Star 48b Third-stage Motor, Leaving the solar system Options

[Guido]

I suppose the STAR 48B third-stage, which put New Horizons on its trajectory towards Jupiter, follows about the same flight-path as the New Horizons spacecraft itself. If this is the case, will it too in the end leave our solar system?
Or has it been deflected after seperation from the spacecraft?

[djellison]

Obviously retro reflectors work out to 400k km, but how far out would they work beyond that? Perhaps one could do radar reflection using Arecbo / DSN instead?

Also - there's no real way of knowing, (perhaps less so with the solid 48b than a liquid upper stage) what potential small forces are being generated by outgassing of remaining fuel, its exact mass etc.

Doug

[Comga]

Obviously retro reflectors work out to 400k km, but how far out would they work beyond that?  Perhaps one could do radar reflection using Arecbo / DSN instead?

Doug

Sorry, but this won't work. The Pioneer anomoly is a grand distance effect. 400M km is barely at Jupiter distance, but that would diminish the return from a Lunar Retroreflector Array by a factor of one trillion (1E12) as it goes as R^4. At Neptune's distance of 4G km the signal would be down by a factor of 1E16. And in order to keep the mass down, the array would have to be more than a factor of ten smaller, which could cut into both legs reducing the signal by ANOTHER factor of 100 at best. No conceovable amount of technological progress would make this signal detectable. Plus one would have to put the retro on the rocket nozzle end to face back at Earth. A radio retroreflector would have to be quite large to have any effect, and could not be carried.

A spent stage is just innert mass on an uncontrolled trajectory. It would be very hard to find a use for this mass that would not have imposed additional requirements on the mission. New Horizons survived by avoiding distractions and extraneous burdens.

Other missions have used their boosters as photographic targets, and NH knows its velocity relative to the spent third stage with high precision, and would be looking at the sunlit side. Don't know if imaging it would serve any purpose.

[Bob Shaw]

Other missions have used their boosters as photographic targets, and NH knows its velocity relative to the spent third stage with high precision, and would be looking at the sunlit side.  Don't know if imaging it would serve any purpose.

Oh? Which ones photographed their boosters?

Bob Shaw