Best lead yet? Satellite spots possible debris field in search for Flight 370

Experts say it's possible the materials may have drifted or sunk.

Search aircraft did spot three objects, but teams weren't able to locate them again in several passes through the area, the Australian Maritime Safety Authority said.

The latest objects seen on satellite images provided by Airbus Defence and Space range from about 3 feet (1 meter) to about 75 feet (23 meters), Hishammuddin said. Some appear bright, indicating they may be solid, he said.

The latest images appear to be the most significant discovery yet in the hunt for the missing plane, which vanished March 8 with 239 people aboard, said CNN aviation analyst Miles O'Brien.

"There's a very good chance this could be the break we've been waiting for," he said.

Aviation safety analyst David Soucie agreed, saying he was particularly intrigued by the size of the 75-foot object.

"It has potential to be a wing that's floating," he said. "So I'm really encouraged by it, I really am."

But satellites have captured images of objects before during the current search, crews have yet to spot anything definitively linked to the airplane and ships haven't recovered anything of note.

"This is a positive indication that the searchers are getting closer to the origin of the crash, but there are many uncertainties," said Ian MacDonald, an oceanographer at Florida State University. "There could be many objects floating in the ocean, that are large or small, that are completely unrelated to the crash."

Until searchers get their hands on the objects, he said, it's too soon to say whether they are parts of the plane or garbage floating in ocean waters.

Officials have warned that objects spotted in the water may turn out to be flotsam from cargo ships, and that finding anything from the plane still could take a long time.

"There's always a possibility we might not actually find something next week or the week after," Mark Binskin, vice chief of the Australian Defence Force, told CNN's Kate Bolduan on Tuesday. "I think eventually, something will come to light, but it's going to take time."

The search resumed Thursday morning as a Chinese military plane took off for the search area in the southern Indian Ocean, Australian authorities said.

Six military reconnaissance planes -- from Australia, the United States, China and Japan -- and five civilian aircraft are set to comb the vast search area again on Thursday.

Five ships -- one from Australia and four from China -- also are in the search zone, Australian authorities said.

An ongoing FBI review of the missing jet's pilots' hard drives, including the captain's flight simulator, has not turned up a "smoking gun," a U.S. official with knowledge of the investigation told CNN.

"They have accessed the data," the official said. "There is nothing that's jumping out and grabbing us right now."

The official would not reveal what was on the hard drive, but said the Malaysia Airlines pilot did not encrypt any of the files nor did he appear to go to any great lengths to scrub the hard drive when he deleted files last month.

FBI Director James Comey said earlier Wednesday that he expects the information would be handed over to the Malaysians in the next day or two. "I have teams working literally around the clock to try and exploit that,'' Comey said. "I don't want to say more about that in an open setting. But I expect it to be done fairly shortly within a day or two, to finish that work."

The information retrieved from the hard drives will hopefully give investigators leads to follow regarding the pilot's backgrounds, such as their finances and emotional state and who they had been communicating with.

U.S. investigators continue to be baffled by the plane's disappearance, with one U.S. official saying, "I don't think there is a prevailing theory. There are counterarguments to every theory right now."

Investigators are still focusing on the pilots, even though no physical evidence, such as a suicide note, has been found in their homes that would suggest they were planning the plane's disappearance. One of the main reasons for the continued focus on the pair is that there is nothing else explaining what happened, sources say.

Citing an anonymous high-ranking officer attached to a special investigative branch of Malaysian police in Kuala Lumpur, USA Today reported Wednesday that investigators believe the plane's captain was "solely responsible for the flight being taken hundreds of miles off course."

Investigators are now pressing Capt. Zaharie Ahmad Shah's family for more details, USA Today world news editor William Dermody told CNN.

"Some of it's process of elimination," Dermody said. "They can't find any other rationale for it, and according to the evidence they have thus far, they don't believe that the plane was mechanically disabled. They feel that it had to have been done manually, and the only person who could have done that on the plane was the pilot."

But a senior Malaysian government official told CNN law enforcement analyst Tom Fuentes that they have found nothing negative so far in 19 days of investigating the two pilots that leads them to any motive, be it political, suicidal or extremist.

"The people in the cockpit are a top priority," a senior U.S. government official said. "We are heavily dependent on the Malaysians to do a deep dive on personal lives."

