Does the gravity assist at jupiter cross within the 4 major moons?

No -- it's a short distance outside Callisto's orbit. Had it been launched in the previous window in Dec. 2004, it could have made a close flyby of Europa; had it been launched in the one before that in Nov. 2003, it could have made a close flyby of Io. Yet more lost as a result of Dan Goldin's idiocy.

I hope that Callisto is in that part of its orbit at the time.

Well, you can't deny the man did leave his mark upon space exploration! (Though not with the legacy he was hoping for I would imagine... )

Missing targeting opportunities like this are an almost unforgivable sin, especially on these "once per professional lifetime" type missions. Losing these fly bys means less science for the buck, an irony so glaring as to be obvious even to The Dan.

His Let's Give Murphy's Law A Head Start Program, also known as Better, Faster, Cheaper was directly at odds with choosing hi-profile PR one off missions. Decreased funding meant decreased testing and missed design flaws; leading to such innovative solutions as the Genesis probe's lithobraking and advances in deconvolving algorithms for imagery.

Perhaps I will start a Better Faster Cheaper rant topic elsewhere, I apologize for topic hijack.

And thanks again to Alan for visiting us and relating all the good news as it happens!

I have been following this forum (as well as ISSDG/Jupiter List and volcanopele's blog) for awhile now (great work by all!) and it's my first post.

The question I have is, re: NH - according to the paper on RH telecom design (DeBoy, C. C. et al. (2005). The New Horizons mission to Pluto: Advances in telecommunication system design. Acta Astronautica), the theoretical possiblity exists for NH to use both TWTA for downlink, resulting in a 44% reduction of downlinking time. Are there any concrete plans for such a capability to be used, esp. immediately after the encounter so that a larger browse dataset can be downlinked back?

Also, re: RALPH, has all the problems with the instrument been more or less dealt with (to a large extent)? I recall reading about LEISA having serious SNR/electronics problems during the optical tests, which when translated to the encouter, could have lead to fatal problems. Thanks!

Well, I have no objection to the "smaller and more frequent" part of "Better, Faster, Cheaper" -- since it means that you lose less from an individual failure due to a design flaw. (Mars Observer cost more than the next 4 US Mars missions combined.) Unfortunately, while this was a very good idea on Goldin's part, it seems to have been his ONLY good idea. (And its advent was probably inevitable at some point after the Challenger disaster had ruined NASA's earlier plans to require ALL US spacecraft to be launched on Shuttles, by the simple technique of making them too big to be launched on anything else.)

As for the Pluto probe: I learned at the 2000 meeting of the Solar System Exploration Subcommittee that he didn't want to fly it at all. All his repeated demands to go back and make the spacecraft even smaller than the last design team had made it were just his way of clandestinely killing it -- "Nobody gives a damn about Pluto", he told one aide. He was totally obsessed with astrobiology instead -- and while it remains my main reason (and that of a lot of other folks) for being interested in space exploration, he ran it into the ground.

hi Bruce, I think I had heard that story about Goldin and Pluto... amazing, really. I would be interested in hearing more about your take on some other bits if I can talk Doug into starting an exploration strategies topic...

I am just glad that he didn't succeed in stopping this mission, if that was his preference!

EDIT: (I started a Better Faster Cheaper topic over in EVA if anyone cares to join me... )

This post has been edited by lyford: Jul 18 2005, 09:41 PM

New Scientist has an interesting article this week about the possibility of a number of reasonably large unfound planets (total mass: sub-Mars) in the region between Pluto and the Oort Cloud. It describes a plausible explanation (the 'Oligarch' theory) for some of the more extreme orbital strangenesses out there, and gives some examples of search strategies etc.

My questions relate to this, and probably I'm hoping that Alan, or perhaps Bruce, can answer:

If an object is identified then what are the constraints on imaging it from New Horizons? At what point in the extended mission will images become impossible (I presume that we'll end up with some very low temperatures and a broken camera). By imaging, I mean anything up from a star-like dot - I'm not expecting pretty pictures!

I presume that if an object was identified before the Pluto encounter then the spacecraft might be retargetted, and that there would be a fair 'spread' of space which might be reached. However, if any sort of slingshot wasn't carried out (perhaps due to any putative body not being discovered in time, or a desire to maximise Pluto/Charon science, or (gasp!) no money) then what sort of maneuvering capability would New Horizons be likely to have by then? I expect that it'd be very slight, and hardly likely to allow much retargetting, but would just like to know for sure!

Bob,
Some good information at the NSSDC here... http://nssdc.gsfc.nasa.gov/database/Master...og?sc=NHORIZONS

"After passing by Pluto, New Horizons will be headed out to the Kuiper Belt where multiple Kuiper Belt Objects on the order of 50-100 km in diameter are expected to be targeted for encounter and similar measurements to those made at Pluto. This phase of the mission will last from 5 to 10 years. "

If they have the capability to image 50-100 kilometer objects, sub-Mars size objects should be a piece of cake. When they refer to "targeted", surely they must be talking visually only. By the time they reach Pluto, there won't be enough hydrazine left to do much of a course correction and flying 9600 kilometers at closest approach to Pluto won't allow for much of a gravity assist.
But it is big open space out there, and the sooner they spot something the more options they have.

Gary

We are hoping for a close encounter with at least one Kuiper Belt Object- we hope to have enough hydrazine after Pluto to target at least one small one. Small ones are easier to target simply because there are more of them so less of a course correction is likely to be needed to get to the closest one. We are currently conducting a search for suitable KBOs along our probable trajectory with the Subaru telescope on Mauna Kea. The KBO encounter is however dependent on having enough hydrazine, and we won't know till after launch whether we'll have the fuel to do it.

But the key is being able to get close with a targeted encounter, within ten thousand kilometers or so. We probably won't be able to do anything useful with large KBOs, except perhaps measuring their brightness at high phase angles, simply because they are few and far between and at our likely closest approach to any of them we still won't be able to compete with ground-based telescopes. Our telescope aperture of a few inches at a range of a few AU can't compete with a 10-meter terrestrial telescope 40 AU away.

Even if you still have half the hydrazine left after the encounter with Pluto, that would give you less than one degree of course correction. (If I did my math right)
And since the spacecraft at that point will be 2-1/2 degrees out of the plane of the solar system, wouldn't that make an encounter with a kbo fairly unlikely?

Gary

We've done the numbers and we have a decent chance of finding a KBO even within that narrow cone, and accounting for the latitude of the spacecraft. We simply have to chose one of the smaller, more abundant, objects.

Hurry up and launch it before someone decides Pluto isn't a planet any longer.

Question: is the final trajectory for the new horizons probe elliptical or hyperbolic? I would have thought that it would be going fast enough to escape (11km/s past pluto is faster than the 6.7km/s escape velocity I get for out there, at least if you're going mostly away from the sun at the time) but a slashdot article today is suggesting it will return to 1au in 50,000 years or so. So what's right?

Hmmm. I'm guessing SlashDot is wrong here. The SlashDot article has one sentence saying it will return, but I've never before heard that it isn't on an escape trajectory. The NH website doesn't even say what the flyby velocity of Pluto is, so there's no way to tell from that site. I've seen other places saying 11 km/sec for the flyby, but I don't know if this takes into account that Pluto is already travelling a few km/sec outbound as this mission is arriving well past preihelion for Pluto. The outbound velocity might be 13-16 km/sec.

I would imagine that NH would not end up returning to 1AU, since after the encounter with Jupiter, it will have a perihelion closer to five AU.

If the galaxy were not filled with gravitational knots (other stars), you might expect the Voyagers and Pioneers to return in 225 million years.