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john_s
QUOTE (tfisher @ Nov 8 2005, 06:35 PM)
I've also seen the number 5024 pixels somewhere.  Unfortunately the "public consumption" websites are pretty coy about such details.  (Is it because they are afraid people will compare these numbers with their digital cameras and wonder why they have more megapixels in their hands than the fancy space probe?)  Anyway, here is what I can glean about resolution.  Maybe someone can confirm or correct these numbers?


*


The New Horizons website does have a table that gives the details for the instrument payload. Your summary is pretty much correct! Yes, I goofed on the MVIC detector length- 5000 pixels is the correct number.
Decepticon
Will this probe carry a gold disk of some kind? Ala Voyager/Pioneer
punkboi
QUOTE (Decepticon @ Nov 8 2005, 04:21 PM)
Will this probe carry a gold disk of some kind? Ala Voyager/Pioneer
*


It will be carrying a compact disc bearing the names of people who submitted 'em through the New Horizons website
edstrick
I suspect some of the most valuable PICTURES during the Jupiter flyby will be of the moons in Jupiter shadow. Io's multi-colored aurora are spectacular, but Galileo's images are pretty horrible due to radiation noise and low light levels. I don't think there was any direct imaging system detections of airglows or hypothetical irradiation induced "iceglows" at the other satellites. Timing of the flyby may randomly allow an observation of Ganymede or Callisto, much more likely for Europa and especially Io because of their shorter orbital periods. Might be able to see torus emissions at Io, too.

Nightside Jupiter imaging.. auroras, airglows and lightning may well be spectacular. Does the spacecraft go through Jupiter's shadow?.... High phase angle ring images which really brings out faint ring-dust features are also potentially spectacular.
ljk4-1
QUOTE (Decepticon @ Nov 8 2005, 06:21 PM)
Will this probe carry a gold disk of some kind? Ala Voyager/Pioneer
*


Go to this post for a response from the New Horizons team on their decision not to include any kind of message/information packet:

http://www.unmannedspaceflight.com/index.p...indpost&p=25901
ugordan
QUOTE (john_s @ Nov 7 2005, 10:40 PM)
The data rate from Jupiter isn't our limiting factor on data storage, it's more to do with the complexity of managing our memory which means that we can only fill up one 32 Gbit section of the solid-state recorder once during the flyby.  Plus we won't be able to crop our images before storing them, so to image a 100-pixel-wide Galilean satellite with our color camera we will need to store the full 4000-pixel width of our CCD array.
*

Didn't you devise any smarter lossless image compression algorithm that would know black space when it sees it? IMO, that sort of thing was feasible probably even in the days Cassini was designed (as opposed to the lossless-although-line-truncating algorithm implemented) let alone today. Sort of like dividing the frame conceptually into two categories: empty space (which would be all low intensity background noise) and actual useful data. The encoding tables could be optimized for two extreme cases then. I read about even more advanced concepts, actually analyzing images taken through different filters and transmitting back only differences, this would be perfect for pushbroom cameras as there wouldn't be any alignment issues due to spacecraft attitude changes.

Hm, maybe I'm getting a wee bit too technical here rolleyes.gif
Myran
Transmitting the difference information was something used on Voyager for the Uranus & Neptune encounters, but this perhaps not the same as what you suggest ugordan.
Decepticon
QUOTE (ljk4-1 @ Nov 9 2005, 09:30 AM)
Go to this post for a response from the New Horizons team on their decision not to include any kind of message/information packet:

http://www.unmannedspaceflight.com/index.p...indpost&p=25901
*



This is very upsetting to me at least. I will email them telling them of my disappointment. sad.gif
just-nick
QUOTE (ugordan @ Nov 9 2005, 08:16 AM)
Didn't you devise any smarter lossless image compression algorithm that would know black space when it sees it?
*


I'm no compression expert, but unless you've got very fast algorithms working in some sort of swap space, you'll still need to stuff all the images into your main memory during the flyby. NH isn't packing a great deal of computing power, so I'd suspect that compression is happening offline, after the hectic time of the flyby so you avoid taxing the computing system any more than necessary. That means you're still maxed out by the capacity of your recorder.

But once all is said and done, I can't imagine some sort of lossless (or even lossy) compression isn't being used for transmission back to Earth.

Anyone in-the-know got anything to correct there?

