The Chinese balloon that floated 60,000 feet over the United States was described by Secretary of State Antony Blinken as a “surveillance asset.” China’s Foreign Ministry released a statement saying it was merely a weather balloon. Experts in national security and aerospace said the craft appeared to share characteristics with high-altitude balloons used by developed countries around the world for weather forecasting, telecommunications and scientific research.
How do stratospheric balloons work? Here’s a visual guide.
Regardless of their specific use, these stratospheric balloons have a few main components.
An eye (very) high in the sky
The balloon floating over the United States appears to match the general characteristics of what aerospace engineers call a zero-pressure ultra-long duration balloon — a high-tech eye in the sky that can hover over a target area for weeks or months.
Pressure envelope
Filled with helium or hydrogen, about the thickness
of a sandwich bag
LIGHTER-THAN-AIR
GAS
OUTSIDE
AIR
Compressor
Solar panels
Payload
Might include cameras,
radar, communications equipment
Ballonet
This second bag
within the balloon
can be pumped full
of outside air, which causes the balloon
to grow heavier
and sink
Zero-pressure balloons come in many sizes; the one over the U.S. is large enough to be seen from the ground as it floats at 60,000 feet
Wind navigation
Operating in the upper stratosphere, these balloons navigate by rising and sinking to find winds blowing in the direction they want to go.
Sources: Aerostar International LLC; NASA
WILLIAM NEFF/THE WASHINGTON POST
An eye (very) high in the sky
The balloon floating over the United States appears to match the general characteristics of what aerospace engineers call a zero-pressure ultra-long duration balloon — a high-tech eye in the sky that can hover over a target area for weeks or months.
Zero-pressure balloons come in many sizes; the one over the U.S. is large enough to be seen from the ground as it floats at 60,000 feet
Pressure envelope
Filled with helium or hydrogen,
about the thickness
of a sandwich bag
LIGHTER-THAN-AIR
GAS
OUTSIDE
AIR
Inflation
valve
Deflation
valve
Ballonet
This second bag
within the balloon can be
pumped full of outside air,
which causes the balloon
to grow heavier and sink
Compressor
Solar panels
Payload
Might include cameras,
radar, communications equipment
Wind navigation
Operating in the upper stratosphere, these balloons navigate
by rising and sinking to find winds blowing in the direction
they want to go.
Sources: Aerostar International LLC; NASA
WILLIAM NEFF/THE WASHINGTON POST
An eye (very) high in the sky
The balloon floating over the United States appears to match the general characteristics of what aerospace engineers call a zero-pressure ultra-long duration balloon — a high-tech eye in the sky that can hover over a target area for weeks or months.
LIGHTER-THAN-AIR
GAS
OUTSIDE
AIR
Inflation
valve
Deflation
valve
Compressor
Solar panels
Payload
Might include cameras,
radar, communications equipment
Sources: Aerostar International LLC; NASA
WILLIAM NEFF/THE WASHINGTON POST
An eye (very) high in the sky
The balloon floating over the United States appears to match the general characteristics of what aerospace engineers call a zero-pressure ultra-long duration balloon — a high-tech eye in the sky that can hover over a target area for weeks or months.
LIGHTER-THAN-AIR
GAS
OUTSIDE
AIR
Ballonet
A second bag
within the balloon that
can be pumped full
of outside air, which
causes the balloon to grow
heavier and sink
Inflation
valve
Deflation
valve
Wind navigation
Operating in the upper stratosphere, these balloons navigate by rising and sinking to find winds blowing in the direction they want to go
Compressor
Solar panels
Payload
Might include cameras,
radar, communications equipment
Sources: Aerostar International LLC; NASA
WILLIAM NEFF/THE WASHINGTON POST
If the Chinese balloon over the United States is in fact a spy balloon, James Lewis, director of the Strategic Technologies Program at the Center for Strategic and International Studies, said there might be cameras or telecommunications equipment potentially capable of relaying information back to other nations.
