The Moondust Diaries
The dark side of returning to the moon is fine, super sticky and may pose health risks to astronauts.
In the public imagination, the American astronauts who landed on the moon five decades ago were superhumans, not the types to worry about housekeeping. But they did, obsessively. Each time after a moonwalk, they were shocked at how much dust they’d tracked in and how hard it was to banish. This was no earthly grime; it was sticky and abrasive, scratching the visors on helmets, weakening seals on pressure suits, irritating eyes, and giving some of them sinus trouble. “It just sort of inhabits every nook and cranny in the spacecraft and every pore in your skin,” Apollo 17’ s Gene Cernan said.
Over the six moon landings, the Dusty Dozen fought valiantly with their foe. They stomped their boots outside, then cinched garbage bags around their legs to stop the dust from spreading. They attacked it with wet rags, bristle brushes and a low-suction vacuum cleaner, which Pete Conrad of Apollo 12 called “a complete farce”. Cernan, upon returning from his last moonwalk, vowed, “I ain’t going to do much more dusting after I leave here. Ever.” In the end, NASA couldn’t find a solution. Years after John Young commanded Apollo 16, he still believed that “dust is the number one concern in returning to the moon”.
Now, with national space agencies and private corporations poised to do just that, the Apollo dust diaries are relevant once more. In January last year, China landed its Chang’e-4 probe on the far side of the moon. Two months later, the Japanese Aerospace Exploration Agency said it was partnering with Toyota to design a six-wheeled moon rover by 2029. Around the same time, US Vice President Mike Pence announced plans to put American boots on the moon by 2024. According to NASA, the goal is “to go sustainably. To stay. With landers and robots and rovers – and humans.” India and Russia have missions planned, too. The private ventures like Moon Express will prospect for water, minerals and other resources to mine.
All of which raises a crucial question: what to do about that troublesome dust? An Australian physicist named Brian O’Brien may have the answer.
O’BRIEN BECAME EARTH’S foremost authority on moondust almost by accident. In 1964, he was a young professor of space science at Rice University in Houston, specialising in radiation. This was during the early
phase of Apollo training, when the astronauts were taking crash courses in all manner of subjects – vector calculus, antenna theory, the physiology of the human nose. O’Brien’s task was to teach them about the Van Allen belts, two regions of radiation that encircle the planet like a pair of inflatable pool tubes. He remembers the Apollo class of 1964, which included Gene Cernan and Buzz Aldrin, as the most “disciplined and alert” cohort of students he ever had.
In the lead- up to the Apollo 11 launch, O’Brien persuaded NASA to include in the payload a small box the size of a thick bar of soap, whose main function was to measure the accumulation of dust on the moon’s surface. O’Brien describes it as “a delightfully minimalist” device. The Dust Detector Experiment, or DDE, was perhaps the least impressive component of the Apollo 11 science package. But it worked well enough that the agency included modified versions of the original DDE on all subsequent Apollo flights.
Four of them are still up there, and to this day they hold the record for longest continually operating experiments on the moon.
For many years, the data that the early DDEs sent back to Earth was thought to be lost. Since its rediscovery in 2006, those in the inner circle of outer space activities have slowly begun to realise that O’Brien’s detectors have a lot more to tell us about moondust. Now 85, sprightly and living in Perth, O’Brien has been waiting half a century for the chance to share with the world what he knows about one of the solar system’s most baffling substances.
O’BRIEN ALWAYS had an affinity for extreme environments. He took up spelunking [cave explorat ion] as a teenager and once got stuck in the depths of the Yarrangobilly Caves in NSW’s Kosciuszko National Park for 79 hours. The experience was traumatising but it didn’t put him off caving. A few years later, while exploring a crystal grotto, he met his future wife, Avril Searle.
