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Philae Found

esa.int

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Re: Philae Found

#41

Post by jonknee »

tqkxzugoaupvwqr wrote: post #35
jonknee wrote: post #30

Earlier quoted context omitted.

> I looked at the pictures and the human eye can barely see the lander. Considering that the chances of losing these landers is not that low, I don't understand why they don't make them visually more distinctive. If it was hot pink it would have made no difference, it ended up in a bad spot with limited solar power.

Finding the lander made a difference. Now they can put the the data into context (“[...] we now have the missing ‘ground-truth’ information needed to put Philae’s three days of science into proper context [...].”). ESA is lucky it had a high-resolution camera to distinguish the lander from the terrain. If you only have low-res cameras, it might be useful to have a visually distinguished lander so you find it despite…

If they didn't have a high res camera and could only identify the lander as a brightly colored speck it would not provide any "context" for their data other than it did not vanish into space.

Re: Philae Found

#42

Post by [deleted] »

dotancohen wrote: post #32
aruggirello wrote: post #25

Earlier quoted context omitted.

INANE (I Am Not A NASA Engineer), but perhaps 4 or better yet more legs arranged in a tetrahedron or analogous polyhedron would better ensure the lander did not get stuck inside a crevasse; an inner rotating body could then bring the lander into a working position. The more the legs, the higher the chance the lander could 'roll' to a lower ground when initially bouncing off the surface, but the optimal number of legs…

How much mass would another leg have? Which scientific instrument with that mass would you suggest to eliminate for that extra leg?

[deleted]

Re: Philae Found

#43

Post by achr2 »

infodroid wrote: post #3

The hi-res image shows how just how unlucky a landing spot this was. http://www.esa.int/spaceinimages/Images/2016/09/OSIRIS_narro...

Or perhaps lucky, since without the outcropping it may have bounced off completely...

Re: Philae Found

#44

Post by NegativeLatency »

andreygrehov wrote: post #33

Off-topic, but why do they usually shoot black and white? Is it something to do with the file size?

Sometimes it's because there's only a black and white camera. Different colored filters are used to build up a color picture.

I imagine it's easier to properly calibrate a monochrome camera, and makes it easier to image stuff outside of the visible wavelengths.

Re: Philae Found

#46

Post by ygra »

hbosch wrote: post #36
andreygrehov wrote: post #33

Off-topic, but why do they usually shoot black and white? Is it something to do with the file size?

Not sure how accurate it is, but an article found via cursory Googling[0] makes it seem like a true-color photo doesn't have as much scientific value as other spectrum recording photography - different filters over the monochrome camera can make it easier to see heat, minerals, radiation, etc. Goes on to mention producing a true-color photo is kind of a pain in the ass for these probes. 0. http://www.straightdope.com…

Cameras often have wavelength filters to allow recording only certain wave lengths, that can be switched. So taking a colour photo requires three different exposures. Depending on how long you can take a single picture and how much changes in between you may not really get a useful result. A Bayer filter like in common digital cameras these days would also reduce resolution and restrict you at the sensor level to colour photos.

About the only use for colour photos in space is PR with non-scientists anyway. That was one major obstacle the Hubble Space Telescope had to face. It's a useful component, to be sure, but not one to justify adding much more weight or cost to a planned mission in all cases.

In case of Rosetta/Philae the probe was very weight-restricted, taking even a very long course towards the comet to save fuel since it didn't have much.

Re: Philae Found

#47

Post by woliveirajr »

andreygrehov wrote: post #33

Off-topic, but why do they usually shoot black and white? Is it something to do with the file size?

Some decisions are made about what is going to be observed. For example, if the objective is to study the methane atmosphere (as it's being done on Jupiter), you calibrate your camera and filters for that. Then photo is taken, with whiter points indicating more emission or reflection on that wavelength. Black and white is how we see "more / less emissions"

Re: Philae Found

#48

Post by proactivesvcs »

bjd2385 wrote: post #45

What's that rather straight `rod`-like protrusion to the lower-left? Looks like some kind of antenna.

Half way down http://www.bbc.co.uk/news/science-environment-37276221 is an overlay describing the parts. It sitting on its side, so I think you're referring to one of its three legs jutting out.
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