Another U.S. official said nothing was flagged after a study of the passengers onboard the plane and that "no terrorism stuff is moving forward" at this stage in the investigation.

If search teams are able to find debris confirmed to be from the plane, it will help officials figure out roughly where the aircraft went down.

They would then be able to focus the search under the water to try to find larger pieces of wreckage and the all-important flight data recorder, which may hold vital clues about what happened the night the plane disappeared.

U.S. hardware designed to help with that task arrived Wednesday in Perth, the western Australian city that is the base for the search efforts.

The United States sent a Bluefin-21 autonomous underwater vehicle, which can search for submerged objects at depths as low as 14,700 feet (about 4,500 meters), and a TPL-25, a giant listening device that can help pinpoint the location of pings from the flight data recorder. Towed behind a ship, the TPL-25 can detect pings at a maximum depth of 20,000 feet (about 6,100 meters).

The Indian Ocean has an average depth of about 13,000 feet (about 4,000 meters).

Time is against that part of the search, though, as the pingers that send signals from the plane's voice and date recorders are expected to run out of power within the next two weeks.

CNN safety analyst David Soucie, author of "Why Planes Crash," said Wednesday there's a chance the batteries powering the pingers could have been stored improperly and might be dead already.

That doesn't mean the recorders can't be found, but it would complicate the investigation. Searchers found the recorders from Air France Flight 447 two years after the plane's 2009 crash, long after the battery died.

The wait for answers about what happened to the plane and where it is now has taken a toll on the relatives of those on the flight.

Chinese kin have been particularly upset by Malaysian authorities' announcement Monday, based on analysis of satellite data, that the plane had crashed into the southern Indian Ocean with the loss of all lives aboard.

"It is still theory, and it's just still analysis" said Stephen Wang, whose mother was on the missing flight. "No one have seen anything."

Many relatives of those missing haven't accepted the theory, and still think their loved ones might still be alive, Wang told CNN's Pauline Chiou.

"To me, I think it might be 5% that there is still hope, but most of the families don't believe that it might be bad news," Wang said. "Most of the families still think that there will be hope."

On Wednesday, some families accused Malaysia Airlines of falling short of its promises to provide volunteer caregivers and accommodations for some family members. The airline couldn't immediately be reached for comment and did not send a representative to a news conference Wednesday.

The complaints came a day after hundreds of Flight 370 family members marched to the Malaysian Embassy in Beijing -- the flight's destination -- to voice their anger and frustration.

Some said the Malaysian government was covering up the truth and demanded tangible evidence the plane had ended up in the ocean.

The Chinese government, whose citizens made up two-thirds of the passengers on board the missing plane, also said it wanted more information from Malaysia. President Xi Jinping has sent a special envoy to Kuala Lumpur to deal with the matter.

Malaysian officials met with the Chinese envoy, said Hishammuddin, the transport minister, and briefed them extensively on the analysis of the satellite data that led to the crash conclusion.

The Malaysians' comments appeared to have done little to placate the anger among the families, however, and it appeared to be spreading more widely among the Chinese public.

Some Chinese celebrities used social media to urge people to boycott Malaysian products and visits to the country.

Chen Kun, one of China's most popular actors, accused the Malaysian government and Malaysia Airlines of "clownish prevarication and lies." His post Tuesday calling for a boycott was reposted more than 65,000 times on Weibo, China's Twitter-like microblogging platform.

"I've never been to Malaysia, and I will no longer plan to go there anymore," Meng Fei, the host of one of China's most popular TV shows, wrote Wednesday on Weibo, calling for others to repost the comments if they felt the same. More than 120,000 users did.

Other social media users, albeit with smaller followings, argued against punishing Malaysia over the matter.

Chen Shu, a journalist, warned that a boycott would "hurt the relationship of Chinese and Malaysians" and long-term regional ties.

Chinese authorities regularly censor Weibo posts. The fact the anti-Malaysian posts by high-profile users weren't deleted suggested either tacit approval or at least an unwillingness to wade into the debate by Chinese government censors.

Hishammuddin, however, praised his country's performance, saying officials had overcome significant diplomatic challenges to bring together 26 countries, at one point, to participate in the search.

"History will judge us well," he said.