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Beware the Rings of Pluto

Unknown Lamer posted about 2 years ago | from the why-not-send-two-or-three dept.

Space 96

Hugh Pickens writes "The Christian Science Monitor reports that scientists are planning a new route for NASA's New Horizons space probe as it approaches a potentially perilous path toward Pluto through a possible set of rings that may create dangerous debris zones for the NASA spacecraft. New Horizons is currently about 1,000 days away and 730 million miles from closest approach to Pluto but given that New Horizons is currently zooming away from the sun at more than 33,500 mph, 'a collision with a single pebble, or even a millimeter-sized grain, could cripple or destroy New Horizons,' says project scientist Hal Weaver. 'We need to steer clear of any debris zones around Pluto.' Researchers are making plans to avoid these hazards if New Horizons needs to. 'We are now exploring nine other options, "bail-out trajectories,"' says principal investigator Alan Stern. New Horizon's current plan would take it about halfway between Pluto and the orbit of its largest moon, Charon. Four of the bail-out trajectories would still take the spacecraft between Pluto and Charon's orbit. The other alternatives would take New Horizons much further away from Pluto, past the orbits of its known moons. 'If you fly twice as far away, your camera does half as well; if it's 10 times as far, it does one-tenth as well,' says Stern. 'Still, half a loaf is better than no loaf. Sending New Horizons on a suicide mission does no one any good. We're very much of the mind to accomplish as much as we can, and not losing it all recklessly. Better to turn an A+ to an A- than get an F by overreaching.'"

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Mess with Pluto... (0)

Anonymous Coward | about 2 years ago | (#41683271)

And it'll mess right back with you.

the man has a lot to answer for (4, Funny)

Thud457 (234763) | about 2 years ago | (#41683409)

I blame Neil Degrasse Tyson for all this.

Re:the man has a lot to answer for (5, Funny)

jellomizer (103300) | about 2 years ago | (#41683457)

Yea too bad Pluto didn't clear up the debris in its area like a real planet.

Re:the man has a lot to answer for (2)

K. S. Kyosuke (729550) | about 2 years ago | (#41683567)

Exactly, Neil has only given Pluto its coup deGrasse and now everybody makes it like he's some kind of monster or something.

Re:the man has a lot to answer for (0)

Anonymous Coward | about 2 years ago | (#41683675)

Well, his ego is certainly a monster.

Re:the man has a lot to answer for (1)

nitehawk214 (222219) | about 2 years ago | (#41685369)

I blame Neil Degrasse Tyson for all this.

Start calling Pluto a comet, and it will start acting like one.

Re:the man has a lot to answer for (1)

formfeed (703859) | about 2 years ago | (#41688677)

I blame Neil Degrasse Tyson for all this.

I used to like the guy till he bit someone's ear off.

Good on him (-1)

Anonymous Coward | about 2 years ago | (#41683305)

Still, half a loaf is better than no loaf.

A statement that any sufferer of constipation can agree with.

Can something that is not a planet (1)

EmagGeek (574360) | about 2 years ago | (#41683311)

still have a moon?

Re:Can something that is not a planet (1)

0racle (667029) | about 2 years ago | (#41683337)

Yes.

Re:Can something that is not a planet (1)

wooferhound (546132) | about 2 years ago | (#41684277)

Can a Moon have a moon ?

Re:Can something that is not a planet (3, Interesting)

camperdave (969942) | about 2 years ago | (#41685117)

The gravitational perturbations would, more than likely, cause the moon's moon to be unstable. Eventually, it (the moon's moon) would either crash into the planet or the moon, or be ejected from the system entirely. However, for the short term, it is entirely possible. Our Moon has quite a number of satellites orbitting it; all artificial, of course.

Re:Can something that is not a planet (2)

turgid (580780) | about 2 years ago | (#41685777)

See Ida/Dactyl.

Re:Can something that is not a planet (1)

poofmeisterp (650750) | about 2 years ago | (#41694049)

Can a Moon have a moon ?

Can a question have a question?

Re:Can something that is not a planet (-1)

Anonymous Coward | about 2 years ago | (#41683371)

That's no moon...

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41683427)

It's to big to be a...

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41684089)

I have a very bad feeling about this...

