- By Sam Cabral in Washington and Madeline Halpert in New York
- BBC News
Investigators will be looking for clues as to why a balloon of Chinese origin flew over US airspace last week when they recovered the wreckage of the plane.
The balloon, which the Pentagon said was spying on sensitive military sites, was shot down over US territorial waters on Saturday.
Debris was spread over a large area off the coast of South Carolina.
China insists it was a stray weather vessel and has expressed “strong displeasure” at its sinking.
US Navy divers are working to salvage as much debris from the balloon as possible, including any equipment on board.
So what do investigators hope to learn once the balloon debris is recovered?
“We don’t know exactly all the benefits that will come from it. But we have learned some technical things about this ball and its surveillance capabilities,” a senior defense official told reporters on Saturday. “And I think if we manage to recover certain aspects of the debris, we will learn even more.”
Experts who spoke to the BBC said the balloon’s contents were key to discovering its purpose and capabilities.
Iain Boyd, professor of aerospace engineering sciences at the University of Colorado at Boulder, said neither official explanations from Beijing nor those from Washington made sense yet.
“There are doubts on both sides and that’s part of what’s so interesting about all of this,” he said. “I think the truth lies somewhere in the middle of it all.”
Mr Boyd said that if rescue teams recovered enough instruments, they would probably be able to find out how much information they contained, what kind of information was being processed and whether any processed data had been or was being processed. sent back to China.
Seeing the balloon up close – and finding out if it had features such as propellers or communications equipment – will also help determine if it was remotely controlled, he said.
Even if the software is damaged or has been erased in some way, Boyd said investigators would be able to assess things like the resolution and quality of the surveillance footage he could have taken.
“It would be very surprising if there was technology on this platform that the United States does not already have in an equivalent form, but it has the potential to give intelligence services here an understanding of technological maturity. that the Chinese have for these types of applications,” he said.
The United States will work to find all the sensors it can in the wreckage of the balloon to use it to discover the plane’s purpose, said Gregory Falco, assistant professor in the Department of Civil and Systems Engineering. from Johns Hopkins University.
But it won’t be easy to do, he told the BBC, because the sensors – which detect different types of wavelengths – are usually small and may have been damaged after the US military fired on them. the spy balloon. He said video footage of the incident could not determine how much damage had been done to the plane.
China, like the United States, is a “pretty clever adversary”, and also likely intended the plane to self-destruct or scramble data as part of the spy mission, Dr Falco said.
“Putting this thing down was just a show of national pride more than anything, because I don’t know what we’re going to get out of it,” he said.
But information from the downed ball could help US officials “understand their opponent a little better”, he said.
The United States could find out how the data captured by the plane was sent back to China, Dr Falco said. The country may have used a “hybrid satellite network,” which uses high-altitude platforms to relay data to the closest orbit-compatible satellite. Once the satellite is in safe territory, it connects to a ground station or antenna that functions as a control system, Dr. Falco said.
China has “a huge range of ground stations that are outside of China,” Dr Falco said. As long as the balloon was able to connect to a satellite, which would then link to a ground station, China would be “all ready with its data” and could clear the balloon, he said.