8 ms·

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

114 points by nealabq 12y ago

dylanrw 12y ago
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.
- john_b 12y ago
  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 http://en.wikipedia.org/wiki/Budget_of_NASA [2] https://www.stemconnector.org/sites/default/files/store/STEM-Students-STEM-Jobs-Executive-Summary.pdf https://www.stemconnector.org/sites/default/files/store/STEM...
  - rbanffy 12y ago
    One could always ask for support saying a given experiment could prove the, say, biblical flood or somethimg equally silly. If someone believes that all animals on Earth descend from the living cargo of a wooden ship, it should be possible to convince them of anything. Hacking a right-wing nutty congresscritter is an intriguing concept.
    - chenelson 12y ago
      And, I guess, Bill Maher is a right-wing nutty? He believes Mars and Moon missions would be a great waste of money. The Bible isn't holding us back....it's our lack of imagination and lazy jokes and the conflation of capital and fiat currency.
      - tekacs 12y ago
        ... or both you and the GP are partially right and _both_ are holding us back. :/
        chenelson 12y ago
        If we took religion away from history, would we have science?
      - rbanffy 12y ago
        > He believes Mars and Moon missions would be a great waste of money. If they fail to inspire people to continue exploring, yes. I would prefer Moon missions because they'd be cheaper and, as far as inspiration goes, they'd achieve the same results. How many brilliant people have chosen to dedicate their talents to building web technologies because space is no longer cool? Also, being able to build self sustaining off world colonies may prove handy if we end up unable to stop climate change...
        chenelson 12y ago
        I think if something is inspirational, it must be realizable; thus, unless we're talking about mining the moon and requiring human's for labor, we're going to miss the point. Climate change on Earth is a constant, and if time is x, human existince is a speed bump.
  - crahrah 12y ago
    NASA is so prestigious that they basically can get away with paying everyone very little. They aren't stuck with bottom of the barrel people even though they pay them bottom of the barrel wages. I'm not saying it's right or wrong, but I don't think more funding would really change much (other than allow them to fund more projects, but I'd argue that there are some serious diminishing returns at this point)
- dnautics 12y ago
  oh interesting. I'm also a lyft driver/scientist. I'm doing a series of in-car interviews of scientists, I'd love to try to talk to him, would you be able to contact me (details in profile)?
  - selimthegrim 12y ago
    Scientists in Sedans getting Sauced?
valarauca1 12y ago
I wonder how it'll compare to eventually to be launched James Webb Telescope.
- privong 12y ago
  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 http://www.sofia.usra.edu/Science/telescope/index.html [1] http://jwst.nasa.gov/faq_scientists.html#whatis http://jwst.nasa.gov/faq_scientists.html#whatis
  - goodcanadian 12y ago
    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.
    - privong 12y ago
      > 2) SOFIA's wavelength coverage is different that JWST's or anything else that is in the pipeline. Depending on what you mean by "pipeline", that isn't quite true. Work is being done on several far-inrared missions, such as SPICA[0]. I'd consider SPICA to be in "in the pipeline" and it will cover much (if not all) of the far-infrared that SOFIA does. So I wouldn't call JWST and SOFIA complementary; rather, SOFIA is a precursor observatory and a potential technology development platform (for things like SPICA; not so much for JWST, since the JWST instruments are already being built). [0] https://en.wikipedia.org/wiki/SPICA_telescope https://en.wikipedia.org/wiki/SPICA_telescope
netcraft 12y ago
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?
- goodcanadian 12y ago
  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.
  - jessedhillon 12y ago
    Is there some way that civilians admirers can ride SOFIA and get to participate in some of those activities set aside for grade schoolers? I would certainly be as excited as any 6th grader to have that chance!
    - goodcanadian 12y ago
      Grade schoolers don't fly on SOFIA. The Airborne Astronomy Ambassadors program is for grade school teachers and other educators. I can't think of any obvious way for the general public to fly on SOFIA. If you are a professional astronomer, apply for time, and you may be invited to fly. If you are an educator, apply to the Airborne Astronomy Ambassador program.