--Nick

PS -- I'd also like to welcome myself to posting after a couple months of lurking and enjoying the best SNR on any Internet forum I've ever seen. Of course its all going downhill now...
mcaplinger
QUOTE (just-nick @ Nov 12 2005, 05:42 PM)
I'm no compression expert, but unless you've got very fast algorithms working in some sort of swap space, you'll still need to stuff all the images into your main memory during the flyby.  NH isn't packing a great deal of computing power, so I'd suspect that compression is happening offline...
*


Lossless compression algorithms can certainly be fast enough to be applied in real time, if that's desirable. For example, the MGS/MOC lossless compressor can compress the raw pixel rate of 5 megapixels/sec. I'm not certain, but I suspect that the NH camera pixel rate is less than that; it probably doesn't need to be more than a megapixel/sec or maybe even less. It would also surprise me if NH was using lossy compression; we certainly didn't propose that for our unselected PKB instruments.
mcaplinger
QUOTE (ugordan @ Nov 9 2005, 07:16 AM)
Didn't you devise any smarter lossless image compression algorithm that would know black space when it sees it?
*


If you are using a first-difference-based lossless compressor, you can get this for free depending on what encoding table you use and what your black-space noise level is. For example, on MGS/MOC, we use a table that compresses black space 8:1, and we occasionally use this for star calibration images.
hendric
QUOTE (john_s @ Nov 7 2005, 11:40 AM)
... 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...
JRehling
QUOTE (Decepticon @ Nov 12 2005, 01:23 PM)
This is very upsetting to me at least. I will email them telling them of my disappointment. sad.gif
*


Personally, I think an intricate spacecraft with nuclear power and state of the art computers on board, on a trajectory that will communicate its origin for at least tens of thousands of years is a pretty good message that doesn't need much elaboration.
ljk4-1
QUOTE (JRehling @ Nov 13 2005, 01:03 PM)
Personally, I think an intricate spacecraft with nuclear power and state of the art computers on board, on a trajectory that will communicate its origin for at least tens of thousands of years is a pretty good message that doesn't need much elaboration.
*


Any interstellar vessel crew, human or otherwise, that eventually finds NH is not going to find its technology, and certainly not its computers, to be very advanced.

It will say something about us, though, to be sure - mainly, why did they attach a data disc that apparently had its data wiped out by cosmic radiation so soon after it left? And what's that odd rectangular symbol with the bicolor stripes? Are those supposed to be stars in the upper left corner? Why didn't they give us some kind of detailed record about themselves, especially if they sent this robot probe into interstellar space? Were the beings who made this craft so primitive that they didn't even consider the rules of galactic ettiquite?

Just ten years after the Voyagers were launched, they kept saying how a home PC could do more than the combined might of the probes' computer systems.

As for messages and information packets on future interstellar probes - which I think should be mandatory, as we will be sending vessels into the greater galaxy - a committee independent of the mission teams, if necessary, needs to be formed to design and implement data records on the probes.

Carl Sagan and his team showed us the way, as they had to instigate and do almost all the work on the Pioneer Plaques and Voyager Records, as apparently almost no one at NASA seemed to show any real care or concern about the fact that those probes were going to exit our Sol system into the Milky Way for the first time in human history. Hardly an insignificant event.

If deep space mission teams are unable and unwilling to put data records on their probes, then they should let others handle that signficant detail. Anyone interested in helping to form a group on this matter?
mike
Every probe we send into space is an expression of who we are. Any advanced alien species will be able to look at the instruments we included and the specific implementation of the craft and discern far more about the human species than you may imagine. If we were to put, say, images or videos of people dancing, dressed in particular cultural garb, the aliens may just ask themselves "Why did they put videos of people dancing on a probe designed to explore the universe?" Then, they would probably obliterate our entire galaxy, because dancing is against all that is Good.

I'm just not sure we can predict that any particular addition to the probe would have any particular effect whatsoever. Personally I'd rather we had more instrumentation to detect just what's out there than that we had a video of some sort of cultural activity. We can save that stuff for our diplomatic probes. If you want to throw on a CD with Bach, or Fifty Cent, or Coldplay, or a picture of people eating sushi, or curried rice, or a McDonald's hamburger, or the latest episode of 'Everybody Hates Chris', or whatever, then go for it, but only if it doesn't interfere with what we know will grant us something useful.

