Where New Horizons is

[Orca]

Soon after the International Astronomical Union designates Ceres as a Dwarf Planet:

"Aw man, I'll always think of Ceres as an asteroid..."

[neufer]

I'll always think of Pluto as a planet.
I think of other so called dwarfs as planets as well; Eris, Sedna, and others.

[youtube]http://www.youtube.com/watch?v=F28iPNsU ... r_embedded[/youtube]

[orin stepanek]

I may not be an authority; but I do have an opinion. What bertter place to express it than here. Art; you must have some opinion also; what is your take on pluto!

[neufer]

I may not be an authority; but I do have an opinion. What bertter place to express it than here.
Art; you must have some opinion also; what is your take on pluto!

• When Neil Tyson won't, Pluto will.

http://en.wikipedia.org/wiki/Pluto_Water

The Perils Of Pluto Water
Posted 08.24.2007 by The Big Wiper

<<My father pledged a fraternity his freshman year, and it was during his initiation when he had his first encounter with Pluto Water. His run-in with Pluto Water was one of many tales he told me a couple of weeks before I matriculated; and because of what my father endured in the spirit of "brotherhood", I was turned off of the entire Greek universe of manic mayhem -- I did not follow in his footsteps and refused to join a fraternity.

My father and his fellow pledges were blindfolded and driven to a remote area far away from campus. Still blindfolded, they were each forced to guzzle a bottle of Pluto Water. Then their blindfolds were finally removed, at which point they were told to find their way on foot back to campus. The active brothers drove away, leaving the pledges to fend for themselves with their systems ticking away like turd time bombs.

Pluto Water takes up to an hour to reach internal gusher status, so my father said it wasn't too bad at first. They were actually able to concentrate, like Hansel and Gretel, on finding their way out of the woods. But eventually the fraternity brother bowel movement came a-knockin' on their back doors, and the results were that my father and his buddies pretty much had to rip down their pants simultaneously and assume the squatting position, spraying their dis-stink-tive signatures in the midst of nature's splendor.

My father said that he remembers it as a rather violent experience all around, with a sudden rush of guts that were probably accompanied by sound effects worthy of today's cheesiest scatological teen movies. Worse still, they had nothing to wipe with except leaves. Maybe some of them even befouled their underwear when they had to get down to the nitty-gritty; but all of them, he said, were walking funny all the way back to campus, bow-legged as cowboys. It took them a good three hours to find their way. Once they returned, of course, the first thing they all did was hit the showers and try to put all the forced bowel bonding out of their minds.>>

[rstevenson]

That's the best argument I've seen so far for demoting Pluto. The last thing our Earth needs is a laxative. We'd be flushing politicians for weeks.

Rob

[neufer]

That's the best argument I've seen so far for demoting Pluto. The last thing our Earth needs is a laxative. We'd be flushing politicians for weeks.

<<French Lick, Indiana, was originally a French trading post built near a spring and salt lick. The sulfur springs were commercially exploited for medical benefits starting in 1840. In the early 20th century it also featured casinos attracting celebrities like boxer Joe Louis, composer Irving Berlin and gangster Al Capone. The town has been best known for being the hometown of NBA great Larry Bird, "the Hick from French Lick". Pluto Water, a best selling laxative of the first half of the 20th century, was bottled here. It was also home to a large 7-Up bottling facility.>>

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[neufer]

Art; you must have some opinion also; what is your take on pluto!

I have already taken a definitive stand:

http://asterisk.apod.com/vie ... 109#p97109

[bystander]

Planetary Trash Talk

Surely we can just grandfather Pluto into the solar system, right? We can look the other way! Science doesn't work like that. Bend the rules for Pluto and you've got to do the same for a few other nearby objects, like Ceres, for example. And as Stephen ("Reality has a well-known liberal bias") Colbert makes clear in the clip below, that's a threat against Earth's own special planet-ness.

http://www.colbertnation.com/the-colber ... asse-tyson

[orin stepanek]

Go Pluto!
http://www.plutoisaplanet.org/

[bystander]

Halfway to Pluto, New Horizons Wakes Up in 'Exotic Territory'
Science@NASA - 18 June 2010

Zipping through space at nearly a million miles per day, NASA's New Horizons probe is halfway to Pluto and just woke up for the first time in months to look around.