“If you really wanted to know what it was, you’d shoot it down,” Lewis said. “You’d get the sensor package and you’d see — does it collect intelligence? Does it collect weather data?”
Those are questions U.S. officials will now try to answer after fighter pilots fired a missile Saturday afternoon to blow the balloon out of the sky off the South Carolina coast. The Navy and Coast Guard mobilized to recover debris, a senior Defense Department official said.
Defense officials said they have been tracking the balloon “for some time.” President Biden was briefed about it on Tuesday. Montana residents reported seeing it from the ground on Wednesday. Residents in Missouri posted social media photos and videos on Friday of the aircraft, which by Saturday had meandered to the Carolinas.
The balloon’s journey
Strategic U.S. nuclear forces bases and other facilities
1
2
3
5
4
Approximate
flow of the
jet stream
The airship came from China, the country's foreign ministry confirmed Friday, but claimed it was a weather balloon that drifted off course.
1
The balloon was spotted over the Aleutian Islands along the southern tip of Alaska.
2
It was sighted Wednesday over south-western Montana, going over Minuteman III launch facilities.
3
On Friday it was seen flying near St.Louis according to local news reports.
4
On Saturday the U.S. military downed the balloon over the Atlantic Ocean near the coast of the Carolinas.
5
Sources: China’s Foreign Ministry, NOAA,
The United Nations
The balloon’s journey
Strategic U.S. nuclear forces bases and other facilities
1
3
2
5
4
Approximate
flow of the
jet stream
The airship came from China, the country's foreign ministry confirmed Friday, but claimed it was a weather balloon that drifted off course.
1
The balloon was spotted over the Aleutian Islands along the southern tip of Alaska early in the week.
2
On Wednesday it was seen above southwestern Montana, over Minuteman III launch facilities.
3
On Friday it was seen flying near St. Louis, Missouri.
4
On Saturday the U.S. military downed the balloon over the Atlantic Ocean near the coast of the Carolinas.
5
Sources: China’s Foreign Ministry, NOAA, The United Nations
The balloon’s journey
The airship came from China, the country's Foreign Ministry confirmed Friday, but claimed it was a weather balloon that
drifted off course.
Strategic U.S. nuclear forces bases and other facilities
Early this week
The balloon was spotted over the southern tip of
Alaska.
Wednesday
Seen above southwestern Montana, over Minuteman III launch facilities.
1
2
5
3
4
Friday
Seen flying near St. Louis, Missouri.
Approximate flow
of the jet stream
Saturday
The U.S. military downed the balloon over the Atlantic Ocean near the coast of the Carolinas.
Sources: China’s Foreign Ministry, NOAA, United Nations
Biden on Wednesday had authorized a takedown “as soon as the mission could be accomplished without undue risk to American lives under the balloon’s path,” Defense Secretary Lloyd Austin said Saturday in a statement.
It’s not clear what the balloon is using to maneuver through the stratosphere. Some high-altitude balloons are carried by the current, while others may use a semiautonomous navigation system to set their course. In some cases, they navigate by finding a wind current heading in the intended direction and lock into it by moving up or down in the air.
The Thunderhead balloon, for instance, made by the aerospace and defense contractor Aerostar for stratospheric missions, can search independently for optimal wind conditions, according to Russ Van Der Werff, an executive at the company who specializes in high-altitude vehicles.
“It's got some ability to make some decision on its own,” he said. “It knows kind of where it's trying to get to. And it's got sort of a limited power budget to do some searching around.”
When these types of balloons finish their flights, their sensor package detaches and parachutes back down to earth, where it’s picked up for analysis. In some cases, an aircraft can collect it while the balloon is still in the sky.
In a briefing Thursday, a senior defense official declined to discuss what the Pentagon knows about the technology onboard the Chinese balloon, but said the payload wouldn’t offer much in the way of surveillance that China couldn’t collect through spy satellites.
“I wouldn’t characterize it as revolutionary,” the official said.