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Anyone watching the comet landing?

 
 
 
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The lander weighs ~1gram. There's nothing connecting it to the comet surface. How can it drill or probe the surface without floating off into space?
 
seyorni said:
The lander weighs ~1gram. There's nothing connecting it to the comet surface. How can it drill or probe the surface without floating off into space?
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Actually, it weighs around 100kg or 220lbs and has two systems to anchor itself to the comet; harpoons that seem to have failed and footscrews that appear to have worked.
 
Philae weighed 100 Kg on Earth. The comet's mass is hundreds of thousands of times smaller than Earth. It's now almost weightless.
Thrusters failed to deploy and the probe bounced hundreds of meters back up, eventually coming down again at an unknown site outside the landing zone.
Philae is sitting at an angle -- possibly on its side.
The harpoons and foot screws failed to deploy, and Project manager Ulamec told the BBC he was reluctant to attempt to get them to deploy, as they could send the featherweight craft tumbling or flying back upwards.

http://www.bbc.com/news/science-environment-30034060
 
An example of the importance of the distinction of mass vs weight... Nothing weighs anything in kilograms and it's important to be careful in a situation where you can be misunderstood.

67P has mass around 1013kg, and can be (very) roughly approximated as a sphere around 2km in diameter. That means that the acceleration due to gravity at the surface is approximately 0.00015m/s2.

The lander weighs around 1000N on Earth but it only weighs around 0.015N on the comet. In kilogram-force, that's around 100kgf vs 1.5gf.
 
seyorni said:
Philae weighed 100 Kg on Earth. The comet's mass is hundreds of thousands of times smaller than Earth. It's now almost weightless.
Thrusters failed to deploy and the probe bounced hundreds of meters back up, eventually coming down again at an unknown site outside the landing zone.
Philae is sitting at an angle -- possibly on its side.
The harpoons and foot screws failed to deploy, and Project manager Ulamec told the BBC he was reluctant to attempt to get them to deploy, as they could send the featherweight craft tumbling or flying back upwards.

http://www.bbc.com/news/science-environment-30034060
Click to expand...

It's mass is still 100kg and the question was "how can it drill or probe?".

Whatever drill or probe may or may not be deployed will still have to overcome the inertia of 100kg object before it pushes the probe away from the surface of the comet.
 
Inertia is not a "force to overcome", it's just the divisor term of the acceleration due to a force.
The resultant acceleration might be slow, due to the inertia of the 100 kg mass, it will still be there. And with such a low downward acceleration due to gravity, the acquired upward speed will take a long time to be canceled (and that's hoping liberation speed wasn't reached, and plus the probable rotation if the drill forces aren't perfeclty linear and aligned with the gravity center of the probe).
Everything happening in slow motion doesn't mean it won't happen, and doesn't mean it won't be disastrous. You will just have plenty of time to appreciate the disaster.
 
dx713 said:
Inertia is not a "force to overcome", it's just the divisor term of the acceleration due to a force.
The resultant acceleration might be slow, due to the inertia of the 100 kg mass, it will still be there. And with such a low downward acceleration due to gravity, the acquired upward speed will take a long time to be canceled (and that's hoping liberation speed wasn't reached, and plus the probable rotation if the drill forces aren't perfeclty linear and aligned with the gravity center of the probe).
Everything happening in slow motion doesn't mean it won't happen, and doesn't mean it won't be disastrous. You will just have plenty of time to appreciate the disaster.
Click to expand...

Exactly. Merci, dx
 
Update:
http://www.bbc.com/news/science-environment-30034060

1 Km off-target.
Upright -- but at yet undetermined angle.
Not anchored and lot likely to be anchored.
In shadow most of the time. Battery charging compromised.
Worrisome...

The robot probe, the size of a washing machine, was dropped from the satellite on Wednesday and spent seven hours travelling down to the icy body.
Click to expand...
American sized washing machine, or European sized?:thinking:
 
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