Any number of reasons. Test ranges are usually in remote areas to avoid any immediate danger, but if the guidance or control systems malfunction, it can go somewhere unfortunate rather quickly.
I can't seem to find any good numbers, but it seems like the F9 rocket should have somewhere around 200 tons of fuel & oxidiser (kerosene & liquid oxygen). That, in addition to the few other hundred tons of rocket landing anywhere public is probably not going to end well.
IIRC, most rockets over a certain size are required to have some form of 'range safety package'[1] which may include a self-destruct capability for exactly these reasons.
In the course of the Challenger shuttle accident, the Solid Rocket Boosters were remotely destroyed by the range safety officer[2]
Comments
Any number of reasons. Test ranges are usually in remote areas to avoid any immediate danger, but if the guidance or control systems malfunction, it can go somewhere unfortunate rather quickly.
I can't seem to find any good numbers, but it seems like the F9 rocket should have somewhere around 200 tons of fuel & oxidiser (kerosene & liquid oxygen). That, in addition to the few other hundred tons of rocket landing anywhere public is probably not going to end well.
IIRC, most rockets over a certain size are required to have some form of 'range safety package'[1] which may include a self-destruct capability for exactly these reasons.
In the course of the Challenger shuttle accident, the Solid Rocket Boosters were remotely destroyed by the range safety officer[2]
[1] https://en.wikipedia.org/wiki/Range_safety
[2] http://history.nasa.gov/rogersrep/v1ch9.htm
https://en.wikipedia.org/wiki/Intelsat_708 comes to mind as an example of when you'd want a failed launch to self-destruct. It went off course and landed in a village.