Last week was an interesting week for stratospheric balloon flights in the United States. Much of the attention was focused on a Chinese “spy” balloon that first made the news when it was spotted over Billings, Montana. It was eventually shot down by an F-22 Raptor off the coast of Myrtle Beach, South Carolina. But there was another balloon making a cross-country flight at the same time. In fact this balloon would be mistaken for the Chinese balloon on several occasions.
HBAL617 (FAA registration N257TH) was a Thunderhead super-pressure balloon launched from a Raven Aerostar facility east of Albuquerque, New Mexico on 31 January. As is typical with these flights the exact mission was unknown but previous missions have been used to monitor forest fires, study the environment, provide cellular communications, and act as an ISR platform for the military.
After launch the balloon drifted east and by Friday morning it was located over northwestern Alabama. Around 8:15am EST, as it was approaching Decatur, it began a climb that resulted in a turn to the southeast. It was at this moment I began to take a serious interest in the flight path since it was tracking toward Harris County. But around 2:30pm it climbed even higher resulting in a turn due east. This only lasted for an hour before it started a descent which resulted in a gradual turn to the east-southeast.
Harris County was no longer under the projected flight path but my previous experience with HBAL608 told me the balloon would be visible from FDR State Park. That previous experience also resulted in my decision to watch from the Park office rather than Dowdell’s Knob. During the drive up the mountain I couldn’t help but notice the near full moon close to the horizon and I remember thinking maybe there was a chance the balloon would pass in front of the moon. After setting up my 8-inch Schmidt-Cassegrain telescope I quickly located the balloon which was easily visible to the naked eye. First contact occurred around 5:30pm at a distance of 28.5 miles.
As I was tracking the balloon I kept looking toward the moon. For quite awhile it looked like the balloon would pass above the moon but the closer it got the more it looked like a crossing might happen. In the end it passed just below the moon. If I had been about 500 feet closer it probably would have crossed in front. This close encounter occurred at 6:09pm when the balloon was at a distance of 39 miles.
The balloon continued southeast and crossed the coast line near Savannah. Tracking was lost when the balloon passed out of range of ADS-B receivers.
Looking at the overall flight path you can see if HBAL617 had continued on the northern track (instead of turning southeast near Decatur) it might have passed over the South Carolina coastline between Charleston and Myrtle Beach about 12 hours before the arrival of the Chinese balloon. This has me wondering if that turn was just a part of the mission profile or was it requested by the US government?