New Horizons at Pluto

sts60 said:
I did a little engineering support for the refurbished RTG which is powering P-NH to the ninth planet* and beyond. Wow, time flies when you're a small spacecraft starting out on a big honkin' rocket. It's great to finally see the awesome science and beautiful images. Exciting stuff.


* Yes, I said planet. Old school!
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Do RTG's put out the same amount of energy continuously or can they be throttled back so that the RTG is only getting used up when energy is required?
 
jhunter1163 said:
Believe it or not, we're still in contact with both Voyagers. 11 or 12 billion miles away, roughly.

http://voyager.jpl.nasa.gov/where/index.html
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I stumbled on this site today:
http://eyes.nasa.gov/dsn/dsn.html

When I found it the first time one of the antennae was communicating with Voyager.

When I took a look at it before I made this post the 70 meter antenna in Spain was communicating with Rosetta.

Totally cool !. I just checked back before I pushed Submit button and the 70 meter Goldstone antenna is communicating with New Horizons.

Picture of the Goldstone antenna when my wife and I visited a few years ago.
https://photos.google.com/u/0/album.../AF1QipN8u_6lz2_NHrCskBYO7cCBFcuNeM2Uhr0IaWra

The area of the antenna is about an acre.

ETA: Perhaps more accurately, the Goldstone antenna is sending messages to New Horizons. It doesn't seem to be receiving anything right now.
 
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davefoc said:
Do RTG's put out the same amount of energy continuously or can they be throttled back so that the RTG is only getting used up when energy is required?
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The radioactive decay rate can't be manipulated. The plutonium is giving off energy all the time, depending on its age. Regardless of how you use it, after so many years the power output will drop below some minimum threshold.

You could use batteries to hold some energy and use it at higher power levels intermittently, but rechargeable batteries tend to have low energy density, so they're often not that useful.
 
Gawdzilla Sama said:
How much longer would the trip have been if they'd tried for an orbit. (Crazy patterns* allowed, but at least one realistic scenario, please.)

*Swing by, loop waaaay out, get pulled back, swing by loop waaay in, oscillate until orbit is stable?
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How would it become stable (by which is presumably meant circular) in anything short of cosmic periods of time? Tidal forces? Braking by Pluto's atmosphere?
 
This is sort of interesting. I took a look at the site I linked to above which shows what satellites the Deep Space Network antennae are communicating with and right not it shows two antennae at Goldstone and two antennae in Australia sending data to the New Horizons space craft. There are many possibilities of what is going on, perhaps at the top of the list should be that I don't understand what I'm looking at and there is a mistake in the information displayed.

Perhaps there is more than one receiver on the New Horizons spacecraft? Rhere is a lot of redundancy. I looked around a bit and according to one source it sounds like the receiver can distinguish between left and right circular polarization signals and there are two receivers for redundancy. So does that explain why there might be four signals at once being sent to the new Horizons spacecraft. I'm not sure.

I'm surprised that transmitting from the much smaller antennae is worthwhile given how much larger the gain of the larger antennae is. If they can send data to the spacecraft with the much smaller antennae it suggests that they will be able to communicate with the spacecraft much farther away than it is now. And I suppose that's true because they can communicate with voyager and it is several times farther away than New Horizons is right now.
 
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Gawdzilla Sama said:
How much longer would the trip have been if they'd tried for an orbit. (Crazy patterns* allowed, but at least one realistic scenario, please.)




*Swing by, loop waaaay out, get pulled back, swing by loop waaay in, oscillate until orbit is stable?
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Possibly. Basically you'd have to carry sufficient "fuel" to brake from constant velocity, so either a slower coast or a far bigger probe. I'm unable to crunch the numbers atm but back-of-the-envelope suggests many times larger.

jhunter1163 said:
I've wondered this myself... what would we do if we spotted something coming in, maybe a kilometer across, and spectroscopically determined that it was metallic. Not many natural metallic objects way out there... we'd have to consider the possibility that it was artificial. Biggest news of the millennium, right there.
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That's tending towards an OCP, I expect it'd shake money loose and not just for NASA.

Foster Zygote said:
What if it's pure neutronium?
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A 1km3 sphere of neutron degenerate matter would mass ~2.1E26kg, more than thirty five times as much as the Earth or about one-ninth as much as Jupiter; it's gravitational pull would be noticed quickly.

CynicalSkeptic said:
Nice:

J002E3WP

eta: Cool animated gif:

[qimg]https://upload.wikimedia.org/wikipedia/commons/3/39/J002e3f_orbit.gif[/qimg]

L1 is a Lagrange point?
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Yep L1 is the Lagrange point between the primary and secondary masses, i.e. between the Earth and Luna in this case.

CapelDodger said:
That'd cause a stir on the collector's market. Worth a short story ... :)
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Hopefully it'll become part of a space station at some point.

davefoc said:
Do RTG's put out the same amount of energy continuously or can they be throttled back so that the RTG is only getting used up when energy is required?
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RTGs rely on radioactive decay, so technically the heat produced is always slowly decreasing. There's no way to alter this bar manipulating the nuclear force in some manner we cannot currently achieve.


And finally, I'm surprised no-one has mentioned New Horizons's passenger; Clyde Tombaugh.
:thumbsup:
 
Craig B said:
How would it become stable (by which is presumably meant circular) in anything short of cosmic periods of time? Tidal forces? Braking by Pluto's atmosphere?
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I was suggesting that it would be captured by Pluto's gravity. It would have to slow considerably for that to happen, and that would have meant a longer trip with a "turn-over" somewhere near half way. Just curious as to how much time that would add to the trip.
 
I believe it is now transmitting data back to earth. Will take awhile to get here though.
 
Via Boingboing:

pluto.gif
 
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