The Apollo landings from 1969 to 1972
marked a high point in lunar exploration
but Apollo didn't just rock up onto the
moon out of a blue, it took many many
missions by probes and Landers over the
preceding years to establish if we could
send men to the moon and get them back
again. It's quite strange to think that
even by the late 1950s just over ten
years before Neil Armstrong set foot on
the lunar surface,
we knew surprisingly little about the
moon other than what we could observe
from the earth from the hypotheses we
could draw from those observations. We
knew but it had no appreciable
atmosphere or large bodies of water
but we didn't know what the surface was
like and we didn't know what was on the
far, side beside which always faces away
from Earth. After the launch of Sputnik
on October 4th 1957 the Soviets made
several attempts at getting a probe to
the moon. The first three launches in
September, October and December of 1958
all failed but the fourth one in January
1959 did work but they missed the moon
and lunar 1 became the first spacecraft
to escape Earth's gravity and enter
orbit around the Sun. After another launch
failure in June in September 1959, Luna 2
became the first man-made object to
reach the surface of the moon. These
probes would not like the Landers we are
used to now, they were impactors which
meant they were designed to crash into
the surface taking measurements on the
way. During the journey to the moon lunar
2 took measurements approximately once a
minute and these were transmitted back
to earth up until the point of impact.
Luna 2's instruments also helped prove
that the moon had no real magnetic field
and also confirm the existence of the
Van Allen belt which had been discovered
by the first U.S. satellite Explorer 1,
it also released a vapor cloud with
bright orange sodium gas that expanded
up to 400 miles, 650 kilometres
across which could be seen by telescopes
on earth. The US was skeptical of the
Soviets and didn't believe that they had
reached the moon that was until Bernard
Lovell at the Jodrell Bank radio telescope
in England using the Doppler
method proved that the signals did
indeed come from the moon. Once again the
US had been caught out by the Soviets
who used Luna 2 and Sputnik as
propaganda to show the superiority of
the Soviet space program but closest the
US had come to the moon by then was
Pioneer 4 which only gotten into
37,000 miles or 60,000 kilometers.
Luna 2 also proved that the impactor
method work and this would also be used
by the later U.S. Ranger probes.
Then in October 1959 the Soviet did it
again with Luna 3 when it became the
first spacecraft to photograph the far
side of the Moon Luna 3 was also the
first craft not only to use the gravity
assist method to swing it around the
moon and back to the earth but also to
position itself in space using three
axis control with thrusters. This was
essential to control the spin of a craft
and also to position the camera towards
the lunar surface. The photographic film
that was used the images of a moon was
high temperature, radiation hardened film
which ironically had been captured from
American Genetrix balloons which the
U.S. used as high-altitude surveillance
devices in effect they will be original
spies in the sky before high altitude
planes and satellites they would float
over the Soviet Union taking pictures
before being intercepted by the US Air
Force once out of Soviet airspace.
However the Soviets found a way to shoot
them down and capture your equipment
onboard,
although the Soviets didn't know how to
make the film at the time they found a
very good use for it in Luna 3. The
pictures were transferred from a
photographic film in the Luna 3
satellite and transmitted it back to
earth using a method similar to a fax
machine. The images were very basic but
showed that the far side of the Moon was
quite different to the side facing earth.
With Kennedy's announcements of the
Apollo missions and the eight year
deadline to get a man onto the moon by
the end of a decade, it meant that the
U.S. had their work cut out to find
suitable landing sites and working out
if the surface was safe to land on as
there was some speculation by some in NASA that
the lander could sink into the lunar
dust. To get close up images
the lunar surface, the latter part of a
Range program will be used. These
probes would use the impactor method
that the Soviet Luna 2 of pioneered. The
program will be done in three blocks or
phases with the first block of ranges 1
& 2 testing the systems without actually
trying for the moon the following ranges
in blocks 2 & 3 or were aimed at the
moon. But things didn't get off to a good
start with Rangers 1 through 6 failing
through a variety of reasons from launch
failures to missing the moon completely.
