The date is April 11th, 1970, and outside
of the Kennedy Space Center three men sit atop millions of pounds of explosive fuel. American astronauts James A. Lovell Jr., T.
Kenneth Mattingly II, and Fred W. Haise Jr. have been safely sealed into the crew module
of their Saturn rocket 45 minutes ago, and have spent that time strapped into their seats
awaiting the long list of final checks required before the launch command is given. At last, Flight Control receives the all clear
from the dozens of different department heads who's jobs are all to ensure a successful
launch, and at 2:13 PM Eastern, the massive Saturn rocket roars to life. Almost 5 million pounds of fuel ignite, and
the mighty Saturn slowly lifts off the launch pad, gradually increasing speed. In moments the crew is already breaking the
sound barrier, roaring into the heavens on a mission for the next manned landing on the
moon. The rocket is a multi-stage vehicle that conserves
fuel by gradually shedding spent stages, and thus lowering the total mass that needs to
be lifted up into orbit. This allows the Saturn to achieve the fuel-efficiency
required to bring significant loads, such as the Apollo spacecraft itself, into orbit-
but it's not without its risks. According to plan, the first stage burns for
2 minutes and 41 seconds, shooting the rocket to an altitude of 42 miles (68 km) at a speed
of 6,164 miles per hour (2,756 m/s). At that point explosive separators would disengage
the first stage from the second stage, shedding tens of thousands of pounds of dead weight. The second stage's five engines would then
flare to life, accelerating the spacecraft for six minutes to a height of 109 miles (175
km) and 15,647 miles per hour (6,995 m/s), which is almost orbital velocity- or the speed
needed for an object to remain in orbit. Then the second stage would separate and the
third stage would fire to put the spacecraft on a parking orbit around the earth. At that point the Apollo Command and Service
Module would detach from the third stage, turn around and dock with the lunar module
which was secured right below the CSM during launch, and extract the lunar module from
the spent third stage. All of this required an incredible amount
of careful engineering, and with millions of moving parts, anything could go wrong at
any time. For the astronauts of Apollo 13 though, those
first few seconds after engine ignition were the most terrifying, as all aboard knew that
if the engines failed while they were still only a few feet off the ground, the entire
rocket would come crashing down and the millions of pounds of fuel would incinerate everything. In fact, the fully fueled Saturn vehicle could
release an energy equivalent of two kilotons of TNT if it failed at lift off, giving the
astronauts on board no chance for survival. Yet today the rocket seems to be working fine,
and in moments the crew is breaking the sound barrier and speeding towards their first stage
separation. Almost three minutes later the crew hears
the explosive bolts fire off as the first stage is successfully cast off, and a moment
later they are kicked back into their seats as the five engines of the second stage fire
off. Carrying a much smaller payload, the engines
quickly accelerate the spacecraft, pinning the astronauts to their seats. Yet in what would turn out to be a precursor
for the doomed mission, the center engine suddenly shuts down as alarms ring both on
the ground at mission control and inside the command module. Unbeknownst to the engineers on the ground
and the astronauts aboard, the flight computer has automatically shut the engine off due
to severe oscillations caused by an uneven burn of that engine's fuel. If left unchecked, the uneven thrust could
produce even more severe oscillations which could lead directly to mechanical damage,
and possibly, outright destruction of the engine. Luckily for the crew though, the computer
has detected the pending problem and shut the engine off just in time, but even more
luckily for the crew the afflicted engine is the center engine- had it been one of the
four outboard engines the spacecraft could have tumbled out of control. At the speeds Apollo is now traveling through
the atmosphere, that would have ended in certain death as wind resistance shredded the spacecraft. To compensate for the loss of the center engine,
the computer re-plots its flight profile and burns the four outboard engines for longer
than planned. As the second stage separates and is cast
off, the third stage's single engine burns longer than originally planned as well to
compensate for the lost engine in the second stage, and though fuel margins are incredibly
tight, luckily the spacecraft has enough fuel to compensate for the emergency. Well over a hundred miles over the Earth,
the spacecraft is now in a parking orbit, and the crew runs system checks and prepares
for their burn window to send them to the moon. When some final checks sound the all clear
both on the spacecraft and on the ground, the third stage begins its translunar injection
burn. After a successful burn sets Apollo on a non-free-return
orbit to the moon- meaning the spacecraft won't simply swing by the moon and be pulled
back to earth- the command module separates from the third stage, and as planned, spins
