QUESTION FROM ALASDAIR TAYLOR
How would you propose to survey and track all NEO of the size of Tunguska?
I mean 25th abs magnitude is faint and I can believe that this is the main reason the red line flattens off. What telescope setup would you describe as being ideal for hunting these objects?
I originally through that survey telescopes like Superwasp etc would be good for it but I see they are limited in there sky back ground magnitude.
ANSWER BY RUSTY SCHWEICKART (ADXP)
Technically speaking we’ll never know if we’ve found all the NEOs of any size. However we’ve already reached over 95% of the objects >1 km (based on the latest Harris size-freq chart… see http://www.asteroidday.org/asteroid-day-expert-blog/2015/2/26/asteroid-day-blog-3-how-many-are-we-talking-about-anyway). But, as you imply, for the smaller objects that can still create havoc (including death) this is still a substantial challenge.
Meeting the Asteroid Day goal of 100,000 newly discovered NEOs per year will substantially increase the numbers of smaller objects in our inventory, including the 40 meter Tunguska-sized objects. It would not be surprising to find that when we reach the 90% completion goal for the 140 meter objects (current Congressional goal) we’ll be approaching 25-30% completion on the 40 meter objects.
This goal now appears quite possible given the recent approval of construction funding for the Large Synoptic Space Telescope (LSST). Asteroid Day is now calling for supplementing the capability of LSST with one or more IR space telescopes as the preferred means to closely approach or achieve the 100x goal (e.g. either of the proposed NEOCam or Sentinel telescopes will likely do). Both of these IR space telescopes are analyzing, and will likely soon publish, the combined discovery performance of their telescopes in partnership with the ground-based LSST. I’d recommend that you periodically monitor their websites to keep abreast of these exciting new performance estimates.
Rusty Schweickart, Asteroid Day Expert