Re:Can something that is not a planet (5, Informative)

jellomizer (103300) | about 2 years ago | (#41683425)

Having or not having a moon isn't part of the definition of a planet.

"(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit." [http://en.wikipedia.org/wiki/Planet#2006_definition]

Pluto meets A,B and not C.

C is there to discredit large asteroids in the asteroid belt.

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41683757)

Depending on how picky you are, earth doesn't meet C. And depending on how needlessly pedantic you are, Mercury was probably not the active factor in clearing that tight orbit of other significant masses.

I haven't checked what the total masses of earth-orbit non-sattelites actually is, but I think a rule like 90% of the mass in an orbit's vicinity being in the planet and its moons is a valid level of granularity to keep earth as a planet and still dismiss Pluto. Even 10% would probably dismiss all the asteroid belt objects, but I don't know how much clutter is dispersed along Pluto's path.

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41684225)

Jupiter technically doesn't meet C either, depending on how you look at it.

The planet redefinition was all about emotional attachment to the idea that there should be a small number of planets. It's a joke.

Re:Can something that is not a planet (1)

Anonymous Coward | about 2 years ago | (#41684373)

Actually, C is met by Jupiter. There is an amount of mass [wikipedia.org] that is allowed in the neighborhood that is not from a satalite of the planet. Earth also has Lagrangian asteroids.

Re:Can something that is not a planet (1)

GNious (953874) | about 2 years ago | (#41684365)

Its a war on planetoids!

Re:Can something that is not a planet (3, Interesting)

mcgrew (92797) | about 2 years ago | (#41684859)

"(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit." [http://en.wikipedia.org/wiki/Planet#2006_definition]

Pluto meets A,B and not C.

Neither has Jupiter. [wikipedia.org]

Re:Can something that is not a planet (3, Interesting)

c++0xFF (1758032) | about 2 years ago | (#41686069)

Trojans don't count in the same way that moons don't count. Basically, the definition of "cleared the neighborhood" means that anything left is dominated by the gravitational influence of the planet. Moons orbit the planet, Trojans orbit the Lagrange points.

Another similar class of objects are those in orbital resonance with the planet. The Pluto/Neptune system, for example. Or Cruithne/Earth. The planet's gravity dominates in each case, so we're OK there.

The term "cleared the neighborhood" is unfortunately misleading. And purposefully vague, I always thought. When does the neighborhood become cleared? There's a lot of asteroids in our near neighborhood (which result in rather significant accretion events, so to speak).

Re:Can something that is not a planet (1)

khallow (566160) | about 2 years ago | (#41691709)

The term "cleared the neighborhood" is unfortunately misleading. And purposefully vague, I always thought. When does the neighborhood become cleared? There's a lot of asteroids in our near neighborhood (which result in rather significant accretion events, so to speak).

It is rather odd that such a slipshod definition has been rationalized on scientific grounds. I'm leaning towards that it's retaliation for the long ago act of naming Pluto [wikipedia.org] in such a way that the planet's name contains the initials for the discoverers' former sponsor, Perceval Lowell [wikipedia.org] . I doubt any one takes seriously the claim that in the future school students might be forced to memorize the names of hundreds of planets, merely because potentially hundreds could be found which would fit the existing definition.

And any discussion of gravitational dominance has to explain why there are more than one planet, Jupiter since Jupiter gravitationally dominates the rest of the Solar System of which we know from the Kuiper belt on in, outside of the Sun itself (the Sun has roughly 99% of the mass of the known Solar System, Jupiter has 90% of what's left).

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41689831)

According to that logic, neither has Earth. We dwell on planetoid Earth :(

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41685533)

The nine planets were discovered by people using their minds, their eyes and simple optical instruments. Clyde Tombaugh used a tool called a blink comparator to study two images of the same region of the sky taken several nights apart. He would display one image and then blink to the second image to see if any objects had moved from night to night. This took years of effort; he worked about 8 hours a day looking at slides.

On February 18, 1930, Tombaugh turned up just such an object. The name “Pluto” was suggested by Venetia Burney, and 11-year old English school girl. It was human beings who discovered the nine planets of our solar system. Recently space-based telescopes, electronic CCD imaging, and modern computers have found hundreds of other objects, but they are not planets. The computers have erroneously been given primacy by the feeble-minded. If Pluto is not a planet, please never refer to "Europe" as a continent.