  - batbomb 12y ago
    Nice to see another NASA-related astronomer here. I work on Fermi Gamma-Ray space telescope project, although I'm deep into the data processing and data management side of things. I also have been helping out with a ton of LSST camera related things.
  - aunty_helen 12y ago
nawitus 12y ago
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_Infrared_Astronomy#The_telescope http://en.wikipedia.org/wiki/Stratospheric_Observatory_for_I...
- greglindahl 12y ago
  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.
  - nawitus 12y ago
    Yes, you can stack short exposures, but long exposures are better in astrophotography (as a single 10 second exposure has a higher signal-to-noise ratio than 10x 1s exposures). If you take it to the extreme, it's very difficult to differentiate between the signal and the noise if your exposures are really short, which makes astrophotography in cities without a tracking quite mount difficult.
    - goodcanadian 12y ago
      SOFIA, like all major observatories, uses tracking. A guider camera tracks on the target itself if it is bright enough, or it does offset tracking on another star in the field. You don't need to have any visible signal from your target at all in order to stack the images. Note also, that not all instruments and observing modes are imaging. Often, spectroscopy is done instead.
      - goodcanadian 12y ago
        Maybe, I shouldn't reply to myself, but I feel like I have oversimplified. First, not all observatories use guiding cameras, but most do. An obvious exception are radio telescopes which do passive tracking, but will check their pointing on a bright source periodically. Second, the sky is very bright and variable in the infrared, so the dominant source of noise is from the sky. For this reason, you take an image on source followed shortly by an image off source to use to subtract the background sky from the on-source image. As the infrared sky can vary quite quickly, you want to sample the background quite often. If there is a "blank" patch of sky near enough to your target, this is accomplished by "chopping" the secondary mirror back and forth between the source and the off position. This occurs at frequencies on the order of 1Hz, so exposures are less than a second. If you have to move further to find "blank" sky, it is accomplished by "nodding" the telescope, i.e. moving the primary to the off position. This takes a bit longer and may only be done every ~30s. Because there is active guiding, there is no issue co-adding an arbitrarily large number of these images, and observations can actually be several hours long. And, because the background sky varies fairly rapidly, stacking short exposures (with the background subtracted) will actually give better noise performance than taking long exposures.
ddrmaxgt37 12y ago
My favorite 747! It's the 747SP. I love how short and fat it looks.
rosser 12y ago
Opening that door must do abysmal things to the plane's drag coefficient.
- goodcanadian 12y ago
  As I understand it, opening the door has negligible effect on the performance of the aircraft. The shape of the fuselage is modified to send airflow past the aperture.
Serow225 12y ago
Very cool, I worked with one of the engineers who did the stress & airflow analysis for cutting that big hole in the plane, it was really interesting to hear his stories! And yes, as goodcanadian stated elsewhere in this thread, there are airflow management modifications in front of and behind the door to make this all possible.
ra 12y ago
There's a fantastic BBC Horizon documentary called, "Seeing Stars" which includes, among other things, a SOFIA mission: http://www.dailymotion.com/video/x1kacli_bbc-horizon-2011-seeing-stars-pdtv-xvid_tech http://www.dailymotion.com/video/x1kacli_bbc-horizon-2011-se...
aunty_helen 12y ago
Here is one of the runs they did last year: http://flightaware.com/live/flight/NASA747/history/20130717/0612Z/NZCH/NZCH http://flightaware.com/live/flight/NASA747/history/20130717/... The arches are when they are doing their observations. Edit: For some reason the map is centering over the Atlantic when I open the link, the flight path is actually from New Zealand if you can't see it to start with.
qwerty_asdf 12y ago
The telescope on board is 10 times as sensitive and has triple the resolution of NASA’s Kuiper Airborne Observatory, originally launched in 1975 on a converted C-141 military cargo plane, and decommissioned in 1995. That telescope was the first to spot the rings around Uranus. "...the rings around Uranus."

