I'm Barbara Klein.
And I'm Steve Ember with EXPLORATIONS
in VOA Special English. Today we continue the history of the American space
program with the flight of Apollo Thirteen, the flight that almost did not
astronauts in Apollo Eleven landed on the moon July twentieth, nineteen
sixty-nine. A second landing was made four months later. Both flights were
almost perfect. Everything worked as planned. Everyone expected the third
moon-landing flight, Apollo Thirteen, would go as well as the first two. But it
Thirteen roared into space on Thursday, April eleventh, nineteen seventy. The
time was thirteen-thirteen, one-thirteen p. m. local time. Navy captain James
Lovell was commander of Apollo Thirteen. He had flown on Apollo Eight, the
first flight to orbit the moon. The two other crew members were civilians --
John Swigert and Fred Haise. Apollo Thirteen was their first space flight.
Apollo Thirteen spacecraft was like the earlier Apollos. It had three major
parts. One was the command module. The astronauts would ride to the moon in the
command module and then ride back to Earth in it. It was the only part of the
spacecraft that could survive the fiery return through the Earth's atmosphere.
lunar module was the second part. It would carry two of the astronauts to the
moon's surface. It would later launch them from the moon to rejoin the command
third part of the Apollo spacecraft was the service module. It had a rocket
engine that the astronauts fired to begin circling the moon. They fired it
again to break out of moon orbit for the return flight to Earth. The service
module carried tanks of oxygen for the flight, and the fuel cells that produced
electricity and water the astronauts needed to survive.
was what seemed to be a minor problem during the ground tests before launch.
Two large tanks in the service module held liquid oxygen. The oxygen was the
fuel that provided water and electricity for the command module. One of the
oxygen tanks failed to empty normally during the ground test. Engineers had to
boil off the remaining oxygen by turning on a heater in the tank. Commander
Lovell said later he should have demanded the oxygen tank be replaced. But it
seemed to be fixed. So no change was made.
After launch, Apollo
Thirteen sailed smoothly through space for two days. Controllers on the ground
joked that the flight had gone so well they did not have enough to do. That
changed a few hours later. The first sign of trouble was a tiny burst of light
in the western sky over the United States. It looked like a far-away star had
the space center in Houston, Texas, some amateur star-watchers were trying to
see the Apollo spacecraft through telescopes. One of the group had fixed a
telescope to a television set so that objects seen by the telescope appeared on
the television screen. The spacecraft was too far away to be seen. But
suddenly, a bright spot appeared on the television screen. Over the next ten
minutes it grew into a white circle. The observers on the ground had no reason
to believe the white spot they saw was made by the spacecraft. They thought it
was a problem with the television. So they went home to bed.
It was not a problem with their
television. It was a serious problem with Apollo Thirteen. It happened a few
minutes after the three astronauts completed a television broadcast to Earth.
astronauts heard a loud noise. The spacecraft shook. Warning lights came on. Swigert
called to mission control.
JOHN SWIGERT: "Houston, we've had a problem here."
The number two oxygen tank
in the service module had exploded. The liquid oxygen escaped into space. It
formed a huge gas ball that expanded rapidly. Sunlight made it glow. Within ten
minutes, it was almost eighty kilometers across. Then it slowly disappeared.
The cloud was the white spot the observers in Houston had seen on their
loss of one oxygen tank should not have been a major problem. Apollo had two
oxygen tanks. So, if one failed, the other could be used. But the astronauts
soon learned that the explosion had caused the other oxygen tank to leak.
The astronauts were three
hundred twenty thousand kilometers from Earth with little oxygen, electricity
and water. Their situation was extremely serious. No one knew if they could get
the spacecraft back to Earth, or if they could survive long enough to return.
astronauts and the flight control center quickly decided that the lunar module
could be their lifeboat. It carried oxygen, water, electricity and food for two
men for two days on the moon's surface.
there were three astronauts. And the trip back to Earth would take four days.
The men greatly reduced their use of water, food and heat. And they turned off
all the electrical devices they could.
on Earth, space scientists and engineers worked around the clock to design and
test new ideas to help the astronauts survive.
enough good air to breathe became the most serious problem. The carbon dioxide
the astronauts breathed out was poisoning the air. The lunar module had a few
devices for removing carbon dioxide. But there were not enough to remove all
the carbon dioxide they created.
Engineers on the ground
designed a way the astronauts could connect air-cleaning devices from the
command module to the air system in the lunar module. The astronauts made the
connector from a plastic bag, cardboard and tape. It worked. Carbon dioxide was
no longer a problem.
the problem was how to get the astronauts back to Earth as quickly and safely
as possible. They were more than two-thirds of the way to the moon on a flight
path that would take them to a moon landing. They needed to change their flight
path to take them around the moon and back toward Earth. They had to do this by firing the lunar
module rocket engine for just the right amount of time. And they had to make
this move without the equipment in the command module that kept the spacecraft
on its flight path.
hours after the explosion, flight controllers advised firing the rocket for
thirty-five seconds. This sent the spacecraft around the moon instead of down
to it. Two hours after Apollo Thirteen went around the moon, the astronauts
fired the rocket for five minutes. This speeded up the spacecraft to reach
Earth nine hours sooner.
lunar module was extremely uncomfortable. The astronauts had very little to
drink and eat. But the cold was the worst part of the return trip. The
temperature inside the lunar module was only a few degrees above freezing. It
was too cold for them to sleep much.
used the electrical power in the lunar module to add electricity to the
batteries of the command module. They would need the electrical power for their
crew moved back to the command module a few hours before landing. They turned on
the necessary equipment and broke away from the damaged service module. As the
service module moved away, they saw for the first time the damage done by the
exploding oxygen tank. Equipment was hanging from a huge hole in the side of
before landing, Lovell, Swigert and Haise said thanks and goodbye to their
lifeboat, the lunar module. They separated from it and sent it flying away from
the command module of Apollo Thirteen headed alone toward Earth. It fell
through the atmosphere. Its parachutes opened, slowing its fall toward the
Pacific Ocean, near Samoa. Ships and planes were waiting in the landing area.
millions of people around the world were watching the live television broadcast
of the landing. People everywhere cheered as the cameras found the spacecraft
floating downward beneath its three parachutes. They watched as it dropped
softly into the water.
Apollo Thirteen astronauts were safely home.
Our program was written by Marilyn Rice
Christiano and produced by Mario Ritter. I'm Steve Ember.
I'm Barbara Klein. Join us again next week for another EXPLORATIONS in VOA
Special English. We will finish the story of the Apollo moon landing program. You
can find earlier programs about American space flights at our web site,