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Unmanned Spaceflight.com _ New Horizons _ Star 48b Third-stage Motor

Posted by: Guido Jan 21 2006, 11:49 AM

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?

Posted by: Alan Stern Jan 21 2006, 12:11 PM

QUOTE (Guido @ Jan 21 2006, 11:49 AM)
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?
*


It's going interstellar. But wll miss Pluto considerably, by >>10^7 km.

-Alan

Posted by: tasp Jan 21 2006, 02:38 PM

Too late now, and probably unworkable across the necessary distances, but a laser retroreflector on an inert booster stage might have been a pretty good experiment for the 'Pioneer Effect'.

Posted by: ljk4-1 Jan 21 2006, 04:38 PM

QUOTE (tasp @ Jan 21 2006, 09:38 AM)
Too late now, and probably unworkable across the necessary distances, but a laser retroreflector on   an inert booster stage might have been a pretty good experiment for the 'Pioneer Effect'.
*


Has anyone ever made scientific use of these final boost stages before they are sent aloft into the Great Unknown? Seems like a wasted opportunity otherwise.

Posted by: Bob Shaw Jan 21 2006, 05:25 PM

QUOTE (tasp @ Jan 21 2006, 03:38 PM)
Too late now, and probably unworkable across the necessary distances, but a laser retroreflector on  an inert booster stage might have been a pretty good experiment for the 'Pioneer Effect'.
*



That's an interesting idea, especially on a spinning solid stage (not a lot of venting going on as it's a solid, use residual attitude control gas (if any) to spin the thing up, no IR from the RTGs). It's the sort of situation where aperture synthesis observations would be the way to go, perhaps amateur-based. I wonder whether laser light from different locations can be tuned to act as one big lump of light (you know what I mean!)? If the LRRR cubes could be 'tuned' somehow then perhaps by putting half a dozen on the motor then you could even gain some notion of the attitude of the stage over the years, too.

Bob Shaw

Posted by: djellison Jan 21 2006, 06:33 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?

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

Posted by: Bob Shaw Jan 22 2006, 02:37 AM

QUOTE (djellison @ Jan 21 2006, 07:33 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?

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
*


Doug:

I think that the laser option is best, inasmuch as you've got 30 years of laser technology upgrades to apply to such an experiment; as for the outgassing, I doubt there's much. Anyway, it's a *cheap* experiment!

Bob Shaw

Posted by: RNeuhaus Jan 22 2006, 03:10 AM

QUOTE (Alan Stern @ Jan 21 2006, 07:11 AM)
It's going interstellar. But wll miss Pluto considerably, by >>10^7 km.

-Alan
*

In the other words, the Star 48B will follow up the NH's track until Jupiter? After Jupiter, will continue following farther or closer to NH toward Pluto? I assume that NH will make many TCM, so every time NH performs the TCM, the Star 48 B will be lagging even farther.

Have the NH team been tought about the usefulness of mass of Star 48 B to hit on Pluto as an experiment about the Pluto's properties of structure and at the same time Clyde will be able to land on that..... smile.gif

Rodolfo

Posted by: mchan Jan 22 2006, 07:17 AM

QUOTE (RNeuhaus @ Jan 21 2006, 07:10 PM)
Have the NH team been tought about the usefulness of  mass of Star 48 B to hit on Pluto as an experiment about the Pluto's properties of structure and at the same time Clyde will be able to land on that.....  smile.gif
*

That would be truly a hole in one type of shot to hit Pluto without any tracking and course corrections after motor burnout!!

Posted by: Alan Stern Jan 22 2006, 11:17 AM

We are setting up for our first course correction. Without it we would miss Pluto
by millions of miles. The third stage has no ability to make a course correction
and will therefore miss by this amount.

-Alan

Posted by: edstrick Jan 22 2006, 12:58 PM

Alan: Any serendipitious distant asteroid flyby's on the to-Jupiter trajectory... with maximum image size over 1 1/2 pixels?

Posted by: tasp Jan 22 2006, 02:55 PM

QUOTE (edstrick @ Jan 22 2006, 06:58 AM)
Alan:  Any serendipitious distant asteroid flyby's on the to-Jupiter trajectory... with maximum image size over 1 1/2 pixels?
*



Or an 'outie' satellite of Jupiter? Seems like there are 60 or so now that we know of. Is the density of objects in the outer moon belt of Jupiter higher than the Kuiper Belt?

It would be useful to have an image to compare to any pictures we might get someday of any of Jupiters Trojan population. And to compare to the outer asteroid belt population.

