A spacecraft hurtling towards Mars will be the first to study the deep interior of the planet if it lands safely.
The InSight probe is scheduled to land on Martian soil at around 8pm GMT on Monday, scientists said.
To accomplish the feat successfully it must slow down from 12,300mph to just 5mph, the equivalent of human jogging speed, in just seven minutes after hitting Mars's atmosphere, Nasa said.
Only around four in 10 missions ever sent to the Red Planet by any space agency have been successful, and the US is the only nation whose missions have survived landings.
The European spacecraft Schiaparelli smashed into the planet in 2016 after switching off its retro-rockets too early, scientists believe.
It was testing the landing system for a British-built rover to be launched on the second phase of the ExoMars mission in 2020.
The extremely thin atmosphere of Mars means there is hardly any friction to slow down spacecraft, meaning InSight will deploy small rockets, parachutes, heat shields and shock-absorbing legs to manage the deceleration.
If successful, the probe will send information back, allowing scientists to learn about how rocky worlds like the Earth and Moon formed more than 4.5 billion years ago.
It comes after a huge 12-mile wide lake of water was discovered beneath the southern ice cap of the Red Planet earlier this year.
The discovery, which has major implications for the chances of life surviving on Mars, was made by an orbiting European probe using ground-penetrating radar.
It is the first time a large stable body of liquid water has been confirmed to exist on Mars.
Additional reporting by Press Association.
