The successful failure

As the 13th Apollo mission prepared for launch, a disinterested America bored with space travel meant that few were watching. Soon enough that would all change - and it was the heroics of backroom scientists and engineers that gave this story a happy ending

By 1970, America had become disillusioned with space travel – they’d already put a man on the moon with Apollo 11 in 1969, so sending another crew into space just wasn’t interesting anymore. It was hardly surprising that no one was watching Jim Lovell’s last broadcast from Apollo 13 on the evening of 13th April 1970, but soon enough – following an onboard explosion – the whole world would be glued to their TV screens.

Lovell – flight commander and a retired US Navy captain – has just finished a TV broadcast about the Apollo 13 mission and life onboard the spacecraft:
“This is the crew of Apollo 13. Wish everyone there a nice evening and, er, we’re just about to close our inspection of Aquarius and get back to a pleasant evening in Odyssey. Good night.”¹.

The next ground control heard from the crew was the famously misquoted line: “Houston, we’ve had a problem.”²

Mission control had asked the crew to turn on the hydrogen and oxygen stirring fans, which were designed to destratisfy and mix up their cryogenic contents – an oxygen slush – and increase the accuracy of their quantity readings. The crew had already done this twice, but this third stir was accompanied by a loud bang and fluctuations in electrical power.

At first the crew – Lovell, command module pilot John ‘Jack’ Swigert and lunar module pilot Fred W Haise – thought the service module had been hit by a meteorite, and it wasn’t until it was jettisoned shortly before the crew attempted re-entry into the Earth’s atmosphere that the full extent of the damage was apparent. The service module bay no 4 cover had been completely blown off: "There's one whole side of that spacecraft missing," Lovell said³.

An electrical fault inside an oxygen tank in the service module – the area of the spacecraft that provides consumables like oxygen, water and power to the mission – caused an explosion. This ruptured and damaged the second tank, causing rapid loss of oxygen; within a matter of hours all stored oxygen within the service module was lost along with a loss of water, electrical power and use of the propulsion system.

The tank was damaged before it was installed in Apollo 13 – it was originally intended for use in Apollo 10 but was removed for modification and was dropped causing a fault in the internal line. This damage was undetected and – although it wouldn’t empty during testing – the tank was installed in Apollo 13.

When at Kennedy Space Centre, the tanks – designed to run off the 28 volt DC power of the command and service modules – were modified to run off the 65 volt current to enable the remaining oxygen to be boiled off and the tanks emptied. A high temperature change in the tank went unnoticed because the temperature gauge never read more than 38°C – which wasn’t considered a problem as the thermostat was designed to open at 27°C. The tank emptied in eight hours when it should have taken days, and the excess heat welded shut thermostatic heater switches and resulted in damage to Teflon insulated electrical wire.

When Lovell switched on the fans to stir the oxygen, the exposed fan wires shorted and the Teflon insulation caught fire, the pressure inside the tank rose and the tank exploded. The service module was rendered non-functional and the command module – Odyssey – was left with limited power. To conserve what little power they had for the final flight home, the team powered down Odyssey and lived in the lunar module Aquarius for four days. The module was designed to sustain two people for two days – namely Haise and Lovell who were due to explore the Moon’s surface – not three people for four days.

Lead flight director Gene Kranz aborted the mission 56 hours in – it was the first Apollo mission to be aborted. The crew was 200,000 miles from Earth – there would be no Moon landing and the crew still had to figure out how to get home.

The existing abort plans – first drawn up in 1966 – were impractical. The quickest plan would have been the Direct Abort trajectory which required using the service module engine to reverse the direction of the craft – but it had already entered the Moon’s gravitational sphere of influence and there was no practical way to get electrical power to fire the engine.

Kranz and flight director Chris Kraft chose the circumlunar free return option that would use the Moon’s gravity to return the ship to Earth, accompanied by an acceleration burn shortly after the ship’s closest approach to the moon to speed up the return. Kranz was determined not to let Aquarius become the trio’s tomb: “We've never lost an American in space, we're sure as hell not gonna lose one on my watch!”

First, the team had to re-establish the free return trajectory with a small burn of the lunar module decent propulsion system. Based on calculations made on Earth, Lovell had to adjust the course twice by controlling the module’s thrusters and engine using just a watch for timing. The first burn was to align the spacecraft towards the centre of the re-entry corridor, the second to fine tune the angle to between 5.5 and 7.5° – too shallow an angle and the spacecraft would bounce across the atmosphere like a pebble on a lake, too steep and they’d burn up on re-entry. Lovell, with the help of his crew, corrected the angle to 6.49° by stopping and starting the engine and pitch and roll manoeuvres.

