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Welcome to a comet

esa.int

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Re: Welcome to a comet

#61

Post by noamyoungerm »

narag wrote: post #48
wlievens wrote: post #15

Earlier quoted context omitted.

Apparently the visible light sensor has RGB color filters. http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=PHILA... I would guess these are probably not a Bayer filter pattern, but filters that are mechanically swapped.

I remember having read long time ago that superposing B&W images took with those filters gives an also B&W image that our brain perceives as coloured. Does anybody know if this is correct or what's the name of that effect?

If you send three grayscale images, each one taken through a different colored filter, you can reconstruct a color image back on earth by setting the red channel, green channel, and blue channel of the image to be each one of the colored filters you used to capture the image.

This isn't a grayscale image that our brain perceives on color, but rather several grayscale images, each colored separately to combine into a color image.

I seriously doubt an actual effect exists that makes us believe black and white images are actually colored.

Re: Welcome to a comet

#62

Post by Igglyboo »

badname wrote: post #16
Lrigikithumer wrote: post #9

You know I have some bad days some times, but seeing shit like this just makes me think "What a fucking time to be alive!" It's truly incredibly and is sometimes that kick in the pants I need to keep on going. We are living in a golden age of humanity right now, at no point before in human history have so many people had such an incredible quality of life and never before has man been doing such incredible feats and…

Yes it is golden age as long as you disregard percentages and trend. "Some 805 million people in the world do not have enough food to lead a healthy active life. That's about one in nine people on earth." http://www.wfp.org/hunger/stats Economy seems like a boiler ready to explode, rich-poor chasm is widening like hell. Global peace doesn't look very rosy either. Not to mention what's happening on the environmental f…

Yes the world isn't perfect and theres still a shit ton wrong, regardless we're better off than we've ever been before except perhaps on the environment.

Re: Welcome to a comet

#63

Post by lisper »

Osmium wrote: post #56
netcan wrote: post #55

Earlier quoted context omitted.

Does the comet have enough gravity to hold on to dust? How do these small space objects even stay together?

> Does the comet have enough gravity to hold on to dust? Yes. Philae's weight on the comet is roughly equivalent to a few ounces/100g* on Earth. It's why there's so much concern about it not being anchored correctly; deploy the wrong instrument and you might push it away from the surface and out into space. So there is a significant gravitational attraction from the comet, just not very much! * I've seen a few differ…

> I've seen a few different estimates for this

Considering the comet's irregular shape, it probably depends a lot on exactly where the lander is.

Re: Welcome to a comet

#64

Post by knowaveragejoe »

badname wrote: post #16
Lrigikithumer wrote: post #9

You know I have some bad days some times, but seeing shit like this just makes me think "What a fucking time to be alive!" It's truly incredibly and is sometimes that kick in the pants I need to keep on going. We are living in a golden age of humanity right now, at no point before in human history have so many people had such an incredible quality of life and never before has man been doing such incredible feats and…

Yes it is golden age as long as you disregard percentages and trend. "Some 805 million people in the world do not have enough food to lead a healthy active life. That's about one in nine people on earth." http://www.wfp.org/hunger/stats Economy seems like a boiler ready to explode, rich-poor chasm is widening like hell. Global peace doesn't look very rosy either. Not to mention what's happening on the environmental f…

Actually, the statistics today are largely better than at any point in history we have statistics for.

Here's a nice aggregate:

http://daeken.com/2014-04-16_Spoiler__The_World_Isn_t_On_Fir...

There is a shitload of good things going on in the world. You just have to pull your head out of the negativity echochamber present in a lot of Internet communities, most notably parts of reddit.

Re: Welcome to a comet

#65

Post by knowaveragejoe »

Tepix wrote: post #18
badname wrote: post #16

Earlier quoted context omitted.

Yes it is golden age as long as you disregard percentages and trend. "Some 805 million people in the world do not have enough food to lead a healthy active life. That's about one in nine people on earth." http://www.wfp.org/hunger/stats Economy seems like a boiler ready to explode, rich-poor chasm is widening like hell. Global peace doesn't look very rosy either. Not to mention what's happening on the environmental f…

805 million means the number is down more than 100 million over the last decade, and 209 million lower than in 1990–92. In the same period, the prevalence of undernourishment has fallen from 18.7 to 11.3 percent globally and from 23.4 to 13.5 percent for developing countries. Source: http://www.fao.org/publications/sofi/en/

Additionally, the UN millenium development goal of halving world poverty by 2010 was met ~2005.

http://www.outsidethebeltway.com/half-a-billion-people-escap...

Re: Welcome to a comet

#69

Post by stromgo »

zachrose wrote: post #50

It almost seems like "landing" is too strong a word: Philae has a mass of 100kg and the gravity of Churyumov–Gerasimenko is estimated to be 10e−3 m/s2, which comes out to a weight of 3.5 ounces, or the equivalent of 100 grams on earth. Let's hope it holds!

10e-3 m/s^2 is hard to believe, as the lander would have to be ~250m away from the center of mass [1]. More likely it is 2500m away from the center of mass, giving 6.67e-11 * 1.0e13 / 2500 ^ 2 = 0.0001 m/s^2, so about 1 gram.

[1] I can't find a reliable estimate of the surface gravity online, but the mass estimate at http://blogs.esa.int/rosetta/2014/08/21/determining-the-mass... seems accurate.

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