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Assuming both launches are successful, if JWST tries to solve Tesla's cherry red body paint light spectrum, what would it tell about it's composition? Could it be confusing if it was an unknown object?

Edit: If it was one 10km radius object on same heliocentric orbit, how could JWST tell it's made out of composite material or concrete, or wood, or ice, since it has some thin misleading coating or paint?

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  • $\begingroup$ I don't understand. What's so special about this Tesla roadster compared to any other (red) car? Surely cars can already be seen from orbit pre-JWST? $\endgroup$ – gerrit Jan 8 '18 at 21:10
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    $\begingroup$ @gerrit Elon Musk is proposing to launch this one into space, which is pretty unique for any color car (as far as we know). $\endgroup$ – Chris Hayes Jan 8 '18 at 21:32
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    $\begingroup$ @ChrisHayes Oh, the car will be in space. That's a very relevant detail and not at all clear from the question! $\endgroup$ – gerrit Jan 8 '18 at 21:56
  • $\begingroup$ @ChrisHayes well, TopGear did launch a Reliant Robin, albeit not quite into space ;-) youtube.com/watch?v=_b4WzWFKQ20 $\endgroup$ – hdhondt Jan 9 '18 at 5:01
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First of all, can the color even be seen? James Webb has a spectrum of 600 nm at the lowest end, which means it can just barely see the color red. In addition, it could potentially be seen in other wavelengths that aren't visible.

The spatial resolution is around 70 milli-arc seconds. That means that the Roadster, being about 4m in size (roughly) in it's longest dimension could be resolved at about 11,800 km. That would require an exceedingly close pass! Of course, it can be seen even if not resolved, but it will still be quite dark.

Basically James Webb would treat a Tesla Roadster similar to a 4m asteroid. From this paper, it seems like even the much larger 275m sized asteroids would be difficult to see.

Bottom line, it might show up as an interesting speck, but is unlikely to actually be observed unless intentionally attempted at a particularly close approach.

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    $\begingroup$ You don't need to have any spatial resolution on an object to figure out what it is; if you take the spectrum of your diffraction-limited point of light you can figure out (for example) that strange asteroid is painted with titanium oxide. The calculated size of that "asteroid" was about 6 times larger by area than the S-IVB really is because the paint has an unnatural albedo. $\endgroup$ – Nick T Jan 8 '18 at 23:36
  • $\begingroup$ This is true, but even that required a fairly close approach to Earth to happen. Added a bit more detail. $\endgroup$ – PearsonArtPhoto Jan 9 '18 at 0:51
  • $\begingroup$ should that be speck? $\endgroup$ – JCRM Jan 9 '18 at 9:44
  • $\begingroup$ Let's see, did Tesla buy Solar City? Maybe they'll slap some solar panels on the roadster, swap out the 18650 cells in the Tesla battery for something that can last longer in space, and flash the headlights once a minute :-) $\endgroup$ – uhoh Jan 9 '18 at 14:28
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    $\begingroup$ @uhoh There's no evidence of solar panel. JWST would barely detect headlight flash. And it's really not as easy as just slapping solar panels on it. Still... $\endgroup$ – PearsonArtPhoto Jan 9 '18 at 15:03

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