud of dust that we saw with the rally car. The presence of the footprints
which the Apollo astronauts made would seem quite compatible with an absence of the atmosphere
on the Moon.
Moreover, as I said, you can measure the curving arch of the dust thrown up by the lunar module
and based on the curvature you can work out what the gravity is. That's a really quite
challenging little experiment but something you might want to have a go at yourself.
There is video capture software which I guess most schools would have access to which would
allow you to analyse the motion of the dust on the footage. We've had a look at that and
sure enough it gives you an answer consistent with the lower gravity of the Moon. And I
will come back in the final few minutes to this idea about the low gravity on the Moon
as well.
[Video stops in background and moves to new slide] So the last of the main topics I want
to briefly look at. I am sorry I don't have time to go through all ten. As I said the
resources are all there on the web as we'll see at the end and I encourage you to go away
and have a think about these for yourself.
Let's just have a brief look at radiation before we wrap up.
[Video commences]
Bill Kaysing on video: Any human being travelling through the Van Allen belt would have been
rendered either extremely ill or actually killed by the radiation within a short time
thereafter.
Voiceover on film: Other than the Apollo missions no other manned space flight has attempted
to pass through this deadly radiation
[Video ends and slide appears]
Dr Martin Hendry: What we have to be reminded of is that the radiation damage both to life
and to buildings and so on caused by those explosions was rather different from the main
radiation threat which the Apollo astronauts would have faced. The main radiation threat
which the Apollo astronauts had to deal with was charged particles coming from the sun,
what we call the solar wind. Now these are trapped by the radiation belts around the
Earth and that's good news for us because it stops them reaching the ground and harming
us. In fact those charged particles are basically protons; they are the nuclei of hydrogen atoms
because the sun is mainly made of hydrogen.
Now radiation comes in a variety of forms. You have got protons, like the solar wind.
You've got the nuclei of helium atoms which are known as alpha particles. And then you
also have another form or radiation called beta particles, which are like the positive
counterpart of the electron, positron. In addition you have ionising radiation which
is in the form of light but light of very high energies - ultraviolet, x-rays and gamma
rays.
[Slide changes]Gamma rays in particular are extremely harmful and moreover if you wanted
to shield yourself from gamma rays, what you really need is several inches of concrete
in order to do it. Even x-rays you need a substantial thickness of lead. That's why
if you go and get an x-ray in the hospital the radiologist will stand behind a lead screen
to shield his or herself from the x-ray exposure. But if you want to shield yourself from protons,
really all you need is a few centimetres of wood.
Now I do concede that building the Apollo lunar module out of wood would not have been
NASA's smartest move but a few metres of aluminium will do just as well. And again a demonstration
I normally take to schools in the UK is a source of, well in fact it's usually alpha
particle radiation but protons are broadly similar, and a Geiger counter - take some
aluminium foil and demonstrates that the foil will shut off most of the signal.
The key message is that radiation comes in these different forms. The sun does produce
gamma rays but in most copious amounts at the time of a major solar flare event. Fortunately
there weren't any such major solar flares during the Apollo missions. If there had been
then the astronauts could have indeed been in big trouble. The proton threat from the
solar wind is much more manageable threat. The aluminium shell of the space craft was
more than adequate. Moreover they pass through these Van Allen belts, fairly quickly, in
just a few hours on the way to the Moon.
[Slide changes] Ironically the claim by the programme that no one has been beyond the
Van Allen belts since, actually there's a much greater threat if you are on board the
international space station. It's still perfectly reasonable. There is no evidence that the
astronauts on board the space station have suffered any long-term harm. But because they
are continually being exposed day after day to small amounts of ionising radiation as
they pass through the Van Allen belts, then it's a threat that has to be taken seriously.
The way the body reacts to radiation exposure is that if it's not too energetic, not too
ionising and doesn't last for long then the body will recover just fine.
[Slide changes] So that really brings me to a few concluding remarks again there is plenty
more to discuss on the other topics I have not had time to cover, but I encourage you
to go away and have a look at them for yourself.
Let me just wrap up with a few remarks about the counter arguments people have often come
along with. They have sometimes said couldn't we use the Hubble space telescope to look
at the Moon. Wouldn't that show us images of the lunar landing sites and that would
settle it one way or another. The Hubble telescope is probably still pound for pound the best
telescope we have up there in space. There are bigger telescopes on the ground but because
they have to look through the atmosphere, they don't give us as sharp a view of distant
objects in the universe.
The trouble is though the Hubble telescope just a few hundred kilometres above the Earth.
The Moon is 400,000 kilometres in the other direction. So we've grown accustomed over
the years to seeing images like this one [Slide appears] that's of Sydney harbour or this
is Frankfurt airport. [Slide changes] The kind of images you see in Google Earth for
example. Many taken by aircraft but some taken by satellites.
