Star 48b Third-stage Motor, Leaving the solar system |
Star 48b Third-stage Motor, Leaving the solar system |
Jan 24 2006, 11:35 PM
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#31
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
QUOTE (BruceMoomaw @ Jan 24 2006, 11:33 PM) Even where actual trips from Earth to Mars itself are concerned, Mariner 9 isn't the record holder -- the Atlas-Centaur had so much excess capacity for the much lighter 1969 Mariner Mars flyby craft that they were able to pound them to Mars in only 5 and 4 months, with a leisurely 1-month gap between launches. I imagine this record will stand for a while. Bruce: Any idea of Mariner 6 and 7's furthest point from the Sun? As in, how far into the Great Galactic Ghoul did they get? Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Jan 31 2006, 06:08 PM
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#32
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Member Group: Members Posts: 540 Joined: 25-October 05 From: California Member No.: 535 |
The third stage is 15,000 km away from NH according to Alan Stern's new PI Perspective on the NH APL site
-------------------- 2011 JPL Tweetup photos: http://www.rich-parno.com/aa_jpltweetup.html
http://human-spaceflight.blogspot.com |
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Feb 2 2006, 05:57 AM
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#33
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Junior Member Group: Members Posts: 87 Joined: 19-June 05 Member No.: 415 |
QUOTE (djellison @ Jan 21 2006, 12:33 PM) 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. |
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Feb 2 2006, 10:32 AM
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#34
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
QUOTE (Comga @ Feb 2 2006, 06:57 AM) 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 -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Feb 2 2006, 11:41 AM
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#35
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Member Group: Members Posts: 593 Joined: 20-April 05 Member No.: 279 |
QUOTE (Comga @ Feb 2 2006, 05:57 AM) ...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. Is that right? I can see that a normal return (radar, for example) from an astronomical body would obey R^4 laws, but the whole point of a retroreflector is to minimise divergence of any reflected signals. So, surely a well made retroreflector should be nearer R^2 than R^4 - a big difference at large ranges, and a more practical option than you seem to suggest? Andy |
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Feb 2 2006, 11:55 AM
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#36
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
QUOTE (AndyG @ Feb 2 2006, 12:41 PM) So, surely a well made retroreflector should be nearer R^2 than R^4 - a big difference at large ranges, and a more practical option than you seem to suggest? Nope, a flat retroreflector would still follow the R^4 law. Consider that a flat reflector receives 1/4 of the power at twice the distance and it also presents only 1/4 of the angular surface area seen from Earth so that combines to 1/16 of the power received back than at the original "unit" distance. I can imagine that if you had a spherical reflector whose curvature would follow the curvature of the sphere centered on the light source on the Earth, you could get a R^2 return power function as it would focus all received light/radio signal back at the source. Then again, that's purely theoretical reasoning and you'd have to change the curvature of the reflector with increasing distance and keep it really precisely pointed back that it's probably undoable. -------------------- |
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Feb 2 2006, 12:19 PM
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#37
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
When the LRRR hare was first set running I simply assumed that there'd be some sort of spatially distributed array of cubical LRRR modules all over the exhausted stage, so that it's orientation was not particularly important (but which could be obtained by applying some sort of statistical process to the light curve of the stage). Such cubical LRRRs would reflect internally and would *not* need to be pointed in any more than a general direction.
The logarithmic issues still apply, of course, but imagine the possibilities inherent in the US military experiments in high power lasers, then add an array of optical telescopes (seeking to resolve only a point source, remember, where optical arrays *are* good). Plainly, though, as Alan Stern pointed out, every bit of mass left on the booster is something left off the spacecraft. Still, let's assume that NH2 flies, and there's (for whatever reason) some spare mass budget - the experiment could be quite interesting... ...and cheap! Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Feb 6 2006, 05:40 AM
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#38
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Junior Member Group: Members Posts: 87 Joined: 19-June 05 Member No.: 415 |
QUOTE (ugordan @ Feb 2 2006, 05:55 AM) I can imagine that if you had a spherical reflector whose curvature would follow the curvature of the sphere centered on the light source on the Earth, you could get a R^2 return power function as it would focus all received light/radio signal back at the source. Then again, that's purely theoretical reasoning and you'd have to change the curvature of the reflector with increasing distance and keep it really precisely pointed back that it's probably undoable. We are agreed on the R^4 scaling, but even adaptable curved surfaces wouldn't help. The diffraction limit is the diffraction limit. That is assuming you could do it for zero mass and zero power with passive controls..... At these distances, anything acts like a point source algeit with limited divergence. This is a wild hare, isn't it? |
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Feb 6 2006, 05:48 AM
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#39
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Junior Member Group: Members Posts: 87 Joined: 19-June 05 Member No.: 415 |
QUOTE (Bob Shaw @ Feb 2 2006, 04:32 AM) A Surrey microsat imaged its booster, and another satelite after rendezvouing using butane cold gas thrusters. It was a test of navigation and pointing. Here's a reference. http://www.spacedaily.com/news/microsat-00x.html |
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Feb 6 2006, 10:35 AM
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#40
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
QUOTE (Comga @ Feb 6 2006, 06:48 AM) A Surrey microsat imaged its booster, and another satelite after rendezvouing using butane cold gas thrusters. It was a test of navigation and pointing. Here's a reference. http://www.spacedaily.com/news/microsat-00x.html Interesting... ...so when do we build one? Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Feb 11 2006, 05:03 AM
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#41
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
-------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Aug 16 2015, 12:47 AM
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#42
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Newbie Group: Members Posts: 1 Joined: 3-October 14 Member No.: 7272 |
With the third stage's passing of Pluto's orbit coming up in two months, I was wondering (and have been asked) whether there is any way of tracking its location. From this thread, I gather there is not. Correct?
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Aug 16 2015, 02:06 AM
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#43
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
Correct.
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