* Daredevil to attempt to break sound barrier during fall
* Previous freefall record was set 52 years ago
* Winds delay two attempts this week
By Irene Klotz
Oct 9 (Reuters) - An Austrian adventurer will have to wait at least until Sunday to skydive from a balloon flying 23 miles (37 km) above New Mexico in an attempt to break a long-standing freefall record and the sound barrier.
Felix Baumgartner, 43, had hoped to make the jump on Thursday following two delays this week because of high winds in Roswell, New Mexico. But the weather will keep Baumgartner, a licensed helicopter pilot, hot-air balloonist and professional skydiver, grounded until at least Sunday.
"Sunday is looking like an option," team spokeswoman Sarah Anderson wrote in an email.
Baumgartner will ride to an altitude of 120,000 feet (36,576 meters) in a capsule dangling from a 55-story helium balloon that is beyond paper-thin. The 30-million-cubic-foot (850,000-cubic-meter) plastic balloon is about one-tenth the thickness of a Ziploc bag.
To successfully and safely launch the balloon, winds need to be no more than 2 miles per hour (3.3 km per hour) at an altitude of 700 feet (213 meters), which is the height of the inflated balloon.
The current record for a high-altitude skydive was set in 1960 by Joe Kittinger, who jumped from a balloon flying at 102,800 feet (31,333 meters). Kittinger, a retired U.S. Air Force colonel, fell for four minutes and 36 seconds and reached a maximum speed of 614 mph (988 kph) before opening his parachute.
Baumgartner hopes to top that by exceeding 690 mph (1,110 kph) -- the speed of sound at the targeted altitude -- and freefalling for 5 minutes and 35 seconds.
(Editing by Jane Sutton and Doina Chiacu)
((1 305 810-2688)(firstname.lastname@example.org))
Keywords: USA SPACE/SKYDIVE