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Explain why We will never be able to see the Tesla in space?

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#1 Nightow1

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Posted 07 February 2018 - 07:54 AM

Ok ImI a Noob and just don't get it. Can someone please explain to me the reason they say we will never be able to see the Tesla in space with a telescope?? Or is this just Talk, if how and when?

And feel free to confuse me, I just don't get it?????

Thanks for helping a dummy...

I need a telescopes for dummies manual?!!😁



#2 einarin

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Posted 07 February 2018 - 08:06 AM

It's too small and far away to see with a telescope.


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#3 Ishtim

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Posted 07 February 2018 - 08:12 AM

Similarly, we can't see the US flag on the moon.  If I remember, the telescope objective would need to be like 200 meters across to be able to resolve the flag on the moon.  

 

Lot's of Google fun regarding this type of calculation:  https://tinyurl.com/y8lo7ewd


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#4 Traveler

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Posted 07 February 2018 - 08:13 AM

I don't look at car ad's  grin.gif


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#5 VeraZwicky

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Posted 07 February 2018 - 08:39 AM

What if you increased the Tesla's albedo to the maximum level, or covered it in iridium panels? You could probably see it as a point source when the angle of the sun was right, pretty far out there in its orbit?


Edited by VeraZwicky, 07 February 2018 - 08:40 AM.


#6 Jim Davis

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Posted 07 February 2018 - 08:40 AM

I can't say you couldn't have seen it last night, but it is a transfer orbit, so it is pretty high up for most of its orbit. Once it is on its way to Mars, it will be way to far away to see.



#7 jallbery

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Posted 07 February 2018 - 09:13 AM

A Tesla roadster is a bout 4m long.   The resolution of a diffraction-limited 14" telescope is about  0.33 arc seconds.    At the distance of the ISS (about 400km), a 4m sphere would have an angular size of about 2 arc seconds.   I'm not sure how far away the Tesla is at present, but it already considerably farther from Earth than the ISS.  Therefore it is too small to resolve.


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#8 happylimpet

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Posted 07 February 2018 - 09:14 AM

Similarly, we can't see the US flag on the moon.  If I remember, the telescope objective would need to be like 200 meters across to be able to resolve the flag on the moon.  

 

Lot's of Google fun regarding this type of calculation:  https://tinyurl.com/y8lo7ewd

Thats a different issue - angular resolution.

 

The issue here is one of the absolute amount of light.

 

Having said that, I would have thought the amount of light would be comparable.



#9 Jim Davis

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Posted 07 February 2018 - 09:31 AM

A Tesla roadster is a bout 4m long.   The resolution of a diffraction-limited 14" telescope is about  0.33 arc seconds.    At the distance of the ISS (about 400km), a 4m sphere would have an angular size of about 2 arc seconds.   I'm not sure how far away the Tesla is at present, but it already considerably farther from Earth than the ISS.  Therefore it is too small to resolve.

It is still attached to the 2nd stage, so it is far larger than that. In the live feed you can see the whole Earth in the camera view at times, depending on where it is in orbit. So it is in a very high orbit. https://www.youtube....h?v=aBr2kKAHN6M


Edited by Jim Davis, 07 February 2018 - 09:32 AM.


#10 jallbery

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Posted 07 February 2018 - 10:04 AM

What if you increased the Tesla's albedo to the maximum level, or covered it in iridium panels? You could probably see it as a point source when the angle of the sun was right, pretty far out there in its orbit?

So let's assume the Tesla is half the distance to the moon and roughly the same albedo, and since the differences in distance to the Sun are negligible, both objects have the same surface brightness.

 

The moon has a diameter of about 3.5 million meters.   

The Tesla is 4m long in its longest dimension.  To make the math simple, let's say it can be modeled with a 3.5-meter sphere.

 

That means the moon is 1,000,000 times wider and has 1,000,000,000,000 the radiating area if we approximate it with a circular disk.    The Tesla is half the distance, though,  so we can divide that advantage by four, leaving us with 250,000,000,000, or 2.5x10^11.   That's about 28 magnitudes difference in brightness (1 magnitude is about 2.5X increase in brightness).  If the moon is -12.7, that still leaves us at magnitude 15 or so, which ought to be about at the grasp of a 14" telescope.   Changing the albedo isn't going to change the brightness more than a couple of magnitudes, I would think.

 

So at present, it seems to me that it should still be bright enough to be seen.

