The ArXiv preprint Technical Note: Asteroid Detection Demonstration from SkySat-3 B612 Data using Synthetic Tracking is an interesting read! The abstract says:
We report results from analyzing the B612 asteroid observation data taken by the sCMOS cameras on board of Planet SkySat-3 using the synthetic tracking technique. The analysis demonstrates the expected sensitivity improvement in the signal-to-noise ratio of the asteroids from properly stacking up the the short exposure images in post-processing.
This is a system optimized for short (20 ms) exposures of Earth's bright, sunlit surface using CMOS imagers (not CCDs), being pointed into space during the eclipse phase of its polar orbit, and imaging dim, deep space objects. For this test asteroids with a visible magnitude of roughly +14 to +16 were tested, but according to section 6.2, the same 35 cm telescope with a small redesign of the hardware would have a limiting magnitude of about +21!
The following caught my eye:
6.3 Future Directions in Asteroid Searches
Recently Pan-STARRS announced the first discovery of an interstellar asteroid. This came after ~10 years of Pan-STARRS operation. Early estimates are that the discovery rate would only increase slightly in the near future, even with telescopes like LSST. The principal reason is that interstellar asteroids move very rapidly compared to normal NEOs, thus producing a streaked image with PanSTARRS and LSST. Synthetic tracking would be able to increase the discovery rate by 10~30, even when using relatively small telescopes such as the 35cm aperture SkySat-3 telescope.
Question: What is synthetic tracking, and why would a 35 cm Earth imager be 10-30x better than Pan-STARRS or LSST for spotting interstellar asteroids? Is there something fundamental about the Pan-STARRS system or the Large Synoptic Survey Telescope that is unalterable for use in this specific application?