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New Horizons: Pre-launch, launch and main cruise, Pluto and the Kuiper belt
Alan Stern
post Aug 12 2009, 01:39 PM
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QUOTE (Enceladus75 @ Aug 11 2009, 10:05 PM) *
The progress made by New Horizons in just 3 and half years is stunning. blink.gif Already half way between Saturn and Uranus.

A question: is the tracking of NH being analysed to see if a "Pioneer Anomaly" exists?


Enceladus75--

The Pioneer Anomaly has been shown to be just that-- an anomaly related to P10 and P11, not new physics. NH isn't pursuing it.

Alan
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Guest_PhilCo126_*
post Aug 13 2009, 10:55 AM
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Interesting but could tracking of the spacecraft past Pluto give any indications about Pioneer anomaly, which has been observed at other spacecraft?
More interesting New Horizons will pass Pluto at the 50th anniversary of Mariner IV Mars flyby cool.gif
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Mixer
post Aug 13 2009, 10:59 AM
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QUOTE (PhilCo126 @ Aug 13 2009, 08:55 PM) *
Interesting but could tracking of the spacecraft past Pluto give any indications about Pioneer anomaly, which has been observed at other spacecraft? More interesting New Horizons will pass Pluto at the 50th anniversary of Mariner IV Mars flyby cool.gif


Alan says above that the anomaly is related to the Pioneer 10 and Pioneer 11 spacecraft and is not new physics, so something in the design of those spacecraft has caused the anomaly, so NH can't possibly shed any light on it.

It was long speculated that there was a leak of some sort causing it, but I need to go look, as I never knew of definitive findings.
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dmuller
post Aug 13 2009, 11:29 AM
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Mixer: if memory serves me right then I think they managed to attribute some percentage of the anomaly to heat pressure from the power source.

PhilCo126: when you say "other spacecraft" I think you may be referring to the "anomaly" that some spacecraft get a bit too much acceleration out of planetary flybys. If you refer to P10/P11 style slowdown then I'd love to know which other spacecraft were affected


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Greg Hullender
post Aug 13 2009, 05:26 PM
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QUOTE (Alan Stern @ Aug 12 2009, 05:39 AM) *
The Pioneer Anomaly has been shown to be just that-- an anomaly related to P10 and P11, not new physics. NH isn't pursuing it.

I just read Toth and Turyshev's 2009 "Thermal recoil force, telemetry, and the Pioneer anomaly" and they seem to think there are still a couple of good papers worth of material here. Quoting from their conclusion (bold added by me):
QUOTE (Thermal recoil force, telemetry, and the Pioneer anomaly)
Newly recovered Doppler data are now available as a result of an extensive data recovery effort [1,7]. This will allow us to extend our analysis and verify whether or not the thermal recoil force can account for the anomalous acceleration of Pioneer 10 and 11. These results will be published elsewhere when they become available.
We emphasize that the approach presented here, notably the direct utilization of flight telemetry in precision spacecraft navigation codes, has never been attempted before. The approach we describe is applicable not only to the case of Pioneer 10 and 11, but also to the case of present and future spacecraft. One mission, in particular, that may benefit from this approach is New Horizons, on its way towards an encounter with Pluto in 2015. While presently not used for gravitational research, such investigations could be conducted during its multiyear cruise. If such an investigation is undertaken, it will require accurate estimates of the thermal recoil force due to the waste heat produced by New Horizons' RTG and electrical equipment.

I agree that these guys aren't trying to find a new force of nature -- they're trying to conclusively prove that thermal effects suffice to explain everything -- but I thought it was interesting that they want to apply their analysis to NH as well.
Finally, I'll admit I liked Michael Nieto's 2007 paper "New Horizons and the Onset of the Pioneer Anomaly"? http://arxiv.org/abs/0710.5135v1 The notion that there might be a local cloud of dark matter with measurable effects is an attractive one, and it'd be nice to test it one way or the other.
Not that I'm offering to fund it myself, but I assume that if someone really wanted to, he/she could play with the NH tracking data at any point? That is, this is the sort of data the NH team would freely give to serious researchers if they asked for it? It makes perfect sense that the NH team would not want to do this analysis themselves, of course -- not even to keep yourselves entertained over the next six years. :-)

--Greg
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Gsnorgathon
post Aug 13 2009, 07:20 PM
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QUOTE (Greg Hullender @ Aug 13 2009, 06:26 PM) *
...The notion that there might be a local cloud of dark matter with measurable effects is an attractive one...

Oh, boo! tongue.gif
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Greg Hullender
post Aug 13 2009, 10:44 PM
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Grin. Actually the hypothesis was that the "Pioneer Effect" was due to resistance from passing through the cloud, not an effect of its gravity. So not an intentional pun on my part. :-)

--Greg

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Guest_PhilCo126_*
post Aug 14 2009, 03:58 PM
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Thanks to all for that detailed answer on the Pioneer anomaly...
(Just for the record: The other spacecraft that I read about for which "similar deviations" occurred: Galileo 1989 & Cassini 1997)
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stevesliva
post Aug 14 2009, 06:11 PM
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QUOTE (PhilCo126 @ Aug 14 2009, 11:58 AM) *
Thanks to all for that detailed answer on the Pioneer anomaly...
(Just for the record: The other spacecraft that I read about for which "similar deviations" occurred: Galileo 1989 & Cassini 1997)


