Apollo 16
Misbehaving engines were among the mishaps on the penultimate Apollo landing. 50 years on, Ezzy Pearson looks back at the mission
MISSION BRIEF
Launch date: 16 April 1972
Launch location: Launch Complex 39A
Landing location: Descartes Highlands
Time on surface: 71 hours, 2 minutes and 12 seconds
Distance covered by the Lunar Rover: 26.7km
Duration: 11 days, 1 hour, 51 minutes
Return date: 27 April 1972
Main goals: Inspect, sample and survey the Descartes region; set up surface experiments; photograph the lunar surface from orbit; test the Lunar Rover’s capabilities
Achievements: First human landing on lunar highland; discovery that the region was an impact crater, not volcanic; collection of 96kg of material to sample, including one taken from 2.2m below the surface.
Lunar Module name: Orion
Command Module name: Casper
When a rubella scare grounded Command Module pilot Ken Mattingly in 1970, he was forced to watch from the sidelines as his two crewmates headed off to the Moon without him on the ill-fated Apollo 13. Two years later in 1972, Mattingly hoped for better luck on his new mission, Apollo 16. Unfortunately, while Apollo 13 had been an Oscar-worthy triumph over tragedy, Apollo 16 would turn out to be something of a farce. In 1972, morale at NASA was low. A curtailed Apollo programme was heading into its final two missions and many staff members were being laid off.
Meanwhile, the Soviets were making headlines with the Lunokhod rover and its robotic sample return missions, doing the work of the Apollo missions at a fraction of the cost and without risking human lives.
Not that the Apollo astronauts themselves minded the risk. In fact, they were pushing for more adventurous missions following the success of Apollo 15. Perhaps to the rugged landscape of the southern pole? Or even the lunar far side. Instead, NASA played it safe, and the fifth lunar landing was set to visit the equatorial lunar highlands for the first time. And so, on 16 April at 17:54 UT, Mattingly along with Commander John Young and Lunar Module Pilot Charles Duke launched on their way to Descartes crater, an area believed to be the site of past volcanic activity.
Though the launch went well enough, it wasn’t long before the first of Apollo 16’s many problems began.
On the second day, as the crew were mounting the Lunar Module on the nose of the Command and Service Module (CSM) and removing the former from its housing, Mattingly noticed a steady stream of white particles flowing from the Lunar Module’s propellant tanks. Were they venting fuel?
“I think you’re going to have to get in the Lunar Module and take a look at the… systems’ gauges to tell what’s going on here,” came the order from the ground.
The crew opened up the Lunar Module in a record 17 minutes, but found there was no sign of a pressure drop in the fuel tanks, much to their relief. However, particles with the appearance of ‘shredded wheat’ continued to move past the window. “It sure is something strange coming out of that,” said Young. “I never saw anything like that on [Apollo 10]. I mean I’m not normally a rabble-rouser.”
The eventual culprit turned out to be a coat of white paint on the Lunar Module that was harmlessly flaking off. Crisis solved, the crew settled down for the long haul to the Moon, ‘enjoying’ a new potassiumrich cuisine, imposed upon them after elevated heart rates on Apollo 15 had left NASA fearing an astronaut might have a heart attack. The usual go-to potassium source – bananas – proved unsuitable for long-haul missions, so they were instead made to drink vast amounts of orange juice. The crew’s thoughts on the menu were uncertain though, as a stuck antenna made radio communications garbled and spotty.
Moon arrival
On 19 April, the trio reached the Moon, and Duke and Young crossed over into the Lunar Module, named Orion. The craft separated, only for them to discover that reflections from the Moon were making their landing radar misbehave. Luckily, this wasn’t a big problem – just another one of the many niggles that had become expected on space missions.
Then, on the 12th orbit around the Moon, a far more serious issue arose. Mattingly was supposed to fire the CSM’s Service Propulsion System for four seconds when passing around the lunar far side in order to circularise their orbit. During his checks, one of the backup mechanisms started shaking badly. Even though it was a backup, the Service Propulsion System was a vital part of making sure the crew returned safely –a malfunction would mean cancelling the landing and coming straight home.
“Good Lord! Look at that hole we almost landed in!”
– Charles Duke’s first words on the Moon
Meet the astronauts
Commander: John Young
Young, born on 24 September 1930, would go on to become one of NASA’s most experienced astronauts, flying six space missions in four different vehicles – Gemini, the Apollo CSM, the Apollo LM and the Space Shuttle. He served as Chief of the Astronaut Office, finally retiring from NASA in 2004. He died on 5 January 2018.
