Sexy, Sexy Mercury

[beccastareyes]

So, MESSENGER (with caps because it's a Cute NASA Acronym -- stands for MErcury Surface, Space ENvironment, GEochemistry and Ranging probe) did its first flyby of Mercury this week, and we got some cool pictures, including parts of Mercury we've never seen before.

Pictures!


So, we've only sent one other spacecraft (Mariner 10) to do a flyby of Mercury -- so, we saw maybe 60% of the planet. And Mercury is hard to see from Earth because it's close to the Sun. This is the first time human beings have seen some of those craters.

The reason is twofold. First, sending stuff to Mercury is expensive. Mercury is a lot lower in the Sun's gravity well, so you have to get rid of a lot of potential energy. That means firing rockets. Rockets are expensive. Expensive missions make Congress whiny, and they cut NASA's funding.

The cheap(er) way is to trade some of the energy to something big -- a planet, for instance. Basically you run past a planet and use gravity to pull yourself away or towards the Sun. The planet then goes the opposite direction, but not nearly as much -- even a large spacecraft is teeny compared to a small planet. This is called a gravity assist, and NASA uses them a lot. Mariner 10 used one assist from Venus. MESSENGER had two from Earth, two from Venus, one (so far) from Mercury, and two more planned so it can get into Mercurian orbit. Which is why the mission takes forever to get going -- the money saved means you spend longer bouncing around the Inner Solar System.

The second problem is that MESSENGER is getting around 10 times more sunlight than Earth gets. While this means it's got plenty of power without having to stick plutonium on it (like we did for Cassini), it also means you need to keep the nice, expensive electronics cool. This is another pain and expense. (For comparison, near-Venus space is only getting twice as much sunlight.)

But, now we have a mission heading there. And we get two more flybys, then MESSENGER goes into orbit. And then the real work begins.

Comments

[yuuo.insanejournal.com]

I think the whole thing is awesome beyond belief. You know, if we could focus more money on NASA and exploring our world and universe around us than we do on some chimp's holy war, I think the world overall would be a helluva better place.

Viva space exploration, man.

[beccastareyes.insanejournal.com]

In my completely biased opinion, I encourage this. A quarter of our semi-weekly coffee hours consist of bitching about NASA's money situation, and about having to do more science with less budget. (Planetary astronomy has it not bad. Comparatively speaking, I mean. On the other hand, our missions cost more.)