If you use the Hubble telescope to look at the Moon, because it's so much further away
in the other direction, even the Hubble telescope doesn't have sufficient resolution to reveal
the Apollo landing sites. [Slide changes] This is an image of the Moon taken by Hubble
and it shows a large crater called Copernicus which is about 100 kilometres across, so each
pixel of the image is still about 17 metres across, way bigger than the Apollo lunar landing
site.
However in the last few years there has been a satellite actually orbiting the Moon itself
called the Lunar Reconnaissance Orbiter. It sent back some images like this one which
NASA released in July of 2009 to mark the 40th anniversary of the first lunar landings.
[Slide changes] According to NASA, that is Apollo 11. [Slide change] According to NASA
for Apollo 14 you get an even better view. You can see the lunar module, footpaths of
the astronauts, some of the instruments left behind. Now of course again the conspiracy
theorists will probably just say that these were faked as well but I am prepared to give
NASA the credit that what we are actually seeing is the lunar landing sites.
[Slide changes] Here's another couple of ways that I would regard as having proof that the
Moon landings really happened. Lots of video footage was tracked by a network of satellite
dishes radio telescopes on the Earth's surface. There was a movie a few years ago called The
Dish, [Slide change] about one such radio telescope in Australia.
The movie fantasised the story a little bit but I know some of the astronomers who worked
there in Australia at the time and as far as I know their story checks out. They say
that basically they were getting signals from the Moon; they can't say that there were really
astronauts up there, but there was something up there beaming those signals back.
[Slide changes] Then there's all the Moon rocks that were brought back, which my geology
colleagues tell me if you look at them under a microscope they show unique signatures of
billions of years of exposure to an airless environment with lower gravity, no water,
but crucially also no air to erode away the surface of the rock in a smooth manner the
way that it happens on Earth.
Then there's a variety of experiments that were carried out to measure the distance to
the Moon by bouncing a laser beam off the Moon's surface. [Slide changes] In fact one
such experiment featured in my very first image, because the instrument that Buzz Aldrin
is carrying, is this little thing left behind, it's a laser reflector to ensure that the
laser beam bounces straight back. Without that being there the beam would be too diffuse
by the time it reflects off the Moon for you to measure anything. There's hundreds of such
experiments been carried out including by scientists in China. Are they in on the conspiracy
as well? Again a question that I should put to the conspiracy theorists.
[Slide changes] Then finally back to this notion of dust and floating dust on the Moon's
surface or in particular the fact that dust doesn't float on the Moon. Let me just wrap
things up by showing you a brief video clip taken by Apollo 15 astronaut David Scott and
I'll let him explain what is going on.
[Video commences]
David Scott on video: On my left hand I have a feather, in my right hand a hammer. I guess
one of the reasons that we got here today was because of a gentleman named Galileo a
long time ago, who made a rather significant discovery about falling objects and gravity
fields. I'll drop the two of them here and hopefully they're going to hit the ground
at the same time. [Drops hammer and feather] How bout that? That proves that Mr Galileo
was correct in his findings.
[Video ends]
Dr Martin Hendry: Not only do you see the hammer and feather fall at the same time,
the same rate, there is no air resistance to make the feather float. But they do take
longer to hit the ground then they would on Earth. If you measure the acceleration, you
get one sixth that of Earth gravity. Now we had a student work with us on this to do some
analysis of that video footage. Maybe he was just trying to wind us up, but he said what
would happen if he did the measurements he and discovered that he got ten metres per
second per second which is the gravity of Earth. So we teased him back and said that's
the point where the men in the dark suits and the dark glasses would come through the
door. I am pleased to say that that is not what he measured and not what's about to happen
to all of you today.
But to emphasise the fact that there is a lot of stuff out there and it's hard to know
what to believe and what not to believe. Let me end with this short video clip, which will
give you food for thought as you take away this question of did we really land on the
Moon?
[Video commences]
Voiceover on video: That's one small step for man, one giant leap [Light comes crashing
down] I guess you want to do it again. OK, Sorry
[Video ends]
Dr Martin Hendry: I am fairly sure that ones a fake though. Let me leave you with a web
address where you can download all of this. I've also got that as a tiny url which is
a bit easier to digest and indeed we have a dedicated email address if anyone's got
any questions about Moon landing conspiracy theories or you come across some evidence
that you think maybe backs them up and you want to see what I think. Then by all means
get in touch.
[Shows web address http://www.astro.gla.ac.uk/users/martin/moonhoax/ and email address moon@astro.gl.ac.uk]
Thanks Very much and I hope you have enjoyed my talk
[Applause]