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41689563)

If Pluto is not a planet, please never refer to "Europe" as a continent.

Because Europe was discovered by computers? Because this is some about some pissing match between computers and humans?

Plus when Eris was discovered, the images were originally skipped over by computer searches because they had a minimum speed to look for. After another TNO was found that was slower than their cutoff, the researchers started looking through old images by eye...

Re:Can something that is not a planet (1)

Anonymous Coward | about 2 years ago | (#41686453)

Neptune is not a planet either since it hasn't cleared Pluto's orbit.

Re:Can something that is not a planet (0)

Anonymous Coward | about 2 years ago | (#41689589)

The fact that Pluto's orbit is locked in resonance with Neptune while Neptune doesn't give a crap that Pluto is there means it counts as cleared. Cleared doesn't mean gone, but means anything that is left is submissive to the gravity of the planet (e.g. moon, trojan, other resonances). In this case, Neptune definitely is the top and Pluto is the bottom, they are not switches.

Re:Can something that is not a planet (3, Informative)

trout007 (975317) | about 2 years ago | (#41683769)

The center of gravity of Pluto and Charon is not inside of Pluto's radius.

Plitteration? (5, Funny)

Anne_Nonymous (313852) | about 2 years ago | (#41683325)

Potentially perilous Pluto path? Perfectly petrifyingly perigee perturbation!

Re:Plitteration? (2)

FingerDemon (638040) | about 2 years ago | (#41684359)

Anxious astronomers allowing a lot of alliteration.

Re:Plitteration? (1)

Tablizer (95088) | about 2 years ago | (#41685349)

Pebble pummeling possibly produces perpetually poorly-performing probe parts

Re:Plitteration? (1)

raulcito (114054) | about 2 years ago | (#41685455)

Positing potential path protuberances placates pedantic Pluto probers.

Re:Plitteration? (1)

poofmeisterp (650750) | about 2 years ago | (#41694063)

Quit playing with PP.

yeah, sure (2)

pietros (1062744) | about 2 years ago | (#41683369)

when I was young, only planets were allowed to have rings!

1/r^2 (3, Insightful)

Khashishi (775369) | about 2 years ago | (#41683383)

I thought if you fly twice as far, your camera will work 1/4 as well, not 1/2.

Re:1/r^2 (1)

Baloroth (2370816) | about 2 years ago | (#41683467)

I'm not a photographer, but I think: 1/4th the light, but 1/2 in terms of resolution. Light can be adjusted for, resolution cannot (well, sort of, there are tricks, but you'd rather use those on a higher resolution image to get better virtual resolution anyways).

Re:1/r^2 (2)

Khashishi (775369) | about 2 years ago | (#41683587)

The brightness of a large object won't change, but the resolution will drop by a factor 2 in each direction, so a factor of 4. The magnitude of a small object (sub-pixel) will drop by a factor of 4.

Light can only be adjusted down, not up. Well, you can integrate for longer, but then you lose temporal resolution, which could be a problem if you are moving.

Re:1/r^2 (2)

Revotron (1115029) | about 2 years ago | (#41683645)

In an optical sense, a camera works just like a flashlight. When you double the distance from a flashlight to a wall, you get four times the coverage on the wall even though the circle of light is twice its original diameter. A camera's viewing area works the same way - double the distance between a camera and an object and the object appears at half its original dimensions, but the surface area of the object in the frame is only a quarter of the surface area in the original image. You've got the same number of pixels covering 400% of the original viewing area, therefore your resolution is 1/4th of the original.

Re:1/r^2 (1)

Dcnjoe60 (682885) | about 2 years ago | (#41684313)

I'm not a photographer, but I think: 1/4th the light, but 1/2 in terms of resolution. Light can be adjusted for, resolution cannot (well, sort of, there are tricks, but you'd rather use those on a higher resolution image to get better virtual resolution anyways).

Your thought is correct in that 1/4th the light, but the resolution remains constant (pixels are pixels). On the other hand, if there is not enough light to illuminate those pixels, they won't detect anything. Doesn't matter whether it is high resolution or not. Without photons, there is no image.