114 points by nealabq 12y ago

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.

john_b 12y ago
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 http://en.wikipedia.org/wiki/Budget_of_NASA [2] https://www.stemconnector.org/sites/default/files/store/STEM-Students-STEM-Jobs-Executive-Summary.pdf https://www.stemconnector.org/sites/default/files/store/STEM...
- rbanffy 12y ago
  One could always ask for support saying a given experiment could prove the, say, biblical flood or somethimg equally silly. If someone believes that all animals on Earth descend from the living cargo of a wooden ship, it should be possible to convince them of anything. Hacking a right-wing nutty congresscritter is an intriguing concept.
  - chenelson 12y ago
    And, I guess, Bill Maher is a right-wing nutty? He believes Mars and Moon missions would be a great waste of money. The Bible isn't holding us back....it's our lack of imagination and lazy jokes and the conflation of capital and fiat currency.
    - tekacs 12y ago
      ... or both you and the GP are partially right and _both_ are holding us back. :/
      - chenelson 12y ago
        If we took religion away from history, would we have science?
    - rbanffy 12y ago
      > He believes Mars and Moon missions would be a great waste of money. If they fail to inspire people to continue exploring, yes. I would prefer Moon missions because they'd be cheaper and, as far as inspiration goes, they'd achieve the same results. How many brilliant people have chosen to dedicate their talents to building web technologies because space is no longer cool? Also, being able to build self sustaining off world colonies may prove handy if we end up unable to stop climate change...
      - chenelson 12y ago
        I think if something is inspirational, it must be realizable; thus, unless we're talking about mining the moon and requiring human's for labor, we're going to miss the point. Climate change on Earth is a constant, and if time is x, human existince is a speed bump.
- crahrah 12y ago
  NASA is so prestigious that they basically can get away with paying everyone very little. They aren't stuck with bottom of the barrel people even though they pay them bottom of the barrel wages. I'm not saying it's right or wrong, but I don't think more funding would really change much (other than allow them to fund more projects, but I'd argue that there are some serious diminishing returns at this point)
dnautics 12y ago
oh interesting. I'm also a lyft driver/scientist. I'm doing a series of in-car interviews of scientists, I'd love to try to talk to him, would you be able to contact me (details in profile)?
- selimthegrim 12y ago
  Scientists in Sedans getting Sauced?

valarauca1 12y ago

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

privong 12y ago
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 http://www.sofia.usra.edu/Science/telescope/index.html [1] http://jwst.nasa.gov/faq_scientists.html#whatis http://jwst.nasa.gov/faq_scientists.html#whatis
- goodcanadian 12y ago
  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.
  - privong 12y ago
    > 2) SOFIA's wavelength coverage is different that JWST's or anything else that is in the pipeline. Depending on what you mean by "pipeline", that isn't quite true. Work is being done on several far-inrared missions, such as SPICA[0]. I'd consider SPICA to be in "in the pipeline" and it will cover much (if not all) of the far-infrared that SOFIA does. So I wouldn't call JWST and SOFIA complementary; rather, SOFIA is a precursor observatory and a potential technology development platform (for things like SPICA; not so much for JWST, since the JWST instruments are already being built). [0] https://en.wikipedia.org/wiki/SPICA_telescope https://en.wikipedia.org/wiki/SPICA_telescope

netcraft 12y ago

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?

goodcanadian 12y ago
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.
- jessedhillon 12y ago
  Is there some way that civilians admirers can ride SOFIA and get to participate in some of those activities set aside for grade schoolers? I would certainly be as excited as any 6th grader to have that chance!
  - goodcanadian 12y ago
    Grade schoolers don't fly on SOFIA. The Airborne Astronomy Ambassadors program is for grade school teachers and other educators. I can't think of any obvious way for the general public to fly on SOFIA. If you are a professional astronomer, apply for time, and you may be invited to fly. If you are an educator, apply to the Airborne Astronomy Ambassador program.
- batbomb 12y ago
  Nice to see another NASA-related astronomer here. I work on Fermi Gamma-Ray space telescope project, although I'm deep into the data processing and data management side of things. I also have been helping out with a ton of LSST camera related things.
- aunty_helen 12y ago

nawitus 12y ago

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_Infrared_Astronomy#The_telescope http://en.wikipedia.org/wiki/Stratospheric_Observatory_for_I...

