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- After all that's been said about Apollo 13, it might
seem there's nothing new to tell. But now, 30 years after NASA's heroic
rescue of the three Apollo 13 astronauts, details have surfaced that give
the story a new twist.
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- Newly analyzed data suggest that the astronauts on the
nearly fatal mission would not have been entombed in space, had efforts
to steer the craft back on course failed. In fact, the capsule eventually
would have passed quite close to Earth, and later collided with it, at
least bringing the astronauts' bodies back to their home planet.
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- Chuck Deiterich, who served as lead retrofire officer
during the mission, aided in the new analysis, supplying the "what-if"
data for a simulation that now shows the crippled spacecraft would have
missed Earth by 2,600 miles (4,184 kilometers), not the 40,000 miles (64,372
kilometers) reported for decades.
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- "I'm very confident that that's the right number,"
Deiterich told SPACE.com.
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- Simulation shows alternative
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- After the explosion of an oxygen tank crippled the Apollo
13 command and service modules 200,000 miles (321,860 kilometers) from
Earth, mission commander Jim Lovell knew he and his crew might not make
it back. Even worse, Lovell feared, Apollo 13 would end up circling in
space forever, as a silent tomb, or in Lovell's words, "a monument
to the U.S. space program."
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- Now, a computer simulation created by two companies,
Analytical Graphics Incorporated of Philadelphia and Colorado-based Space
Exploration Engineering, shows what would have happened to Apollo 13 had
the astronauts failed to get back on the proper course for a safe return
to Earth.
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- If the Apollo 13 astronauts had not been able to get
onto the free-return path to Earth, they would have followed the orbits
shown. After launch from Earth and outbound voyage (green), Apollo 13 loops
around the moon (red) and heads back toward Earth. The craft passes 2,645
miles from Earth, then continues on a long ellipse (white) that reaches
past the moon's orbit (yellow). Another orbit (blue) brings Apollo 13 within
29,500 miles of the moon, whose gravity bends the spacecraft's path onto
a direct course for Earth.
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- The simulation is one of several created for SPACE.com
(AGI is a vendor that supplies this site with visual animations), and the
discovery of the new trajectory came up during the project to create animations
for SPACE.com's special report on Apollo 13.
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- The new simulation starts with the path that Apollo 13
was on before the accident on April 13, 1970. On the day of the explosion,
the astronauts were following a course called a hybrid trajectory. Unlike
the so-called free-return trajectory followed by most of the earlier moon
missions, the hybrid path did not guarantee the astronauts a "free
ride" back to Earth in the event of an abort.
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- In the first hours after the explosion -- after determining
that the command/service module engine would not work, or could not be
fired safely -- Mission Control devised a plan for the astronauts to fire
the engine of their lunar lander to steer back home. Lovell and his crew
worked feverishly to get back onto the free-return trajectory, and they
succeeded. But what if they hadn't achieved this critical step?
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- 40,000 miles?
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- Many published accounts of the Apollo 13 mission, including
this writer's, have stated that Apollo 13 would have missed the Earth by
an enormous margin, on the order of 40,000 miles, and circled indefinitely.
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- The origin of that figure is unknown. Neither flight
controller Deiterich nor Apollo 13 flight director Gene Kranz could trace
the origin of the 40,000-mile estimate, but it shows up in Henry S.F. Cooper's
book, Thirteen: The Flight that Failed, published in 1973.
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- The new computer simulation suggests a very different
scenario. If the astronauts could not alter their path after the explosion,
Apollo 13 would have looped around the moon and then, its path bent by
lunar gravity, would have headed homeward.
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- On April 18, 1970, the spacecraft would have flown past
Earth, missing it by a distance of 2,645 miles.
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- Initially, the analysts were taken aback by their findings.
"We were puzzled how our results could be so different from what's
been written about the mission," said Bob Hall, AGI's director of
Technical Services. Then, after speaking with Apollo 13 veterans, Hall
and his colleagues resolved the discrepancy.
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- Third time would bring them home
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- In making their calculations, AGI received special assistance
from Deiterich. Before, during and after the flight, Deiterich was instrumental
in analyzing the spacecraft's trajectory. He is perhaps the only existing
source of detailed information on this subject, and he supplied AGI with
the data for the simulation.
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- Because the astronauts would not have survived much,
if at all, beyond a first Earth flyby, Deiterich never calculated what
would have happened next. But the AGI results reveal the craft's ultimate
fate -- and that is where the biggest surprise turns up.
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- Apollo 13, after flying past Earth in AGI's simulation,
travels back out into deep space, tracing a vast ellipse that stretches
beyond the orbit of the moon. On April 27 Apollo 13 reaches its maximum
distance from Earth, at 355,949 miles (572,829 kilometers). By this time,
the astronauts have surely perished. (Their oxygen reserves at the time
of the accident were enough to keep them alive for eight to 10 days; food
and water were in much shorter supply.)
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- On May 6, the craft makes another Earth flyby, this time
passing 1,563 miles (2,515 kilometers) from the planet and heads moonward
once more. Sometime around May 9, Apollo 13's path is altered when it passes
within 30,000 miles (48,279 kilometers) of the moon. On May 13, after reaching
the far point of its orbit again, Apollo 13 heads Earthward one last time.
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- This time, the spacecraft is on a collision course. On
May 20, 1970, some five weeks after the explosion, the spacecraft plunges
into Earth's atmosphere at a steep angle over the eastern Atlantic Ocean.
The steepness of the reentry would have meant that the spacecraft, carrying
the bodies of the astronauts, would have been destroyed by crushing gravity
forces and searing heat.
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