By 23, O’Brien had completed a PhD in physics at the University of Sydney and been appointed deputy chief physicist for the Commonwealth Antarctic Division. He was assigned to the icebreaker Magga
THE DDE SOLDIERED ON AND QUICKLY REVEALED THE MISCHIEF DUST COULD MAKE
Dan and found himself gazing at the Aurora Australis rippling in reds, purples and greens across the polar sky. This was in 1958, a year after the Russians launched Sputnik and the same year NASA was founded. O’Brien began to dream of putting a satellite into orbit to study how energised protons and electrons gave rise to the southern lights. He got his chance the following year, when James Van Allen, discoverer of the Van Allen belts, got him a job at the University of Iowa. O’Brien and a few students built a satellite in five months. Other launches followed, and in 1963 O’Brien was of fered a post in Rice University’s new space science department.
NOT LONG AFTER, he got a call from NASA. The agency hoped to hire him as an astronaut instructor, but it also invited him to submit a proposal for a science experiment to go to the moon. He suggested a device – the Charged Particle Lunar Environment Experiment (CPLEE) – that would measure the energy spectra of charged particles as they rained down on the lunar surface. From a field of 90 submissions, his was one of seven that got the green light. NASA told him that the experiment should include a dust cover. No one knew at this stage just how pesky moondust would be, but O’Brien figured that if the agency was going to the trouble of installing dust covers, it should also include a dust detector. At first, NA SA baulked. It would be too difficult, they believed, to construct a detector that was l ight enough to meet the mi s s i on specs and simple enough that it wouldn’t take up any of the astronauts’ limited time. O’Brien came up with a design to allay their concerns – three tiny solar cells mounted on a box, painted white to reflect sunlight. As dust settled on the cells, their power output would drop, providing a clear record of accumulation over time. O’Brien threw in a few temperature sensors for good measure, bringing the experiment’s total weight to 280 grams. Because the DDE was so small, it could be bolted onto the seismometer that Aldrin and Neil Armstrong were setting up to measure moonquakes. NASA relented: the DDE could go to the moon.
Once there, it would feed its data to the seismometer, whose antenna would transmit the readings back to Earth. They’d be stored on reels of magnetic tape for analysis.
O’Brien, Avril and their three children moved back to Sydney in 1968, so he made arrangements to have the tapes shipped to him.
On the morning in late July 1969 when the Apollo 11 Lunar Module alighted on the moon, O’Brien vividly remembers the moment Aldrin said the module was “kicking up some dust” as it came in to land, as well as Armstrong’s observation that the surface was “almost like a powder”. With a spike of excitement, O’Brien realised his DDE might very well prove its worth.
THE SEISMOMETER overheated shortly after Apollo 11 left the moon. But the DDE soldiered on and quickly revealed the mischief dust could make. As the Lunar Module took off, two of the detector’s three solar cells registered a sudden drop in output, one of them by 18 per cent. This was accompanied by a spike in temperature. To O’Brien, there was only one explanation: the DDE had been blanketed in dust, which, like blackout blinds, kept light out and heat in. It seemed obvious to him that the seismometer had met the same fate.
If NASA hoped to keep its moonbased instruments working on future
Apollo missions, O’Brien concluded, it would need to study the matter of dust-spraying thoroughly. That August, he wrote proudly to an Australian colleague that “the DDE may really have earned its trip!” But his American counterparts were not so enthused. The seismometer stopped accepting commands from mission control, and the whole experiment – DDE included – was shut down after 21 days.
NASA’s preliminary science report on Apollo 11 rejected O’Brien’s explanation for the DDE readings, blaming the solar cells’ unexpectedly low output on calibration errors. O’Brien says he “strongly disagreed” with the findings and tried to argue his case in the Journal of Atmospheric Physics, using one of Australia’s first supercomputers, SILLIAC, to crunch and plot the data on endless ribbons of paper. But the article was barely cited by researchers in the decades that followed.
O’Brien was forced to admit defeat in round one of the moondust wars. He changed careers, becoming the first head of the Environmental Protection Authority of Western Australia. The position was based in Perth, and when Avril made the trip from Sydney, she brought the kids and the 172 reels of DDE data with her. O’Brien asked a colleague at a local university to put the tapes in storage. And so, for 40-odd years, that’s where they stayed.
