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The slingshot technique works because Jupiter is also moving--it's in orbit around the Sun, at about 30,000 mph (48,000 km/hr). When the probe approaches Jupiter from behind, the probe is gravitationally attracted to something (Jupiter) traveling at 30,000 mph, so it speeds up. Relative to Jupiter, you're right, it's a zero-sum game (i.e., the probe does seem to speed up and then slow down again, relative to the planet) but the velocity of concern is the so-called heliocentric velocity, or the velocity relative to the Sun, and that is greatly increased.

Note that there is conservation of energy, of course; Jupiter also slows down in its orbit slightly in response to the energy it adds to the probe, but the amount is unmeasurable due to the mass ratio between Jupiter and the probe. The speedup is therefore considered "free."

Google is your friend; see this page, this page, this page for more information.

Regarding your second question, the probe doesn't slow down again, and does do a very fast flyby. However, we know so close to nothing about Pluto that we don't have to get very close to get new information--for example, the resolution of the New Horizons cameras will exceed that of the best Earth telescopes (including Hubble) for 150 days. (Of course, it will take 4-9 months, depending on which estimate you like, to transmit the data back to the earth at the probe's minimum data rate--which it likely will use at that distance--of 800 bits/s.)

The key here is the energy required. Space travel is still dominated by propulsion. That is, the engines and the fuel they need, and the fuel needed to launch that fuel to orbit, etc., is where most of the cost is.

It is important to travel on a trajectory, called the transfer orbit, that requires the least energy. For a high thrust spacecraft, the minimum energy trajectory is called a Holman transfer. Simply, it is an orbit that just touches the orbits of both planets. The periapsis, the closest point to the sun, touches the orbit of the one planet and the apoapsis, the furtherest point, touches the other planet. For this to work, the destination planet needs to be half an orbit away when the spacecraft arrives. This is a lot easier to see in a picture.

For Earth to Mars, the spacecraft launches and then the thrusters fire to change the spacecraft's orbit of the sun from Earth's orbit to the transfer orbit. It then travels half of the transfer orbit and fires its thrusters to change its orbit to match Mars. This can be done by aerocapture, aerobraking or propulsion. The opportunity for a Holman transfer to Mars occurs every 26 years. It is based on the length of the orbit for the bodies being transferred between. The return trip also needs to be a Holman transfer to save fuel. The opportunity does not occur until many months after arrival. I forget the actual number. That is why Mars trips will have a long stay on Mars before returning.

Low thrust is different. Low thrust spacecraft thrust all or most of the time during the trip and the trajectory is more complicated. It is not usable for manned flight because it is to slow but is useful for unmanned spacecraft sometimes.

This is called Celestial Mechanics. When you add propulsion, it becomes Orbital Mechanics.

The best site I have found is NASA's Spacefligh Basics.

Also good is this site.

For explanation of gravity assists see this site.

Also see, Science World at Wolrram

Just in case you actually care. The reason spinning space stations don't work is called coriolis acceleration. Basically spinning results in horizontal as well as vertical acceleration. The vertical is what you want. The horizonal is what disorients and makes astronauts sick. Now, if you happen to have a really really big wheel you can reduce the effects of coriolis acceleration but yeah, you need all that mass. One solution to this is to use a tether and spin a small station around a very very long axis (like kms). That's great an all but 1) it doesn't work in low earth orbit and 2) if the tether breaks you've got a nice uncontrollable projectile there. Then there's the actual problem of getting it spinning in the first place.

While I've not read all of these books, in my high school The Chocolate War by Robert Cormier was a required reading. However it mentions masturbation, but for a group of 16 year olds that's not a big deal. I was distraught to see at least 2 Mark Twain titles on there.

Some of the titles I can see, however, "what's happening to my body" can help kids at "that stage" in life learn how to deal with things changing. It's much better then the "Fuzzy Bunny" cartoon they used on The Simpsons(tm)

Also the Halifax explosion of 1917 (see also here) -- 2300 tons of explosive picric acid, 2115 tons of TNT, and other assorted nasties. A fireball that rose a mile high, windows shattered 100 km away, 1635 killed, 9000+ injured, 325 acres destroyed.

So a 747 wouldn't replace fifteen smaller craft. It might replace three or four... If you didn't factor in the increased accuracy of the purpose-built water-bomber.

