Tuesday, April 12, 2016

Combined amateur telescopes for asteroid detection.

Copyright 2016 Robert Clark

 NASA is conducting an interesting program to get the public involved in the upcoming ORISIS-REx mission to retrieve a sample from an asteroid. It is asking amateur astronomers to make observations of known asteroids using their telescopes:

Target Asteroids!

 However, a slight modification of this program should allow it to also to discover unknown asteroids. This article discusses that even an 8-inch scope equipped with a CCD camera can discover new asteroids:

Hunting Asteroids From Your Backyard
By: Dennis Di Cicco | July 28, 2006
There are no hard and fast rules regarding the telescope or CCD camera needed for asteroid work. To be effective, the system should record stars as faint as 18th magnitude with a single, 4-minute exposure. Almost any CCD camera on an 8-inch telescope can do this under a clear, dark sky.

 The article discusses down to magnitude 18. But combining the observations of many of these scopes acting in concert should allow the discovery of asteroids of weaker magnitude and therefore smaller size.

 As discussed in the article, CCD's can have imaging artifacts where a pixel will show as lit but it's not really corresponding to a light photon hitting the device. Moreover, the weaker the imaging source, the more difficult it is distinguish these imaging artifacts from a real light source.

 However, since these imaging artifacts are occurring at random, the idea would be to have several of the amateur scopes from different parts of the world focused on the same spot in the sky. Then several of the scopes' CCD's registering a hit on a pixel corresponding to the same point in the sky at the same time would be taken as indicating a real light source.

 The scopes would have to have a high degree of sky location specificity and timing synchronization for this to work.
 Another aspect of the imaging artifacts of the CCD's is that at low imaging illumination the CCD might correctly register a lit pixel but at a later time not register it. For individual scopes used to detect asteroids, it's done by noticing the light source moving between exposures. But if the imaging light source is too weak the CCD for the scope might not register the light source the second time to detect the motion. Then in this proposal of using multiple scopes, you also need to be able to correlate a second detection by another scope as indicating the light source moved, even if this scope did not detect the light source the first time. All the information would need to be correlated at a central site for this to work.

 Then after sufficient numbers of scopes give a high level of confidence the asteroid is indeed there, larger professional telescopes could be used to confirm the detection.

 This would have importance also for planetary protection purposes since it would allow the detection of smaller asteroids.

Credit and Financial Rewards for the Discovery?
 Certainly the amateur astronomers whose scopes detected the asteroid should get credit for the discovery. But an intriguing question of financial rewards arises because of the companies such as Planetary Resources, Inc. and Deep Space Industries that are working towards returning valuable minerals from asteroids. According to this article an asteroid potentially worth $5 trillion in platinum passed nearby to Earth last year:

‘Platinum’ asteroid potentially worth $5.4 trillion to pass Earth on Sunday.
Published time: 18 Jul, 2015 11:21

 There are very many near Earth asteroids still to be discovered. Then one can imagine these coordinated amateur scopes detecting one of these highly valuable asteroids. If one of them is eventually used to recover valuable minerals should the amateur astronomers who discovered it take part in the financial rewards?

 Not an easy question but it is notable that it would increase the interest and participation of amateur astronomers in the program. In view of its potential importance for planetary defense purposes this participation should be encouraged.

   Bob Clark