Astronauts' meals have come a long way from the freeze-dried powders and semi-liquid pastes of decades ago: now US scientists want to grow vegetables in mini-greenhouses on the moon.

Scientists say they are looking forward to a time when residents of future lunar or even Martian outposts will be able to dine on fresh vegetables. Paragon Space Development Corporation has unveiled what it called the first step toward growing flowers - and eventually food - on the moon.

Paragon, which has partnered with NASA in previous experiments on the Space Shuttle and the International Space Station, calls it a "Lunar Oasis".

This is a sealed greenhouse that looks like a bell jar encased in a 46-cm triangular aluminum frame. It is designed to safely land a laboratory plant on the lunar surface, and protect it while it grows.

The miniature greenhouse is to be launched into space by Odyssey Moon Ltd, a participant in the Google Lunar X Prize. This competition offers $20 million to any entrant who can launch, land and operate a rover on the lunar surface.

Paragon officials say future testing of the "Lunar Oasis" will be driven by Odyssey's flight schedule, which will not happen until 2012 at the earliest.

When it does lift off the greenhouse will contain the seeds of Brassica, a hardy plant related to Brussels sprouts and cabbage. Because Brassica goes from seed to flower in just 14 days, it can complete its life cycle in a single lunar night.

"Colonizing the Moon or Mars seems so far away, but it is important that we do this research now," Paragon president Jane Poynter said.

"It takes a long time to get a lot of research, and to get integrated, reliable efficient systems" before colonists move in, she said.