"Our spacecraft is way out in exotic territory, in the middle of nowhere," says Hal Weaver, New Horizons project scientist at Johns Hopkins University. "And we have a lot to do."

It's the perfect opportunity to test New Horizon's instruments before the probe reaches Pluto in 2015. "We don't want to miss a single breathtaking moment during the Pluto encounter," he says. "So we're checking everything out now to make sure we're ship-shape and ready to go."

The 9 weeks of testing commenced on May 25th. Mission controllers plan a thorough checkout and recalibration of all seven science instruments onboard.

First up is LORRI, the Long-Range Reconnaissance Imager, one of the largest interplanetary telescopes ever flown.

"On July 14, 2015, the date of closest approach, we'll be able to distinguish objects on Pluto as small as a football field," says Weaver. "That's about 300 times better resolution than anything we have now."

LORRI will be working together with "Ralph," a spectrometer designed to probe the surface of Pluto at visible and infrared wavelengths. Ralph will reveal Pluto's temperature, color, and chemical composition.

"During the current tests, we'll point both LORRI and Ralph at something in the sky to make sure they can be operated together with full sensitivity. Since New Horizons is far from any large bodies right now, we'll aim the cameras at a star field to test them." ...

• More Information:
  
  New Horizons -- home page
  
  Check it Out: System Tests, Science Observations and a Course Correction -- latest news about New Horizon's ongoing wake up period
  
  Ever Farther Across the Ocean of Space to a Distant and Unknown Shore -- an essay by New Horizons principal investigator Alan Stern

[orin stepanek]

Thanks bystander! I knew they were going to run some tests soon. I didn't realize that time was here already. New Horizons passed the half way distance mark a while back; in 4 months it will pass the half way mark; time wise.

[RJ Emery]

Is the New Horizons mission just a flyby of Pluto, or will the probe attempt some kind of orbit? If it just a flyby, what will New Horizons do, if anything, for its remaining life in space?

[neufer]

Is the New Horizons mission just a flyby of Pluto, or will the probe attempt some kind of orbit? If it just a flyby, what will New Horizons do, if anything, for its remaining life in space?

<<New Horizons is designed to fly past one or more Kuiper belt objects (KBO) after passing Pluto. Because the flight path is determined by the Pluto flyby, with only minimal hydrazine remaining, objects must be found within a cone, extending from Pluto, of less than a degree's width, within 55 AU. Past 55 AU, the communications link becomes too weak, and the RTG wattage will have decayed significantly enough to hinder observations. Desirable KBOs will be well over 50 km in diameter, neutral in color (to compare with the reddish Pluto), and, if possible, possess a moon. Because the population of KBOs appears quite large, multiple objects may qualify. Large ground telescopes, such as Pan-STARRS[37] and later the Large Synoptic Survey Telescope, will find suitable objects up until the Pluto flyby; the Pluto aim point, plus some thruster firing, will then determine the subsequent trajectory. KBO flyby observations will be similar to those at Pluto, but reduced due to lower light, power, and bandwidth.

# July 14, 2015 — Flyby of Pluto around 11:47 UTC at 13,695 km, 13.78 km/s.
# July 14, 2015 — Flyby of Charon, Hydra and Nix around 12:01 UTC at 29,473 km, 13.87 km/s.
# 2016-2020 — Possible flyby of one or more Kuiper Belt objects (KBOs).
# 2029 — The probe will leave the solar system.

Provided it survives that far out, New Horizons is likely to follow the Voyager probes in exploring the outer heliosphere and mapping the heliosheath and heliopause.

