Story highlights The Bluefin-21 begins 12th mission after scanning more than 90% of search area 
 
 Analysis of photos shows an object found near Augusta isn't a lead in the search 
 
 Passenger's family member asks: Are they searching in the right place? 
 
 Analyst: Search area is "the place they had to look" 
 
 A metal object that washed ashore on Australia's coast wasn't from Malaysia Airlines Flight 370, officials said. 
 
 Detailed pictures of the object were enough to convince investigators that it wasn't a lead in the search for the missing plane, the Australian agency leading the search for the aircraft said on Thursday 
 
 Officials had previously called the piece of metal, which appeared to have rivets on one side, an "object of interest" in the search. 
 
 Police picked it up near Augusta, Australia, roughly 1,000 miles away from the suspected crash site, after many futile days of searching for the missing plane. 
 
 Authorities haven't said what they think the object could be. 
 
 Possible promising leads have turned out to be false alarms for weeks in the lengthy search for the missing plane, which disappeared mid-flight on March 8 with 239 people aboard. One major challenge that's complicated the search: the ocean is full of garbage . Other objects search teams have spotted in the Indian Ocean turned out to be trash, jellyfish and fishing gear. 
 
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 Bad weather grounded planes searching for signs of debris on Wednesday. And a high-tech underwater drone found no sign of the Boeing 777 jetliner. 
 
 And as the search came up empty again, a key question loomed: Are they looking in the right place? 
 
 "They have been searching for more than a month. All of the ships, the planes, the satellites they're using, not even a small piece of the plane was found," Steve Wang, whose mother was aboard the aircraft, told CNN's "The Lead with Jake Tapper" on Thursday. 
 
 Abbott: 'We may rethink the search, but we will not rest' 
 
 Up to 11 military aircraft and 11 ships are set to search for the plane on Thursday. 
 
 And there's still ground left to cover. 
 
 The Bluefin-21 has scanned more than 90% of the underwater search area set out by investigators and began its 12th mission on Thursday. 
 
 "We will continue with the search operation until we fully cover the search area," Hishammuddin Hussein, Malaysia's acting transport minister, said Wednesday. 
 
 Despite the search efforts for MH370 repeatedly coming up empty during the 48 days since it started, there's no suggestion the hunt in the southern Indian Ocean is anywhere close to ending. 
 
 Quite to the contrary, according to Australian Prime Minister Tony Abbott, whose country is heading up the search for the missing aircraft. 
 
 "We are not going to abandon ... the families of the 239 people who were on that plane by lightly surrendering while there is reasonable hope of finding something," he said Wednesday. "We may well rethink the search, but we will not rest until we have done everything we can to solve this mystery." 
 
 What comes next? 
 
 Malaysian and Australian authorities are already mapping out a long-term strategy for the search, which could go on for months or years, if the two-year search for Air France Flight 447 is any guide. 
 
 Guidelines drafted by Malaysia raise the possibility of a significantly wider search area should the current underwater search fail to turn up evidence of the plane. The document discusses how best to deploy resources, including new underwater search assets. 
 
 If the underwater search comes up empty, it could ground the air search as well, CNN aviation analyst Miles O'Brien said. 
 
 "If it doesn't pan out, then all the equations that have been put in the mix to determine where debris might be ... all of that is for naught," he said. 
 
 The next logical step after the underwater search is to "rethink all of the information we have at hand," ocean search specialist Rob McCallum told CNN. 
 
 An expanded search area might include the last 370 miles of the plane's flight path, perhaps 15 miles on either side, he said. 
 
 He also said it would make sense to turn to deep-towed sonar, which provides less resolution than the Bluefin-21 but about 10 times the range. 
 
 If the search changes tacks, that doesn't mean investigators did the wrong thing by looking where they did for the plane, said CNN analyst David Gallo, who co-led the search for Air France Flight 447. 
 
 "It's the place they had to look. ... Everything pointed to this area," he said. 
 
 Going forward, he said, investigators may double or triple the size of the search area while using sonar to map the ocean floor "so you see where every pebble is." 
 
 "I just don't know how you leave this place before you take that area of the seafloor apart completely," he said. 
 
 What happens if data recorders are found? 
 
 Investigators would love to find the flight data recorders from Flight 370, a potential treasure trove of information into what happened to the jetliner and the 239 passengers and crew on board. 
 
 If found, the "black boxes" probably would go to the Australian Transport Safety Board's accident investigation lab. 
 
 But the investigation is officially Malaysian, so that country's officials would decide where the boxes would go. 
 
 Australia is just one of a handful of countries that have the capability and technical know-how to decipher what's inside a black box. 
 
 The investigation into Flight 370's disappearance is Malaysia's responsibility. Australia is leading the search for the missing aircraft and participating in the investigation as an accredited representative. 
 
 The Malaysian Cabinet approved the appointment of an international investigation team to look into the disappearance of Flight 370, Hishammuddin said. 
 
 The names of the members will be announced next week, he added. He also said the team will not be looking at the criminal aspects of the investigation, which remain under the Royal Malaysian Police. 
 
 "The main purpose is to evaluate and determine the cause of the accident," Hishammuddin said. 
 