 

However, it's going to get much, much farther away.  The moon is less than 1% the earth-sun distance (1AU), and the Tesla's elliptical orbit will take it as far as almost 3AU from the sun (or almost 4AU from Earth at the farthest).   A 2AU, the Tesla would be 775 times the distance used above, making it roughly 600,000 times or about 14 magnitudes dimmer.

 

At least that's the back-of-napkin estimates I get with my (currently) flu-addled brain.   


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#11 jallbery

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Posted 07 February 2018 - 10:10 AM

 

A Tesla roadster is a bout 4m long.   The resolution of a diffraction-limited 14" telescope is about  0.33 arc seconds.    At the distance of the ISS (about 400km), a 4m sphere would have an angular size of about 2 arc seconds.   I'm not sure how far away the Tesla is at present, but it already considerably farther from Earth than the ISS.  Therefore it is too small to resolve.

It is still attached to the 2nd stage, so it is far larger than that. In the live feed you can see the whole Earth in the camera view at times, depending on where it is in orbit. So it is in a very high orbit. https://www.youtube....h?v=aBr2kKAHN6M

 

 

Good point on the 2nd stage, although even if the rocket is resolvable, the actual roadster would not. 

 

It's actually in a fairly elliptical orbit around the sun, varying from 0.98AU to 2.61AU.



#12 Jim Davis

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Posted 07 February 2018 - 10:15 AM

The car just passed perigee low over Indonesia. The orbit is very elongated, so it is rapidly climbing away from Earth at the moment.

 

Edit: The Mars transfer burn happened during that low pass. It is now on its way.


Edited by Jim Davis, 07 February 2018 - 11:00 AM.


#13 BrooksObs

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Posted 07 February 2018 - 11:10 AM

Perhaps to put the situation into perspective, I recall the days when Americans were still going to the moon. I watched several of the joined command module/lander units - drastically larger than the Tesla - enroute to the moon using my 12.5" Newtonian. The first night after launch the ship and discarded associated panels were easily watched, being something like 8th magnitude stars IIRC. By the second night they were much more challenging to spot under excellent skies and thereafter, simply out of sight. So, I'd concur with the poster upstream who suggested that once at a significant fraction of the lunar distance from Earth, the little Tesla will be far beyond the reach of hobbyists' telescopes.

 

BrooksObs



#14 mbrio76

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Posted 09 February 2018 - 06:00 AM

"The Virtual Telescope Project": Elon Musk’s Tesla Roadster imaged and filmed!

 

https://www.virtualt...ged-8-feb-2018/


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#15 Cotts

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Posted 09 February 2018 - 09:14 AM

"The Virtual Telescope Project": Elon Musk’s Tesla Roadster imaged and filmed!

 

https://www.virtualt...ged-8-feb-2018/

In the GIF the 'car' is clearly visible going from left to right.  I immediately noticed a much fainter little dot ahead of it.  Look by the bright star near the right edge - you'll easily see it.  The speeds and directions of the two objects match very well (over the admittedly small sample size of the GIF).

 

What have we got here?  Wasn't the car attached to a 'booster stage' which recently separated after the burn?  Then I'll venture the guess that the bright moving dot is the booster and the tiny dot ahead of it is actually the car....

 

Dave 



#16 Nightow1

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Posted 09 February 2018 - 09:22 AM

 

What if you increased the Tesla's albedo to the maximum level, or covered it in iridium panels? You could probably see it as a point source when the angle of the sun was right, pretty far out there in its orbit?

So let's assume the Tesla is half the distance to the moon and roughly the same albedo, and since the differences in distance to the Sun are negligible, both objects have the same surface brightness.

 

The moon has a diameter of about 3.5 million meters.   

The Tesla is 4m long in its longest dimension.  To make the math simple, let's say it can be modeled with a 3.5-meter sphere.

 

That means the moon is 1,000,000 times wider and has 1,000,000,000,000 the radiating area if we approximate it with a circular disk.    The Tesla is half the distance, though,  so we can divide that advantage by four, leaving us with 250,000,000,000, or 2.5x10^11.   That's about 28 magnitudes difference in brightness (1 magnitude is about 2.5X increase in brightness).  If the moon is -12.7, that still leaves us at magnitude 15 or so, which ought to be about at the grasp of a 14" telescope.   Changing the albedo isn't going to change the brightness more than a couple of magnitudes, I would think.

 

So at present, it seems to me that it should still be bright enough to be seen.

