European Mars lander Schiaparelli has smashed into the Red Planet and exploded, dramatic satellite images suggest.
Photos taken by a powerful camera on an American orbiting spacecraft appear to show evidence of the probe's 12m (39ft) diameter parachute and a large dark patch that could be the scorched crash site.
Scientists estimate the spacecraft dropped from a height of two to four kilometres (1.2 - 2.4 miles) and hit the ground at more than 300 km/h (186 mph).
A statement from the European Space Agency said: "It is also possible that the lander exploded on impact as its thruster propellant tanks were likely still full.
"These preliminary interpretations will be refined following further analysis."
Experts have been trying to piece together what happened to the disc-shaped craft after it stopped transmitting less than a minute before it was due to land on Wednesday.
Data received from the probe during the earlier part of its six-minute descent indicated its three clusters of retro rockets had fired for just three to four seconds instead of 29.
It was also thought to have jettisoned its parachute too early.
The retro rockets were supposed to slow the probe's descent from about 270km/h to 7km/h (4.3 mph) before switching off and allowing Schiaparelli to freefall the last few feet to the ground.
The probe has a "crushable" structure designed to absorb the shock of the landing - but at walking pace.
The parachute jettison and ignition of the retro rockets should have occurred at about the same time, about 4,000ft above the Martian surface.
Scientists used Nasa's Mars Reconnaissance Orbiter (MRO) spacecraft to scour the landing site - a flat equatorial region known as Meridiana Planum - for any sign of Schiaparelli.
The images released by the European Space Agency (ESA) at a resolution of six metres per pixel show ominous features that were not there when the same spacecraft photographed the region in May this year.
One is a bright spot thought to be the probe's parachute. The other is a "fuzzy dark patch" roughly 15m by 40m (50ft by 131ft) in size and about one kilometre north of this feature.
"This is interpreted as arising from the impact of the Schiaparelli module itself following a much longer freefall than planned after the thrusters were switched off prematurely," ESA officials said.
The location of the dark mark suggests the probe crashed roughly 5.4km (3.3 miles) west of its intended landing point. This was still well within its 100km by 15km (62 by 9.3 miles) "target" ellipse.
A closer inspection of the features will be taken next week with HiRISE, the highest resolution camera on MRO.
It is hoped they may also reveal the location of the probe's front heat shield, which was discarded at higher altitude.
The apparent loss of Schiaparelli, part of the two-stage ExoMars mission to search for signs of past or present life on Mars, comes at a sensitive time.
ESA member states meeting at a the agency's next ministerial council meeting in Lucerne, Switzerland, in December will be asked to pledge continued support - and funding - for the mission's ambitious second phase.
ExoMars Rover will launch a British-built six-wheeled laboratory to Mars in 2020 to drill deep into the surface and analyse samples for signs of life.
Together, the two stages of the mission are estimated to cost 1.56 billion euros (£1.39 billion).
Schiaparelli's main function was to test the automated Russian-designed landing system to be used on ExoMars Rover.
The 8ft (2.4m) wide craft also carried a small suite of instruments to take measurements of the Martian weather.
Open University space scientist Dr Manish Patel, a leading member of the ExoMars research team, said: "It comes down to what we can learn from this, if we can get enough information about why it went wrong. We might then still have a chance.
"Ultimately, it depends on the politicians in December and if they have sufficient faith in what we've learned. But it's always going to be a worry if something doesn't work from end to end."
Airbus Defence and Space, which is developing the rover in Stevenage, earlier refused to comment on the failed Mars landing.
Everything initially went according to plan after the probe entered the planet's atmosphere at 21,000 km/h (13,000 mph) on Wednesday.
Scientists know that its heat shield remained intact and its parachute deployed as intended, at an altitude of 11km (6.8 miles).
But something went badly wrong about the time the lander was due to jettison its parachute and fire up its retro rockets.
ESA has stressed the main part of the mission - to put Schiaparelli's "mothership" in orbit around Mars - was a complete success.
The ExoMars Trace Gas Orbiter will sniff the planet's atmosphere for trace gases including methane, which may have a biological origin.