Wellington, Mar 4 (IANS): US space agency NASA is planning to set a record for the longest ever flight for a scientific balloon to be launched in New Zealand next month.

NASA's Balloon Programme team was on the cusp of expanding the envelope in high-altitude, heavy-lift ballooning with its super pressure balloon (SPB) technology, an agency statement said on Friday.

NASA experts are in the South Island resort town of Wanaka, preparing for the fourth flight of a 532,000-cubic-metre balloon, with the goal of an ultra-long-duration flight of up to 100 days, Xinhua news agency reported.

The launch of the pumpkin-shaped, football stadium size balloon was scheduled for sometime after April 1.

The SPB was made from almost 8 hectares of polyethylene film and would ascend to a nearly constant float altitude of 33.5 km.

The balloon would travel eastward carrying a 1,025 kg payload of tracking, communications and scientific instruments, and was expected to circumnavigate the globe once every one to three weeks, depending on wind speeds in the stratosphere.

The current SPB flight duration record is 54 days and was set in 2009.

Longer duration flights enabled longer observations of scientific phenomena, the ability to survey more sources, and more time to observe weak or subtle sources, while such mid-latitude flights were essential for making observations at night, a requirement for certain types of scientific investigations.

These two aspects combined with the relatively low-cost of balloon missions could make the SPB a competitive platform for a number of scientific investigations that would otherwise need to launch into orbit.

As the balloon travels around the Earth, it might be visible from the ground -- particularly at sunrise and sunset.