What happened?

Altimeter failure. The instrument indicates a much lower altitude than
the real one. So, thinking they are much lower, software ejects the
parachutes, then when the rockets are turned on, the altimeter tells
that they have landed and software shuts down the rockets.

Then it goes from there till the crash at 300Km/h with no parachute and
no rockets...

Single point failure. All mission relies on the altimeter.

jacob navia wrote:
Altimeter failure. The instrument indicates a much lower altitude than
the real one. So, thinking they are much lower, software ejects the
parachutes, then when the rockets are turned on, the altimeter tells
that they have landed and software shuts down the rockets.

Then it goes from there till the crash at 300Km/h with no parachute and
no rockets...

Single point failure. All mission relies on the altimeter.

Is this your personal guess or the first outcome of the investigations?
Boeing made that mistake as well... Turkish Airlines 1951

Le 22/10/2016 à 23:11, Rob a écrit :
Boeing made that mistake as well... Turkish Airlines 1951

Yeah, a bug can happen to anyone. Fortunately there wasn't anybody on
board of the esa probe.

Another advantage of the "toasters". Nobody was killed.

In article ,
says...

Altimeter failure. The instrument indicates a much lower altitude than
the real one. So, thinking they are much lower, software ejects the
parachutes, then when the rockets are turned on, the altimeter tells
that they have landed and software shuts down the rockets.

Then it goes from there till the crash at 300Km/h with no parachute and
no rockets...

Single point failure. All mission relies on the altimeter.

Sounds like a possibly. But designing the thing to have a single point
of failure like this? Seems awfully silly. But, I suppose the lander
was a technology demonstrator, so perhaps not so surprising. Tech
demonstrators often lack redundancy in certain areas.

Unfortunately in this case failure means not being able to get back all
of the sensor data that was recorded, but could not be transmitted due
to limited "uplink" bandwidth. The lander reportedly had battery power
to enable it to transmit this data after a successful landing.

Jeff
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Le 23/10/2016 à 15:40, Jeff Findley a écrit :
Seems awfully silly.

All bugs are that: stupid mistakes. ESA was able to land on Titan, and
now they are unable to land on Mars.

Why not copy the opportunity/spirit design?

It was robust and very simple.

jacob navia wrote:
Le 23/10/2016 Ã* 15:40, Jeff Findley a écrit :
Seems awfully silly.

All bugs are that: stupid mistakes. ESA was able to land on Titan, and
now they are unable to land on Mars.

Why not copy the opportunity/spirit design?

It was robust and very simple.

It looks like this was an attempt to land a device with much higher mass.
It seems like this one was very heavy for what it was intended to do
on the surface, they wanted to experiment for the next mission which
intends to land a much larger rover.

Le 23/10/2016 à 15:40, Jeff Findley a écrit :
Sounds like a possibly. But designing the thing to have a single point
of failure like this? Seems awfully silly.

If you look he
http://www.esa.int/var/esa/storage/i...images/2016/02
/exomars_2016_schiaparelli_descent_sequence_16_9/15826994-1-eng-GB/ExoMars_2016_Schiaparelli_descent_sequence_16_9.jp g

you see that radar turns on after the heat shield separates.

If that radar sent a wrong altitude to the software... mission was
doomed to failure.

P.S. CAREFUL with the URL being cutted in pieces by the old USENET system.

Le 22/10/2016 Ã* 22:54, jacob navia a écrit :
Altimeter failure. The instrument indicates a much lower altitude than
the real one. So, thinking they are much lower, software ejects the
parachutes, then when the rockets are turned on, the altimeter tells
that they have landed and software shuts down the rockets.

Then it goes from there till the crash at 300Km/h with no parachute and
no rockets...

Single point failure. All mission relies on the altimeter.

This is being confirmed by the french journal "liberation" today.
The inertial altimetre that took the relay from the radar altimetre got
"saturated" and stayed at its maximum value for a second. That led to
the crash. The computer received a negatiuve measure (it thought it was
under the soil) and started the soil sequence at 3 Km over the real
martian soil.

On Sunday, October 23, 2016 at 9:54:03 AM UTC+13, jacob navia wrote:
Altimeter failure. The instrument indicates a much lower altitude than
the real one. So, thinking they are much lower, software ejects the
parachutes, then when the rockets are turned on, the altimeter tells
that they have landed and software shuts down the rockets.

Then it goes from there till the crash at 300Km/h with no parachute and
no rockets...

Single point failure. All mission relies on the altimeter.

That's why airliners have multiple altimeters on board.

http://www.pmflight.co.uk/wp-content...deck_panel.jpg

The pilot and co-pilot have separate altimeters and rate of climb indicators. The digital flight system has two separate radar based altimeter and rate of climb indicators on the CRTs, and the guidance computer has a separate altitude readout that can also be set to show vertical speed at the press of a button.