Europe’s Schiaparelli lander did not behave as expected as it headed down to the surface of Mars on Wednesday.
Telemetry data recovered from the probe during its descent indicates that its parachute was jettisoned too early.
The rockets it was supposed to use to bring itself to a standstill just above the ground also appeared to fire for too short a time.
The European Space Agency (Esa) has not yet conceded that the lander crashed but the mood is not positive.
Experts will continue to analyse the data and they may also try to call out to Schiaparelli in the blind hope that it is actually sitting on the Red Planet intact.
In addition, the Americans will use one of their satellites at Mars to attempt to image the targeted landing zone to see if they can detect any hardware. Although, this is a slim hope because the probe is quite small.
For the moment, all Esa has to work with in understanding what happened on Wednesday is the relatively large volume of engineering data Schiaparelli managed to transmit back to the “mothership” that dropped it off at Mars – the Trace Gas Orbiter.
This shows that everything was fine as the probe entered the atmosphere. Its heatshield appeared to do the job of slowing the craft, and the parachute opened as expected to further decelerate the robot.
But it is at the end of this parachute phase that the data indicates unusual behaviour. Not only is the chute jettisoned earlier than called for in the predicted timeline, but the retrorockets that were due to switch on immediately afterwards, fire for just three or four seconds. They were expected to fire for a good 30 seconds.
In the downlinked telemetry, Schiaparelli is seen to continue transmitting a radio signal for 19 seconds after the apparent thruster shutoff.
Esa experts say it is impossible at this stage to fully interpret what happened until they can reconstruct the velocity profile of the probe.
Once they have done that, they can match it against known events and predict the altitudes at which those events occurred.
It should then be possible to gauge with some confidence whether Schiaparelli really did crash.
Landing on Mars is always a daunting prospect.
It is necessarily a high-speed approach that has to be just right or the spacecraft runs the risk of smashing into the ground.
Schiaparelli had a heatshield, a parachute and rocket thrusters in order to slow its approach to the surface.
If the robot is later confirmed as lost, it will clearly be a major blow to Esa which suffered the disappointment of the Beagle-2 lander’s failure at Mars in 2003.
But officials here have underlined the fact that Schiaparelli was always viewed within the agency as a technology demonstrator – a project to give Europe the learning experience and the confidence to go ahead and land a more ambitious six-wheeled rover on Mars in 2021.
“This is typical for a test,” said Prof Jan Woerner, Esa’s director general. “We did this in order to get data on how to land on Mars with European technology. Therefore, all the data we will get this night will be used to understand how to manage the next landing when we go with the rover.”
This future vehicle is expected to use some of the same technology as Schiaparelli, including its doppler radar to sense the distance to the surface on descent, and its guidance, navigation and control algorithms.
What will concern commentators is that the budget for the rover is not yet secure. If Schiaparelli is indeed lost, Esa officials may find themselves having to work harder to explain to member states why the extra investment remains worthwhile.
and follow me on Twitter: @BBCAmos
Source: BBC News Reference: www.bbc.co.uk/news