 

However, it's going to get much, much farther away.  The moon is less than 1% the earth-sun distance (1AU), and the Tesla's elliptical orbit will take it as far as almost 3AU from the sun (or almost 4AU from Earth at the farthest).   A 2AU, the Tesla would be 775 times the distance used above, making it roughly 600,000 times or about 14 magnitudes dimmer.

 

At least that's the back-of-napkin estimates I get with my (currently) flu-addled brain.   

 

Ok  thank you I get it now. Sorry for the dumb ???. But I just couldn't seem to get it. People were saying we would never be able to see it again from.earth.



#17 Michael Covington

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Posted 09 February 2018 - 09:29 AM

Summing this up:

 

- Telescopes aren't infinitely powerful.  Some objects are too dim and too small to see from Earth with any telescope.

     (There are 2 reasons.  A telescope gathers only a finite amount of light, and light is made of waves and can never be focused to a perfectly sharp point.)

- The Tesla is one of them, or will be when it gets a little farther away.
 



#18 mbrio76

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Posted 09 February 2018 - 09:36 AM

 

"The Virtual Telescope Project": Elon Musk’s Tesla Roadster imaged and filmed!

 

https://www.virtualt...ged-8-feb-2018/

In the GIF the 'car' is clearly visible going from left to right.  I immediately noticed a much fainter little dot ahead of it.  Look by the bright star near the right edge - you'll easily see it.  The speeds and directions of the two objects match very well (over the admittedly small sample size of the GIF).

 

What have we got here?  Wasn't the car attached to a 'booster stage' which recently separated after the burn?  Then I'll venture the guess that the bright moving dot is the booster and the tiny dot ahead of it is actually the car....

 

Dave 

 

Good question :)



#19 Special Ed

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Posted 09 February 2018 - 01:20 PM

There is an image on today's Spaceweather made with a scope in Australia.



#20 BrooksObs

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Posted 09 February 2018 - 03:21 PM

Something not mentioned as far as I can tell so far is that the Musk's Tesla is in an Earth-crossing orbit and that at some point in the future could well encounter our planet once again. If you keep track of satellite news, every once and a while small bodies initially classified as "asteroids" are discovered...ultimately to be recognized as spent boosters from our past interplanetary launches! To my knowledge, so far none has re-entered Earth's atmosphere, but when one ultimately does, there will be some real nice fireworks. smirk.gif

 

BrooksObs



#21 B l a k S t a r

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Posted 09 February 2018 - 03:29 PM

Keep an eye out for additional occupant(s) ie Hitchhikers.


Edited by B l a k S t a r, 09 February 2018 - 03:30 PM.


#22 mvas

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Posted 09 February 2018 - 03:48 PM

Ok I'm a Noob and just don't get it.

Can someone please explain to me the reason they say we will never be able to see the Tesla in space with a telescope??

Or is this just Talk, if how and when?

And feel free to confuse me, I just don't get it?????

Thanks for helping a dummy...

I need a telescopes for dummies manual?!!

 

Who is "they" ?

The roadster is still visible from earthbound telescopes, currently at 16th magnitude.

It's orbital period is about 558 days.

Approx every 3 years, the Roadster's orbit and the Earth's orbit will align, making it periodically easily visible in a telescope.


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#23 gregj888

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Posted 10 February 2018 - 02:40 AM

 http://udalosti.astr.../Tesla_FRAM.gif

 

 (courtesy of Martin Mašek, FRAM and RTS2)

 

You can detect things below the resolution limit, we do that all the time with stars.



#24 t_image

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Posted 10 February 2018 - 06:01 PM

FWIW,

The talk of resolving resolution only immediately applies if you are trying to see it transit the Moon or Sun in shadow. (Why it's nearly impossible to see satellites other than ISS, Tiangong 1, and a few very close and really big others to transit across in shadow in front of Moon or Sun).....

 

When it comes to objects reflecting sunlight,

please note this point as it could save your life:

A search plane miles up can spot a credit card reflecting sunlight................

google "signaling mirror" if you don't believe me.

 

You all might enjoy this blog with images of the tesla&R/B from different individuals than the link above:

 

Other images of tesla taken from Earth:

https://sattrackcam....dster-2018.html

 

Cheers!



#25 RBA

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Posted 11 February 2018 - 01:27 PM

My capture... About 2 hours of video compressed in just a few seconds:

 

https://www.facebook...54192527981387/


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