Epistemophilia: no LaGrange for Hubble

I listened to an episode of Astronomy Cast that answered listener questions. Most were hard to follow such as the one about whether you can accelerate matter to a speed sufficient to cause a black hole. Sorry, too dumb to understand that bit of quantum weight gain. But there was one about Hubble that was interesting.

So, Hubble cannot be pointed at the Sun and its caretakers take pains not to do so, lest it be seriously damaged. If that is the case, why didn't they launch it into a LaGrange point? Specifically, L2 (or even more specifically, Sun-Earth L2, as opposed to the Earth-Moon L2.) L2 being the point on a line drawn between two large masses where the point lies beyond the smaller of the two. In other words, so that the Earth would be shielding Hubble from the Sun. In fact, that's where Planck (observing Cosmic Microwave Background) and the European Space Agency's Herschel (looking for water and like molecules) are now. And that's were the James Webb telescope will be headed.

The reason Hubble is not in L2 is simple: the Space Shuttle. It was designed to be periodically serviced by it (it's the only space-based telescope so designed) and getting out to L2 is simply beyond the Shuttle's reach. Since Hubble was originally launched with optics that caused it to be near-sighted, it's also a good thing we could get to it. The Shuttle that carried out the initial corrective mission was Endeavour.

Here is a link to a great NASA article about LaGrange points. L1, L2 and L3 are unstable and I believe require periodic corrections to remain in the sweet spot. Aha, NASA says, "The L1 and L2 points are unstable on a time scale of approximately 23 days, which requires satellites parked at these positions to undergo regular course and attitude corrections."