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Re: Philae pictures show bounce

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  Re: Philae pictures show bounce RS Wood <rsw@therandymon.com> - 2015-11-13 11:42 +0300
    Re: Philae pictures show bounce Stephen Thomas Cole <usenet@stephenthomascole.com> - 2015-11-13 10:12 +0000
      Re: Philae pictures show bounce RS Wood <rsw@therandymon.com> - 2015-11-13 13:53 +0000

#1931 — Re: Philae pictures show bounce

On 2014-11-16 22:42:22 +0300, RS Wood said:

> From the «boinggg» department:
> Title: Pictures show comet probe 'bounce'
> Author:
> Date: Sun, 16 Nov 2014 13:30:05 -0500
> Link: 
> http://www.bbc.co.uk/news/science-environment-30074258#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa 
> 
> 
> Images of the Philae probe moments after its initial touchdown on comet 67P
> have been published by the European Space Agency.

And now the studies have shown how and why the landing mission had trouble.

http://www.theregister.co.uk/2015/11/12/esa_explains_philae_landing/

//--clip
The ESA operators knew they had problems before the Philae landing was 
attempted. The thruster refused to arm itself ahead of the attempt. 
It's thought a dodgy seal caused the failure, although it may have been 
sensor problems. ESA went ahead with the landing attempt regardless.
The harpoons failed to fire and the lander started to bounce across the 
comet's surface, out of control. The agency released a simulation of 
its path.
"It seems that the problem was either with the four 'bridge wires' 
taking current to ignite the explosive that triggers the harpoons, or 
the explosive itself, which may have degraded over time," explained 
Stephan Ulamec, Philae lander manager. "In any case, if we can regain 
contact with Philae, we might consider an attempt to retry the firing."
Despite not being able to recharge its batteries, Philae managed to 
perform 80 per cent of its scheduled scientific experiments before 
being shut down. Since then there have been sporadic signals from the 
lander, but nothing concrete.
"We had already determined that one of Philae's two receivers and one 
of the two transmitters were likely no longer working," said technical 
manager Koen Geurts, "and it now seems that the other transmitter is 
suffering problems. Sometimes it did not switch on as expected, or it 
switched off too early, meaning that we likely missed possible 
contacts."
As the comet reached its closest point to the Sun, the Rosetta probe 
was forced to retreat out of range of Philae's radios because of the 
amount of offgassing as the cosmic snowball heated up. Now that the 
comet is heading back out into space, Rosetta is approaching again and 
is now 170 kilometers from the surface and heading back in range.
Sooner or later the Rosetta probe is going to run out of power as it 
speeds away from the Sun, and the ESA crew had planned to leave it in 
permanent orbit. But now there's a new plan: another attempted landing.
"Next year, we plan to do another far excursion, this time through the 
comet's tail and out to 2000km," said Matt Taylor, ESA's Rosetta 
project scientist. "To complement that, we hope to make some very close 
fly-bys towards the end of the mission, as we prepare to put the 
orbiter down on the comet."
The probe will start a series of maneuvers in August that will see it 
swoop as low as a kilometer from the comet's surface. It will then move 
further away and slow down for a landing attempt in September.
"Landing Rosetta on a comet will be a fitting ending to this incredible 
mission," says Patrick Martin, ESA's Rosetta mission manager. ®

//--clip

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#1932

RS Wood <rsw@therandymon.com> wrote:
> On 2014-11-16 22:42:22 +0300, RS Wood said:
> 
>> From the «boinggg» department:
>> Title: Pictures show comet probe 'bounce'
>> Author:
>> Date: Sun, 16 Nov 2014 13:30:05 -0500
>> Link: >
>> http://www.bbc.co.uk/news/science-environment-30074258#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa
>> > > > Images of the Philae probe moments after its initial touchdown on comet 67P
>> have been published by the European Space Agency.
> 
> And now the studies have shown how and why the landing mission had trouble.
> 
> http://www.theregister.co.uk/2015/11/12/esa_explains_philae_landing/
> 
> //--clip
> The ESA operators knew they had problems before the Philae landing was
> attempted. The thruster refused to arm itself ahead of the attempt. It's
> thought a dodgy seal caused the failure, although it may have been sensor
> problems. ESA went ahead with the landing attempt regardless.
> The harpoons failed to fire and the lander started to bounce across the
> comet's surface, out of control. The agency released a simulation of its path.
> "It seems that the problem was either with the four 'bridge wires' taking
> current to ignite the explosive that triggers the harpoons, or the
> explosive itself, which may have degraded over time," explained Stephan
> Ulamec, Philae lander manager. "In any case, if we can regain contact
> with Philae, we might consider an attempt to retry the firing."
> Despite not being able to recharge its batteries, Philae managed to
> perform 80 per cent of its scheduled scientific experiments before being
> shut down. Since then there have been sporadic signals from the lander,
> but nothing concrete.
> "We had already determined that one of Philae's two receivers and one of
> the two transmitters were likely no longer working," said technical
> manager Koen Geurts, "and it now seems that the other transmitter is
> suffering problems. Sometimes it did not switch on as expected, or it
> switched off too early, meaning that we likely missed possible contacts."
> As the comet reached its closest point to the Sun, the Rosetta probe was
> forced to retreat out of range of Philae's radios because of the amount
> of offgassing as the cosmic snowball heated up. Now that the comet is
> heading back out into space, Rosetta is approaching again and is now 170
> kilometers from the surface and heading back in range.
> Sooner or later the Rosetta probe is going to run out of power as it
> speeds away from the Sun, and the ESA crew had planned to leave it in
> permanent orbit. But now there's a new plan: another attempted landing.
> "Next year, we plan to do another far excursion, this time through the
> comet's tail and out to 2000km," said Matt Taylor, ESA's Rosetta project
> scientist. "To complement that, we hope to make some very close fly-bys
> towards the end of the mission, as we prepare to put the orbiter down on the comet."
> The probe will start a series of maneuvers in August that will see it
> swoop as low as a kilometer from the comet's surface. It will then move
> further away and slow down for a landing attempt in September.
> "Landing Rosetta on a comet will be a fitting ending to this incredible
> mission," says Patrick Martin, ESA's Rosetta mission manager. ®
> 
> //--clip

There's nothing that's not amazing about this whole mission. Fantastic
stuff. 

-- 
STC // M0TEY // twitter.com/ukradioamateur

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#1933

>> And now the studies have shown how and why the landing mission had
>> trouble.
>> http://www.theregister.co.uk/2015/11/12/esa_explains_philae_landing/
>> 
>> //--clip
...
>> scientist. "To complement that, we hope to make some very close
>> fly-bys towards the end of the mission, as we prepare to put the
>> orbiter down on the comet." The probe will start a series of
>> maneuvers in August that will see it swoop as low as a kilometer from
>> the comet's surface. It will then move further away and slow down for
>> a landing attempt in September.  "Landing Rosetta on a comet will be
>> a fitting ending to this incredible mission," says Patrick Martin,
>> ESA's Rosetta mission manager. ®
>> 
>> //--clip
>
> There's nothing that's not amazing about this whole mission. Fantastic
> stuff. 
>

Yeah, I totally agree.  I hope they are able to crash land Rosetta on
the thing somehow, or die trying.  The whole mission is so packed with
awesomeness I can barely stand it.  Landing a probe on an asteroid
traveling at phenomenal velocities and at a phenomenal distance, and
then sending back data ... the engineering just blows the mind.  Yay,
science.

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