The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

including views of nearby rocks and of the horizon
1.4 km away.
Lunas 10 to 12 and 14
Lunar orbiter missions that returned photographs
and took measurements of infrared, X-ray, and
gamma emission from the Moon (to determine chemical
composition), on-orbit radiation conditions,
micrometeorite collisions, and variations in the lunar
gravitational field caused by mass concentrations, or
“mascons.” They typically functioned for several
months.
Luna 13
A soft-lander, similar to Luna 9, that arrived on the
Ocean of Storms on Christmas Eve, 1966. In addition
to a camera that sent back photographic panoramas
under different lighting conditions, Luna 13 was
equipped with two spring-loaded arms. One of these
was used to determine the density of the surface by
measuring the effect of the landing capsule’s impact
on the soil—a piece of information crucial to the
designers of a manned mission. The other arm
probed the chemical composition of the surface.
Lunas 15, 16, 18, 20, 23, and 24
Automated lunar sample-return craft, three of which
were successful. Luna 15 entered lunar orbit two
days ahead of Apollo 11 and, on the day Apollo 11
began circling the Moon, lowered its own orbit to 9
by 203 km. At this point there was concern in the
United States that the Russian probe would somehow
interfere with the manned mission. However,
assurances were quickly given by the Soviets that
this would not be the case. On July 20, just hours
before Apollo 11’s scheduled landing, Luna 15 carried
out another maneuver to put it in a 16-by-110km
orbit. The next day, while Armstrong and Aldrin
were on the surface, the little probe made its last
retro-rocket burn and began to descend to what was
supposed to be a soft landing. Unfortunately, it
made contact instead at 480 km/hr in the Sea of
Crises. Almost twenty years would pass before the
Soviets officially admitted that Luna 15 was a failed
sample-return attempt. Whether it could have
beaten Apollo 11 if all had gone well is unclear.
Even if its landing attempt had succeeded, it would
not have returned to Earth until the day after Apollo
11 splashed down. On the other hand, Luna 15 did
spend one day longer in lunar orbit than was typical
of later sample missions. If the probe had made it
down in three days instead of four, or if Apollo 11
had failed to return samples, the Soviets might just
have pulled off an outrageous coup.
Luna 16 landed safely on the Moon on September
20, 1970, on the Sea of Fertility and deployed an
extendable arm with a drilling rig to collect 100 g of
soil and rock. After 26 hours 25 minutes on the surface,
the ascent stage, with a hermetically sealed soil
sample container, took off and returned to Russia on
September 24. The lower stage remained on the lunar
surface and continued sending back data on temperature
and radiation.
Luna 18 used a new method of navigation in lunar
orbit and for landing. However, after 54 lunar orbits,
it failed as it descended toward the Sea of Fertility on
September 11, 1971, and crashed into mountainous
terrain. On February 21, 1972, Luna 20 soft-landed in
the Apollonius highlands, just 120 km from where
Luna 18 had come down, collected 30 g of samples,
and returned to Earth four days later.
A similar scenario played out with Lunas 23 and 24.
The former actually survived its landing on the Sea of
Crises but was sufficiently battered that its samplecollecting
apparatus was knocked out of action. However,
its successor, the final Luna mission, touched
down just a few hundred meters away and returned
triumphantly with 170 g of Moon rock.
Lunas 17 and 21
Soft-landers carrying Lunokhod automated rovers.
Luna 17 entered lunar orbit on November 15, 1970,
and landed two days later on the Sea of Rains. Having
taken pictures of its surroundings, Lunokhod 1 then
rolled down a ramp and began exploring the surface.
The rover would run during the lunar day, stopping
occasionally to recharge its batteries via the solar panels.
At night it would hibernate until the next sunrise,
kept warm by the radioactive source. Although
intended to operate through three lunar days (earth
months) the rover actually operated for eleven, officially
ending its mission on October 4, 1971, the
anniversary of Sputnik 1. By then it had traveled 10.5
km, transmitted more than 20,000 TV pictures and
200 TV panoramas, and conducted more than 500
soil tests.
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