Even though it was launched far faster than any outward probe before it, New Horizons will never overtake Voyager 1 as the most distant man-made object from Earth. Close fly-bys of Saturn and Titan gave Voyager 1 a massive advantage with its extra gravity assist. When New Horizons reaches the distance of 100 AU, it will be travelling around 4 km/sec slower than Voyager 1 at that distance.>>

[Chris Peterson]

Is the New Horizons mission just a flyby of Pluto, or will the probe attempt some kind of orbit? If it just a flyby, what will New Horizons do, if anything, for its remaining life in space?

It's a flyby mission. There is no practical way to put a probe in orbit around Pluto. Once New Horizons passes Pluto, there will hopefully be enough fuel left to conduct flybys of one or more Kuiper Belt objects. In any case, the probe will simply keep moving outwards, eventually leaving the Solar System and heading into deep space. By then it won't be communicating, however.

[bystander]

New Horizons Web Page: Mission Time Line
John Hopkins University / Applied Physics Laboratory (JHU/APL)

see also: NASA's New Horizons Mission Page

[neufer]

[New Horizons] will simply keep moving outwards, eventually leaving the Solar System and heading into deep space. By then it won't be communicating, however.

The RTG powered Voyager space craft were designed to transmit for 48 years.

<<A cylindrical radioisotope thermoelectric generator, or RTG, protrudes from one vertex in the plane of the triangle. The RTG will provide about 240 W, 30 V DC at launch, decaying to 200 W at encounter in 2015. The RTG, model "GPHS-RTG," was originally a spare from the Cassini mission. The RTG contains 11 kg (24 lb) of plutonium-238 oxide pellets. Each pellet is clad in iridium, then encased in a graphite shell.>>

[rstevenson]

It's a flyby mission. There is no practical way to put a probe in orbit around Pluto. ...

Does "practical" in that sentence stand for "cost-effective"? Surely it's possible to send a probe which can achieve orbit. We just have no reason at the moment to do so.

Rob

[Chris Peterson]

It's a flyby mission. There is no practical way to put a probe in orbit around Pluto. ...

Does "practical" in that sentence stand for "cost-effective"? Surely it's possible to send a probe which can achieve orbit. We just have no reason at the moment to do so.

Of course it is possible, but it would be extremely difficult. There is simply no practical way to get rid of the big delta-V required to get to Pluto over a time period that is likely to be funded, and over which you might reasonably expect the spacecraft systems to continue functioning. New Horizons will arrive at Pluto carrying something like 15 times that planet's escape velocity. The possibilities for slingshot orbits involving the outer planets get pretty thin.

[rstevenson]

Ah! I didn't realize it was 15 times Pluto's escape velocity. That's a bit of a problem in orbital mechanics. Where are the brakes when you need them?

I suppose if you wanted to orbit Pluto, a different trajectory around the gas giants might get you onto a more favourable approach, catching up to Pluto from behind and taking a long time to do it. As you say, not practical -- for now.

Rob

[neufer]

Ah! I didn't realize it was 15 times Pluto's escape velocity.
That's a bit of a problem in orbital mechanics. Where are the brakes when you need them?

Actually, a high escape velocity for the planet that one wishes to orbit simply complicates the procedure because it requires that one lose half that energy (after applying the initial brakes) in order to orbit(; though one can always orbit so far out that this wouldn't pose a problem).

The real issue here is that if one doesn't have a fast final velocity (>10 km/s)
at Pluto it would simply take too long to reach Pluto in the first place
(regardless of whether gas giant sling shot orbits are used or not).

It is the ratio of this final velocity (>10 km/s) to
the on board fuel exhaust velocity (not the planet's escape velocity)
that is prohibitive here.

In order to reach Pluto in less than 10 years it was necessary to have a final velocity near Pluto of 13.78 km/s.
This is 6.4 times faster than the ~2.16 km/s exhaust velocity of it's hydrazine rockets.

