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Want a consumer grade telecope in orbit?

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#1 nholden

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Posted 16 September 2021 - 06:19 PM

Hi Astrophotographers,

 

I originally posted this over in the general forum: https://www.cloudyni...ecope-in-orbit/. Some feedback suggested this would be a more appropriate forum.

 

I’m a Space Systems Engineering masters student working on my final capstone project. The topic I’m exploring is into the viability of putting a consumer telescope in space. However, I’m an engineering student and not an astronomer, so the question I have is, would you want it?

 

My current working assumptions are:
Small <15kg telescope, otherwise launch costs are too expensive.
Accessible to anyone, you could rent time on the telescope.
Probably only capable of still images, but as I research more it might be possible to stream live video, would this be of value?

 

Love to hear your thoughts, is this worth exploring? Is there any value in putting a small telescope in space? Any obvious problems etc…?

 

Thanks for your help!
Nick


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#2 jshinal

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Posted 16 September 2021 - 08:15 PM

I think there is value in creating a small satellite under amateur control. The specification of it being a commercial consumer telescope seems to me a tempting trap. I believe the temperature issues would lead to rapid failure in orbit.

 

Using a re-engineered scope from a suitable maker (APM ?) in light materials...that might work pretty well. Just a modern 200mm ED refractor would be impressive to orbit. It's a dead simple design.

 

It would be similar to a simplified old-style spy satellite. In fact, using it for earth science may "sell" your project easier than astronomy. (I feel terrible for saying that. blush.gif)



#3 crgood2

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Posted 17 September 2021 - 10:15 AM

I believe there was a company working on this - like a 10" SCT/CDK design in a cubesat form factor.  I had heard about on one of the OPT podcasts.  It'd be great for amateurs, but challenging from an imaging perspective; maintaining pointing/tracking with reaction wheels, thermal expansion and uneven heating on the sunward side/dark side, etc.



#4 whwang

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Posted 17 September 2021 - 10:59 AM

One needs to ask why needing a small scope in space.  Can observe any time regardless of weather?  How about getting 10 such scopes on the ground and putting them in a place where 1/4 of the nights are clear?  Comparing to launching a scope to space, will the ground-based 10-scope system be much cheaper to built and maintain?  Remember that even in space, half of your sky will be blocked by Earth.  Hubble typically can only observe 50 to 60 minutes every 90-minute orbit.  So there are down times in space too, just not caused by weather.

 

To overcome seeing? Yes, this is 80% why we have Hubble.  (The other 20% is that the sky is much darker in space.)  However, now amateurs are building their remote telescopes at places where seeing is 0.4 to 1 arcsec.  A scope of 20 cm diameter has a diffraction limit of 0.6 arcsec.  So you really need something much larger than that to benefit from the space seeing (no seeing) while justifying the cost.  So I would say you need to have a scope that's larger than at least 50 cm.  And this goes far beyond your proposed weight limit.  In space, you don't have gravity, so in principle the scope does not need a super rigid/heavy structure. However, the structure needs to at least survive the launch and maintain the optical collimation (or having mechanisms to re-collimate the optics once in the orbit).  It won't be very light weight.  Remember, here we are talking about diffraction limit of better than 0.3 arcsec or so.  So the collimation requirement will be much stronger than a typical seeing limited amateur scope.

 

It's just cool?  Then of course.  It's cool.



#5 dan_1984

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Posted 18 September 2021 - 05:13 PM

And SCT in orbit, Who would collimate it after a while? What happens when the mirror flops? This seems all kinds of wrong lol.gif



#6 oneredpanther

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Posted 18 September 2021 - 06:28 PM

I hereby volunteer to collimate it every eight weeks. It's really no trouble at all. I don't mind taking it for the team. 



#7 calypsob

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Posted 19 September 2021 - 12:37 AM

And SCT in orbit, Who would collimate it after a while? What happens when the mirror flops? This seems all kinds of wrong lol.gif

Everything would need to be automated with servos or steppers. Primary and secondary mirrors, focuser, rotation.  

 

My vote would be for a carbon truss newtonian that could autofocus and self collimate. You would need a conical zerodur primary. A 20” f3.3 with a monochrome 6200 sensor would sample .3 - .4 arcseconds in space. You may still need the peltier unit but to warm instead of cool, and obviously the fans can go. Im sure someone like FLI or Sbig could produce a space ready camera. It would also be a good idea to write simple custom drivers to automate everything like an industrial version of asi air pro. It would be interesting to even see a simple os like rpi uses. If the computer is cheap, maybe send 4 connected to the same camera in case there are ever failures or issues.



#8 TareqPhoto

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Posted 20 September 2021 - 09:21 AM

Hubble Telescope is an RC based design, and it kept working always, i don't know how often they collimate it or do maintenance, but for years it did the job unbelievably, so i vote for RC or at least Newtonian design [or why not a Mak design].




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