Near-vertical peaks and pinnacles often rose higher than NASA's DC-8 flying laboratory during low-level data-gathering flights in the Operation IceBridge campaign. Many of the flight tracks were flown at an average of only 1,500 feet above ground. (Photo courtesy Chris Miller) › View Larger Image
NASA's DC-8 airborne science laboratory has completed 2011 Operation IceBridge science flights over Antarctica, and returned to base in Palmdale, Calif., on Nov. 22. The IceBridge flight and science team flew a record 24 science flights during the six-week campaign, recording data with a suite of sophisticated instruments on the thickness and depth of Antarctic ice sheets and glacial movement.
The aircraft departed the deployment base at Punta Arenas, Chile, and after a refueling stop in Santiago, Chile, set course for Los Angeles International Airport for customs clearance. The flying lab continued on to the Dryden Aircraft Operations Facility, arriving about 8:30 p.m. after almost 15 hours in the air.
A highlight of the IceBridge mission was discovery, during an Oct. 14 low-level overflight, of a large crack that had recently begun across the Pine Island Glacier ice shelf, a precursor to the expected separation of an estimated 310-square-mile iceberg into the ocean. The growth of the estimated 18-mile-long rift was documented on several subsequent flights.
The serrated surface of this glacier gives evidence of glacial movement is this view from NASA's DC-8 airborne science laboratory during one of the final flights in the fall 2011 IceBridge campaign. The IceBridge team made a record 24 science flights during the six-week campaign, recording data with a suite of sophisticated instruments on the thickness and depth of Antarctic ice sheets and glacial movement. (Photo courtesy Chris Miller) › View Larger Image Final science flights on Nov. 17 and 19 focused on the middle of the Antarctic Peninsula and the George VI Sound on the peninsula's western side.
Mission manager Chris Miller's report on the former noted that clear weather over the eastern side of the peninsula provided "a rare opportunity to collect data over glaciers that are more regularly shrouded in cloud."
The mostly clear weather allowed the science team to collect data at low altitudes of only 1,500 feet above ground for almost seven of the more than 11 hours it was aloft.
After a down day on Nov. 18 for crew rest and aircraft maintenance, the converted four-engine jetliner-turned-flying-laboratory was airborne again Nov. 19 on the final science mission. The IceBridge team found perfect weather conditions over their survey target, the George VI Sound.
Data collection began with a long transect down the center of the sound, Miller said, and then continued with 11 flight-data lines stitching across the sound, shore to shore. Minor glitches with the Digital Mapping System and the aircraft's GPS system complicated one of the tracks for the Airborne Topographic Mapper instrument during the flight, but Miller said all objectives were met and the ATM data should be recoverable in post-flight processing.
"Views of mountain peaks and ranges were abundant," during the 11-hour flight, he added.
Due to fuel supply issues at Punta Arenas, a 25th and final science flight on Nov. 20 was cancelled, and the team prepared for the return flight to the United States.
Including the transit flights between Punta Arenas and California, the modified 45-year-old flying laboratory logged about 308 flight hours during Operation IceBridge, including 127 hours of actual data collection with the suite of seven specialized instruments. The instruments and science teams represented several NASA centers, the University of Kansas, the University of California at Santa Cruz and the Lamont-Doherty Earth Observatory at Columbia University in New York City.
Operation IceBridge was begun in 2009 to bridge the gap in data collection between the time NASA's ICESat-1 satellite stopped functioning and when the ICESat-2 satellite becomes operational in 2016. By comparing the year-to-year readings of ice thickness and movement on land and sea, scientists can learn more about trends that could affect sea-level rise and climate around the globe. In addition to NASA's DC-8, a smaller Gulfstream V aircraft operated by the National Science Foundation and the National Center for Atmospheric Research also were used in the IceBridge mission.
DC-8 research pilot Troy Asher, who flew the final science flight, offered his reflections on the 2011 Antarctic campaign.
"As you will undoubtedly hear from other reports from the science and mission director community, this has been a fantastic deployment from many different aspects," he said.
Center Director David McBride emailed his congratulations to the science team and the flight and ground crews on completion of the mission.
"This was a great campaign, and it makes all proud," McBride wrote.