posted 12-06-2015 05:30 AM               

Apollo 13 crew signed cover originated from the astronaut suit-up area at Kennedy Space Center, and mailed by a colleague on the crew's launch date of April 11, 1970, America's third astronaut mission to attempt to land on the Moon. The crew's launch cover was mailed to Kenneth Sharp in Houston, Texas, a friend of the Apollo 13 crew, after their dramatic and spectacular launch from Pad 39A, Kennedy Space Center, Florida.

Space Cover #346: Lucky Flight of Apollo 13!

Marilyn Lovell had felt uneasy since the previous August when she learned that her husband Jim Lovell would command Apollo flight number 13. It wasn't that she was superstitious. Jim Lovell had been too lucky too long, and she felt it was only a matter of time until her husband's luck would run out. But, she also knew how much this flight as Commander of Apollo 13 meant to him. After eight years of training as an astronaut, her husband was finally going to command a mission to land on the Moon!

Prior to the launch of Apollo 13, Marilyn had traveled to Cape Canaveral to see Jim, and she had planned to return to their home in Houston to watch his launch. She stayed at the Cape instead to say goodbye the way she had on his Apollo 8 flight. Watching Apollo 13 rocket away from launch pad 39A at Kennedy Space Center on a bright white hot thundering plume, she quietly whispered, "Goodbye," and was thankful that everything was going well. She was also contemplating Jim's comment as they walked on the beach at the Cape a few days before, that Apollo 13 would be his last flight.

Landing on the Moon would be difficult enough, but the lunar landing site at Fra Mauro would indeed be a challenge. A free return trajectory approach which had worked so well on the two earlier Moon landing missions was changed for this flight. The rough terrain at Fra Mauro made the landing site a dangerous one. The ambient lighting for the projected landing time on the lunar surface was considered poor with normal shadows for the Moon's topography at the wrong angle and not useable. Without shadows defining craters, obstacles, rocks, and rifts, a clear landing site would be much more difficult to determine by the crew descending to the lunar surface. The crew would have only one shot in making the lunar landing, and the landing would be perilous.

Now on April 13, well into their mission to the Moon and going about their duties, Apollo Control's Sy Libergot had requested the crew to stir up the cryo tanks when they got a chance. As requested, crew member Jack Swigert commenced this process. Sixteen seconds later the crew heard a loud bang and whump sound followed by a severe shudder transmitted throughout the spacecraft. Jack Swigert checked his instruments and sees that there is a sudden and unexplained loss of power in main bus B, one of only two main power distribution panels providing power to all the hardware and systems in the Command Module. The bus losing power is a serious problem. Half of the hardware and systems in the spacecraft are also dead.

Swigert immediately reports to Apollo Control, "We've got a problem here." CapCom Jack Lousma, puzzled in Houston, says, "This is Houston, say again, please?" Lovell intercedes and yells, "Houston, we've had a problem. We've had a main B bus undervolt!" EECOM Engineer George Bliss in Houston, jumps-in and says, "We've got more than a problem!" Libergot glances at his instruments and notices the data for the spacecraft's oxygen tanks. Oxygen tank number two holding half the oxygen for the Apollo 13 flight appeared to be empty. EECOM's Bliss confirms this, saying, "We lost O2 tank pressure!" Libergot sees more bad news, "Ok, you guys, we've lost fuel cell one and two pressure." Two of three fuel cells that require oxygen to function are not putting out any power at all. If the fuel cell data is accurate, Apollo 13 will have to abandon the mission's landing at Fra Mauro. Apollo 13's flight would have to be aborted.

Jim Lovell, frustrated, and exasperated, decided to make a quick check around the spacecraft as if he were doing a preflight check to try to determine what in the world was happening. As he looked out of Odyssey's spacecraft window, he sees a thin, gauzy looking white cloud surrounding Odyssey and the Service Module and forming an iridescent halo that extended from Apollo 13 far into the black distance. He immediately recognizes the serious danger the crew is in as their oxygen from their oxygen tanks appears to be venting. He reports to Lousma in Apollo Control, "We're venting something…into space."

He quickly observes that oxygen tank 2 is empty and oxygen tank 1 is slowly dissipating into space. If true, there only would be enough oxygen left for five hours of stay time in Odyssey. Lovell does some quick calculations and realizes that from this point in their transit to the Moon, their return to Earth would take approximately 100 hours. He straightforwardly says to his crewmates, "If we're going to get home, we're going to have to use Aquarius." Jim Lovell's desperate plan is to use the mission's lunar module Aquarius as a "lifeboat" to enable the crew to return safely to Earth. Apollo 13's Moon landing was off.