A purely 'diplomatic probe' would be fine with me, or maybe someday we'll be able to pack every instrument we could ever want on one platform and still have room left over, and hey, why not stick whatever you want on there (a piece of the World Trade Center, an unexploded suicide bomb, a Snickers bar, a copy of the UN charter, pictures of people playing jump rope, whatever ya want).
ugordan
QUOTE (mcaplinger @ Nov 13 2005, 05:21 AM)
If you are using a first-difference-based lossless compressor, you can get this for free depending on what encoding table you use and what your black-space noise level is.  For example, on MGS/MOC, we use a table that compresses black space 8:1, and we occasionally use this for star calibration images.
*

That's sort of what I was getting at. If the scan lines were encoded on the fly after being read out, there wouldn't even need to be a large memory buffer to store the whole image at first, like just-nick pointed out. I wonder if there would be a significant improvement if the image was processed in 2D, dividing it into variously sized blocks that are either black space or useful data. In any case, I'd think stating that you need to store the whole 5000 pixels to capture a Jovian moon can be a bit misleading in this perspective.
Then again, I really don't know about the inner workings of NH so I can't say anything for sure.
ljk4-1
QUOTE (mike @ Nov 14 2005, 01:27 AM)
Every probe we send into space is an expression of who we are.  Any advanced alien species will be able to look at the instruments we included and the specific implementation of the craft and discern far more about the human species than you may imagine.  If we were to put, say, images or videos of people dancing, dressed in particular cultural garb, the aliens may just ask themselves "Why did they put videos of people dancing on a probe designed to explore the universe?"  Then, they would probably obliterate our entire galaxy, because dancing is against all that is Good.

I'm just not sure we can predict that any particular addition to the probe would have any particular effect whatsoever.  Personally I'd rather we had more instrumentation to detect just what's out there than that we had a video of some sort of cultural activity.  We can save that stuff for our diplomatic probes.  If you want to throw on a CD with Bach, or Fifty Cent, or Coldplay, or a picture of people eating sushi, or curried rice, or a McDonald's hamburger, or the latest episode of 'Everybody Hates Chris', or whatever, then go for it, but only if it doesn't interfere with what we know will grant us something useful.

A purely 'diplomatic probe' would be fine with me, or maybe someday we'll be able to pack every instrument we could ever want on one platform and still have room left over, and hey, why not stick whatever you want on there (a piece of the World Trade Center, an unexploded suicide bomb, a Snickers bar, a copy of the UN charter, pictures of people playing jump rope, whatever ya want).
*


You seem to be equating data records on interstellar probes with poorly planned and stocked time capsules. No one is going to (or should not at least) just throw a bunch of random "junk" into such a record on such a vehicle. Though as any anthropologist will tell you, one often learns a lot more about a community through its refuse than its official records and monuments. But that doesn't mean we should just send whatever into the galaxy, at least not at this early stage.

I am well aware that much can be learned about our level of technology and other things just by examining a probe. But any probe by itself will leave quite a bit unanswered about us and our world. Adding information about us will not harm anything.

Any ETI that is bent on harming or destroying us will do so regardless of what may or may not be on such a data record. I also have my doubts about marauding aliens scouring the galaxy looking for worlds to conquer, but that is for another topic.

While I certainly would not oppose it, I also do not think at this stage we should build and launch a purely "diplomatic" probe, as you call it, unless we have an actual destination for it and some means of getting it there a bit faster than what we can muster at present.

You may find the ideas on this Web site of interest:

http://www.winlab.rutgers.edu/%7Ecrose/cgi-bin/cosmicB.html
john_s
QUOTE (ugordan @ Nov 14 2005, 08:21 AM)
That's sort of what I was getting at. If the scan lines were encoded on the fly after being read out, there wouldn't even need to be a large memory buffer to store the whole image at first, like just-nick pointed out. I wonder if there would be a significant improvement if the image was processed in 2D, dividing it into variously sized blocks that are either black space or useful data. In any case, I'd think stating that you need to store the whole 5000 pixels to capture a Jovian moon can be a bit misleading in this perspective.
Then again, I really don't know about the inner workings of NH so I can't say anything for sure.
*


These are good suggestions, and indeed, there are many ways that on-the-fly compression could be enabled. But every feature that's added to the software carries the risk of adding bugs too, and more testing is needed to check everything out. Therefore we are keeping things very simple for the Jupiter flyby, so the flight software team can concentrate on the really crucial details that affect the health of the spacecraft.

