Three separate missions are nearing Mars as humanity seeks out answers to the universe and whether the red planet was ever home to life.

The United States, the United Arab Emirates and China have each launched efforts to reach the fourth planet from the Sun.

If successful, the UAE’s Hope probe will be first of the trio, entering the red planet’s orbit on Tuesday, followed by China’s orbiter-rover Tianwen-1.

Nasa’s Perseverance rover is expected to touch down a week later on February 18.

Here’s what you need to know about these latest missions to Mars:

– Why Mars?

Mars is seen as an ideal candidate for exploration because it is close by in our solar system and is the most similar planet to Earth.

One of the biggest questions is whether life has existed beyond Earth, and Mars is a good place to start investigating, given that evidence points to it once being full of water, warmer and with a thicker atmosphere, making it a potentially habitable environment.

– What is the UAE’s mission about?

The UAE will be the fifth region in history to reach Mars if Amal – known in English as Hope – goes to plan, following in the footsteps of the US, Russia, Europe and India.

It will study the red planet’s atmosphere using three key instruments, which will try to understand conditions throughout the Martian atmosphere, as well as analysing seasonal and daily changes.

But like any mission to Mars, entering orbit is tricky and will require a complex manoeuvre known as Mars Orbital Insertion (MOI), where the spacecraft is rotated to position it for a deceleration burn of 27 minutes, and slowed down from its cruising speed of 121,000 km/h to something nearer to 18,000 km/h.

– What about China’s mission?

China’s latest attempt to reach Mars is expected to enter the planet’s orbit on Wednesday.

The country will be hoping to add its name to the list of nations that have successfully reached the planet, after its first attempt with Russia in 2011 failed to make it through Earth’s orbit.

Tianwen-1 – or the Quest for Heavenly Truth – is a double orbiter and rover and should all go well, the latter will make its way to the surface in May, a feat that would make China only the second country to successfully do so.

The aim is to explore for underground water as well as searching for evidence of possible ancient life.

Its solar-powered rover weighs 529lb (240kg) and should operate for about three months, while the orbiter is expected to last two years.

– And Nasa?

America’s Nasa is the only operator to have succeeded in landing a rover on Mars and it is trying once again with new technology on board its Perseverance mission.

The six-wheeled rover will attempt to touch down on February 18.

Scientists believe evidence of microbial life could be preserved in the clay and muddy rocks in the crater, if it ever existed on the planet.

Along with several sophisticated instruments that will gather information about Mars’ geology, atmosphere, and environmental conditions, the rover is also carrying a small 1.8kg helicopter called Ingenuity.

Perseverance will also trial technologies to help astronauts make future expeditions to Mars.

– Are there any future missions?

Yes, Europe and Russia’s Rosalind Franklin rover also hopes to reach the red planet in the future, but the ExoMars mission has been hit by delays.

Given that the journey from Earth to Mars can only be attempted when the planets are in specific positions, the next launch date will not be until between August and October 2022.