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

strap-on urine receptacles were provided for the
astronauts’ use.
During the flight, Shepard withstood a maximum
6g during ascent, about five minutes of weightlessness,
and slightly under 12g during reentry. He successfully
carried out all his assigned tasks, including
manually guiding the capsule from the time it separated
from the Redstone booster. This proved the
important point that a human could competently
handle a vehicle during both weightlessness and highgravity
situations. The Freedom 7 capsule lacked a window,
but Shepard was able to see out through a
periscope—but only in black-and-white, because a gray
filter had been mistakenly left on the lens. 130
Mercury MR-4
Launch attempts on July 18 and 19, 1961, were
scrubbed due to bad weather—the first scrubs in the
history of American manned spaceflight. On his suborbital
flight, Grissom became the second American
in space, reached a maximum altitude of 190 km, and
ended up 488 km downrange of the launch site. The
mission goals were almost identical to those of Shepard’s
flight, but the Liberty Bell 7 capsule had a window,
easier-to-use hand controls, and explosive side
hatch bolts that could be blown in an emergency.
Unfortunately, after splashdown these bolts were
unexpectedly blown, causing the capsule to start filling
with water. Grissom made his way out but had to
struggle to reach a sling lowered from a rescue helicopter
because his spacesuit had become waterlogged.
He was recovered without injury after being in the
ocean for about four minutes, but an attempt to lift
the water-laden Liberty Bell 7 capsule by helicopter
failed and the capsule sank—the only such loss following
an American manned spaceflight. NASA ran a
battery of tests and simulations to find out how Grissom
might have blown the hatch and determined that
it would have been nearly impossible for him to have
done this accidentally. Instead, the loss of the capsule
was blamed on an unknown failure of the hatch itself,
although it became a standing joke that a crack that
had been painted on the side of Liberty Bell 7 (like the
crack in the real bell) prior to the flight was the true
cause of its sinking. Following the successes of missions
MR-3 and MR-4, NASA decided that no more
suborbital flights were needed before a manned
orbital attempt, and it canceled the flights that had
been designated MR-5 and MR-6.
Mercury MA-6
After a series of scrubs that delayed his launch for
nearly a month, John Glenn became the first American
to orbit the Earth. His Friendship 7 capsule completed
a 130,000-km flight, three times around the
planet, with Glenn becoming the first American astronaut
to view sunrise and sunset from space and to take
pictures in orbit—using a 35-mm camera he bought in
Mercury MA-6 John Glenn
entering Friendship 7 before
becoming the first American in
orbit. NASA
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