So the plan is that we'll fill up one 32 Gbit buffer with uncompressed data (including all 5000 lines of every MVIC image), and use the second 32 Gbit buffer for compression of the data prior to downlink to Earth.
ilbasso
A prototype for a diplomatic probe exists already, one that is fluent in over 6 million forms of communication:
mike
My point in mentioning in all that 'junk' is that all those things are surely very popular - what makes them so horrible? What do you think we should place on a probe meant to inform an alien species just what we're all about? Personally, I haven't the vaguest idea.. a copy of the entire planet, miniaturized somehow, is all that currently comes to mind.
ljk4-1
QUOTE (David @ Nov 14 2005, 12:02 PM)
Not that, in my opinion, that would do much good.  I think the complete failure of SETI to turn up anything thus far tells us one of two things, and probably both: one, that intelligent species, assuming there to be others than humans, are scattered thinly across the universe; there might be no more than one per galaxy. Two, that carrying living beings across interstellar space is very, very difficult, and that optimistic scenarios about colonizing the entire galaxy in a matter of a millennia are untenable.

One thing we can be pretty sure about is that when humans emerge from the solar system, they are not going to find great Star Empires and Space Trading Federations full of busy aliens waiting for them -- or we would have learned of them already.  Instead there will be a vast, desolate, and wild sky.
*


The Milky Way Galaxy is 10 billion years old, 100,000 light years across, and contains 400 billion stars. And the only recently technological beings on Sol 3 think that after a few decades of sporadic searches into space that they are going to find ETI, or have said beings find them?

Especially if the ETI are really advanced, why would they contact us? We might serve as an anthropological study of sorts, which would likely mean Do Not Disturb the Study Subjects.

To an earlier point you made, I never considered probes with data records to be the best way to communicate with ETI - at least if you wanted a fast response. As you can see above, I am well aware of the distances and numbers involved with the task. I just think it would do well for both us and any other residents of the Milky Way to preserve some record of ourselves that will long outlive Earth.

Maybe the chances of an ETI finding such a probe or SETI succeeding as we are currently conducting it are slim, but as they said in the famous 1959 Nature paper on the subject:

"The probability of success is difficult to estimate; but if we never search, the chance of success is zero."

http://www.coseti.org/morris_0.htm

The odds of any of our probes being found out there are slim, but if there is that chance, then we should send them out with some record of who were are and what our world is like. Is it really such a problem?
ljk4-1
QUOTE (mike @ Nov 14 2005, 01:49 PM)
My point in mentioning in all that 'junk' is that all those things are surely very popular - what makes them so horrible?  What do you think we should place on a probe meant to inform an alien species just what we're all about?  Personally, I haven't the vaguest idea.. a copy of the entire planet, miniaturized somehow, is all that currently comes to mind.
*


The contents of the Voyager Records are a good start.

http://re-lab.net/welcome/

Have you ever read Murmurs of Earth?
john_s
QUOTE (hendric @ Nov 13 2005, 07:49 AM)
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...
*


We'll mostly be photographing boring stuff like stars to calibrate and commission the instruments. Deep-space targets are an interesting idea, though our maximum exposure time with LORRI is about 10 seconds, which would cramp our style. The Jupiter encounter is also an important part of the calibration process, despite the saturation problems with MVIC and LORRI, because the Jupiter system will give us our only extended (non point source) targets before Pluto.
mike
No, I haven't read Murmurs of Earth.

They did cover a wide variety of subjects with their imagery - I only knew about the plate with the naked people and the basic model of our solar system.. Realistically of course you can't include everything. If there was enough worldwide interest there could be a submission process followed by a voting process - what better way is there? Britney Spears, iPod nano, and [insert other popular thing here], here we come. smile.gif I'm sure we'd have a christian bible, and a buddhist statuette, and [insert other religious artefact here], too, and anything of any moderate popularity.

