Washington, Nov 26 (IANS): The US space agency NASA is planning to kickstart a challenge for developing airships that can break records in terms of duration of flight at high altitudes.

The idea behind the "20-20-20 Airship Challenge" would be to achieve unprecedented airship milestones, NASA said in a statement.

Airships are not just powered balloon-like vehicles that hover above sporting events. Unlike a balloon, which travels with air currents, airships can stay in one spot.

The stationary nature of airships allows them to have better downlink capabilities, because there is always a line-of-sight communication.

Researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, have floated the idea that airships have potential for important scientific and commercial uses.

"We are seeking to take astronomy and earth science to new heights by enabling a long-duration, suborbital platform for these kinds of research," said Jason Rhodes, astrophysicist at NASA's Jet Propulsion Laboratory in Pasadena.

The first tier of the competition would be to get an airship with a 20-kg payload to stay at an altitude of 65,000 feet for 20 hours.

More ambitious ship-builders can aim for the second tier, with the same height but carrying a 200-kg payload for 200 hours.

So far, no powered airship has been able to sustain this altitude for more than eight hours.

Balloons do fly at this height - for example, weather balloons - but they are subject to prevailing winds and may be less reliable.

The agency has issued a request for information for this contemplated "20-20-20 Airship Challenge".

Submissions will be accepted till Dec 1.