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Cassini-Huygens Saturn Orbit Insertion Imminent
Anonymous Explorer writes "Fresh
off of its fly-by with the Saturnian satellite Phoebe, the
Cassini-Huygens
craft is set for Saturn
Orbit Insertion on June 30, 2004.
Cassini-Huygens has a planned four year mission ahead for Saturn
and its many moons. With 450 watts of power for the electronics, this
mission has plenty enough horses to run the stretch with plenty-o-pep
to spare. Thanks to all that power, and the plethora of electronics on Cassini
and the Huygens
probe, we
can now hear sounds from Saturn. Pretty cool stuff! Festivities are
scheduled to begin on June 29th with a broadcast of Cassini Saturn
Orbit Insertion Press Conference on Nasa TV. SOI [PDF link] will occur after Cassini
fires its main engine for 96 minutes, in order
to slow down and be grabbed by the pull of Saturn. As always we extend
an invitation to everyone to join
#cassini on irc.freenode.net and
help us celebrate this historic mission."
I have the same amount of power in my computer's power supply. Something seems fundamentally wrong with that.
..for transmitting from millions of miles away and some HAMs are using 10 kilowatts upwards just for transmitting earth-to-earth!
Do the rings make the same noise represented on the Star Trek Voyager intro?
Here, I'll help you out.
-1, Troll.
Alas the only other time geeks encounter this situation is when they plug in a new video card.
Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
What truth?
There is no dupe
Yes, the greenies were making a mountain out of a molehill. Nuclear powered satellites have been launched for years, and the reactors are specifically designed to survive the destruction of the spacecraft.
The problem is that we live in a world that is only willing to offer 30 seconds of attention about any subject at a time.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
Hearing sounds from Saturn is nothing new. My 1997 SL1 (like most old Saturns) is VERY noisy ... you can hear it coming from a mile away. Step on the gas and it sounds like the power steering pump is going to pop through the hood.
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What are you talking about? It's not like the entire World has ADD or some... Hey, what's that shiny thing over there?
Hmmm.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
People theorizing about asteroid mining in the past had talked about complicated ways of getting ice out of the rare ice-bearing asteroids. Now that we know Phoebe is icy, I wonder if it ends up being the most practical place in the solar system to get ice. Although it's in the outer solar system, which is inconvenient, that's not necessarily such a big deal with solar-powered ion drive propulsion (as demonstrated by NASA already), which theoretically allows you to send anything into any orbit without paying for energy.
Find free books.
Your little computer is a lot bigger if you include the size of the Power Station it is attached to through a long peice of wire.
Someone should calculate how the amount of coal or oil that would be needed to provide power for Cassini if it weren't nuclear. Or the size of solar cells needed at that distance from the sun (and their wieight).
Letter To Iran
The sound they refer to is a frequency-shifted and time-compressed recording of emissions from charged particles in the magnetic field around Saturn. There is no actual "sound" there, as sound requires an athmosphere(sp?) of some sort. There's athmosphere a-plenty on Saturn (most of it IS probably gas, after all), but none near or around the probe.
Black holes are where God divided by zero
Lots of people are saying that Cassini uses a nuclear reactor... this is not the case as Cassini actually uses 3 Radioisotope Thermoelectric Generators (RTG). RTGs are different from reactors in that they are much simpler devices which produce electricity directly from the decay of radioactive material, in this case PU-238. Reactors on the other hand produce power from heat generated by a controlled nuclear chain-reaction.
Today marks an interesting first (at least as far as I have been able to tell): the NASA channel has had to choose which current space activity to put on TV.
On Wednesday there will be an EVA on the ISS right around the time the Cassini stuff will be happening. Thus, NASA TV had to choose, for the first time, which thing happening in space was more exciting.
How cool is that? There's actually enough going on up there that one TV channel is not enough!
Whadya know, the revolution IS televised.
The travelling-wave amplifier gives only 20 Watts of output power, which feeds into a 4 meter dish antenna. At 8.4 GHz this gives a gain of about 50 dB. EIRP then at 2 MW. (And a free space loss to Saturnus of about 300 dB....)
wakka-chikka-wakka-chikka "Hello Saturn, I'm Cassini-Huygens. I'm here to repair your plumbing."
You know, though... when people complain about there being sound in the middle of a big space battle, it always kind of bothers me a bit. Because if you were in space with space ships and missiles blowing up all around you, you *would* hear the sound of explosions as the pressurized gasses and debris from the ship expand in a shock wave travelling at speeds probably quite similar to what we're used to for sound. Sure, it would be all sudden bursts as your spacecraft was hit by the shockwaves, with no prolonged rumbles, but there *would be sound* to a viewer in a spacecraft somewhere.
And then there's the other things that could possibly cause sound - some of these futurisitic engines are supposed to be powerful ion drives or plasma thrusters, which means that there are very powerful magnetic fields being used and streams of high-velocity charged particles, both of which could possibly have an impact on certain parts of your spacecraft when you get close and make noise. If a beam weapon starts cutting at your ship's hull, your hull is definitely going to make some noise, especially when mechanical components are damaged or gasses start to leak. Etc. There would be lots of sound in a space battle.
I'm an owl exterminator!
Long ago, when I thought I wanted to be an EE, I did a couple of summer internships at JPL. I worked on the Cassini flight computer. My coworkers, especially the lead ASIC designer, were blisteringly smart people. If Cassini fails, it won't be the computer design at least!
Back then, the project was called "CRAF/Cassini" where CRAF was "Comet Rendezvous/Asteroid Flyby." CRAF was supposed to be the sister ship to Cassini, but it was cut for budgetary reasons. Too bad... with all the design work done how much could it have cost to just build another ship?
See, we were building this neat computer that would be reused on the next generation of probes, instead of having custom computer hardware for each... but of course it didn't work out that way.
I was lucky enough to see Cassini (and Galileo) in the Vehicle Assembly Facility. There was an observation deck where you could watch the guys in the clean room building the spacecraft. It was very cool to look down and realize, "that is going to Saturn." Or wherever.
Cassini is the last of the old school probe designs... a gigantic and expensive. She'll give us a heck of a show.
In a nutshell, here's how Cassini will interact with the rings during the orbital insertion.
Saturn right now is tilted, so that the south/"bottom" side of its rings is facing towards the Sun and Earth. Hence, Cassini is approaching Saturn from "underneath" as we see it from Earth. The orbit insertion requires Cassini to pass through the equatorial/ring plane south-to-north as it approaches the planet. It will fire its rocket while on the north side of the rings, and then coast back to the south side on its way back out.
Now, how is Cassini doing that safely? It's doing so by going through the ring plane where there are no rings. It could be thought of as a "gap", but Cassini really isn't anywhere near the rings when it crosses them. The crossing points are far outside the main mass of the ring system.
A rough analogy is this. Suppose you lived in Alaska, and had a sailboat named Cassini. Now suppose you had to sail from Alaska to Mexico without bumping into anything. Naturally, you'd pass between Hawaii and the continental US. That's a rough analogue to what's going on at Saturn - the main mass of the rings is like the continental US landmass (and there's a few small intra-ring gaps like the Mississippi River), while there's a few small outside rings sort of like the Hawaiian islands.
Would it be possible that your sailboat bumped into a rock or debris or something that we didn't know was there? Yes. Is that possibility remote enough that it makes for the safest course to your destination? Also yes.