Oil-rich United Arab Emirates said Wednesday it was pressing ahead with plans to send the first Arab unmanned probe to Mars by 2021, naming it "Hope".

The probe will leave Earth in 2020 on a mission "designed to complement the science work of other missions and fill important gaps in human knowledge," the Gulf state said in a statement.

Sheikh Mohammed bin Rashid al-Maktoum, the UAE vice president and ruler of Dubai, said the mission "represents hope for millions of young Arabs looking for a better future".

The probe, the size and weight of a small car, will reach a speed of 126,000 kilometres (78,000 miles) per hour on the 600 million kilometre journey, which will take around 200 days, it said.

The spacecraft will orbit Mars until at least 2023 and send back data to be analysed by experts in the UAE and shared with more than 200 institutions worldwide.

"Its unique orbits and instruments will produce entirely new types of data that will enable scientists to build the first truly holistic models of the Martian atmosphere," the statement said.

"These models will help the global Mars science community to unlock more mysteries of the Red Planet, such as why its atmosphere has been decaying into space to the point that it is now too thin for liquid water to exist on the surface," it added.

The UAE government launched in October the plan to send the unmanned probe to Mars by 2021. In July, it said that UAE investments in space technologies had already topped 20 billion dirhams ($5.4 billion, 4.8 billion euros).

The UAE, a seven-emirate federation formed in 1971, will become the ninth country in the world with space programmes to explore the Red Planet, according to the statement.