AFTER THE FINAL APOLLO landing in 1972, NASA lost interest in the moon. There were space stations to assemble, exotic planets to explore, and only so much funding to go around. Then, in 2004, President George W. Bush announced the Constellation Program. There would be powerful new rockets, redesigned crew capsules and roomier lunar modules – “Apollo on steroids”, as one NASA administrator put it. Part of the plan was to establish a permanent “foothold” on the moon, which meant a renewed focus on the logistics of regular landings and long-term settlement.
This was something that Philip Metzger, a planetar y scientist, had been interested in for a while. Metzger was the co- founder of Swamp Works, a tech incubator at NASA’s Kennedy Space Center that creates practical solutions to the challenges of working and living in places beyond Earth. He’d done research on how to prevent rocket exhaust from stirring up dust and damaging lunar infrastructure, and had scoured decades’ worth of studies on rock and soil samples brought back by the Apollo astronauts. He even had four rare vials of genuine moondust in his laboratory. Over the years, he’d perfected a quick lesson in lunar geology for his team.
It went something like this. The regolith, a blanket of rocky material on top of the primordial lunar bedrock, contains mixed-up dust, gravel and pebbles. It is thought to be about 4.5 metres thick in the plains and nine metres thick in the highlands. The moon is constantly bombarded by cosmic rays and solar wind, which means the dust can become electrostatically charged, like a balloon rubbed on hair. It also receives a steady hail of micrometeoroids.
When the micrometeoroids hit, they create miniature shock waves in the soil, causing some of it to melt and forming tiny pieces of glass. These pieces are, Metzger says, “jagged, sharp and very frictional”. Unlike on Earth, where wind and water would smooth them out, they remain this way forever. When Aldrin and Armstrong planted an American flag near their landing site, they struggled to work the pole into the regolith, stymied by its high glass content. “It took both of us to set it up, and it was almost a public relations disaster,” Aldrin recalled years later. Thanks to the constant hammering by micrometeoroids, the soil is extraordinarily fine, which makes it sticky.
For all of Metzger’s moondust expertise, there was one enigma that kept stumping him. Sitting in his laboratory at the Kennedy Space Center were a few pieces of an old spacecraft called Surveyor 3. Between 1966 and 1968, five Surveyor probes had set down on the moon, providing hard proof that the regolith was firm enough to land on and allaying fears that the astronauts
might sink up to their chins in lunar quicksand. Surveyor 3’ s final resting place was within walking distance of the Apollo 12 landing site, and the astronauts had been instructed to bring parts of it home for examination. One of them, Alan Bean, noted at the time that the probe’s bright- whi te sur face had, after two- anda-half years on the moon, turned a tan colour.
In 2011 Me t z g e r a nd his colleagues proved that “it was actually ultrafine dust embedded all over the microtexture of the paint”. The bigger question was how the dust got there. As Surveyor 3 landed in the near-vacuum of the moon, the exhaust gas from its engine should have pushed dust away from the spacecraft. Metzger’s team couldn’t explain it.
By that point, the Constellation Program had been cancelled. The new rockets were over budget and behind schedule, and the Obama administration decided that this particular headache was better left to the private sector.
A few years later, Metzger joined the planetary science faculty at the University of Central Florida. His final project at Swamp Works was to come up with moondust mitigation strategies – magnets, reusable dust filters, artificial electrostatic charges to repel the dust and make it fall off surfaces, and ‘air showers’ or ‘wands’ to blast it off suits. Even with plans for an American moon base off the table, Metzger says, it had become “the consensus belief” while he was at NASA that “the biggest challenge to lunar operation is the dust”. In 2015, long after he’d given up on solving the mystery of the Surveyor 3 dust deposits, Metzger heard about a series of recently published papers by Brian O’Brien. They contained a truly remarkable theory about moondust. As he read, Metzger realised this was the first acceptable explanation he’d found for his conundrum. And it was based, amazingly, on the data from the original DDE tapes.
