Most of the laboratory is expected to burn up in earth's atmosphere, but experts believe that pieces as heavy as 100 kilograms (220 pounds) may survive re-entry and impact earth's surface. Nobody will be able to predict with any precision where those chunks of space laboratory will land on Earth until a few hours before re-entry occurs. The chance that anyone would be harmed by Tiangong-1's debris is considered unlikely.
When NASA's SkyLab fell to earth in 1979, an Australian town fined them $400 -- for littering.
Our space agencies won't be able to push out farther into space, to a destination like Mars, until we can learn more about how to strengthen the weakest links in the chain that make space flight possible: the human body and mind... [V]ery little is known about what occurs after month six. The symptoms may get precipitously worse in the ninth month, for instance, or they may level off. We don't know, and there is only one way to find out... On my previous flight to the space station, a mission of 159 days, I lost bone mass, my muscles atrophied, and my blood redistributed itself in my body, which strained and shrank the walls of my heart. More troubling, I experienced problems with my vision, as many other astronauts had. I had been exposed to more than 30 times the radiation of a person on Earth, equivalent to about 10 chest X-rays every day. This exposure would increase my risk of a fatal cancer for the rest of my life.
Kelly says the Space Station crew performed more than 400 experiments, though about 25% of his time went to tracking his own health. "If we could learn how to counteract the devastating impact of bone loss in microgravity, the solutions could well be applied to osteoporosis and other bone diseases. If we could learn how to keep our hearts healthy in space, that knowledge could be useful on Earth." Kelly says he felt better a few months after returning to earth, adding "It's gratifying to see how curious people are about my mission, how much children instinctively feel the excitement and wonder of space flight, and how many people think, as I do, that Mars is the next step... I know now that if we decide to do it, we can."
A member of NASA's Advisory Council on Planetary Defense told the BBC he'd concluded "the super volcano threat is substantially greater than the asteroid or comet threat."
In my town it was cloudy all morning -- though I got a postcard from friends experiencing "the path of totality" in Idaho City. But how about you? How did you experience this week's solar eclipse?
Cassini's radar will be able to look into the atmosphere and see features as small as 16 miles (25 km) wide, about 100 times smaller than what it could see from its usual orbital positions. The Grand Finale will include one final swing by Saturn's largest moon, Titan, on Sept. 11. Titan's gravity will slow Cassini's orbit around Saturn and bend its path to send the spacecraft toward its September 15 encounter with the planet... Cassini will keep sending back data on September 15 until it gets to an altitude where atmospheric density is about twice what it encountered during its final five passes, NASA officials said. At that point, mission controllers will lose contact with the probe because its thrusters won't be able to keep Cassini's antenna pointed toward Earth; there will simply be too much air to push against.
The second dip happens this weekend, and NASA has created a special web page tracking Cassini's current location for its final 28 days.
The $408 million TDRS-M was built and launched with the sole purpose to extend the useful life of NASA's constant communications infrastructure, supporting the astronauts around-the-clock aboard the International Space Station, supplying contact with the Hubble Space Telescope and transmitting the data from almost 40 science spacecraft studying Earth's environment and space.