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The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

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Re: The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

#3
post #2

During one of my many Lyft rides I learned the driver was also one of several managers on this project. We had an interesting chat about it, and it left me wishing that the people involved in this sort of work were paid substantially more.

Agreed, unfortunately meaningful projects such as this are not a high priority for the US electorate (and thus the US Congress) [1]. My hope is that growing interest by college students in STEM subjects [2] will ultimately lead to an increased understanding of the importance of these projects in the long term.

[1] http://en.wikipedia.org/wiki/Budget_of_NASA

[2] https://www.stemconnector.org/sites/default/files/store/STEM...

Re: The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

#5
I wonder if the plane flies during the day or night? I would assume that for a given mission its one or the other, which makes me also wonder how fast or slow it flies. Even though it is looking in the infrared - wouldn't the daylight still affect it?

Re: The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

#6

I wonder how it'll compare to eventually to be launched James Webb Telescope.

At wavelengths which they both observe (~1–28.5 microns; SOFIA goes out to longer wavelengths than JWST), JWST will be far superior in terms of both sensitivity and resolution. For one, the mirror on SOFIA is less than half the diameter of that on JWST ([0],[1], so the resolution is less than half as good and the collecting area is down by more than a factor of four). Even though SOFIA flies above a lot of the infrared-absorbing atmosphere, it still suffers from some absorption. Additionally, the aircraft and the remaining atmosphere emit in the infrared, so the background levels for SOFIA are much higher.

That being said, SOFIA operates at far-infrared wavelengths as well, which JWST will not support. There are satellite missions being propose which would work in the far-infrared; none have been fully approved yet (to my knowledge), but any of them would surpass SOFIA in most metrics (except perhaps spectral resolution).

[0] http://www.sofia.usra.edu/Science/telescope/index.html

[1] http://jwst.nasa.gov/faq_scientists.html#whatis

Re: The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

#7
How long are the exposures? One would think that due to vibration etc. the exposures need to be extremely short, but long exposures are beneficial in astrophotography.

EDIT: Wikipedia answers the vibration issues: http://en.wikipedia.org/wiki/Stratospheric_Observatory_for_I...

Re: The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

#8
post #5

I wonder if the plane flies during the day or night? I would assume that for a given mission its one or the other, which makes me also wonder how fast or slow it flies. Even though it is looking in the infrared - wouldn't the daylight still affect it?

We only fly at night. Well, technically speaking, we can observe with the sun up, but the guider cameras are optical which makes it nearly impossible to track any targets when the sky is bright. Moreover, we have to stay well away from the sun as the telescope would focus the sunlight with enough intensity to destroy itself. So, yeah, we only fly at night.

Airspeed is roughly mach 0.85.

Re: The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

#9
post #6

I wonder how it'll compare to eventually to be launched James Webb Telescope.

At wavelengths which they both observe (~1–28.5 microns; SOFIA goes out to longer wavelengths than JWST), JWST will be far superior in terms of both sensitivity and resolution. For one, the mirror on SOFIA is less than half the diameter of that on JWST ([0],[1], so the resolution is less than half as good and the collecting area is down by more than a factor of four). Even though SOFIA flies above a lot of the infrar…

Indeed, there are a couple of key things to note:

1) JWST has not been launched, yet.

2) SOFIA's wavelength coverage is different that JWST's or anything else that is in the pipeline.

So, really, they are complimentary observatories.

Re: The Jet With a 17-Ton Telescope That NASA Uses as a Flying Observatory

#10
post #7

How long are the exposures? One would think that due to vibration etc. the exposures need to be extremely short, but long exposures are beneficial in astrophotography. EDIT: Wikipedia answers the vibration issues: http://en.wikipedia.org/wiki/Stratospheric_Observatory_for_I...

It's normal to take many short exposures and stack them up to get a long one. The length is dictated by the amount of noise in your detector. From a look at the Wikipedia article, it looks like they need a lot more than just short exposures on Sofia.
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