Mar 19, 2011

Mercury and Messenger

I was planning to write Mercury a week before, but there was the earthquake and so I'm writing this now. Turns out, it's the perfect timing! Go figure.
Messenger spacecraft orbiting MercuryWhy the timing's perfect is that this spacecraft called "Messenger" just went into a oval orbit around the planet a few days ago.

Oh, and the interesting fact is that "Messenger" stands for "MErcury Surface, Space ENviroment, GEochemistry and Ranging". Folks at NASA, you don't have to spend days just to come up with a good acronym!!

The graph below's from Wiki, and I don't really comprehend the jumble of trajectories so let's just focus on the image below that.
Turns out, Messenger didn't just go to Mercury, it also did a flyby of Venus! Looks like it did 1 flyby of our planet, 2 flybys of Venus and 3 of Mercury and then finally got into a orbit around Mercury. Why did they do this?
It's probably because, 
to go to Mars or some planet with a thick atmosphere, we can use a technique called "aerobraking" to slow down. It uses the friction of the atmosphere to brake, and it's useful because once you use this, you don't need the fuel to slow down.
But Mercury doesn't have a thick atmosphere! So, the guys at NASA used "gravity assist". This is a bit trickier than aerobraking, so let's leave it at "gravity assist uses gravity to change the path and speed of a spacecraft". 

And so, that's why they did flybys so many times, to gradually brake down.

The departure of Earth is beautiful. Just take a look!


And, I realized that this blog post's been invaded by Messenger, no mention of the planet. So I'll write about Mercury on the next article, which will probably be tomorrow.

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