Why did they build the International Station in Space, when they could have built an International Moon Base?

Half of all the probes sent to Mars have crashed or gone off course.

It would cost too much. It costs about $10,000 to send one pound to Earth orbit. It would cost many times more than that to send it on to the Moon due to the added fuel needed, all of which would have to first get to Earth orbit at a cost of $10,000 per pound. This is explained by the rocket equation. See the source if you want the details.

Working and living in orbit may be easier, not harder, than working and living on the Moon. The Moon has 2 week long nights which means no solar power for 2 weeks at a time. And it gets down to 250 degrees below zero and stays that cold for 2 weeks. The dust on the Moon is very abrasive, clogging and damaging equipment. If there were any emergency, you would need to launch from the Moon and travel 3 days to get to Earth, while from an orbiting station you only need a small vehicle with a weak retro rocket to return to Earth in an hour or so. The Space Station orbits inside Earth's magnetic field which protects it from charged particle radiation, while a Moon base would have no such protection.

Sending the crew out there is the expensive part.

Extremely expensive.

You have to go all the way to the Moon (accelerate the stuff and the people to 11 km/s), then land on the Moon (braking against 1/6 gravity is not free), take off from the Moon again (some of the people would insist on being brought back alive) which takes more fuel, then arrive back at Earth at 25,000 mph (11 km/s) and... hope for the best.

In comparison, the shuttle only needs to reach a little less than 8 km/s to achieve orbit. Drop off the material (which, being in the cargo hold of the shuttle, is already in the proper orbit) and the people. Those who insist on coming back, hop back into the shuttle which simply needs to brake a bit, causing it to drop into the atmosphere at a safer speed of 17,000 mph.

Also, on the Moon, you do not get any of the benefits of being in orbit (e.g., microgravity experiments). On the space spation, the "lifeboat" is a simple Soyouz capsule. You hop in, separate, brake a bit... and you fall back to Earth.

From the Moon, you'd need a much more elaborate space vehicle as a "lifeboat".

Of course, if YOU have the money to build a Moon base, go right ahead.

It's actually a lot harder to build a moonbase than a space station. With a space station you send up the sections, you dock them together in space, and it's done. Then you just keep building, each time just sending up the components, rendezvous in space and dock them together.

For a moonbase you have to lift every part to the Moon, which requires a LOT more energy than getting into orbit, plus it has to have additional fuel and propulsion to allow it to land on the Moon rather than just smash into it. You then have to move the parts across the surface to join them together, and you have to deal with lunar regolith. That stuff is fine, abrasive, and will ruin seals and wear down tools.

So floating in space is actually quicker and easier than building something on a surface.

Because of the ridiculous extra cost of getting to the moon so you can work in 1/4 gravity rather than so much closer to work in Zero Gravity.

What they do at the space station is Zero Gravity research, not Reduced Gravity research.

The ISS is 250 miles up, the moon is 250 000 miles up, outside the range of the shuttles.

It would have cost at least 100 times as much in cash and lives lost.

I don't see the point of having a base on the Moon in the first place. There is nothing there. Mars on the other hand has a lot to offer in terms of exploration. The International Space in my opinion was a gigantic waste of money. Estimates put the total cost of the station at around $127 billion.

havnt you seen the new transformers movie???? thats why

Simple. Because you cannot perform experiments in Constant Freefall on the Moon.

There's a reason we've never been back to the moon...

it is more expensive