 Malaysia has completed a preliminary report on the incident, as required by the International Civil Aviation Organization, but has not released it publicly, he said. ||||| CANBERRA, Australia (AP) — Unidentified material that has washed ashore in southwestern Australia is being examined for any link to the lost Malaysian plane, authorities said Wednesday. 
 
 In this map provided on Wednesday, April 23, 2014, by the Joint Agency Coordination Centre, details are presented in the search for the missing Malaysia Airlines Flight 370 in the southern Indian Ocean.... (Associated Press) 
 
 Police secured the material, which washed ashore 10 kilometers (6 miles) east of Augusta in Western Australia state, the search coordination center said in a statement, without describing the material found. The Australian Transport Safety Bureau is examining photographs to assess whether further investigation is needed and if the material is relevant to Malaysia Airlines Flight 370. 
 
 Augusta is near Australia's southwestern tip, about 310 kilometers (190 miles) from Perth, where the search has been headquartered. 
 
 Meanwhile, Australia's prime minister said Wednesday that failure to find any clue in the most likely crash site of the lost jet would not spell the end of the search, as officials plan soon to bring in more powerful sonar equipment that can delve deeper beneath the Indian Ocean. 
 
 The search coordination center said a robotic submarine, the U.S. Navy's Bluefin 21, had scanned more than 80 percent of the 310-square-kilometer (120-square-mile) seabed search zone off the Australian west coast, creating a three-dimensional sonar map of the ocean floor. Nothing of interest had been found. 
 
 The 4.5-kilometer (2.8-mile) deep search area is a circle 20 kilometers (12 miles) wide around an area where sonar equipment picked up a signal on April 8 consistent with a plane's black boxes. But the batteries powering those signals are now dead. 
 
 Defense Minister David Johnston said Australia was consulting with Malaysia, China and the United States on the next phase of the search for the plane, which disappeared March 8. Details on the next phase are likely to be announced next week. 
 
 Johnston said more powerful towed side-scan commercial sonar equipment would probably be deployed, similar to the remote-controlled subs that found RMS Titanic 3,800 meters (12,500 feet) under the Atlantic Ocean in 1985 and the Australian WWII wreck HMAS Sydney in the Indian Ocean off the Australian coast, north of the current search area, in 2008. 
 
 "The next phase, I think, is that we step up with potentially a more powerful, more capable side-scan sonar to do deeper water," Johnston told The Associated Press. 
 
 While the Bluefin had less than one-fifth of the seabed search area to complete, Johnston estimated that task would take another two weeks. 
 
 Australian Prime Minister Tony Abbott said the airliner's probable impact zone was 700 kilometers (430 miles) long and 80 kilometers (50 miles) wide. A new search strategy would be adopted if nothing was found in the current seabed search zone. 
 
 "If at the end of that period we find nothing, we are not going to abandon the search, we may well rethink the search, but we will not rest until we have done everything we can to solve this mystery," Abbott told reporters. 
 
 "We owe it to the families of the 239 people on board, we owe it to the hundreds of millions — indeed billions — of people who travel by air to try to get to the bottom of this. The only way we can get to the bottom of this is to keep searching the probable impact zone until we find something or until we have searched it as thoroughly as human ingenuity allows at this time," he said. 
 
 The focus of the next search phase will be decided by continuing analysis of information including flight data and sound detections of the suspected beacons, Johnston said. 
 
 "A lot of this seabed has not even been hydrographically surveyed before — some of it has — but we're flying blind," he said, adding that the seabed in the vicinity of the search was up to 7 kilometers (4 miles) deep. 
 
 The search center said an air search involving 10 planes was suspended for a second day because of heavy seas and poor visibility. 
 
 But 12 ships would join Wednesday's search of an expanse covering 38,000 square kilometers (14,500 square miles), centered 1,600 kilometers (1,000 miles) northwest of Perth. 
 
 Radar and satellite data show the jet carrying 239 passengers and crew veered far off course on March 8 for unknown reasons during its flight from Kuala Lumpur, Malaysia, to Beijing. Analysis indicates it would have run out of fuel in the remote section of ocean where the search has been focused. Not one piece of debris has been found since the massive multinational hunt began. 
 
 ___ 
 
 Associated Press writer Kristen Gelineau in Sydney contributed to this report.
– As the search for Malaysia Airlines Flight 370 continues, an "object of interest" has turned up in southwestern Australia—but officials are cautioning that it may not offer much of a breakthrough. "It's sufficiently interesting for us to take a look at the photographs," says an Australian official. But "the more we look at it, the less excited we get." An insider tells CNN the object's size is unclear based on photos, but it's "kind of rectangular" with rivets and an apparent fiberglass coating. Meanwhile, the Bluefin-21 underwater robot has completed more than 80% of its planned search without finding anything, the AP reports. But the overall investigation won't stop anytime soon: Indeed, it could continue for years, CNN notes. "The next phase, I think, is that we step up with potentially a more powerful, more capable side-scan sonar to do deeper water," says Australia's defense minister. Adds Australian PM Tony Abbott. "We are not going to abandon ... the families of the 239 people who were on that plane by lightly surrendering while there is reasonable hope of finding something."