Hence, one has the choice of a fly by spacecraft of mass ~ 400 kg
or an orbiter spacecraft of mass of ~ exp(-6.4) 400 kg = 665 grams.
(And that 665 grams payload would have to include the hydrazine rocket motor.)

One could switch to ion rockets, of course, but that would require decades of flight.

[Chris Peterson]

Actually, a high escape velocity for the planet that one wishes to orbit simply complicates the procedure...

Right, I wasn't very clear (and I looked up the wrong value). What I was actually talking about is the solar escape velocity at Pluto's orbit, which is around 7 km/s, or half the velocity of the New Horizons probe. Without a practical gravity assist orbit, and without the option of aerobraking, that just leaves thrusters for dumping all that velocity in order to stay in orbit around Pluto. And that would require an impractical amount of fuel.

[makc]

Where are the brakes when you need them?

Without a practical gravity assist orbit, and without the option of aerobraking, that just leaves thrusters for dumping all that velocity in order to stay in orbit around Pluto. And that would require an impractical amount of fuel.

Exacly the situation with these things. It is mostly easier to roll without brakes, but then there are times you wish you had them.

[rstevenson]

I was about to object to the statement that there was no "option of aerobraking", but first I went and looked up what I could find on Pluto's atmosphere -- always a good thing to learn before opening one's mouth. I found that at the best of times Pluto has a very thin atmosphere -- on the order of 1/300,00 to 1/700,000 of Earth's atmospheric pressure -- and now is not the best of times. The planet is moving away from the sun on the outward bound leg of its highly elliptical orbit, and what atmosphere it has will be starting to condense and freeze out, depositing back onto the surface from which it sublimated.

Oh well, given Pluto's orbital period of 248 Earth years, we'll probably be capable of performing an earobraking maneuver the next time Pluto has enough atmosphere to make it possible. If we're around to care, that is.

Rob

[neufer]

Actually, a high escape velocity for the planet that one wishes to orbit simply complicates the procedure...

Right, I wasn't very clear (and I looked up the wrong value). What I was actually talking about is the solar escape velocity at Pluto's orbit, which is around 7 km/s, or half the velocity of the New Horizons probe. Without a practical gravity assist orbit, and without the option of aerobraking, that just leaves thrusters for dumping all that velocity in order to stay in orbit around Pluto. And that would require an impractical amount of fuel.

"If anything I said this morning has been misconstrued in opposite effect, I want to apologize for that misconstruction." - Joe Barton

To tell the truth, the disparity between the spacecraft's velocity and Pluto's escape velocity was the very first thing that came to my mind as well.

But since you posted in before me I had the distinct advantage of rethinking the whole issue.

However..... after rethinking yet again I retract my statement that
"a high escape velocity for the planet that one wishes to orbit simply complicates the procedure..."

Rather: a high escape velocity (V_e) for the planet can be used advantageously for an orbiter
by using a close approach and applying the retrorockets (or preferably aerobrakes)
at maximal velocity (since power = velocity x force).

A spacecraft orbiter with approach velocity V_a only requires
a initial breaking delta V_δ = sqrt{V_a²+V_e²} - V_e.

Of course, with no atmosphere and weak gravity this is of no help as regards Pluto
but it should prove critical for future orbiters to Uranus (V_e: 21.3 km/s) & Neptune (V_e: 23.5 km/s).

[bystander]

Course Correction Keeps New Horizons on Path to Pluto
John Hopkins Applied Physics Laboratory - 01 July 2010

A short but important course-correction maneuver kept New Horizons on track to reach the “aim point” for its 2015 encounter with Pluto.

The deep-space equivalent of a tap on the gas pedal, the June 30 thruster-firing lasted 35.6 seconds and sped New Horizons up by just about one mile per hour. But it was enough to make sure that New Horizons will make its planned closest approach 7,767 miles (12,500 kilometers) above Pluto at 7:49 a.m. EDT on July 14, 2015.