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Comment by thr0waway1239 | Hacker News Reader

"At 2.7 km, the resolution of the OSIRIS narrow-angle camera is about 5 cm/pixel, sufficient to reveal characteristic features of Philae’s 1 m-sized body and its legs, as seen in these definitive pictures."

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.

Andrew Ng gave a talk recently where he talks about designing the autonomous cars not for aesthetics, but predictability (via visual distinctiveness). [1] In the same spirit, shouldn't there be efforts to make these spacecraft modules more visually distinctive?

[1] https://www.youtube.com/watch?v=4eJhcxfYR4I&t=16m35s

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"the human eye can barely see the lander" is a bit exaggerated. It's not immediately obvious where in the image the lander is (it took me a few seconds to find it), but well visible once you've got the position.

"Considering that the chances of losing these landers is not that low" - most of the time, when the mission fails, they don't make it to the surface, though. As far as I know, Beagle 2 is the only lander that was lost and later found. The Mars Polar Lander likely dropped onto the surface from some 40m up, maybe a wreckage could be found there. But other than that, I'm not aware of any landers that could be found with a camera in orbit. Debris is hard to find, even on earth - it took over 20 hours to find a crashed fighter jet in Switzerland last week, and another day to find the pilot's body.

My entirely uneducated guess is that a layer of paint would impede the cooling of electronics that depend on the housing to dissipate heat.Paint would also absorb more solar heat than plain metal.

A dye bomb is used for aerial crash/rescue. That would contaminate a surface, but also provide a possible visual marker. Maybe several launched away from the lander, but which could be used to triangulate it, in the rare case that might actually be of interest.

I suspect there's a lot of re-thinking of how to land on a comet going on as well.

Certainly I started thinking about better ways once this image made it clear what we (humans) are dealing with here.

I can imagine a cage-like outer shell where the robot inside is able to rotate on two axes under power. Let it tumble any which way and then use sensors to determine the correct orientation and right itself.

NASA has a concept for this: https://ti.arc.nasa.gov/tech/asr/intelligent-robotics/tenseg...

That's pretty much what Spirit and Opportunity's airbag landing system was, although a lot simpler --- it was set up so that no matter what way up it was after it came to a rest (after bouncing and rolling!), when the bags deflated it would automatically roll the right way up so that when the deployment mechanism finally opened, the rover could just drive out.

I've tried to find a video showing it happening, but while there's lots of animations of bouncing, rolling, and the final opening up, they all miss the critical moment. Also, car safety videos are really badly poisoning the search results...

https://youtu.be/-_9BYSDtwRc?t=197

Here you go. Really enjoyed watching that.

Adding paint means adding mass, and the final stage of a space mission is very sensitive to adding mass.

> 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 of poor resolution (1 bright pixel).

A naive solution might be to make future landers reflect a certain wavelength and use a tiny camera that is tuned to capture that wavelength. Finding the lander should be much easier then.

But then you probably have a camera that has exactly one use – finding the lander – which doesn't necessarily yield the same quality of scientific results than having a camera that is more useful to the actual goals of the mission. Yes, finding Philae is nice, but not finding it wouldn't have been that bad, and the camera surely generated worthwhile data even without finding Philae.

s/camera/filter or sensor/

You could probably have any number of multi-purposed systems for that task.

> A naive solution might be to make future landers reflect a certain wavelength and use a tiny camera that is tuned to capture that wavelength. Finding the lander should be much easier then.

That's a complicated way of saying "paint it like barricade tape", isn't it?

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.

The suggestion, I think, is to have both, under the assumption that one extra low-res single-purpose camera would be relatively easy to add. Once you find it with one camera, you can find it with the other.

If they were to commit resources to this situation, a simple, tiny, low power radio beacon would be an option.

Rather than search for it, let it tell Rosetta where it is.

The problem with this is that even though the beacon could be only a few grams and use micro-watts (1 milliwatt transmission 1/1000th of the time?) of energy, Rosetta would need a receiver capable of picking it up.

I assume Rosetta has something like software defined radio but due to when it was designed, not sure if this is the case. In any case Rosetta is loaded with really sophisticated radio gear probably it could be build such that there is no weight or energy penalty for this.

Wish more NASA folk would read hacker news and could chime in

It seems that the beacon is not necessary. They already have radio localization. The problem is confirmation from imagery.

> Radio ranging data tied its location down to an area spanning a few tens of metres, but a number of potential candidate objects identified in relatively low-resolution images taken from larger distances could not be analysed in detail until recently.

Ah hah... good spotting. Using radio to locate down to 10's of meters is a heck of an achievement. Makes me wonder how many other amazing things are hidden under the surface of this effort that are similarly amazing but don't see the light of day.

I'm confused about the appearance of autonomous cars. When is the car observing itself? How does its own appearance come into play?

I believe he is talking about an autonomy-enabled region, which is full of autonomous cars. It includes things such as modifying even the road infrastructure.

It's not observing itself, it's being observed by other autonomous vehicles.

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