I still say put the stuff on only if there's extra weight that can't be used on another instrument or more fuel (is more fuel ever not useful?). By the time the probe reaches the edge of the solar system, everything on it will be terribly unfashionable and when the aliens mock us for our afros and polyester suits, we'll feel like jerks - I know it sounds like I'm joking, but that's what will happen - "Oh, you thought we all still only had TWO arms? We can have as many as want now, of course.. Our ancestors just weren't very smart back then.." "Oh, you thought that tube-shaped metal thing with the giant flat bars and jets was our best mode of transportation? Oh, you thought that dinky probe wasn't outdated 1,000,000,000 years ago?"

I like data, being sent back, lots of data. smile.gif But really, it does seem a shame to not send out something - how about every 5 probes or so they send out a larger than usual batch of terribly outdated photos and movies and books, and we can be embarassed at the 1,000,000-year reunion - along with everyone else. smile.gif If nothing else it would be good for PR (eventually everyone could get a chunk), and it would give us a snapshot of what life was like when the probe was launched.

Another way of looking at it is what sort of alien probe would I want slamming into the ground at my feet - I would much rather have a probe packed with advanced technology than one with pictures of variously-cultured people dancing, climbing mountains, etc., and even a picture of an advanced alien craft wouldn't be much use - detailed plans would be nice, though (Contact, anyone).. but it would be interesting to see how the guys who built it looked, how they talked (or flashed, or transmitted). And realistically a larger portion of people would enjoy that, and who knows, bah.

I return to my original assertion that we have no idea what result any particular probe will generate, and that personally I want to know what's beyond the glow of our sun, so instruments for me, cultural stuff later, maybe. And if you think I rambled too much, IT'S CULTURE, BABY
JRehling
This thread is becoming a demonstration of signal to noise ratio on the Internet.
Maybe we could create a separate topic branch for "Highly speculative topics rooted barely in fact" and keep the Saturn, Pluto, etc., branches a rich source of discussion on those topics.
hendric
QUOTE (john_s @ Nov 14 2005, 01:17 PM)
We'll mostly be photographing boring stuff like stars to calibrate and commission the instruments.  Deep-space targets are an interesting idea, though our maximum exposure time with LORRI is about 10 seconds, which would cramp our style.
*


Well, just basing on what's on the opposite side of the sky from the sun the day of launch, there should be a nice grouping of "bright" DSOs to try for, including M31, The Pleiades, the Virgo galaxies, M51, Orion nebula, and a large number of open clusters in the area. I couldn't find any really detailed instrument information on LORRI or RALPH, but based on 5000 lines at 20 urad/pixel, should give ~5.7 degrees, enough for a very cool picture of M31.

10 seconds might not be long enough, but if you're afraid of oversaturation of the CCDs and will have to image in Jupitershine, maybe M31, M51, or the Orion nebula will work. The open clusters should definitely be worthwhile targets, like the Pleiades, the Beehive, or others. A few months after launch the best globular clusters should be far enough away from the sun.

I'm sure I'm screwing something up along the line. Can you talk about the basics of the cameras, like resolution, focal length and F/ratio? I'm sure the QE must be pretty close to 100%, and since LORRI is a clear filter it gets the best case light.

Of course, beyond the first commissioning shots I'm sure it would be difficult to justify to the DSN to take photos of DSOs for EPO...
ljk4-1
QUOTE (JRehling @ Nov 14 2005, 04:45 PM)
This thread is becoming a demonstration of signal to noise ratio on the Internet.
  Maybe we could create a separate topic branch for "Highly speculative topics rooted barely in fact" and keep the Saturn, Pluto, etc., branches a rich source of discussion on those topics.
*


You gentlemen are absolutely right. In fact, not only will I no longer even consider the idea of ETI or sending probes with messages on them for them, I have even begun to question the concept of Pluto as an actual world. After all, I have never seen it with my own eyes. Oh sure, there are photos and such of this "Pluto", but they can easily be faked. Most of them just look like a star anyway. And what decent astronomer would seriously name a planet after a cartoon dog? What next, a warrior princess?

tongue.gif
Rob Pinnegar
Okay, that's funny... but he's right, guys. The reason this forum is so good is that it has been kept as a science forum instead of a speculation forum. If we start getting away from that, we will start losing some of the scientists who like to post here. IMHO, this type of thing really is best nipped in the bud.

