US spy satellites detected no sign of a mid-air explosion when a Malaysian airliner lost contact with air traffic controllers, American officials said Wednesday.
The US government in the past has used its satellite network to identify heat signatures linked to exploding aircraft but in this case, nothing was found, according to US officials, who spoke on condition of anonymity.
The absence of evidence of any mid-air explosion has added to the mystery surrounding the fate of Malaysia Airlines flight MH370, which disappeared at about 1730 GMT Friday after taking off from Kuala Lumpur bound for Beijing.
NBC News first reported the lack of satellite results.
With no specific area identified by satellites, US naval ships that joined the search effort in the South China Sea were not sent to a particular location to look for debris, officials said.
"If they had picked up something (by satellite), our ships would have been sent to that spot,"one official told AFP.
The hunt for the missing Boeing 777 now covers a vast area of nearly 27,000 nautical miles (over 90,000 square kilometres).
Organizers said Wednesday an international pool of satellites from different countries has joined the search effort for the missing airliner, with plans to share images from orbiting satellites.
According to author and intelligence historian Jeffrey Richelson, the US government's space infrared satellite system detected the blast that brought down TWA Flight 800 in 1996 in the Atlantic Ocean, shortly after take-off from JFK airport in New York City.
In his book "America's Space Sentinels," Richelson describes the satellite network that was initially set up to relay instant warning of an imminent Soviet missile launch.
Although the "Defense Support Network" satellite system was created to detect the infrared signals from missile launches, it "proved to be valuable in a number of other ways -- such as detecting aircraft flying on afterburner, spacecraft in orbit, and terrestrial/atmospheric explosions, if of sufficient intensity," Richelson said by email.
"Thus, DSP data was examined after a number of air crashes," he said.
The satellites have detected a mid-air collision over the Grand Canyon, the crash of a stealth fighter jet, the crash of an A-10 aircraft and the collision of US and German military planes off the coast of Africa in 1997, he said.
Investigators examined DSP satellite data after the disappearance of Air France Flight 447 in 2009, which went missing after taking off from Rio de Janeiro en route to Paris, he said. But it's not clear any clues were found, he added.
The spy satellites also have been used to track forest fires and detect meteorites, according to the book.