Authorities say they were always "confident" they were going to find a Tic Tac-sized radioactive capsule that sparked a frantic search after it "fell off the back of a truck" in Western Australia's outback.
The tiny capsule, which was found Wednesday after being lost somewhere along a 1,400-kilometre journey between a Pilbara mine site and a depot in Perth's north, arrived in Perth on Thursday evening.
No chances were being taken with the transport of the 6mm-by-8mm capsule after its remarkable recovery, with it being escorted by 14 personnel from the Department of Fire and Emergency Services (DFES), the Australian Defence Force, and personnel from the Australian Nuclear and Science Technology Organisation to a top-secret facility.
DFES incident controller Darryl Ray said he was "pretty confident" the capsule was going to be found.
"If it was on the route that we were going to search, the equipment was going to find it," he said.
"The question was whether or not a tyre had picked it up and taken it off the route — that was probably the only doubt I would have had about locating it.
"But I was pretty confident since day one of finding it where we looked."
There was palpable relief when authorities announced they had found the capsule.
Its loss had sparked a desperate search and even made international headlines.
So, what do we know about the disappearance and remarkable recovery of this minuscule capsule that sparked an urgent health warning, what questions remain unanswered and what can we learn to ensure this never happens again?
What do we know?
The capsule was found around 11am on Wednesday about 74km south of Newman on the Great Northern Highway, not far from the Rio Tinto mine site where it started its ill-fated journey.
It was recovered following a painstaking search by specialist teams spanning more than 1,000km, which was likened to trying to find a needle in a haystack.
Authorities had informed the public the caesium-137 capsule had disappeared on January 27, two days after they learned it was missing when the container it was being transported in was unpacked.
At that press conference, they theorised it had literally fallen off the back of a truck some time between January 11 and January 16, when it arrived in Perth.
The good news is the capsule does not appear to have been moved after it fell from the truck, indicating that no-one had handled the potentially deadly object, which emits radiation equivalent to 10 X-rays an hour.
Authorities had warned a person exposed to the capsule could suffer burns and radiation sickness.
"It does not appear to have moved, it appears to have fallen off the back of the truck and landed on the side of the road, it is remote enough that it's not in any major community," assured Chief Health Officer Andy Robertson.
"So it is unlikely that anybody has been exposed to the capsule."
What don't we know?
The public will need assurance there were no environmental consequences, including whether there was any impact on flora and fauna.
Department of Fire and Emergency Services Commissioner Darren Klemm's comments on Wednesday were encouraging, but these issues will need to be considered as part of a full investigation that has been launched into the debacle.
"In the extremely unlikely situation that the capsule leaked, we will remediate the area," Commissioner Klemm said on Wednesday.
The capsule was part of a gauge to measure the density of iron ore, which is commonly used in the mining industry.
Authorities believe it came loose from the gauge before falling through a hole left by a bolt that had been dislodged, after a container collapsed on the truck as a result of "vibrations" during the trip.
But this explanation has left multiple experts baffled, with Radiation Services WA general manager Lauren Steen describing it as a "highly unlikely" scenario, in light of stringent safety measures typically in place for the transit of radioactive materials.
"Typically they're transported in highly protected casing that are subject to a certification verification stage. The housing is subjected to rigorous testing for vibrations, heat, high impact," Ms Steen said.
Wearing his other hat as the chair of the WA Radiological Council, Dr Robertson will take carriage of the investigation that will aim to get to the bottom of exactly how the dangerous capsule escaped from the truck.
Crucially, investigators will look at whether strict protocols for the preparation and transport of radioactive materials were followed.
Dr Robertson said a failure to adhere to the requirements would result in a prosecution, and a final report will be handed to the health minister for further action.
Can we expect tighter regulations?
The WA government has already committed to reviewing its penalties for mishandling radioactive materials, after the ABC revealed the penalty for failing to safely store, pack and transport such items was a measly $1,000 fine.
Even Prime Minister Anthony Albanese weighed into the issue when he visited WA on Wednesday, describing the fine as "ridiculously low".
WA Health Minister Amber-Jade Sanderson said the government would consider how it can amend the outdated legislation, which was developed in the 1970s.
"The current fine system is unacceptably low and we're looking at how we can increase that," she said on Wednesday.
Radiation experts hope the saga comes with a silver lining by bringing attention to an important issue that has flown under the radar for too long.
Magdalena Wajrak from Edith Cowan University believes the attention can bring about positive change to prevent this from happening again, as well as reducing stigma and improving education about radiation.
"I think this story has highlighted the fact that ... we need people who understand about radiation, how to deal with radiation, how to handle it," she said.
"We need to train more people ... we need more radiation radio-pharmacists, we need more radio-chemists, and physicists."
It's a sentiment shared by ECU PhD student Madison Williams-Hoffman, currently researching radiation in collaboration with the Australian Radiation Protection and Nuclear Safety Agency, which helped to find the capsule.
"Radiation is inevitable. We're surrounded by it every day," she said.
"Hopefully there will also be lessons that can be learned from an event like this."
At a press conference on Thursday, Dr Robertson said the regulations for handling radioactive materials were among the most up-to-date in the world.
"Whilst a few people have raised concerns about the regulations, we comply with the national and international regulations around the transport and storage of these materials," he said.
"They are linked to any changes to national or international regulations."
Who will foot the bill for the search?
The potential $1,000 fine that may or may not eventuate following the investigation seems paltry in comparison to the yet-to-be-confirmed cost of the search operation, which spanned hundreds of kilometres and involved more than 100 personnel using highly specialised detection equipment.
The manufacturer of the gauge, Rio Tinto and the contractor used by the miner to transport the capsule will be grilled as part of the probe.
While the cost of the search is still yet to be worked out, DFES incident controller Mr Ray said it was likely to be in the tens of thousands of dollars.
"No dollar figures on it at the moment," he said.
"There's been 60 people [involved in the search], there's a lot of aircraft flying over, there's accommodation, there's vehicles, there's overtime, it all adds up."
Rio Tinto iron ore chief executive Simon Trott said the company would reimburse the state for the search if asked to.
"I would be happy to reimburse the cost of the search, of course that ultimately is a matter for the state government," he said.
"There will be a full investigation, we'll fully cooperate with the investigation, if as part of that there's a request from government, we would be happy to reimburse the cost of the search."
He said the world's second largest metals and mining corporation was committed to learning from the incident, to ensure a similar incident is not repeated.
"We need to learn from this so we can put in place additional controls to ensure that this never happens again," he said.