One place you might want to check out is the subforum titled "Community Chit Chat" that appears near the bottom of the main Unmanned Spaceflight page. If you really want to chat about speculative stuff, that might be a good place to do it. (I'm suggesting this because, although I'd really like to see this forum retain its quality, I don't much relish the idea of telling people to shut up -- that really isn't a very effective way of encouraging people's interest in science.)
spfrss
QUOTE (RNeuhaus @ Nov 7 2005, 04:32 PM)
Very nice pictures. The inquietud I have is that the probe is totally covered by a gold sheed except to the nuclear stick which looks somewhat worn with lots of scars.

Rodolfo
*


as the picture captions says, the RTG is a dummy, I think used for weight/balance testing.

IMHO the flight one will be installed at launchpad or just befoe encapsulating NH in PF.

live long and prosper

Mauro
BPCooper
QUOTE (spfrss @ Nov 16 2005, 05:42 AM)
as the picture captions says, the RTG is a dummy, I think used for weight/balance testing.


Mauro
*


It was a dummy used for just that, yep. The real one looks nearly identical, if not exactly.

The RTG will not be covered in gold.
Comga
Weeky NASA update on expendable launchers

http://www.nasa.gov/centers/kennedy/launch...ets/status/2005

Mission: New Horizons
Launch Vehicle: Lockheed Martin Atlas V 551 (AV-010) Launch Pad:
Complex 41, Cape Canaveral Air Force Station, Fla.
Launch Date: Jan. 11, 2006
Launch Window: 2:08 to 4:07 p.m. EST

The bottom portion of the payload fairing was installed this week on the Atlas V. A Launch Vehicle Readiness Review was successfully completed Tuesday. The fit check of the Radioisotope Thermo-electric Generator power system with the spacecraft was performed last week. The generator will be installed for flight at the launch pad. A "dry" spin balance test of the spacecraft will be completed this week. After Thanksgiving, hydrazine fuel for attitude control and course-correction maneuvers will be loaded on the spacecraft and a "wet" spin balance test performed.
BPCooper
The past few days neither the real or mockup RTG was installed. It looks (on the web feeds) like a cylindrical aluminum fitting similar in size, but it's hard to tell details. Does anyone know what that is? Perhaps just ballast to keep it balanced.
Redstone
The flight RTG was not installed, but there was a fit check made. The flight RTG will be installed once the spacecraft is atop the rocket. I suspect this is because generally it is best to have as few people around an RTG as possible.

Here is a picture of the real RTG being removed from New Horizons after the fit check.
Alan Stern
QUOTE (BPCooper @ Nov 17 2005, 03:48 AM)
The past few days neither the real or mockup RTG was installed. It looks (on the web feeds) like a cylindrical aluminum fitting similar in size, but it's hard to tell details. Does anyone know what that is? Perhaps just ballast to keep it balanced.
*


Good question, here's the scoop:

That's the mass model that simulates the mass and moments of inertia of the RTG.
It doesn't look as much like the real deal as the black thermal/electrical simulator
does, but it is what you want to have on for spin balance.

-Alan Stern
BPCooper
QUOTE (Alan Stern @ Nov 17 2005, 06:45 AM)
Good question, here's the scoop:

That's the mass model that simulates the mass and moments of inertia of the RTG.
It doesn't look as much like the real deal as the black thermal/electrical simulator
does, but it is what you want to have on for spin balance.

-Alan Stern
*


Interesting, thanks. Is that simulated RTG not useful for spin balance testing? And was that simulator an active heat and electrical generating system minus the Pu?
Alan Stern
QUOTE (BPCooper @ Nov 17 2005, 01:51 PM)
Interesting, thanks. Is that simulated RTG not useful for spin balance testing? And was that simulator an active heat and electrical generating system minus the Pu?
*


The thermal/electrical simulator has no radioactive material. It doesn't match the
mass properties at all.

-Alan Stern
RNeuhaus
What is the purpose of the balancing test? In the space has no gravity and the balance of weight is of no matter or not?

As it is performing, I see that the weight balance is of vital importance and would like to understand its implications to the navigation control during the space cruise.

Whenever the spacecraft is in the space, does it matter the stability of route toward Pluton?

Does the balancing of rotation stability of spacecraft is like to balance a new tire?

Rodolfo
Alan Stern
QUOTE (RNeuhaus @ Nov 17 2005, 02:11 PM)
What is the purpose of the balancing test? In the space has no gravity and the balance of weight is of no matter or not?