Similarites of distant small Jovian satellites to D-type asteroids may also have some relevance in studying Cassini Regio and perhaps the dark crater floors of Hyperion.

Posted by: tasp Jan 22 2006, 03:03 PM

Both Voyagers had Centaur stages that left earth at interesting velocities in interesting directions, too. And the Voyager final solid stages would have had trajectories even closer to the the Voyagers.

Wonder what happened to them?

Posted by: Alan Stern Jan 22 2006, 04:10 PM

All.

Things are going well here at the APL MOC. New Horizons is operating
virtually flawlessly. TCM 1a and 1b are planned for 28 Jan and 30 Jan,
respectively, with a total delta-V of 18 m/s-- which is far smaller than
the 92 m/s budgeted for pre-flight. Good news!

Today we are planning to complete the spacecraft's planned spin down to 5
RPM (was 68 RPM for the STAR-48 firing, is now 19.2 RPM after an open-loop
burn on launch day). Once we slow it down this afternoon, we'll do the
initial star tracker turn ons. Until then, we're still relying on the sun
sensors and IMUs-- both of which are performing very well. The s/c temps
are running a little hot, but that's just due to our attitude combined
with our <1 AU helio distance (we're inside 1 AU because we launched near
Earth's perihelion).

About the heliocentric distance, we will be inside 1 AU until late on 29
Jan UT. That makes us officially an inner planet mission for the first 10
days, I guess.

We will pass the orbit of Mars on 8 April, just a little after MRO
gets there, and it had a 5.5 month head start.

FYI-- The C/A to Jupiter is going to be at approx 6 hrs UTC on 28 Feb
2007. A better number will be forthcoming, but that is good to an accuracy
of better than an hour already. C/A is to be at 32 RJ.

Because we have to slow down in TCM-1a and TCM-1B by those 18 m/s,
our intrepid Boeing STAR-48 third stage will beat New Horizons to
Jupiter by 6 hrs. However, because it will not hit the Pluto aim point, it will not
beat us to Pluto (a relief-- can you imagine us having to be the second to
Pluto after all this, having been beat by a derelict Boeing upper stage?).
In fact, the projected C/A distance of the third stage to Pluto will be
213 million km (well over 1 AU), occurring on 15 Oct 2015.

-Alan

Posted by: Redstone Jan 22 2006, 04:19 PM

"C/A is at 32 RJ"

For comparison, the outermost Galilean moon, Callisto, is at about 26 RJ.

Alan, thanks for all the details. Do you have any idea yet what targets look promising for the Jupiter encounter?

Posted by: Alan Stern Jan 22 2006, 04:36 PM

QUOTE (Redstone @ Jan 22 2006, 04:19 PM)
"C/A is at 32 RJ"

For comparison, the outermost Galilean moon, Callisto, is at about 26 RJ.

Alan, thanks for all the details. Do you have any idea yet what targets look promising for the Jupiter encounter?
*




...I will in a couple of weeks.

Posted by: Roby72 Jan 22 2006, 07:34 PM

Hi Alan, hi all,

after checking the Jupiter encounter date in the Guide8 software I see all Galilean satellites on the left side of the planet, the aim point from NH, I suspect, is on the right side, isnt, it?
Only Himalia could be possible better placed, but I have no depth information currently. I recall that Cassini encounters Himalia a few days ahead of the main Jupiter encounter.



By the way congratulations Alan for the perfect launch of the NH spacecraft and many wishes for a flawless mission !!

Robert

Posted by: djellison Jan 22 2006, 07:56 PM

But - that will put them in a good position to image their dark sides in Jupiter shine smile.gif

Doug

Posted by: john_s Jan 22 2006, 10:59 PM

QUOTE (djellison @ Jan 22 2006, 07:56 PM)
But - that will put them in a good position to image their dark sides in Jupiter shine smile.gif

Doug
*


I think Jupiter deserves a dedicated thread, so I just started one http://www.unmannedspaceflight.com/index.php?showtopic=2088&view=findpost&p=37718

John.

Posted by: RNeuhaus Jan 23 2006, 09:14 PM

Thanks Alan for the detailed info. Indeed, NH will break a new trip record between Earth and Mars with 2 months and 19 days. The old record trip record between Earth and Mars, I think, is held by Mariner IX which took 166 days (5 months and 16 days, at May 30, 1971-Nov 14, 1971). It is a milestone! wink.gif

Rodolfo

Posted by: AlexBlackwell Jan 24 2006, 12:14 AM

QUOTE (Alan Stern @ Jan 22 2006, 11:17 AM)
We are setting up for our first course correction. Without it we would miss Pluto
by millions of miles. The third stage has no ability to make a course correction
and will therefore miss by this amount.
Alan, was there any deliberate trajectory bias by the LV for any reason, or are the TCMs needed strictly to correct unplanned (albeit very minor) injection errors?

