Stephen HutcheonNovember 9, 2007 - 9:50AM
Two months after adventurer Steve Fossett disappeared over the Nevada desert, the plug has been pulled on an experimental online search mission that harnessed the collective efforts of some 50,000 volunteers around the world.
Last week, without warning, online retailer Amazon.com shut down the collaborative search it began hosting just days after the 63-year-old aviator failed to return from a routine flight on September 3.
Amazon's Mechanical Turk (MTurk) site enabled volunteers to pore over high-resolution photographs covering parts of the 44,000 square kilometres of uninhabited wilderness where the physical search mission has been taking place.
The decision to wrap it up was made, according to Amazon spokeswoman Kay Kinton, in consultation with the official Fossett search team on the ground, which is now pinning its hopes on computer-aided image-scanning technology.
It came exactly four weeks after the US Civil Air Patrol ended what it said was "one of the largest, most intensive searches for a missing aircraft in modern history".
The online component of the search reached a similar scale. "Tens of thousands of people participated in the [online] search overall", Kinton said in an email, with "several thousand" participating on any given day,
The Amazon decision, however, came as a surprise to Kenneth Barbalace, an internet publisher from Portland in the US state of Maine who had been scanning the satellite images posted on MTurk since day one.
"We had just gotten all the tools in place for it to become really effective and then they cut us off," he said in a telephone interview.
An enthusiastic supporter of the online effort, Barbalace spent between 10 to 14 hours a day examining images on is computer during the first few weeks after Fossett went missing. Overall, he perused 25,500 photos over eight weeks.
He considers this exercise to be one of the "noble uses of the internet" and has mused on his blog about how enabling volunteers to scour the landscape from their desks could one day revolutionise the practise of search and rescue.
But, in the early weeks of the Fossett search, he had to take a reality check. Poor coordination and communication, the use of images with less than optimal resolution and a large posse of well-meaning but uninformed helpers combined to hobble the online effort.
And according to Landis Bennett, a volunteer searcher from San Francisco who participated in both the physical and online missions, the experiment in mass collaboration even disrupted the official search effort on the ground.
"In the beginning, it was a lot along the lines of the boy who called wolf," Bennett said in a telephone interview.
To make matters worse, some of the online volunteers circumvented the protocol for reporting finds, opting to "go vigilante" - as Bennett put it - and convey their theories directly to the official search coordinators.
He recalled one incident where a man spotted something on a satellite image, insisting it was a strong lead in the search for Fossett's single-engine Bellanca Super Decathlon.
Bennett, who is also a cartographer, examined the image and concluded it was old data. "But we ended up going out just to keep everyone happy," he said.
The Amercians' take on the experience is supported by Kevin Pusey, the publican at the Grand Hotel in Kookynie, a mining town about 150km north of Kalgoorlie in Western Australia.
Pusey is also one of 16 moderators on the Google Earth Community site and he monitored much of the conversation about the online search that was taking place on the forums.
A record number of comments - over 5000 - have been posted on the Steve Fosset thread on the Google Earth forums and Pusey observed that some people were "a bit pissed off" when Amazon pulled out.
Mechanical Turk - named after an 18th century chess-playing mannequin that was dressed in Turkish costume and controlled by a chess master secreted inside - is a site where people perform paid or unpaid tasks that cannot be adequately performed by computers.
It was first used in a similar search mission when Jim Gray, a renowned Microsoft computer scientist, went missing in his yacht in the seas off San Francisco in January. He was never found, but when Fossett disappeared, Amazon quickly put the MTurk experiment back into action.
Thousands of photographs, each representing about 85 square metres of the rugged Nevada terrain, were posted onto the Amazon site initially from data supplied by satellite imaging companies DigtialGlobe and GeoEye.
Anyone interested could sign up and participate in the search by overlaying the recent images onto the Google Earth program. This made it easier to scan the photos and check their findings against the reference point of older satellite shots.
The process of tapping a distributed knowledge base is known as crowdsourcing. It is similar to the way Wikipedia works, for instance. Entries in the online encyclopedia are the culmination of the efforts of many different contributors and editors.
The downside to crowdsourcing is that when every man and his dog jumps in, it can swamp the exercise. And that's exactly what happened in the Fossett search.
Both Barbalace and Bennett say because many volunteers had no idea what to look for, the process began to get overwhelmed with false positives.
"Let's just say that the signal-to-noise ratio was really not good enough to be of much use," said Bennett who flew a total of eight 2½- to 3½-hour sorties over the search zone as well as spending hours online.
The inadequate image resolution meant there was a lot of guessing going on. "People were reading into the imagery and seeing whatever it was they wanted to see," he said.
Like a poorly organised ground search, the online version was literally going around in circles.
Despite the initial hiccups, Barbalace said the experience was gained from the Fossett search could be used to improve the system the next time a similar opportunity arose.
And, even as Amazon was winding down its involvement, the fog was clearing. The searchers were better informed, there were fewer cowboys and the images were of a higher resolution.
"I'm sure [with some refinements] it could become a fantastic search tool," said Barbalace.
And Kevin Pusey pointed out that although the online searchers failed to find any trace of Steve Fossett, they did discover about half a dozen earlier crash sites - vindicating the theory that the wisdom of the crowds works ... sometimes.
:: Official Steve Fosset site
:: Landis Bennett's site
:: Kenneth Barbalace's site
:: The Google Earth Community Steve Fossett discussion thread
:: Mechanical Turk's Steve Fossett page