An Apollo 13 event cover for the blown out section of the Odyssey service module is pictured April 13, 1970, as the crippled service module with its lunar module continue on its path to the Moon. The crew moves into the LM to conserve their power, water, and oxygen and will use the Moon's gravitational force as a slingshot for using the lunar module as a lifeboat for the crew on an expedited emergency return to Earth.

NASA officials in Apollo Control determine that a free return burn and loop around the Moon will provide an accelerated return back to Earth. Lovell comments, "…make sure we get this burn-off right." At the designated time, Lovell flips the master arm switch on. The LM computer flashed 99:40, a computer signal asking if the Commander was sure he wanted to make the burn. Lovell hits the proceed button and has ignition and low throttle. Jack Lousma in Apollo Control says, "Aquarius, you're looking good!"

The burn is precise and requires no smaller burn, called a trim. Aquarius speeds on its way around the Moon at an expected altitude of 136 miles off the lunar surface instead of the 60 miles that would have been used for executing its lunar landing. As Aquarius rounds the Moon, Lovell recalculates the earliest time the crew could reach Earth, but he is concerned. He comes up one day short. They will not make it!

A speed-up burn, shortened as PC+2, would be a slower and longer burn after Apollo 13's Aquarius rounded the Moon. The speed-up burn would put the crew on a faster and revised computer derived trajectory back to Earth with a safer recovery window. Taking their improvised stations in Aquarius, Lovell reports, "We are go for the burn." As the countdown for the burn signals zero, the crew feels the LM's rocket engine slowly rumbling to life beneath their feet. The burn runs for two minutes and forty seconds.

As the speed-up burn is completed as relayed by CapCom, Lovell yells, "Shutdown," at the completion of the burn period. Capcom Vance Brand affirms, "Roger, shutdown. Good burn, Aquarius!" Houston Control in contact with the communications' team on the designated primary recovery ship, USS Iwo Jima, relays his voice message, "Pericynthion plus 2 burn complete. Predicted splashdown 600 miles southeast of American Samoa, at 142 hours, 54 minutes ground elapsed time."

NASA recovery team's Mel Richmond at sea on USS Iwo Jima turns to the ship's Communications Officer next to him and says, "It looks like we will have work to do this Friday." On Aquarius, though, Commander Jim Lovell does not feel quite as confident. They were only 15,000 miles from the Moon and 225,000 miles from Earth. The Apollo 13 crew now in Aquarius and mated with Odyssey still had a very long way to go.

As Apollo 13 reenters Earth's gravitational pull, Apollo Control confirms that Apollo 13's trajectory is too shallow for a safe return and requires a mid-course correction burn of 14 seconds with 10 percent thrust to correct the spacecraft's present track. Jim Lovell manually controls the engine burn from Odyssey using start and stop switches on his console. After the burn, Lousma, says, "Nice work!" Lovell rechecks the Earth's position through the spacecraft's optical sight and comments, "Well, let's hope it was."

A final midcourse burn is made by the crew to improve the return flight path angle. Now, a prime news media and front page newspaper item, the reentry of the Apollo 13 crew holds the world's attention as they approach Earth from 37,000 miles out in space and a reentry speed of 7,000 miles per hour inside Earth's gravity pull. Odyssey will splashdown in only six hours, but the crew has work to do and must still jettison its inoperative service module, lifeboat and lunar module Aquarius, and Odyssey must successfully splashdown in the South Pacific Ocean.

As Odyssey's three main parachutes follow the drogue chutes and unfurl, Jim Lovell tells his crew, "Hang on, if this is anything like Apollo 8, it could be rough." Thirty seconds later, Odyssey splashes down gently into the ocean and nothing like Apollo 8's hard jolting splashdown. Buoyed up by the gentle Pacific Ocean, Lovell, Haise, and Swigert glance out their portholes. Jim Lovell says, "Fellows, we're home!"

On April 19, 1970, President Richard Nixon presents Presidential Medals of Freedom to Gene Kranz, Glynn Lunney, and the other Apollo 13 flight directors at Houston's Manned Spaceflight Center. NASA Administrator Tom Paine is also in attendance at the awards ceremony as President Nixon praises the ingenuity, perseverance, and tenacity of NASA engineers and NASA contractors who saved the lives of the crew of Apollo 13 and brought their spacecraft back to Earth for a successful recovery. Apollo flight number 13 turned out indeed to be a lucky flight. For many people, it was also NASA's finest hour.

A difficult to find Apollo 13 astronaut cover, as denoted by the Apollo astronaut insignia under Mattingly at the bottom of the mission's insignia, is shown, and the cover is cancelled on the crew's splashdown date, April 17, 1970, in the South Pacific Ocean. The Apollo 13 crew is recovered by the recovery helo from the USS Iwo Jima, LPH-2, the emergency primary recovery ship awaiting the crew's splashdown near American Samoa.