O’BRIEN GOT BACK in the moondust game by happenstance. In 2006, when he was in his 70s, a friend mentioned reading something on a NASA website about the sorry state of certain Apollo tape archives. O’Brien decided to track down his own reels.
HAMMERING BY MICROMETEOROIDS MAKES THE SOIL FINE AND GLASSY
They turned up in a room beneath the physics department at Perth’s Curtin University. They were covered in dust, but they were there, all 172 of them, each one containing about 750 metres of tape. The only problem was that they were in a format so obsolete that the data was beyond O’Brien’s reach. He sent an email to NASA, offering to repatriate the tapes, but the agency politely declined.
A loca l radio journal ist heard rumours of the discovery and broadcast a story. The news made it s way to Guy Holmes, a physicist who founded Spect rum
Data, which specialised in digitising large volumes of data from old tape formats. Holmes phoned O’Brien and offered his help, for free. He said he would store the tapes in a special climate-controlled vault until they could find the right machine to decode them. O’Brien gratefully accepted.
Even if Holmes succeeded in his search, O’Brien wasn’t sure he’d ever find funding to reanalyse the data. But he felt he had one last chance to set the record straight on moondust. So he got to work revisiting his old SILLIAC analyses and paper printouts, determined to publish a peer-reviewed article. It appeared in 2009, almost 40 years after his original moondust paper. O’Brien examined data from the DDE that flew on Apollo 12. That detector differed from its predecessor: it had one horizontal solar cell on top and two vertical ones on the sides. They’d been blanketed in dust as the astronauts loped around on moonwalks, t hen bl a s ted pa r t l y c l ea n when the Lunar Module took off. Curiously, though, one of the ver t ical cel ls became completely clean overnight. O’Brien’s explanation for this was that the electrostatic charge of the dust – the major source of its stickiness – changes over the course of the long lunar day. When the sun is high and UV radiation is at its peak, the dust is extra charged, and thus extra sticky. When the sun goes down, the dust seems to lose some of its adhesive force. If Pete Conrad had still been on the moon at sunset, he might have had better luck vacuuming off his suit. Within two months of the article’s publication, O’Brien had been made
an adjunct professor at the University of Western Australia. He was invited to speak at the second annual Lunar Science Forum, held at NASA’s Ames Research Center in California. The room was so packed at his presentation that people spilled out into the corridor. There was communal disbelief among the younger moon enthusiasts that they’d never heard of O’Brien or his DDEs. “After that, things started to bubble,” he says.
IN EARLY 2010, Holmes located an old IBM 729 Mark 5 tape drive in the warehouse of the Australian Computer Museum. It was the size of a two-door refrigerator and in terrible condition. The museum agreed to lend it to him. A group of SpectrumData employees donated their time to fix it up. The tapes were carefully heated to draw out any moisture, then unravelled at extra-low speed. Holmes says he was very emotional during this salvage process, keenly aware of its historic importance and the trust O’Brien had placed in him.
Eventually, the team managed to decode and extract most of the data. An undergraduate named Monique Hollick, now a space systems engineer for the Australian Department of Defence, signed up to help him analyse the resurrected data. This took them several years. By 2015 they were ready to unveil an even stranger new theory about moondust.
O’BRIEN HAD ALREADY EXPLAINED how the Apollo 12 DDE got clean; what he hadn’t explained was how, in the days following the astronauts’ departure, it got dusty again. His and Hollick’s hypothesis went as follows: after the astronauts set off on their journey home, leaving the DDE behind to broadcast its readings, the sun went down for about two Earth weeks.
