ERS 2 took this image of the Larsen Antarctic ice shelf

Earth-observing satellites are capable of peering through cloud to send back images of areas of deforestation in all weather and at night.

Esa intends to supply the data to the United Nations Educational, Scientific and Cultural Organisation (Unesco) to help protect the animals.

"The satellites we have are our eyes in the sky," Franco Bonacina, an Esa spokesperson, told BBC News Online.

"We can improve our vision and the instruments we have in our hands to make the environment more liveable for the gorillas in this particular case."

Environmental spy

One such satellite - ERS 2 - which was launched in 1995, has already sent back a wealth of environmental data about the planet.

The satellite uses radar to take images of the Earth. Areas of forest that have been removed by human activity will be visible from space.

"You can see new areas where gorillas can populate," said Mr Bonacina. "Or where they should try to install themselves because human interaction has taken away their food and their habitat."

Gorilla factfile

Mountain gorillas live in the highland rainforests of Rwanda, the Democratic Republic of the Congo, and Uganda There are two lowland subspecies of gorilla, which are also endangered One group is found in the Democratic Republic of the Congo, and the other, Western lowland gorillas, are found throughout Central Africa

The mountain gorillas of Rwanda, the Democratic Republic of Congo and Uganda, are critically endangered.

They are under threat from poaching and loss of their forest habitat. Only about 650 mountain gorillas remain, a population that may not be large enough to maintain genetic diversity.

The first pilot study, to monitor gorilla habitat in Central and East Africa, is planned for next year. Esa is seeking other countries interested in collaborating on the project.