Re:1/r^2 (1)

wonkey_monkey (2592601) | about 2 years ago | (#41684647)

Your thought is correct in that 1/4th the light, but the resolution remains constant (pixels are pixels).

I think what was meant was "pixels per unit surface area of the object." Still, personally I'd refer to an image resized from, say, 100x100 to 50x50 as being half the resolution.

Re:1/r^2 (0)

Anonymous Coward | about 2 years ago | (#41686909)

Your thought is correct in that 1/4th the light, but the resolution remains constant (pixels are pixels).

I think what was meant was "pixels per unit surface area of the object." Still, personally I'd refer to an image resized from, say, 10k to 2.5k as being half the resolution.

So, is a quarter the same as half-dollar? If so, I'd like to make a few even exchanges with you...

Re:1/r^2 (0)

Anonymous Coward | about 2 years ago | (#41683913)

Come on, give the guy a break, you're talking about an engineer here. He did the best he could.

As long as it keeps him busy and away from writing code then I'm good.

Re:1/r^2 (1)

poofmeisterp (650750) | about 2 years ago | (#41694139)

I thought if you fly twice as far, your camera will work 1/4 as well, not 1/2.

He was talking to Kindergarteners, not Khashishis. :)

That'll teach those silly astrophysicists! (0)

Anonymous Coward | about 2 years ago | (#41683395)

Downgrade ME from a planet, will ya? Say, that's a nice little toy you've got flying out near me. Shame if some part of me crashed into it, you know?

Our New Motto (0)

Anonymous Coward | about 2 years ago | (#41683397)

To Boldly Plot Nine Bail-Out Trajectories That No Man Has Plotted Before.

Tholen (0)

Anonymous Coward | about 2 years ago | (#41683399)

Tholen is that you?

Outrage (4, Funny)

Joehonkie (665142) | about 2 years ago | (#41683435)

Now even our spacecraft are getting bailouts!

U.S.S.R. (0)

Anonymous Coward | about 2 years ago | (#41683471)

Soviet Cosmonauts were the first to explore Pluto's rings during Project Manifesto, otherwise codenamed "Goulash".

http://kremlin.ru

Beware the Rings of Pluto? (1)

MarkGriz (520778) | about 2 years ago | (#41683511)

Damn right. I hear they are pretty pissed about the whole "planet" thing.

pluto (0)

Anonymous Coward | about 2 years ago | (#41683553)

they decided it was a planetoid because it couldn't clear its orbit of debris (orbit around the sun), but its still big enough to attract material to orbit it (hence moons and rings). The only reason Earth doesn't have rings is that it is relatively small and all of the material in orbit around it was pulled into the gravity well of our freakishly large moon.

I'm more worried about the ring on uranus (0)

Anonymous Coward | about 2 years ago | (#41683679)

that picture scarred me for like, why didn't its camera work worse

Re:I'm more worried about the ring on uranus (0)

Anonymous Coward | about 2 years ago | (#41685383)

I'm sorry, AC, but astronomers renamed Uranus in 2620 to end that stupid joke once and for all.

Analogies (0)

Anonymous Coward | about 2 years ago | (#41683731)

Could someone PLEASE explain this with another analogy?

Re:Analogies (0)

Anonymous Coward | about 2 years ago | (#41683793)

The shopping cart corral is surrounded by a bunch of random carts that lazy people couldn't be bothered to properly return, so you're going to have to swing a wider path around it to avoid denting your car.

Re:Analogies (0)

Anonymous Coward | about 2 years ago | (#41683863)

Yea, it sure does sound like he's not too sure of what's going to happen.

Rings (1)

Cro Magnon (467622) | about 2 years ago | (#41683843)

I always thought I had to worry about the rings around Uranus!

Re:Rings (1)

Ignacio (1465) | about 2 years ago | (#41684855)

No, just the Klingons.

Re:Rings (0)

Anonymous Coward | about 2 years ago | (#41685519)

Yeah, be careful about the rings about Uranus!

Re:Rings (0)

Anonymous Coward | about 2 years ago | (#41686495)

Can't wait to 2620 when they'll end these jokes for good by renaming the planet!

Single pale blue dot (1)

gmuslera (3436) | about 2 years ago | (#41683957)

Even Pluto is married this days. Maybe we should nuke the moon to have a respectable ring around our planet, won't be a signal of intelligent life here (at least, not intelligent enough) but at least will be noticed by eventual visitors from outside.