Aquarius was powered to the lowest level possible to help keep communication and life support systems operational. Ironically, oxygen was the least critical consumable as the module had a plentiful supply which would have been used on the moon had it reached it. Water – for both drinking and cooling – and electrical power, supplied by silver-zinc batteries however, were in short supply.
The most critical consumable was lithium hydroxide – a carbon dioxide scrubber used to remove the gas from the air to produce lithium carbonate and water:
2LiOH + CO₂ —> Li₂CO₃ + H₂O

The non-regenerating system used anhydrous lithium hydroxide (LiOH) because it has a lower mass and allowed for less water production in respirator systems than its hydrated version.

The lunar module’s supply of LiOH wasn’t enough to support the crew until re-entry: although the Aquarius had back-up canisters in the modular equipment stowage assembly (MESA) – along with video camera which would have filmed the crew’s first few steps on the moon – they were out of reach.

Odyssey had plenty but their cube-shaped canisters were incompatible with the Aquarius’ cylindrical canister sockets – the classic square peg in a round hole scenario. Engineers on the ground at the Manned Spacecraft Centre designed and tested a filtering device which the astronauts dubbed ‘the mailbox’. They had improvised a way to connect the canisters – using duct tape, cardboard and spacesuit hosing – it wasn’t pretty, but it worked.

To ensure a safe return, the team had to accomplish a complete power-up of Odyssey from scratch – something which was never intended to be done in-flight. NASA men on the ground – including Ken Mattingly who was due to fly on Apollo 13 but had been exposed to German measles and grounded – came up with a new protocol to do this with the ship’s limited power supply.

As the crew neared Earth, they moved back into the re-started Odyssey and jettisoned their make-shift lifeboat, the service module Aquarius, which re-entered the Earth’s atmosphere over Fiji and burned up.

Normal re-entry is accompanied by a four minute communications blackout caused by ionisation of the air around the command module, but Odyssey blacked out for an extra 33 seconds – mission control were beginning to fear the worst.

However, Odyssey regained radio contact and splashed down safely in the Pacific, southeast of American Samoa and around 40 miles from recovery ship USS Iwo Jima. Surprisingly the crew were in good condition – except Haise who had urinary tract infection caused by lack of water intake. The crew and the mission’s operations team were awarded the Presidential Medal of Freedom for their actions during the mission.

Jim Lovell never flew into space again and retired from the space program in 1973 although he did speak at colleges and universities on his experiences as an astronaut. He is one of 24 men to have flown to the moon – the first of three to fly twice and the only one never to have actually landed! A small crater on the far side of the moon is named Lovell in his honour and he even appeared as captain of the USS Iwo Jima in the Ron Howard film Apollo 13.

Jack Swigert took a leave of absence from NASA in 1972, becoming executive director of the committee on science and technology in the US House of Representatives. He officially resigned from NASA and the committee in 1977 to enter politics. He was elected into the US House of Representatives in November 1982 but died in December that year before he could be sworn in; he had bone cancer.

Fred Haise was scheduled as commander for the cancelled Apollo 19 mission, and he later flew five flights in 1977 as commander of the Space Shuttle Enterprise. He retired from NASA in 1979 and later worked for Grumman Aerospace, who had built the lunar module Aquarius for the Apollo 13 mission.

Despite the close shave, NASA was undeterred; seven more Apollo missions were planned but only four came to fruition. Apollo 14 launched in January 1971 and landed at Apollo 13’s intended landing site Fra Mauro – a widespread geological area covering large portions of the lunar surface. Apollo 15 and 16 launched in July 1971 and April 1972 – both were successful. Apollo 17 – launched in 1972 – was the last successful lunar landing. Apollo 18, 19 and 20 were cancelled in 1975 as part of a cost cutting exercise to make funds available for the development of the Space Shuttle program.

Apollo 13’s explosion was one of only two setbacks experienced in the Apollo program – the other was Apollo 1. While Lovell, Swigert and Haise narrowly escaped with their lives, the crew of Apollo 1 – Gus Grissom, Ed White and Roger Chaffee – died in a launch pad fire.

The Apollo program – specifically the lunar landings – has been called the greatest technological achievement in human history. Apollo 8 – on which Lovell was command module pilot – was the first human spaceflight to leave Earth’s orbit and see the far side of the Moon. Apollo 11 landed Neil Armstrong and Buzz Aldrin on the moon, and a further 10 men landed on the moon in subsequent missions. Apollo stimulated many areas of technology related to spaceflight, including flight computer design and integrated circuits and development of the fuel cell. The program also prompted other nations to attempt lunar missions and build lunar bases.

And it wasn’t just a boom in technology – the sheer drama of the event and the success of bringing the astronauts home means the event has been turn into films, dramas and stage shows alike – the best known being Apollo 13 starring Tom Hanks. Even today there is an interactive theatrical show called APOLLO 13: Mission Control touring Australia.

Perhaps the most iconic image of the Earth – the Blue Marble (pictured) – was taken by the crew of Apollo 17, en route to the moon. The image shows the now commonly held view of the Earth as a small fragile planet, which only a handful people have had the opportunity to see.