A European space lander has reached Mars in what scientists hope will mark a milestone in exploration of the red planet, but whether it touched down on the surface in good health was far from certain.
Older European and US spacecraft already in orbit relayed data of the lander's six-minute descent.
Then transmission stopped, leaving questions over what state the disc-shaped 577kg Schiaparelli probe was in.
"It's clear that these are not good signs but we will need more information. And that's what's going to happen tonight," the European Space Agency's (ESA) head of mission operations Paolo Ferri said.
He added that more information about Schiaparelli should be available tomorrow, when scientists have had a chance to analyse data from the orbiting craft.
"It's fundamental that tonight we look at this telemetry, all the experts here from the industry, from ESA will look at this. And for me this is not a hope it's an objective and I'm quite confident that tomorrow morning we will know," he said.
The primary goal of ExoMars, the European-Russian programme that launched Schiaparelli, is to find out whether life has ever existed on Mars.
The spacecraft on which the lander travelled, Trace Gas Orbiter (TGO), carries an atmospheric probe to study trace gases such as methane around the planet.
Schiaparelli, which is testing technologies for a rover due to follow in 2020, represents only the second European attempt to land a craft on the red planet.
Britain's Beagle 2 was ejected from the Mars Express spacecraft in 2003 but never made contact after failing to deploy its solar panels on landing.
Landing on Mars, currently some 56 million kilometres away from its nearest planetary neighbour Earth, is a notoriously difficult task that has thwarted most efforts by Russia and given US space agency NASA trouble as well.
The planet's hostile environment has not detracted from its allure, with US President Barack Obama recently highlighting his pledge to send people to the surface by the 2030s.
"Today we are here in the control centre of ESA laying the foundation for humans to go there," astronaut Alexander Gerst, who is set to become the first German commander of the International Space Station in 2018, told Reuters TV.
Elon Musk's SpaceX is developing a massive rocket and capsule to transport large numbers of people and cargo to Mars with the ultimate goal of colonising the planet, and the US entrepreneur has said he would like to launch the first crew as early as 2024.
The second part of the ExoMars mission, delayed to 2020 from 2018, will deliver a European rover to Mars. It will be the first with the ability to both move across the planet's surface and drill into the ground to collect and analyse samples.
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Crew blasts off for space station
Two Russian cosmonauts and a NASA astronaut have soared into orbit in a Soyuz spacecraft to begin a two-day journey to the International Space Station.
NASA's Shane Kimbrough, and Andrei Borisenko and Sergei Ryzhikov of Roscosmos blasted off at 9.05am Irish time from the Baikonur cosmodrome in Kazakhstan.
Their launch had been delayed by nearly a month over technical issues.
AND LIFTOFF! Launch of @Astro_Kimbrough & crewmates launching to @Space_Station. Watch: https://t.co/KX5g7zfYQe pic.twitter.com/CuqhiCGwDw
— NASA (@NASA) October 19, 2016
