gina? reporter: good morning, rob, linsey. nasa says they really don t think north america, north america is going to be threatened by this at all. its orbit just won t be anywhere near north america when it really starts to descend. but as the satellite enters the atmosphere everything changes. bit by bit pieces will cross the threshold, 50 miles up, enter the atmosphere and drop like stones traveling at several hundred miles an hour depending on their shape. the chunks will fall at different points along the satellite path. meaning debris when it does hit will come about 500 miles. this may be in the ocean. anyone in that area might see a streak of fire for less than two minutes. eyewitnesses will be critical, radar will no longer be able to see the satellite. once it is in free fall. they re thinking about de-orbit late this afternoon. no one knows for sure. gina. we have been threatened by space junk in the past? reporter: we have, and you should know, 150 tons of space