Lunar Module Pilot: Charles Duke
Born on 3 October 1935, Duke is (currently) the youngest person to have walked on the Moon, aged 36. He served as the Capcom (capsule communicator) during the Apollo 11 landing and was in the Apollo 13 backup crew before getting rubella. Apollo 16 was his only mission and he retired in 1976, continuing his career in the US Air Force.
Command Module Pilot: Thomas Kenneth Mattingly
Born on 17 March 1936, Mattingly was a Navy pilot before joining NASA’s fifth astronaut class. Initially meant to fly on Apollo 13, he was reassigned to Apollo 16. He stayed with NASA for another decade, flying on two Shuttle flights, before retiring in 1985 to work for spaceflight companies, including Grumman and Lockheed Martin.
Beset by delays
As soon as Mattingly emerged from the far side of the Moon, he immediately began reporting his troubles to Mission Control. As engineers on the ground tried to trace the issue, Mattingly reflected on how this compared to their worst-case-scenario training simulations, quipping, “It’s really the worst sim I’ve ever been in.”
It took the ground team four hours to discover that the wobble wouldn’t prevent the Service Propulsion System working properly. Mattingly conducted the burn, allowing Young and Duke to land on the lunar surface, six hours behind schedule.
After 100 hours of dealing with issue after issue, the pair closed in on the lunar surface. Even the usually taciturn Duke indulged in a whoop of joy, exclaiming, “Wow! Wild man, look at that!”
After a good night’s sleep and a potassium-loaded breakfast, the pair stepped out onto the surface. The communication issues meant they are the only moonwalkers without a video record of their first steps, but their first words did make it back to Earth.
“Hey… mysterious and unknown Descartes, Apollo 16 is going to change your image,” said Young. Duke meanwhile, went with the less poetic, “Good Lord! look at that hole we almost landed in!” referring to a 7.6m-deep crater just 3m from Orion.
The spotty transmission was soon improved with the deployment of the Lunar Rover, which had its own communications hardware that could transmit video footage. The two got to work setting up experiments around the Lunar Module, including the most important of the mission –a heat flow probe to measure how the Moon radiates heat. Duke set about drilling into the surface, easily reaching 3m down.
Meanwhile, Young was halfway through setting up the ALSEP (Apollo Lunar Surface Experiments Package) when his foot caught on something. Hopping to free himself, he was soon surrounded by a floating mess of ribbon cables (pictured).
“Uh-oh,” said Duke, looking over. “That’s the heat flow. You’ve pulled it off.”
The cable had broken right at the connector – it would be impossible to fix and they had no replacement. The experiment was useless.
“Oh, rats!” exclaimed Duke. “A bunch of spaghetti over there.”
The pair continued on, finishing up the other experiments before setting off in the Lunar Rover to explore the surrounding area with a relatively short 4.2km jaunt to pick up some samples from a nearby crater, including a bright white rock that appeared to be thrown up by a meteorite impact. The excursion finished with one last, fun exercise – racing the Lunar Rover in a ‘Lunar Grand Prix’, driving flat out and skidding in circles as a more extreme test of its capabilities. The Lunar Rover managed a maximum speed of 17km/h across the uneven landscape.
Too many oranges
Covered in dust – especially Duke, who had fallen over at least three times – the two clambered into their module. After undressing in a completely sealed room, which was a little larger than two phone boxes, Young made a distressing declaration.
“I’ve got the farts again. I got ‘em again Charlie. I don’t know what the hell gives them to me,” he mourned, though he soon laid the blame on the potassium-rich, orange-fuelled diet. “I haven’t eaten this much citrus fruit in 20 years! And I’ll tell you one thing, in another 12 f***ing days I ain’t never eating any more.”
At this point, Houston cut in to inform him he’d left his microphone on and was broadcasting his laments to not just Mission Control, but the journalist-filled media room.
After eight hours of rest, the pair headed outside for their second extra vehicular activity (EVA), 4.1km away at the base of Stone Mountain. Over the 11.1km-long round trip the duo stopped to take samples, including a set where they scraped one sample from the top of a boulder which had been exposed to cosmic rays for millennia and another from the underside that had been protected, so that geologists could compare the two samples.