As it is performing, I see that the weight balance is of vital importance and would like to understand its implications to the navigation control during the space cruise.

Whenever the spacecraft is in the space, does it matter the stability of route toward Pluton?

Does the balancing of rotation stability of spacecraft is like to balance a new tire?

Rodolfo
*


It has nothing to do with the trajectory.

During the final phase of launch and most of the flight to Pluto, NH is spinning
endlessly like a top in order to simplify operations and reduce the amount of fuel
needed for pointing. The s/c has to be balanced for the spin to be stable and
without any excessive nutation. Thus the need to do the spin balance testing.
This was done back in Maryland and then again for a final check at the Cape
with the spacecraft fully configured for launch.
dvandorn
Ah, the old misunderstanding -- if there's no gravity in space, why worry about mass distribution?

Just because you're in a microgravity environment does not mean that mass goes away. Mass is a constant -- a kilogram of mass is a kilogram of mass, whether it's on Earth and weighs a kilogram or its in deep space and "weighs" nothing. (And no, I'm not inviting discussion of far-end-of-the-bell-curve theories about mass itself changing based on its distance from other large masses.)

Mass works the same way in space as it does on Earth, too -- it takes the same amount of force to overcome inertia in a microgravity environment as it does deep within a gravity field. So, balance is ultimately the same wherever you are, and it's just as important to know the mass balance on a spacecraft as it is on any piece of machinery you're going to be moving.

I hate to admit, I'm unsure whether New Horizons is planned to be spin-stabilized or three-axis stabilized. If it's to be spin-stabilized (which I'm thinking it is), then the mass balancing is even more important. It's exactly like the tire example you mentioned -- if there's a mass imbalance in a spinning object, the object will begin to wobble, and the wobble will reinforce itself until the object flies apart or until other motions couple into the wobble and the thing goes entirely out of control.

But even for three-axis-stabilized craft, you need to know your mass distribution very accurately, so you can place your thrusters in the right places, and fire them properly, to achieve both attitude and translation changes. Especially when you translate (i.e., change your overall path and speed), you have to thrust through your center of mass, and so you need to know your center of mass pretty accurately.

-the other Doug
dvandorn
That's what I get for taking 15 minutes to write and edit my post -- Alan got in ahead of me. biggrin.gif

Yeah, I thought NH was to be spin-stabilized for most of its flight, I was just not completely sure. Thanks for the confirmation, Alan!

-the other Doug
RNeuhaus
Good explanations. I was able to grasp them.

I tought the spin had the purpose to distribute uniformly the heat, cool and solar radiation and cosmic as I have learned it from others spacescrafts which orbit around the Earth and also to Moon and Mars.

As the spacecraft is going farther from the sun, the spin for this space might be less importance every time it is moving further away. Now I realice that the spin helps the spacecraft to avoid any wobbing during its trajectory and also to helps to manage better the thrusters after knowing the mass' properties of NH.

Well, as I see it, NH will be spinning on all way toward the Pluto. It would become an even more complicated to control the pointing of any navigation instrument to stars, to photograph any images on planets when the spacecraft is spinning.

Then maybe, before to take any picture, or any measurement, one of three (x-y-z?) reaction wheels will be activated to stop before conducting any science activities when it is flying-by to any celestial bodies (Jupiter, Galliean Moons, Saturn?, Uranus, Neptune and Pluto and its three moons).

Here, I have an inquietant question. It is related to reaction wheels as it is one of the most delicate since it has short Meant Time Between Failures. Will the NH have enough redundancies to cover all NH's lifetime trip to Pluto. I am thinking that the spinning factor will help to NH to avoid the use as less as possible the wheel reactions or not?

Rodolfo
BPCooper
QUOTE (Alan Stern @ Nov 17 2005, 09:55 AM)
The thermal/electrical simulator has no radioactive material. It doesn't match the
mass properties at all.

*


Despite not having the Pu, as I know, I would have figured it was designed to have the same mass/weight while still providing power using electricity.
john_s
QUOTE (RNeuhaus @ Nov 17 2005, 03:11 PM)
Then maybe, before to take any picture, or any measurement, one of three (x-y-z?) reaction wheels will be activated to stop before conducting any science activities when it is flying-by to any celestial bodies (Jupiter, Galliean Moons, Saturn?, Uranus, Neptune and Pluto and its three moons).