Posted by: djellison Jan 24 2006, 12:17 AM

I'd thought the same Alex - the Mars policy of targetting off-target, so that the fact you have a healthy spacecraft to adjust its course back to target means that it isnt going to plough straight into the planet - or perhaps in this case Europa?

Doug

Posted by: AlexBlackwell Jan 24 2006, 12:37 AM

QUOTE (djellison @ Jan 24 2006, 12:17 AM)
I'd thought the same Alex - the Mars policy of targetting off-target, so that the fact you have a healthy spacecraft to adjust its course back to target means that it isnt going to plough straight into the planet - or perhaps in this case Europa?
I'd never heard of any planned Jupiter aimpoint biasing; indeed, I remember Alan http://www.unmannedspaceflight.com/index.php?showtopic=675&view=findpost&p=31279 that New Horizons was a Category III mission for planetary protection purposes.

Posted by: djellison Jan 24 2006, 12:39 AM

Ahhh - in that case, it's going to be just residuals from the LV I'd imagine.

Doug

Posted by: AlexBlackwell Jan 24 2006, 12:51 AM

QUOTE (djellison @ Jan 24 2006, 12:39 AM)
Ahhh - in that case, it's going to be just residuals from the LV I'd imagine.
You're probably right, but maybe it's possible that an injection bias was planned for other, operational reasons (e.g., to extend the daily launch window). I guess it's one of those loose ends that niggle away at me.

Posted by: Alan Stern Jan 24 2006, 01:08 AM

QUOTE (AlexBlackwell @ Jan 24 2006, 12:14 AM)
Alan, was there any deliberate trajectory bias by the LV for any reason, or are the TCMs needed strictly to correct unplanned (albeit very minor) injection errors?
*



The latter.

Posted by: djellison Jan 24 2006, 02:09 AM

It niggled away with me as well, I guess when you're getting THAT much of a kick, even 100m/s could be considered damn accurate - thanks for 'de-niggling' it Alan smile.gif

Doug

Posted by: mchan Jan 24 2006, 10:58 AM

QUOTE (RNeuhaus @ Jan 23 2006, 01:14 PM)
Thanks Alan for the detailed info. Indeed, NH will break a new trip record between Earth and Mars with 2 months and 19 days. The old record trip record between Earth and Mars, I think, is held by Mariner IX which took 166 days (5 months and 16 days, at May 30, 1971-Nov 14, 1971). It is a milestone!  wink.gif
*

The NH time of flight is for Earth to Mars orbit. Mars will be far away when NH crosses Mars orbit. For the purpose of records, there are two categories. One is from Earth to a Mars encounter (some arbitrary distance, e.g. 1000 km of Mars surface. Second is from Earth to Mars orbit. For the second case, I would guess the old record was held by Ulysses.

Posted by: djellison Jan 24 2006, 11:11 AM

I guess it depends if you want to include the journey for Galileo and Cassini from their last Earth Flybys to Mars orbit. It's cheating, and I don't know the figures, but it would be an interesting comparison.

Doug

Posted by: BruceMoomaw Jan 24 2006, 10:33 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.

Posted by: Bob Shaw Jan 24 2006, 11:35 PM

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

Posted by: punkboi Jan 31 2006, 06:08 PM

The third stage is 15,000 km away from NH according to Alan Stern's new http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_current.html on the NH APL site

Posted by: Comga Feb 2 2006, 05:57 AM

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.

Posted by: Bob Shaw Feb 2 2006, 10:32 AM

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

Posted by: AndyG Feb 2 2006, 11:41 AM

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

Posted by: ugordan Feb 2 2006, 11:55 AM

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.

Posted by: Bob Shaw Feb 2 2006, 12:19 PM

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

Posted by: Comga Feb 6 2006, 05:40 AM

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?

Posted by: Comga Feb 6 2006, 05:48 AM

QUOTE (Bob Shaw @ Feb 2 2006, 04:32 AM)
Oh? Which ones photographed their boosters?

Bob Shaw
*



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

Posted by: Bob Shaw Feb 6 2006, 10:35 AM

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

Posted by: ljk4-1 Feb 11 2006, 05:03 AM

Earlier thread on this:

http://www.unmannedspaceflight.com/index.php?showtopic=1418&view=findpost&p=20609

Posted by: Katie B Aug 16 2015, 12:47 AM

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?

Posted by: djellison Aug 16 2015, 02:06 AM

Correct.

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