greglindahl 12y ago
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.
- nawitus 12y ago
  Yes, you can stack short exposures, but long exposures are better in astrophotography (as a single 10 second exposure has a higher signal-to-noise ratio than 10x 1s exposures). If you take it to the extreme, it's very difficult to differentiate between the signal and the noise if your exposures are really short, which makes astrophotography in cities without a tracking quite mount difficult.
  - goodcanadian 12y ago
    SOFIA, like all major observatories, uses tracking. A guider camera tracks on the target itself if it is bright enough, or it does offset tracking on another star in the field. You don't need to have any visible signal from your target at all in order to stack the images. Note also, that not all instruments and observing modes are imaging. Often, spectroscopy is done instead.
    - goodcanadian 12y ago
      Maybe, I shouldn't reply to myself, but I feel like I have oversimplified. First, not all observatories use guiding cameras, but most do. An obvious exception are radio telescopes which do passive tracking, but will check their pointing on a bright source periodically. Second, the sky is very bright and variable in the infrared, so the dominant source of noise is from the sky. For this reason, you take an image on source followed shortly by an image off source to use to subtract the background sky from the on-source image. As the infrared sky can vary quite quickly, you want to sample the background quite often. If there is a "blank" patch of sky near enough to your target, this is accomplished by "chopping" the secondary mirror back and forth between the source and the off position. This occurs at frequencies on the order of 1Hz, so exposures are less than a second. If you have to move further to find "blank" sky, it is accomplished by "nodding" the telescope, i.e. moving the primary to the off position. This takes a bit longer and may only be done every ~30s. Because there is active guiding, there is no issue co-adding an arbitrarily large number of these images, and observations can actually be several hours long. And, because the background sky varies fairly rapidly, stacking short exposures (with the background subtracted) will actually give better noise performance than taking long exposures.

ddrmaxgt37 12y ago

My favorite 747! It's the 747SP. I love how short and fat it looks.

rosser 12y ago

Opening that door must do abysmal things to the plane's drag coefficient.

goodcanadian 12y ago
As I understand it, opening the door has negligible effect on the performance of the aircraft. The shape of the fuselage is modified to send airflow past the aperture.

Serow225 12y ago

Very cool, I worked with one of the engineers who did the stress & airflow analysis for cutting that big hole in the plane, it was really interesting to hear his stories! And yes, as goodcanadian stated elsewhere in this thread, there are airflow management modifications in front of and behind the door to make this all possible.

ra 12y ago

There's a fantastic BBC Horizon documentary called, "Seeing Stars" which includes, among other things, a SOFIA mission: http://www.dailymotion.com/video/x1kacli_bbc-horizon-2011-seeing-stars-pdtv-xvid_tech http://www.dailymotion.com/video/x1kacli_bbc-horizon-2011-se...

aunty_helen 12y ago

Here is one of the runs they did last year: http://flightaware.com/live/flight/NASA747/history/20130717/0612Z/NZCH/NZCH http://flightaware.com/live/flight/NASA747/history/20130717/... The arches are when they are doing their observations. Edit: For some reason the map is centering over the Atlantic when I open the link, the flight path is actually from New Zealand if you can't see it to start with.

qwerty_asdf 12y ago

The telescope on board is 10 times as sensitive and has triple the resolution of NASA’s Kuiper Airborne Observatory, originally launched in 1975 on a converted C-141 military cargo plane, and decommissioned in 1995. That telescope was the first to spot the rings around Uranus. "...the rings around Uranus."