At one point it was called the "shoot and
hope program". It wasn't until the block
three missions that they had the first
successes with Rangers 7,8 and 9
working as planned. The block three
Ranger probes had six TV cameras fitted
to them each with different lenses,
fields of views, exposure settings and
scan rates. During the final few seconds
of the flight at a height of around around
600 meters the images captured were a
thousand times better than could be
obtained from earth-based telescopes
with the TV images being transmitted
back to earth live until the probe
impacted the surface. In all 17,100 images
of a lunar surface were sent back to
NASA including the area where Apollo 11
would land some four and a bit years later.
Due to the high failure rate of the
earlier Ranger missions the next stage
which was the send robotic probes was
brought forward to conduct tests to see
if it was possible to land on the moon
and to get a close-up look at the
composition of the lunar soil or
regolith. But once again the Soviets just
pipped the U.S. to the post with the
first soft landing of Luna 9 on the 3rd
of February 1966. Although it wasn't the
first time the Soviets had tried, luna 9
being their 12th attempt at a soft
landing on the moon. Whilst Luna 9 was a
soft landing it was a simple system with
the lander part ejecting up and away
from the main craft just before impact.
The sphere-shaped Lander had an
inflatable balloon to cushion it as it
fell the short distance back to the
surface once he settled the sphere
opened with four petals which orientated
it to the correct position. Luna 9 also
had a TV camera which sent back the
first panoramic images of the surface
these were intercepted by the Jodrell
Bank radio telescope and leaked to the
press in the West before the Soviets
published them. This landing also proved
that a craft would not sink into the
lunar dust as was thought by some. On the
2nd June 1966, four months after the
landing of the Soviet Luna 9, Surveyor 1
the first of the U.S. Landers
touched down on the lunar surface. The
surveyor Landers were built not only to
demonstrate the feasibility of a soft
lunar landing but also to test the
closed-loop control system of the radar
guided descent with throttle-able engines
in the space environment similar to
those that would be used in the later
Apollo Landers. The landing control was
more sophisticated than the Soviet Luna
9 with the final descent being
controlled by a doppler radar and three
vernier thruster engines and it landed
upright on three outstretched legs. The
Surveyors were fitted with TV cameras
and other sensors and some incorporated
an extendable arm which could grab and
test soil samples. In all seven Surveyor
Landers were sent to the moon with five
of them making successful landings.
Apollo 12 later landed about 600 meters
from Surveyor 3 and several other parts
from the Surveyor craft, including the TV
camera were brought back to earth by the
Apollo 12 crew for examination to see
how they survived on the lunar surface
for the past few years. To help select
the Apollo landing sites NASA also used
the Lunar Orbiter program,
it consisted of five missions in 1966
to 67. In all these lunar satellites
photograph 99% of the moon's surface
down to a resolution of 1 meter or 3
feet, returning 2188 high-res images an
882 medium res images
to earth by radio. They also monitored
radiation levels and in micro meteor
impacts with the results confirming that
the design of the Apollo craft would
protect crew for the time that they will
be on the moon. After the missions were
over the lunar orbiters were crashed
into the surface of the moon.
The Soviets continued to send lunar
orbiters with Luna 10, 11, 12, 14. Luna 13
was the only other Lander up until the
Apollo 11 mission. In the culmination of
the moon race and as a last moment
attempt to get a lunar soil sample back
to earth before Apollo 11, the Soviet
Luna 15 which had been launched three
days before Apollo made its descent to
the moon's surface,
just as Aldrin and Armstrong were making
their preparations for Apollo 11 to lift
off and head back to earth. It's not
known exactly what happened but radio
contact was lost with Luna 15 four
minutes after de-orbiting at an altitude
of about 3 kilometers with the most
probable explanation being but it had
crashed into a mountain range during the
descent. Even if it had have landed
successfully and gathered its all
samples Apollo 11 would still have made
it back to earth before Luna 15. On
August the 22nd 1976, almost four years
after the final Apollo 17 mission the
last soviet lunar craft Luna 24 landed
successfully and returned 170 grams or 6
ounces of lunar samples back to earth
and the moon lay silent for a further 37
years before the Chinese Cheng'e 3 lander
and its rover returned to the moon
surface in 2013. So as always thanks for
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