I recently wrote a paper (will attach soon if feasible) for an astronomy class that analyzed the usefulness of the Cosmic Microwave Background as a static reference for attitude determination. The main benefit of this over other attitude determination techniques is that the CMB has a constant pattern, even in intergalactic space. There is some variation over time, but it’s on the order of 1000+ years.

I was able to apply common computer vision algorithms to match randomly rotated rendered images of the CMB to their respective RA, Dec, Roll coordinates. These (completely unoptimized) algorithms tended to require a field of view of (Will find this in a moment) and a resolution of (Will find this in a moment) to be reasonably accurate.

One of my main assumptions is that it would be feasible to make a detector with sufficient resolution and signal-to-noise to be able to spot the CMB variation patterns within a few hours of observation. Is this true? What level of volume, specialization, and/or budget would be needed for this sensor: Cubesat? Smallsat? James Webb Space Telescope?

  • $\begingroup$ Do you mean the large-scale dipole caused by the Earth's motion through space, the background caused by the Milky Way foreground sources or the very small scale structure seen in e.g. the COBE or Planck maps (which have had the first 2 effects (at least) removed) ? $\endgroup$ – astrosnapper Aug 24 '19 at 19:22
  • $\begingroup$ @astrosnapper Preferably the small scale structures, so the dipole isn’t necessary. Sensing the dipole can be a secondary objective, for relative velocity determination $\endgroup$ – CourageousPotato Aug 24 '19 at 19:23
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    $\begingroup$ This is a really cool idea, both conceptually and literally! The temperature of the CMB is less than 3 Kelvin, in order to not be overwhelmed by noise, your receiving optics and sensors will likely have to be cooled to a very low temperature, and still you'll have just a tiny modulation on top of a much stronger system thermal noise background. You'll have to have a thermal management system, either a refrigerator, or a really good thermal shield from the Sun and Earth, letting radiation to space passively cool the cold part of your system. So I don't think this can be done in a cubesat. $\endgroup$ – uhoh Aug 26 '19 at 4:34
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    $\begingroup$ For example, Planck's passive and active cooling systems allow its instruments to maintain a temperature of −273.05 °C (−459.49 °F), or 0.1 °C above absolute zero. From August 2009, Planck was the coldest known object in space, until its active coolant supply was exhausted in January 2012. It was decommissioned when the refrigerant ran out. Since you are just doing pattern recognition and not full radiometric characterization, your system wouldn't have to be that cold. $\endgroup$ – uhoh Aug 26 '19 at 4:35

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