When it rose again, it showered the ‘collateral dust’ they’d kicked up – more than two tonnes in total – with UV radiation. This caused the dust particles to become positively charged. They began to “mobilise and shuffle around,” O’Brien says, like a “ground mist swirling”. Repelled by one another and by the moon’s surface, they levitated. This created a small dust storm high enough to reach the DDE. The next time the sun rose, the same thing happened, and the next, and the next. Each time, the storm got a little smaller, until finally there was no collateral dust left to feed it.
This is still a somewhat controversial theory. Schmitt, the astronaut- geologist who f lew on Apollo 17, is not entirely convinced, because most of the rocks he saw on the moon were free of dust. “If fine dust were levitating and redepositing with any lateral motion at all,” he wrote to me, “I would not expect rock surfaces to be clean.” In his own correspondence with Schmitt,
O’Brien suggested that those rocks had lost their dusty coating as the sun’s angles changed.
The debates are ongoing.
“We really won’t know until we go there,” Metzger says. He feels pretty confident, though, that O’Brien is right and that his theory solves the Surveyor 3 mystery. Anyone planning a moon mission, he says, should expect levitat ing dus t s t orms every sunrise and dust stickiness during the lunar day.
Wi t h cou ntries and companies jostling to set up operations in the moon’s most desirable sites
– mainly the lunar poles, where water ice is supposedly abundant – life up there could quickly devolve into a dusty and chaotic mess, ripe for human conf lict. The Hague International Space Resources Governance Working Group has already begun drafting recommendations for lunar ‘safety zones’ and ‘priority rights’. Perhaps they ought to include a clause on housekeeping.
ON THE WALL of O’Brien’s garage office in Perth is a signed photograph of the Apollo astronaut class of 1964. Buzz Aldrin and Gene Cernan smile from the bottom row, looking nifty in suits and ties. Beside this is a photo of O’Brien with Cernan during Cernan’s visit to Perth in 2016, the year before he died. “We both look a bit different there to when I lectured him,” O’Brien said when I stopped by his house one afternoon in February 2019. I asked what they’d talked about. “Moondust,” he replied with a grin. O’ Brien was gearing up for a trip to Texas, where he was due to present at a NASA conference cal led Microsymposium 60: Forward to the Moon to Stay. He’d be making the journey alone; his beloved wife died in 2017. O’Brien was concerned about how he’d get the compression stockings off on his own after the flight, but undaunted by the thought of presenting to a crowd of 200, including representatives from the US companies authorised by NASA to deliver payloads to the moon. He said, somewhat enigmatically, “I look forward to a lot more dust detectors.” On the shelves of O’Brien’s office, space memorabilia worthy of a major geek-out was unceremoniously jumbled. I inspected life-size models of his various DDEs, with plaques affixed describing which
MOONDUST IS DEFINITELY WORKING ITS WAY INTO THE ZEITGEIST
Apollo mission they flew on. O’Brien was happy to let me play with shiny models of China’s Chang’e-3 lander and Yutu rover on the coffee table, so long as I first put on white gloves. They were given to him in Beijing by the Chinese Academy of Space Technology, which got in touch after he suggested that the cause of Yutu’s unexplained immobilisation in 2014, after its first lunar sunrise, was a dust storm – and cheekily recommended that next time they equip the rover with a dust detector. It seems that Chang’e-3 made some dust measurements, which the Chinese have confidentially shared with O’Brien.
A few days after O’Brien returned from Texas, I called him to ask how the conference had gone. Moondust is definitely working its way into the zeitgeist, he was happy to report. Back in 2009, when he gave his first talk to the lunar research community, “I knew nobody and nobody knew me.” This time around, almost everyone knew him.
He admitted that, as he wandered down the long, endless corridors of strange airports and conference complexes, he felt every bit his advanced age. “But when I came out of the Microsymposium, and for several weeks after,” he said, “I felt young again.”
Brian O’Brien is due to return to Texas this year to speak at the Lunar and Planetary Institute’s conference, ‘The Impact of Lunar Dust on Human Exploration’. Philip Metzger has been awarded a NASA grant to research how rocket exhaust blows dust.