The June 2018 news item in Science To find small asteroids that could hit Earth, private foundation embraces small satellites says:

On 10 May, B612 announced a partnership with York Space Systems, a Denver-based maker of standard 85-kilogram satellites, to investigate building a fleet of small asteroid hunters. [...] Now, B612 has developed a new technique to do the same thing at a far lower cost with small space telescopes. Ed Lu, B612's co-founder, expects the first telescope to cost about $10 million and believes a full constellation “would be a factor of many, many cheaper” than Sentinel.

Some asteroid astronomers are skeptical of the new approach, saying the technology is far from proven. “To be very, very blunt, what they are proposing and what they’ve demonstrated is not going to help us find more NEOs [near-Earth objects],” says astronomer Timothy Spahr, CEO of space consultancy firm NEO Sciences in Marlborough, Massachusetts, who does independent work for NASA.

Is it known what technology is described and how it is proposed to help identify a large number of near Earth asteroids?

Are there similarities with B612's Sentinel proposal, or is this something different? Would these be in LEO? Does that suggest they would not use thermal IR to identify the asteroids?

How would it compare to NeoCAM? (now NEO Surveyor)

  • $\begingroup$ How can a fleet of small satellites equiped with small telescopes finding asteroids better than a single large space telescope? May be interferometry will be used, but this will require distances between fleet members to be known very precisely. $\endgroup$
    – Uwe
    Dec 2 '18 at 20:55
  • $\begingroup$ What about image differences processing comparing several images of the same star region taken not at different time but from different satellite locations? The position of fixed stars will be the same in several images, but small asteriods close to Earth will apear at different image positions. $\endgroup$
    – Uwe
    Dec 2 '18 at 21:36

In theory, a smaller telescope can see a dim object by just looking longer than a larger one. There are issues of noise and stability that limit this, but for small factors it works.

So their plan seems to be to break up a large-telescope observing plan into plans for longer observations with multiple smaller telescopes. This (somehow) saves lots of cost.

Except that for a survey project, you’re not looking for an object but rather looking for many possible objects on various trajectories. A big telescope has an advantage here, as a quick photo keeps the photons from a moving-in-the-telescope image close together for an above-background image.

This is where the synthetic tracking comes in. Using computational effects to combine a lot of short images, relative motion can be corrected out. This lets the small telescope with long gaze times still effectively see moving objects, at the cost of large amounts of computation and some false positives from noise that will have to be reimaged.

  • $\begingroup$ I think if you take realistic CCD sensor noise into consideration, your first sentence while possibly technically true, might be misleading. If the aperture area difference was a factor of 10 for example, for objects well above the noise level in the smaller telescope might indeed be imagable with exposures 10x longer, but if that gets near the detector noise level you may have to expose much longer to average it out. $\endgroup$
    – uhoh
    Oct 6 '19 at 13:22

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