Last night, the first of the twin GRAIL spacecraft successfully entered its 56-mile by 5,197-mile orbit around the Moon. The second one should have its engine burn for orbital insertion this afternoon.
The Dawn mission to the asteroid Vesta has already found something we didn’t expect – a 13-mile high mountain in the southern polar region. (Mount Everest is about 5.5 miles high.) Vesta itself is only 326 miles in diameter, so that’s a pretty big bump on the surface.
I’m no geologist (help, Viki?), but apparently they know that some of the meteorites collected on Earth came from Vesta, because Vesta has a unique pyroxene signature.
[Principal investigator Chris] Russell believes the mountain was created by a ‘big bad impact’ with a smaller body; material displaced in the smashup rebounded and expanded upward to form a towering peak. The same tremendous collision that created the mountain might have hurled splinters of Vesta toward Earth.
“Some of the meteorites in our museums and labs,” he says, “could be fragments of Vesta formed in the impact — pieces of the same stuff the mountain itself is made of.”
To confirm the theory, Dawn’s science team will try to prove that Vesta’s meteorites came from the mountain’s vicinity. It’s a “match game” involving both age and chemistry.
Last but not least, I found a nice series on NASASpaceFlight.com about recent discoveries on the International Space Station. The good news is that taking bisphosphonates (drugs to treat osteoporosis) once a week plus exercising two hours a day can slow the bone density loss typical of a long stay in space. The bad news is that astronauts are reporting vision loss after 6 months in space, possibly due to extra cranial pressure from fluid that’s not being pulled down by gravity. For most, their vision returned to normal back on Earth. They also found that some medicines stored on ISS for a long period of time lost their potency, even before what was supposed to be the expiration date. Whether it’s due to radiation, temperature, humidity, or some other factor is unknown, but better packaging may solve the problem.