This climate has existed on the planet since its creation 4 billion years ago, which made oceans or any life form unlikely, according to research by University of Colorado at Boulder scientists.

The research challenges a popular theory that Mars is a hot and humid planet.

Teresa Segura and her thesis director, professor Owen Toon -- both from the University of Colorado -- used photographs of Mars and computers to calculate the effects of the impacts of asteroids that bombarded the planet some 3.5 million years ago.

The clash of asteroid and meteorites that collided with Mars unleashed frozen water, which released brief bouts of torrential rains and created the planets canyons and river valleys.

According to Segura, some 25 meteorites of 100 to 250 km (60 to 150 miles) in diameter showered Mars every 10 to 20 million years produced periodic layers of hot debris that covered the surface, warming it above the freezing point of water for decades or centuries at a stretch.

The short duration of the warm episodes that the study discusses likely made it difficult for life to ever establish itself on Mars, Segura said.

"There apparently were some brief warm and wet periods on Mars, but we believe that through most of its history, Mars has been a cold, dry planet," said Segura, now a visiting researcher at NASA's Ames laboratory in California.

"When the river valleys on Mars were confirmed in the 1970s, many scientists believed there once was an Earth-like period with warmth, rivers and oceans," Toon said.

"What sparked our interest was that the large craters and river valleys appeared to be about the same age," he added.

SPACE.WIRE