around to dock with the lunar module, which is then released from the third stage. Moments later, the command module makes a
small burn to alter its own trajectory- the original translunar injection burn has put
the third stage directly on a collision course with the moon as part of an experiment that
NASA plans on conducting. The third stage is plotted to impact within
just a few kilometers of where Apollo 12 had deployed seismometers, with the resulting
seismic shock giving NASA scientists insight into the inner structure of the moon. The astronauts are now safely on their way
to the moon, and broadcast live to the world below. After their brief tv broadcast, the astronauts
remove their heavy pressure suits and settle in for the long, three day ride to the moon. Their goal is the Fra Mauro highlands, a region
fraught with hazards as it is rather hilly and will make landing challenging. Yet the site promises to hold a treasure trove
of geological data, as it is full of ejected debris from the impact that had formed the
huge Mare Imbrium lava plain- the remains of one of the largest craters discovered in
the solar system and the iconic large dark spot visible to us every night on the moon's
face. Thirty hours into their flight, the astronauts
light up the command module's engines for a small midcourse correction in order to fine-tune
their final orbit around the moon. All is still well aboard the spacecraft and
on the ground all systems are reading green- the historic mission is set to be the success
that all of the USA's previous moon landings have been to date. Fifty six hours into the mission Apollo 13
is 205,000 miles (330,000 km) from Earth. The astronauts have just ended a live tv broadcast
and are stowing the equipment when flight controllers ask Command Module Pilot John
L. Swigert to turn on the stirring fans inside the hydrogen and oxygen tanks in the service
module which would help them get even more accurate readings on their levels. Two minutes later there's a large bang and
the electrical power inside the command module begins to fluctuate wildly, while outside
the spacecraft the attitude control thrusters fire briefly. In what have become the second most famous
words ever uttered in space, Swigert radios home, saying, “Houston, we've a problem.” Electrical power is slowly being drained from
the service module, and oxygen tank no. 2 reads completely empty. The astronauts are confused, and initially
think that they may have been struck by a micrometeorite, not realizing that one of
the oxygen tanks has exploded. On the ground NASA technicians and engineers
have been recalled to mission control from home and their offices, the situation already
looking dire. Three minutes later two more fuel cells fail,
plunging power levels in the service module to critically low levels. Outside the window, Astronaut James Lovell
can see that the spacecraft is venting gas into space- likely oxygen. Over the next two hours, the main oxygen tank
also depletes until finally runs empty. The crew is in serious trouble, and desperately
needs a way back home. Lead Flight Director Gene Kranz officially
orders an abort of the mission, and engineers on the ground begin scrambling to find a way
to provide enough power to the remaining fuel cells to save the astronaut's lives. With the Service Module, which was meant to
return the crew to earth, out of commission, flight engineers fall back to an abort plan
originally drawn up in 1966 but never actually put into practice or even tested. The crew will shut down all systems aboard
the command module completely and move into the cramped lunar module, which they'll then
use as a lifeboat to get them back to earth. Designed for only two astronauts, the ride
is not going to be comfortable for the three man crew, but it's the only chance the crew
has to get back home safe. The original plan for an abort though had
called for the jettisoning of the lunar module entirely, and burning the command module's
engines at exactly 60 hours flight time in order to achieve a free-return lunar fly by. However the crew would die without the lunar
module, so the planned burn is scrapped. With the moon's sphere of gravitational influence
just a few hours away, flight planners have to work fast to figure out a way to bring
the crew home using the lunar module. Yet there is another critical problem to solve
as well- the lunar module was designed to sustain two people for a day and a half, not
three people for four days as it now needs to. The spacecraft still carries plenty of oxygen,
as the lunar module had to repressurize after each EVA on the moon's surface- but the lithium
hydroxide which is critical for removing carbon dioxide from the atmosphere is in short supply. Most of the lunar module's lithium hydroxide
canisters are stored on the descent stage and out of reach of the astronauts, who can
not conduct a space walk to retrieve them. If a solution is not found swiftly, the crew
will asphyxiate long before returning to earth. The command module has enough lithium hydroxide
stores to safely clean the crew's air supply, yet the CM's canisters are cube shaped, and
the Lunar module's sockets are cylindrical. As NASA engineers go into a flurry of brainstorming