Re:Single pale blue dot (1)

confused one (671304) | about 2 years ago | (#41684925)

Nuking the Moon won't get anyone's attention, it'll just create more mess.

The 3rd rock around this star draws attention because it has copious liquid water, free oxygen in its atmosphere, and has both artificially produced light and sub-atomic particles emitting from it's surface. That should be more than enough to get someone's attention, if they happen to fly by.

The christian science monitor? (0)

Anonymous Coward | about 2 years ago | (#41683989)

I thought all christians believed the earth was flat, the earth is the center of the solar system and the universe ended at the barrier around our solar system..

Re:The christian science monitor? (2, Insightful)

Anonymous Coward | about 2 years ago | (#41684465)

I thought all christians believed the earth was flat, the earth is the center of the solar system and the universe ended at the barrier around our solar system..

That's because you're a bigot.

Re:The christian science monitor? (1)

Tablizer (95088) | about 2 years ago | (#41685883)

Maybe you can answer something that has puzzled me. Why don't the more rational Christian groups denounce the whackier sects more vocally? Otherwise, they ruin the reputation of Christianity in general. Letting them fester may be a sin itself.

Re:The christian science monitor? (2)

bzipitidoo (647217) | about 2 years ago | (#41686551)

You can blame that one on the drama peddlers. Interviewing rational Christians would be boring. They sell a lot more newspapers by seeking out the kooks and covering them. They might hold a book burning in which they throw scientific textbooks about evolution into the flames. Makes for great copy.

Re:The christian science monitor? (2)

Tablizer (95088) | about 2 years ago | (#41686855)

Yes, but leaders of rational denominations should NOT stay silent. Otherwise, their organization risks being painted and tainted by the same brush. Speak up against the BS or risk owning it!

Re:The christian science monitor? (1)

TangoMargarine (1617195) | about 2 years ago | (#41689405)

So what decibel is an acceptable "volume" for you?

Re:The christian science monitor? (1)

Tablizer (95088) | about 2 years ago | (#41713023)

Top leaders denounce publicly

Re:The christian science monitor? (0)

Anonymous Coward | about 2 years ago | (#41689611)

Why don't the more rational Christian groups denounce the whackier sects more vocally?

They do, all the time. Half the time, jerks respond, "Well, if you don't clean up your own house, it is still your fault," and just move the goal line. What is with such lack of common sense for people to think, "Gee, you said you don't believe in X and think Y is bad, but you haven't denounced people that support X and Y, you must actually believe and support such things yourself."

And as an atheist myself, I sure do not want to be held responsible for the idiots who also use that label. So to play it safe, consider this an official denouncing of this BS argument.

Crazy thought (3, Insightful)

Nethemas the Great (909900) | about 2 years ago | (#41684045)

So since most of the cost in any given NASA science project is in the hardware research and engineering not the construction, neither launch nor operation side why they hell aren't they making use of economies of scale? Stop building only one of something (well technically two, the "on earth version" and the "mission" version). Spread the risk out by flying in multiples. It would be unfortunate if one of them hits a "pebble" but the science returned would be magnitudes better because they're able to take advantage of opportunities that wouldn't be possible due to risk aversion. Take it a step further and make use of the same hardware R&D for multiple missions. Engineer a few platforms that are robust, and reasonably customizable. Each platform with a particular type of mission in mind. Put a Curiosity on Europa, Titan, and/or Ariel. Get an MRO around Ganymede, etc.. You don't need 7 minutes of terror if the hardware you spent more than $2B developing has already been flown and proven on other missions. You wouldn't be (as) scared to death that Congress will cut your funds because you're making good, efficient use of the R&D money. "Yes senator, that $2B from Congress has given us a platform we've reused on 10 missions now."

Re:Crazy thought (1)

JTsyo (1338447) | about 2 years ago | (#41684427)

oops, misclicked mod

Re:Crazy thought (1)

Squidlips (1206004) | about 2 years ago | (#41684447)

Actually JPL should send MSL (Curiosity) clones to other places on Mars such as Mawrth Vallis (especially here). Sending MSL to Europa would be problematical because of the RTG; what happens to it when the mission ends? Could it kill putative Europeans? If you sent it to Titan it would boil away a hole in the ice and disappear or sink in a lake.