Here, I have an inquietant question. It is related to reaction wheels as it is one of the most delicate since it has short Meant Time Between Failures. Will the NH have enough redundancies to cover all NH's lifetime trip to Pluto. I am thinking that the spinning factor will help to NH to avoid the use as less as possible the wheel reactions or not?

Rodolfo
*


That's correct, we stop the spin when we want to make observations. However we do not carry reaction wheels- instead we use thrusters for controlling the spacecraft orientation and spin. This saves us mass compared to using reaction wheels, and eliminates a moving part that might fail, as you say. However it means that we have to be conservative in our maneuvering, because we have only a limited fuel supply. So spin mode helps us save fuel.
BPCooper
Spin test Monday:

http://www-pao.ksc.nasa.gov/kscpao/images/.../05pd2498-m.jpg

Alan Stern
New Horizons highlights for the week ending 11/18/05 include:

* Conducted Autonomy Review on 11/15
* Conducted Pre-Fueling Review on 11/16
* On basis of the above, decided to delay hydrazine fueling by six days to allow
for additional autonomy testing on the spacecraft and NHOPS.
* Observatory hydrazine fueling now scheduled for Sunday, 12/4. No change
to beginning of launch window; holding firm at 1/11/06.
* Completed dry spin balance on 11/17. No surprises.
* MSIM 4 Part 3 repeat for pactice began 11/17 and is scheduled to complete 11/19.
Rakhir
New Horizons Launch Preparations Move Ahead
http://pluto.jhuapl.edu/news_center/news/111805.htm

"Rocket motor set to boost NH toward Pluto will be delivered safely and within the rigorous engineering standards demanded in the assembly and testing of such hardware.

Boeing replaced the five striking workers with six non-striking workers; the extra assembly worker was added to provide additional oversight. Each of the six current workers has at least eight years of experience with Boeing upper stage motors and is fully qualified to work on the project.

"We expect this experienced team to finish processing the rocket motor on schedule, so New Horizons can meet its prime launch opportunity in January."
Comga
QUOTE (BPCooper @ Nov 17 2005, 10:58 AM)
Despite not having the Pu, as I know, I would have figured it was designed to have the same mass/weight while still providing power using electricity.
*



If you need to confirm what Alan says, look at the image from BPCoooper in

http://www.unmannedspaceflight.com/index.p...=27817&st=285&#

You will see the dummy RTG on the floor during the spin test. The blur of the RTG mass simulator is metalic gray, without heat fins. Obviously a completely different piece of hardware. Perhaps trying to get the power, mass, CG, and all other parameters equal to the real RTG was more complex than just building two simpler devices, one for temporary power, one for the spin tests.
Decepticon
I have a question that has been asked of me before but I really had no answer to.


Are Pluto and Charon close enough to cause tidal heating?
Could Pluto's core be warm?
john_s
QUOTE (Decepticon @ Nov 26 2005, 03:34 PM)
I have a question that has been asked of me before but I really had no answer to.
Are Pluto and Charon close enough to cause tidal heating?
Could Pluto's core be warm?
*


They are certainly close enough, but closeness isn't the only requirement. For one body to cause tidal heating in another, the relative distance and/or orientation of the two bodies must change, so that there's some periodic change in the shape of the body being heated- it's the changing shape that causes the heating. Pluto and Charon are locked into almost perfectly circular orbits around their center of mass, so while each is creating a large bulge in the surface of the other, the bulge never changes shape, so there's probably no significant tidal heating.

Pluto's core might still be warm, but it would be from radioactive heat in its interior, not from heating by Charon.
tasp
QUOTE (Decepticon @ Nov 26 2005, 09:34 AM)
I have a question that has been asked of me before but I really had no answer to.
Are Pluto and Charon close enough to cause tidal heating?
Could Pluto's core be warm?
*



Assuming Pluto and Charon did not form tide locked (probably a pretty good bet), they would have interacted tidally till they did achieve lock.

Dissipation of significant amounts of heat in either body, considering their composition, would have been very interesting.

Consider that we know Charon's surface is depleted in methane compared to Pluto. Considering the volatility of methane, we may have some evidence of a past period of significant tidal heating on Charon.

Perhaps the NH mission will photograph signs of past heating on Charon.
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