Hmm. Or, on a non-obescene note, we could try Lipsticks in Piccadily Circuis (by Claes Oldenburg)... Bah. Modern art.

IMHO these are merely remote controlled surveillance systems generously equipped with a grenade launcher and 12 gage shotgun.

The buzz bombs of WWII were more autonomous than these and thus more like a true robot. In the same vein, cruise missiles are more autonomous and thus much more "robotic" to me.

Don't believe the hype...

Generating artificial gravity is actually quite simple, as it can be done using centrifugal force. A space station (or space ship) that employed this technique would look like a giant wheel and would rotate around it's axis (just like in the 2001 movie).
You can easily demonstrate the centrifugal force by swinging a large object around yourself.

• More Orbits
• Way indepth, should give you enough - as long as you have a basic understanding of physics
• more equations than you can shake a stick at

If more satellites for a GPS-like system, wouldn't it be possible to get a more accurate fix on your location? According to this page, three satellites are required to get a fix on your location (four to perform time correction). However, a number of problems exist: (taken from above site)

1. The receiver clock is not exactly synchronized with the satellite clock so the time of flight will be imprecise.
2.The satellite and receiver are in different velocity reference frames and gravitational regimes so there are relativistic differences (both special and general)
3. The speed of light is 300,000 km/s in a vaccum. However, while travelling through the Earth Ionosphere and Troposphere, the radio waves travel at slightly slower speeds
4. Radio signals traveling through the atmosphere travel differents paths depending on the location of the receiver.

Although the first problem is correctable using a fourth satellite, the remaining three problems persist. However, if you receive signals from several satellites (not just your minimum 4), if you average your reported locations, you should be able to get a more accurate fix on your location.

If more satellites for a GPS-like system, wouldn't it be possible to get a more accurate fix on your location? According to this page, three satellites are required to get a fix on your location (four to perform time correction). However, a number of problems exist: (taken from above site)

1. The receiver clock is not exactly synchronized with the satellite clock so the time of flight will be imprecise.
2.The satellite and receiver are in different velocity reference frames and gravitational regimes so there are relativistic differences (both special and general)
3. The speed of light is 300,000 km/s in a vaccum. However, while travelling through the Earth Ionosphere and Troposphere, the radio waves travel at slightly slower speeds
4. Radio signals traveling through the atmosphere travel differents paths depending on the location of the receiver.

Although the first problem is correctable using a fourth satellite, the remaining three problems persist. However, if you receive signals from several satellites (not just your minimum 4), if you average your reported locations, you should be able to get a more accurate fix on your location.

Here is a good description of rotating space stations and the coriolis effect.
Basically, if you run 'with' the rotation of the station, you will get heavier, and if you run 'against' the rotation, you will get lighter. That can be a little confusing. It also makes ball games a little difficult, since the trajectory of a ball will change depending on which direction you throw it!
Another good site explaining the effect and its problems is here

To me, even more interesting is whether or not man killed off Neandertals. These guys were all over Europe for a very long time, and they were smart enought to fight back. A war with them would have truly been "World War One".

It's possible, but it's only a possibility among others. The only thing we know about interactions between Cro Magnon (the modern man) and Neanderthal is that they actually existed. Other than that, the evidence is scarce, and it's difficult to figure out. As of now, we think that Neanderthal were simply displaced by Cro-Magnon (modern man) immigrants who pushed them further and further, until they got "cornered" in southern Spain and Gibraltar, then eventually disappeared altogether. Interbreeding was long thought impossible, but recent evidence indicates that it was. Maybe we (white men of European descent) all have Neanderthal genes. Maybe not. We don't know.

The first genocide in history probably happened quite some time later, between two kind of people belonging to modern mankind: mongoloids and blacks: it was the destruction of Australian-like Aborigines (i.e. Blacks) by Northeast-Asians (i.e. the ancestors of what you call "Native Americans"). We have some archeological evidence, and more surprisingly, we even have documents !

However, even in this case, it is very possible that actual fighting only took a minor role, and that the first inhabitants were simply driven out of their lands further and further, up to Terra del Fuego (the island that forms the other side of the Magellan Strait).

When the number of years exceeds four figures, the only thing we know is that we hardly know anything.

Thomas Miconi

So I guess the point of this (rambling) post is that computers are not the solution to illiterate kids and crappy grades. They are a fine educational tool, if used correctly, but we can't forget the importance of good old teaching, and work. and stuff.