to figure out a solution, flight control works on figuring out a safe return trajectory for
the stricken spacecraft. Flight director Kranz orders the crew to burn
the lunar module's descent engine for thirty seconds, this will allow the spacecraft to
slingshot around the moon and be hurled back to earth, and after a second burn on the far
side of the moon, Apollo 13 would be on its way for a splashdown in the south pacific. But if the crew can’t breathe, all the US
Navy would be recovering from the spacecraft are three perfectly preserved corpses. Inside Mission Control, NASA engineers furiously
work at solutions to the lithium hydroxide problem, gathering together a store of all
materials available to the astronauts themselves. With just hours of clean air left, an ingenious
solution is found- the crew is ordered to cut off one of their spacesuit's air hoses
and using tape, velcro, and other odds and ends, fashion it into an adapter for the cube-shaped
lithium hydroxide canisters from the command module. Much to everyone's relief, the improvised
solution works brilliantly, and at last the crew of Apollo 13 sees some real hope of returning
to earth safely. Yet the crew is not out of the woods yet. To conserve very limited power supplies, most
of the lunar module's systems and all of the command module's computers have been shut
down. This means temperature control as well, and
the plummeting temperature has the crew shivering. Even more dangerous though, condensation has
begun to form on the inside of the stricken spacecraft, and there are serious concerns
that when the command module is powered up, it will cause catastrophic electrical shorts. To add to the astronaut's worries, the command
module was never designed to be completely shut down in flight and then restarted. With time running out and power at too low
of levels for a normal power-up routine, flight controller John Aaron and astronaut Kenneth
Mattingly- who was originally supposed to be on board- work with engineers to figure
out a way to restart the power hungry command module with the limited power supply available. Working tirelessly and without sleep, the
ground team manages to figure out a way to restart the CM's systems while avoiding unnecessary
power draws. With the earth in their sights and re-entry
just a few hours away, Apollo 13's crew begins to power up the CM per Houston's very careful
instructions. Back on earth, the ground team holds its breath
as Apollo 13's systems come back online one by one, and then explode into cheers as the
command module comes fully to life. Yet as the earth looms large before the astronauts,
one final challenge remains: the lunar module must be safely separated from the command
module before reentry, or both vehicles will burn up in the atmosphere. Typically the service module's reaction control
system would fire off a small series of thrusters to gently pull away form the undocked lunar
module, yet the power failure has left the RCS system inoperable and the now useless
service module was going to be released before the lunar module anyways. On the ground Nasa engineers in conjunction
with counterparts at the Univeristy of Toronto conclude that the only way to separate the
command module from the lunar module would be to pressurize the tunnel connecting the
two just before separation, and once separated the rush of the gases venting into space would
push the lunar module away. Yet the ground team has to carefully calculate
the exact pressure required to do so, as too much pressure will damage the command module's
hatch and seal, leading to the astronauts burning up in the atmosphere. Too low pressure would not push the lunar
module far enough away, putting the two craft at risk of collision during re-entry. Using just slide rules and with six hours
before atmospheric re-entry, the ground team, lead by Bernard Etkin, work furiously at their
calculations. With an hour left, the exact figure is radioed
up to Apollo 13, and the astronauts seal the hatch to the command module, venting oxygen
into the tunnel that connects them to the lunar module. The astronauts hold their breath as they prepare
to undock, knowing that if the calculations are wrong, they are certainly dead men, and
with no way of averting atmospheric re-entry anymore they'll have a long time to think
about their certain death. At last, the lunar module is undocked, and
with a hiss of escaping air, the vented oxygen successfully pushes the lunar module away
to a safe distance. Apollo 13 would go on to splash down just
southeast of American Samoa in the South Pacific. Easily the most harrowing mission ever undertaken
in manned spaceflight, Apollo 13 may have been a technical failure, but was a complete
success in testing mankind's ingenuity and resolve in the face of incredible odds and
adversity. More than a successful mission ever could
have, Apollo 13 proved that mankind truly has what it takes to make the bold move into
space so vital for our shared future, even if sadly, just a few years later the United
States and other nations of the world would seemingly lose all interest in ever visiting
the heavenly bodies above us ever again. If you enjoyed this video, I suggest you our
other video Why You Could Never Be An Astronaut. Thanks for watching, see you next time!
