Quote from: simonbp on 09/02/2011 05:16 pmThe search area becomes narrower over time as New Horizons's (and Pluto's) orbits become better constrained.Isn't it getting narrower because any target objects NH could fly by are slowly moving toward the viable trajectory cone (delta-v reserve-mandated) as time passes, not because Pluto and NH orbits are unconstrained?I would have hoped they have a really good idea of NH's trajectory to be able to both get to Pluto aimpoint in the first place and also cancel the most recent TCM.
The search area becomes narrower over time as New Horizons's (and Pluto's) orbits become better constrained.
* Still no word on the post-Pluto target (searches under way), but they might go to up to two of them (depending on what the searches find). The search area becomes narrower over time as New Horizons's (and Pluto's) orbits become better constrained.
Interesting. Does that mean that there is work ongoing to improve knowledge of Pluto's orbit in order to finalise planning of the rendezvous?
Surely the target objects would be limited by the gravity assist which could be achieved at Pluto and/or Charon? Hence I'm guessing what is meant that as time passes there is less ability to change the Pluto aimpoint and thus achieve the necessary gravity assist to reach the next object.
There will be no targeting by "gravity assist" at Pluto. The trajectory is determined by science goals, and survival issues as just mentioned, which will not be compromised to optimize the trajectory to a tiny Kuiper belt object.
The PI's PerspectiveIs the Pluto System Dangerous?http://pluto.jhuapl.edu/overview/piPerspective.php
More specifically, a good candidate SHBOT aim point would be near Charon’s orbit, but about 180 degrees away from Charon on closest-approach day. Why this location? Because Charon’s gravity clears out the region close to it of debris, creating a safe zone.
No, L3 is a saddle point that's really hard to accidentally capture into. The "danger zone" is the regions around L4 and L5, as well as anything much interior of L1. So, at L3 you only really have to worry about horseshoe orbits (going between L4 and L5), and they are much easier to perturb than L4/5 halo orbits.Also, Pluto-Charon is an extremely close system (a=17 Pluto radii, compared to the Moon at 60 Earth radii), so the gravity on objects at the L-points is not simply two point sources, thus making perturbations much easier.