New Horizons: Pre-launch, launch and main cruise, Pluto and the Kuiper belt Options

[cIclops]

Yes it's happening after all these years, the mission to the last planet!

And maybe to celebrate the confirmation of budget, NASA approval preparations and the fueling of the RTG (radioisotope thermoelectric generator), there is an updated web site at http://pluto.jhuapl.edu/

Launch will be January 2006 with arrival at the Pluto Charon system July 2015 (mark your calender!) and then on through the Kuiper belt during 2016-2020 and beyond.

20.8-centimeter telescope for 100m resolution at closest approach
IR/UV spectrometers
2 x 8GB data recorders
data rate: 768 bps (sic) to 70m DSN
465kg including fuel
$650m

336 days to launch

[Decepticon]

New Horizons would fly 3 to 4 times closer to Jupiter than the Cassini spacecraft, coming within 31.7-32.4 Jupiter radii of the large planet."

That puts it just outside Callisto orbit?
Did I figure that out right?

[ugordan]

That puts it just outside Callisto orbit?
Did I figure that out right?

Yep, Callisto orbits at a distance of about 26 Jupiter radii. The sooner the spacecraft launches in the launch window, the closer it will get to Jupiter and proportionally faster to Pluto.

[JRehling]

Yep, Callisto orbits at a distance of about 26 Jupiter radii. The sooner the spacecraft launches in the launch window, the closer it will get to Jupiter and proportionally faster to  Pluto.

Of course, this means that NH may fly within 6 or so Jr of Callisto, if the timing is right -- I hope it is! Ganymede could also be favorable positioned. For Io and Europa, the margin of difference is less.

I doubt if an opportunistic Callisto flyby is worth tweaking any mission constraints over, although with such a long lag between Jupiter and Pluto flybys, I would guess that it would be possible in principle to time the Jupiter encounter as desired, then tweak Pluto arrival quite easily in the years to come. But that propellant budget could buy us a KBO or not post-Pluto, and it would end up being a poor tradeoff if a KBO were missed so that a so-so Callisto image sequence could be obtained!

[ugordan]

I doubt if an opportunistic Callisto flyby is worth tweaking any mission constraints over, although with such a long lag between Jupiter and Pluto flybys, I would guess that it would be possible in principle to time the Jupiter encounter as desired, then tweak Pluto arrival quite easily in the years to come. But that propellant budget could buy us a KBO or not post-Pluto, and it would end up being a poor tradeoff if a KBO were missed so that a so-so Callisto image sequence could be obtained!

I don't think timing a Callisto nontargeted flyby would be much of an issue at all. Callisto's orbital period is 16 days and the arrangement between Jupiter and Pluto varies slowly on a timescale of +/- 8 days (which is enough to optimize for a closest approach to Callisto for the worst case scenario). The only difference would be in the actual Jupiter C/A, that would only be changed by I guess a few tens of thousands of km yet in return it would bring Callisto at an optimal point in its orbit to cut down C/A distance from millions to a few hundred thousand km.

[john_s]

I don't think timing a Callisto nontargeted flyby would be much of an issue at all. Callisto's orbital period is 16 days and the arrangement between Jupiter and Pluto varies slowly on a timescale of +/- 8 days (which is enough to optimize for a closest approach to Callisto for the worst case scenario). The only difference would be in the actual Jupiter C/A, that would only be changed by I guess a few tens of thousands of km yet in return it would bring Callisto at an optimal point in its orbit to cut down C/A distance from millions to a few hundred thousand km.

Sorry, but we won't be able to adjust the Jupiter flyby timing to optimize the view of the moons- we'll take what we can get. We can't afford the fuel it would take to slow down or speed up to catch Callisto, for example. As soon as we launch we will know our Jupiter flyby date and thus the flyby geometry for the moons, and as I remember no launch date gives us a really close look at Callisto.

However, despite the geometry limitations, we'll be doing our utmost to maximize the science return from Jupiter and its moons. Our other major constraints will be our limited data storage capacity (which is designed for a quick flyby of little Pluto, not an extended flyby of giant Jupiter), and the fact that our cameras are designed to work at Pluto's dim illumination levels and thus will tend to give overexposed images at Jupiter- our best images of Io, for instance, will probably be taken in Jupiter shine, not sunshine!

To answer Rob Pinnegar's question, we've been checking for close flybys of any of the outer moons, and we might get a couple of pixels on the largest ones. Nothing too spectacular though.

[hendric]

... and the fact that our cameras are designed to work at Pluto's dim illumination levels and thus will tend to give overexposed images at Jupiter

John,
How do you plan to commission the instruments after launch? Taking pictures of DSO's? I'm sure some amateur astronomers could recommend a few for you to try out...