Some news about this interesting target. As a reminder, it will make its close flyby on Wednesday January 13 at 12:46 pm UT (4:46 pm PST) so in a few hours, when it will pass at 122,000 km from Earth.
Yesterday, Tuesday Jan 12, Lance Benner reported successful observations with the radar Goldstone antenna using the recent orbit estimate. I am assuming that they are processing the data to derive the size, shape and the true nature of the target.
Interestingly using an update of the orbit, Bill Gray from the MPML list mentioned that the target has not been near us for a long time (0.014 +/- .004 AU on 12 January 1929). This result is true only assuming gravitational forces and neglecting solar wind interaction which should played a major role for such small object (see the famous Yarkosky effect that I mentioned in several of my previous posts). We need to know precisely the size, shape and the albedo to be able to predict this effect so that’s one of the reasons we need these radar observations.
Michael Kahn, mission analyst at ESA, posted on his blog a discussion on the nature of this object that I ...