i'm joined tonight by keith cowing. he is a blogger, and the founder of the web site nasa watch as well as a former rocket scientist. keep us good to see you again. what are the chinese hoping to achieve with these moon rocks and this mission? well, there's 2 things. one is now the scientific goal, which is to live in an area where we have not landed before. in this case, it's able kinnock deposit and by leaning there in getting some rocks and bringing back to earth, we'll be able to better understand the history of the moon. how long it had volcanoes, what it's interiors like. and you know, to be able to understand that with the rocks right in our hands of a speak. but the other thing is, this is a very complex mission, and it's probably the most complex thing china has done in space. and it's the sort of thing that if you're getting ready to think about putting humans in spacecraft, this is sort of thing you want to practice being able to do departing from earth. undocking landing, launching from the litter surface do

. >> said i just called keith reed's phone, and bus stop answered it. >> reporter: a holy cow moment.yes. >> reporter: it was a construction foreman on a bridge near harrisburg. the phone had been found on scaffolding which suggested to detectives someone in a car had tried to toss the phone in a river. >> it landed on a bridge deck set up to do repairs to the bridge. it was a very lucky break for us. >> reporter: what are the odds? >> one in a billion. >> reporter: while the recovered phone was on its way to the fbi lab, crime scene analysts spent the next day at reed's house scouring the property for clues. district attorney david foley knew the climber community on, edge about a school-related shooting, was anxious for the case to be solved. but an arrest was a long ways off. you can't calm people don'wn, c you? >> no. >> reporter: then something out of the blue happened that turned the investigation upside down. the sheriff was in a closed door meeting when his secretary interrupted. >> i thought it was a family emergency. her face looked like she'd seen a ghost. she said, sheriff