Not much economies of scale at those quantities. (3, Interesting)

pavon (30274) | about 2 years ago | (#41685167)

You don't really get much improvement in per-unit cost by building 10 of something vs 2. The biggest factor in the cost even with just the first couple isn't the engineering but the testing and qualification. Most of that has to be repeated for every unit you build until you are creating enough to have confidence in the past performance and to fall back to statistical testing, or at least are building enough for automating that work to be economical. But you would need to be creating several dozen of them for that to kick in. Furthermore, construction is more expensive that you are allowing for at those low quantities since it's all is done by hand, by highly skilled labor. That won't drop by much until you get into mass-manufacturing quantities, hundreds at least.

So you would get minor savings, and at the loss of a huge amount of science. There is a reason that each of these probes is wildly different, and that is because the have wildly varying requirements. There is no one-size fits all suite of sensors. They will want different spectral ranges, different optics setups (detailed, narrow FOV vs wide coverage), different transmitter requirements (Horizon has much farther to transmit than MRO), all of which drives different battery requirements.

Finally, the point of science is to keep learning; to keep pushing things forward. You do that by sending probes with improved and/or different capabilities, not just more of the same. Sure we could have sent 3 more MERs (Spirit/Opportunity) for the cost of Curiosity, but we wouldn't have learned as much as Curiosity will be able to tell us.

Re:Crazy thought (0)

Anonymous Coward | about 2 years ago | (#41689631)

The problem is operating costs. When missions that are already in space have to deal with threats of operating costs being pulled, putting more up isn't going to help.

Charon (1)

broginator (1955750) | about 2 years ago | (#41684105)

Charon doesn't make change.

Re:Charon (1)

conureman (748753) | about 2 years ago | (#41687439)

I think my transfer expired.

subject (1)

Legion303 (97901) | about 2 years ago | (#41684249)

From TFA:

"RELATED: Are you scientifically literate? Take or quiz."

I'll settle for just being literate.

Twice as far away... (1)

Dcnjoe60 (682885) | about 2 years ago | (#41684267)

'If you fly twice as far away, your camera does half as well; if it's 10 times as far, it does one-tenth as well,' says Stern.

I was always taught that with optics it is the square of the distance, so twice as far away is 1/4 as well and 10 times further is 100th as well. But then, maybe when the changed the science that said Pluto wasn't a planet, it changed the physics, too.

Re:Twice as far away... (1)

wonkey_monkey (2592601) | about 2 years ago | (#41684667)

Technically speaking yes, but casually speaking an image that's 10"x10" is generally regarded as being the "twice the size" of 5"x5", so it's that kind of thinking they're going with.

Re:Twice as far away... (1)

Dcnjoe60 (682885) | about 2 years ago | (#41686325)

Technically speaking yes, but casually speaking an image that's 10"x10" is generally regarded as being the "twice the size" of 5"x5", so it's that kind of thinking they're going with.

But that is the point, it's not 1/2 the size, but 1/4 (you can fit 4 5x5's in a 10x10).

Re:Twice as far away... (1)

wonkey_monkey (2592601) | about 2 years ago | (#41686979)

Yeah, and that's my point. TFA is going with the popular easy-to-understand way of explaining things, rather than the technically-correct-but-not-how-people-think-of-it way.

Re:Twice as far away... (1)

cyn1c77 (928549) | about 2 years ago | (#41689979)

Technically speaking yes, but casually speaking an image that's 10"x10" is generally regarded as being the "twice the size" of 5"x5", so it's that kind of thinking they're going with.

But that is the point, it's not 1/2 the size, but 1/4 (you can fit 4 5x5's in a 10x10).

It's half the width and a quarter of the area. Size generally does not refer to area, but rather a length scale. Thus, the article is correct.

get ballsy, go for broke (1)

rubycodez (864176) | about 2 years ago | (#41684357)

Send the craft on a close approach, count on likelihood it will get most of the closer-up pictures on approach first and then maybe get destroyed. so what if it is destroyed while leaving?