I didn't think that was true... all of the thruster firings for spacecraft pointing swamp the anomaly with noise. Planetary Society's FAQ covers Voyager:
http://www.planetary.org/programs/projects...e_20050720.html

[edit] Wiki mentions Galileo and Cassini: http://en.wikipedia.org/wiki/Pioneer_anomaly
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Guest_PhilCo126_*
post Aug 14 2009, 06:30 PM
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Yep but for Galileo & Cassini it was about an " Earth flyby " anomaly...
Anyway, looking forward to the next distance milestone for New Horizons; crossing Uranus' orbit in March 2011 cool.gif
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tfisher
post Aug 15 2009, 03:17 PM
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QUOTE (Alan Stern @ Aug 12 2009, 08:39 AM) *
The Pioneer Anomaly has been shown to be just that-- an anomaly related to P10 and P11, not new physics.


Interesting. Do you have a reference for that?

The latest I had seen was the Toth work, where it sounds like the situation was still uncertain. That is, the best modeled trajectories disagree with physics, and it wasn't obvious yet whether further improvements in the modeling could eliminate the anomaly. Of course extraordinary claims require extraordinary evidence, so the most likely thought is no new physics, but I this is the first time I've seen a claim that anything conclusive had been shown.

I also seem to remember early on it had been proposed that New Horizons would investigate the phenomenon. Am I remembering wrong, or was the study considered and dropped?
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imipak
post Aug 15 2009, 05:22 PM
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Interesting indeed, but doesn't it belong on the Pioneer Anomaly thread?


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Alan Stern
post Aug 16 2009, 01:15 AM
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QUOTE (tfisher @ Aug 15 2009, 04:17 PM) *
Interesting. Do you have a reference for that?

The latest I had seen was the Toth work, where it sounds like the situation was still uncertain. That is, the best modeled trajectories disagree with physics, and it wasn't obvious yet whether further improvements in the modeling could eliminate the anomaly. Of course extraordinary claims require extraordinary evidence, so the most likely thought is no new physics, but I this is the first time I've seen a claim that anything conclusive had been shown.

I also seem to remember early on it had been proposed that New Horizons would investigate the phenomenon. Am I remembering wrong, or was the study considered and dropped?



We never planned to study this, but we did listen to several technical talks. It turns out to be very expensive-- million of dollars, because it requires exquisite modeling of spacecraft thermal and radiation forces. Broke for discretionary funding to follow this, we declined.

-Alan
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DrShank
post Aug 25 2009, 02:37 PM
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I too noted the Mariner IV 50th anniversary coincidence. Maybe NH can turn around and take a commemorative pic of Mars for the occasion.
(Just joking Alan, I know we will be busy and the bad Sun angle and all that . . .)

paul


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Alan Stern
post Sep 3 2009, 11:58 PM
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http://pluto.jhuapl.edu/overview/piPerspective.php

The PI’s Perspective: Science Never Sleeps
September 2, 2009

Project bumper sticker
Our project bumper sticker — the coolest one any space mission has, I’d say.

We put New Horizons back into hibernation last week, on Aug. 27. This event signaled the completion of our third active spacecraft and payload checkout, which occupied us for most of July and August.

Active Checkout Three (“ACO-3”) went very well, its objectives completed with no serious glitches. Our spacecraft and payload are healthy, on course and ready for a set of three hibernation periods that will stretch into late May.

Twice during the next nine months we’ll wake the spacecraft up for about 10 days at a time to re-point its antenna toward Earth and conduct a few minor maintenance activities. The first of these two wakeups will occur Nov. 9-18. Until then, New Horizons will report in with status beacon checks every Monday and telemetry sessions every other Thursday that update us on key spacecraft engineering parameters.

Meanwhile, our science and flight teams are reviewing ACO-3 data, scoping the list of activities for next summer’s ACO-4 (already!) and finalizing our Pluto near-encounter activities sequence. The science team is also planning a selection process for teams to search for our target Kuiper Belt Objects (KBOs); proposals will be due early next year, with searches to take place in 2011 and 2012. And we’ve also been planning a science workshop at the Space Telescope Science Institute in Baltimore next May.

Pluto encounter planning schedule
To get a feel for why we say “Science Never Sleeps,” take a look at our Pluto encounter planning schedule for this fall. As you can see, our small team uses the spacecraft hibernation periods to get this kind of planning and testing done in preparation for Pluto encounter. Unlike our baby out there in deep space, we’re not hibernating at all on the ground. (Click on the graphic to enlarge.)

New Horizons is now almost 14.4 astronomical units from the Sun, and will cross the halfway point between the orbits of Saturn and Uranus next week. We’re now firmly in the “Centaur region” where escaped KBOs roam between the giant planets. (In fact, we regularly check to see if there is a chance encounter coming with any Centaurs, but so far, no known Centaur is passing closer than about half a billion kilometers from New Horizons.)

Map of New Horizon's path
New Horizons will reach the halfway point between Saturn and Uranus on Tuesday, Sept. 8. That officially puts us in “Uranus space.”

That’s my update for now; thanks for following our journey to a new frontier. I’ll be back in touch in November, around the next time we wake up our spacecraft.

In the meantime, keep on exploring, just as we do!
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