The pair of astronauts constantly communicated what they saw to the geologists on the ground, supplementing the video feed coming in from the Lunar Rover’s camera. The longer the moonwalkers explored, the more apparent it was becoming there were no signs of the volcanism they’d been expecting; it was actually an impact basin. They’d got it wrong, which was an embarrassing mistake on the geologists’ part, but one that demonstrated the need for first-hand exploration to get close to the surface.
Duke, meanwhile, was getting a little too close for comfort, falling over another six times. He soon found he could use a hole or crater to lever himself up. Despite his constant slips both Duke and Young were enjoying their mission, and when they arrived back at the Lunar Module Duke begged their Capcom, Tony England, “How about an extension?… How about 10 minutes, Tony? Please.”
“Okay, we’ll go ahead and give you 10 minutes,” England acquiesced.
“Attaboy,” said Duke. They finished up their EVA and returned for another eight-hour rest before getting started on the third and final moonwalk. They travelled a total of 11.4km, exploring around the North Ray crater, 4.4km away from the Lunar Module. During one stop, they found a 10m-high boulder, named House Rock, samples from which would incontrovertibly prove the area was not volcanic.
‘Lunar Olympics’
As the final EVA wrapped up, the pair indulged in one last moment of hijinks by competing in the ‘Lunar Olympics’, seeing who could jump the highest. In the one-sixth gravity, Young managed an impressive 1.2m, but when Duke followed suit he, true to form, fell over. Only this time he came down hard on the fibreglass shell which protected his life support equipment. If the shell cracked, he would have died before Young could drag him back to the lander. Fortunately, it held.
“That wasn’t very smart, Charlie,” Young said as he helped him up and the pair, quietly, climbed aboard before relaunching from the lunar surface. While all this had been going on down on the surface, up in orbit in the CSM, Mattingly had been far from idle. His attempts at studying the Moon from above had been plagued with malfunctions – the cameras didn’t work properly, overexposing many of the images; an external mass spectrometer wouldn’t fully retract; and an altimeter became increasingly unreliable before failing entirely. To cap it all off, NASA decided they should begin the return to Earth a day early, meaning he had to rush to set up for the journey.
The 10m-high ‘House Rock’ on the rim of North Ray crater was visited during the final EVA on 23 April 
Poignantly, Charles Duke left a family portrait photo on the Moon – at 36, he was the youngest person to have landed 
John Young tested the Lunar Rover to its limits, kicking up dust at speeds of 17km/h during the ‘Lunar Grand Prix’ on 21 April 
Mission completed, the crew of Apollo 16 are greeted on board the USS Ticonderoga
Concerns aside, the Service Propulsion System fired perfectly and sent the crew on their way home. There was a brief interlude on the voyage, while Mattingly performed a deep-space EVA to retrieve film cassettes from the outside of the spacecraft, and the crew arrived back on Earth on 27 April.
Despite wobbly engines, a broken heat flow and an astronaut who couldn’t stay on his feet, the mission had largely been a successful one. The crew certainly didn’t seem put out by the difficult mission, with Duke running across the deck of the recovery ship in high spirits – possibly giddy at the prospect of never having to eat another orange. In fact, the crew’s good health had convinced NASA doctors to give the green light to missions up to 56 days long, just in time to begin planning lengthy stays on the Skylab space station due to fly in a few years’ time. Although the Apollo programme was one mission away from its end, the future of spaceflight was just beginning.
Dr Ezzy Pearson is BBC Sky at Night Magazine’s news editor
MISSION TIMELINE
16 April 17:54*
The Apollo 16 crew blast off from Cape Kennedy
16 April 21:15
The Command Service Module and (CSM) Lunar Module (LM) dock; Mattingly sees ‘shredded wheat’ particles moving past the window
19 April 20:22
Apollo 16 reaches lunar orbit
20 April 19:34
A fault is discovered in the backup circuit of the Service Propulsion System, forcing a cancellation of the circularisation burn and a delay to the landing
21 April 02:23
The lunar landing occurs six hours behind schedule
21 April 16:47
First EVA begins, lasting 7 hours, 11 minutes
22 April 16:33
Second EVA begins, lasting 7 hours, 23 minutes
23 April 15:25
Final EVA begins, lasting 5 hours, 40 minutes
24 April 01:25
The LM lifts off from the Moon’s surface and redocks with the CSM
25 April 20:33
Mattingly starts deep-space EVA to retrieve film canisters, lasting 1 hour 23 minutes
27 April 19:45
Splashdown
*All times are UT