Re:get ballsy, go for broke (1)

R3d M3rcury (871886) | about 2 years ago | (#41685359)

Because while Pluto's visit is an important part of the mission, it's not the only part of the mission. So ending at Pluto would kind of cut off all the other research into the Kuiper belt.

Re:get ballsy, go for broke (1)

Tablizer (95088) | about 2 years ago | (#41685543)

so what if it is destroyed while leaving?

The problem is that it uses on-board storage to collect and save the data and images, and then relays it all back weeks after the encounter. If it gets destroyed during a ring-crossing, it won't get a chance to send info back.

To save money, it doesn't have highly maneuverable instrument booms the way Voyager did. Instead the whole craft rotates each instrument into position, and the instruments take turns doing their thing (at least the highly-directional instruments). This also saves on power (and weight) because not all instruments need to be active at a given time. But the downside of moving the whole probe is that the antenna is not pointed at Earth. Thus, it's mostly silent during the main mission.

There will be a couple of snapshots sent back to Earth roughly 2 weeks before primary encounter as an insurance policy. If the probe is destroyed by ring/moon debris, this "insurance shot" will be our ONLY souvenir.

Half a loaf is better than no loaf? (0)

Anonymous Coward | about 2 years ago | (#41684375)

Well, damn, if you want a full load just fly by Uranus.

Watch for rings there, too.

Can we just take a chance on Pluto then? (1)

xxxJonBoyxxx (565205) | about 2 years ago | (#41684495)

IANAA* but from a layman's perspective, I'd rather zoom in and see what we can of Pluto even if we're taking a chance on destruction, than increase the chance this is a half-and-half mission. (I don't want another major mission aimed at Pluto - there are other things to look at out there.)

* Astrophysicist

Makes my head hurt, just thinking about it... (1)

LeadSongDog (1120683) | about 2 years ago | (#41685381)

The imager can see 12th magnitude stars. It has both high resolution and high sensitivity, but no moving parts. A decade ago it was state of the art stuff. But physics is still physics. At twice the radius, a pixel will get one fourth the light flux, so will need four times longer exposure. That means four times fewer images. However, doubling the CPA also means half the slew rate, so it may not be so bad.
The original article: http://www.space.com/18087-pluto-moons-rings-risk-new-horizons.html [space.com]
The craft: http://www.space.com/1800-horizons-voyage-edge-solar-system.html [space.com]
The telescope (LORRI): http://www.universetoday.com/566/new-horizons-telescope-sees-first-light/ [universetoday.com]

Re:Makes my head hurt, just thinking about it... (1)

blueg3 (192743) | about 2 years ago | (#41686103)

Actually, the light flux per pixel is constant with respect to distance. The total flux from the object decreases as 1/r^2, but the number of pixels taken up by the object on the sensor also decreases as 1/r^2, cancelling this out.

You can try this out yourself: set a camera to manual exposure and take a picture of a brick at distances of 1 and 10 feet. Compare brightness of brick between photos. (Alternately, simply consider the apparent brightness different between a tree tens of feet away and trees a mile away. Does the latter appear hundreds of thousands of times darker?)

Pluto is angry/pissed. (1)

antdude (79039) | about 2 years ago | (#41686647)

For being demoted from its planet status. :P

Cassini recorded 'sand' impacts in Saturn's rings (1)

Herve5 (879674) | about 2 years ago | (#41690477)

I was part of the Huygens european team in the Cassini/Huygens mission to Titan.
On the US Cassini orbiter, there was a microphone, which was turned on when Cassini went to flyby Saturn, passing in the clear between two rings.
The craft had been reoriented at that moment to get the large high-gain antenna facing speed, so as to protect everything between, and because of this the key crossing moment happened without Earth contact --only afterwards was it due to reorient back to Earth and tell us whatever happened.
Well we definitely did record sand/dust impacts with the mic, and I can tell you, even 'a posteriori' it was quite frightening to listen...

Inverse square law...? (1)

Half-pint HAL (718102) | about 2 years ago | (#41690791)

Sorry, have I missed something about the camera they're using? Isn't every camera two-dimensional and subject to the inverse square law?

'If you fly twice as far away, your camera does half as well; if it's 10 times as far, it does one-tenth as well,' says Stern

Surely "twice as far away" = "a quarter as well", and "10 times as far" = "one-hundredth as well"...?

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