Why Launch in Florida or California?
Since we're on the topic of California, have you ever thought about why the US launches rockets from where we do? Not many people think about this. Florida's arguably the lightning capital of America: You go down there in the heat of summer and you can pretty much set your watch by the afternoon thunderstorms. (Apollo 12, the one after the famous Neil and Buzz landing, got struck by lightning on the way up.) I can't even begin to tell you how many scrubbed launches I've been to in Florida due to weather. So why launch from there?
Well, for one thing, ideally, you want to launch from a coast*. Rockets are essentially controlled bombs, and sometimes, rockets are uncontrolled bombs. And when they go out of control, you don't want their shrapnel landing on populated areas. Or even un-populated areas, for that matter: A lot of unmanned rockets contain small nuclear fission reactors on them because fission power is powerful and lightweight and perfect for exploring the solar system when no humans are around. (Did you watch or read The Martian? Recall when Mark Watney dug up the Radioisotope Thermoelectric Generator to heat his martian buggy and jokingly "cited" from the astronauts' manual: "Lesson #1: Never dig up the Radioisotope Thermoelectric Generator.") You don't want bomb-scattered radioactive material landing on land.
* Note: Russia doesn't really have the option to launch from a coast, so they launch over a huge patch of nothingness land.
Another consideration when launching a rocket: The Earth's rotation gives you free speed. Earth rotates from east to west, and if you launch from west to east, you're going against its rotation, therefore picking up that rotational velocity for free. If you stand at the South Pole, you're barely rotating at all. But if you move to the equator, you're now at the fastest point of rotation. So, the closer to the equator you launch, the faster you fly. Hence, Florida.
So why California? Well, we already know that California has a big coastline, so there's one reason. But Vandenberg allows for something else: You can launch rockets into polar orbits, ie. orbits where you fly over the North and South Poles. The International Space Station flies at an orbital inclination of 51.6° with respect to the equator. (The "why" of that is a really cool story but too long for this already-long post.) So if you point your space shuttle at 51.6° northeast when you launch, your rocket will never get past 51.6° North or South latitude. If you want a polar orbit, you must launch due North or South. Satellites that survey the entire Earth get polar orbits. Some spy satellites get polar orbits. So that's why we use Vandenberg: You can fly a rocket due south over water into a polar orbit.
Mars InSight Lander
The launch I saw is called the Mars InSight Lander. As its name suggests, it's not a spy satellite: It's headed to Mars as I write this blog post. So it didn't really need a polar orbit. But the reason why it launched from Vandenberg is because the launch manifest is too crowded at Kennedy Space Center right now. This rocket has about a month's worth of launch windows to try to get to Mars, and if it doesn't go up before June, we'd have to wait another 26 months for Mars and Earth to align themselves to make a good launch. (In fact, it was supposed to go up in 2016, but oops: One of the instruments wasn't holding a vacuum in cold tests, so it was postponed until now.) You want an un-crowded launch manifest so you can do this as many times as it takes to get off the ground.
InSight is different than the other robots we're sending to Mars. Spirit, Opportunity, and Curiosity are all rovers acting as geologists, taking soil samples and analyzing them. InSight is more of a seismic geologist: It's measuring
My Own Journey
Tonight, I'm flying out to Los Angeles, renting a car, driving two hours to a hotel, sleeping for less time than my drive, and then headed out into the foggy night to find Vandenberg, setup a camera, and hopefully capture the launch of this one-time event.
I've been to so many scrubbed launches that I just have to accept them as the cost of doing business. But in this case, because I haven't taken any time off from work for this, I only have two shots for this to work: tomorrow and Sunday. May good fortune by on our side.