A European spacecraft has detached from its mothership in an attempt to make a tricky landing on Mars, the European Space Agency (Esa) has said.
Schiaparelli is the first Esa probe in nearly 15 years to try and make contact with the Red Planet.
The 8ft (2.4m) disc-shaped lander is designed to monitor aspects of Martian weather rather than search for signs of life.
However, it will also test out a landing system to be used for a future rover mission that will look for evidence of past or present living organisms.
It is hoped Schiaparelli will fare better than its predecessor Beagle 2, which vanished on Christmas Day in 2003 after separating from the Mars Express orbiter.
The lander is expected to land on Wednesday after a three-day coast.
Schiaparelli was launched on March 14 on the first stage of an ambitious joint European and Russian mission to go in search of the first clear evidence of life on Mars.
It has crossed 310 million miles (500 million km) of space on its seven-month journey from Earth.
Open University space scientist Dr Stephen Lewis, who co-heads the team that will receive data from the probe's engineering sensors during the descent, has said: "Landing on Mars has always been a perilous endeavour, not least because Mars has an active atmosphere and weather.
"Understanding the atmosphere on Mars now, and how Mars' climate has changed, is a key part of finding out whether the planet ever had a habitable environment and supports our understanding of our own climate."
ExoMars Rover, due to be sent into space in 2020, will land a six-wheeled mobile laboratory on the planet to drill samples from beneath the surface and analyse them for signatures of life.
A key function of Schiaparelli is to try out the rover's parachute and retro-rocket landing system.