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]
The more robustly constructed crew cabin also survived the breakup of the launch vehicle; while the SRBs were subsequently destroyed remotely by the Range Safety Officer, the detached cabin continued along a ballistic trajectory and was observed exiting the cloud of gases at T+75.237.
In the images, you can see the solid rocket booster (SRB) following a random path after the explosion.
Not only do these rockets have them, but manned craft like the Space Shuttle are destructible from the ground (one hopes the encryption keys are well-protected). You don't want an out-of-control bomb heading towards Orlando.
On the other hand, they had a system on their unmanned spacecraft that blew them up with TNT if there was a chance of them coming down outside the USSR. It was regularly triggered during their heyday in the 60's. There was a lot of gnashing of teeth from the engineers when that prevented them from collecting data on failed missions.
I read about it in Boris Chertok's memoirs (http://www.nasa.gov/home/hqnews/2012/feb/HQ_12-054_Chertok_R...), which are huge and sprawling, he was there from the beginning, from the mission to get V2 stuff from Germany after WW2, through the Soviet Union's fall.
I agree. I'm glad nobody got hurt, so I can enjoy it without guilt.
My favorite part is at the end when the sound from the explosion arrives. Everything is calm, then suddenly KABOOM! Really drives home how far away the thing is (because it takes so long for the sound to arrive) and how big it is (because it's still a massive KABOOM even at that distance).
probably isn't such a difficult system to add when you're adding that capability to a massive tank of pressurized fuel.
One can imagine all sorts of instances where it'd be preferable to litter the area with debris rather than missle-ing the rocket into a densely populated area.
Comments
It's interesting these rockets are equipped with self-destruct systems. What scenario would warrant a rocket purposely self-destruct?
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.
When they're out of control and could hit someone.
From: http://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disast...
In the images, you can see the solid rocket booster (SRB) following a random path after the explosion.
Avoidance of cases like this: https://en.wikipedia.org/wiki/Intelsat_708
A video link to the actual launch failure https://www.youtube.com/watch?v=yfMbGPf4r9g
Not only do these rockets have them, but manned craft like the Space Shuttle are destructible from the ground (one hopes the encryption keys are well-protected). You don't want an out-of-control bomb heading towards Orlando.
http://en.wikipedia.org/wiki/Range_safety#Range_safety_in_US...
Actually, your link states that the orbiter wasn't destructible.
It wasn't much of a bomb in comparison to the rest of the components.
Honestly, play KSP. Once you flip a rocket, its nearly unrecoverable and it just accelerates into the ground.
Not only that, but it accelerates at a higher rate because the thrust vector and gravitational pull are pointing in the same direction.
I wonder if the reusable rockets from SpaceX could recover from a flipped position during re-entry?
No, they can't. Once you're supersonic, the aerodynamic stress will tear a rocket into shreds if there's even a few degrees of angle of attack.
But if you're high enough, the forces are not very high, so there's probably a Q limit, (that is, proportional to density * speed^2).
Yeah, the landing attempts obviously flip before entry, while they're out of the atmosphere.
Because if they lose guidance but the motor keeps running the thing could hit a populated area.
Interestingly the Russian space program never used range safety systems, but then they had an empty part of Kazakhstan to launch in.
On the other hand, they had a system on their unmanned spacecraft that blew them up with TNT if there was a chance of them coming down outside the USSR. It was regularly triggered during their heyday in the 60's. There was a lot of gnashing of teeth from the engineers when that prevented them from collecting data on failed missions.
I read about it in Boris Chertok's memoirs (http://www.nasa.gov/home/hqnews/2012/feb/HQ_12-054_Chertok_R...), which are huge and sprawling, he was there from the beginning, from the mission to get V2 stuff from Germany after WW2, through the Soviet Union's fall.
Great video of an example:
https://www.youtube.com/watch?v=Zl12dXYcUTo
Then imagine if it was headed for somebody's house (or a city). You'd want to blow it up in the air before it reached the ground.
I absolutely love that video - it's pretty much Kerbal Space Program in real life!
I agree. I'm glad nobody got hurt, so I can enjoy it without guilt.
My favorite part is at the end when the sound from the explosion arrives. Everything is calm, then suddenly KABOOM! Really drives home how far away the thing is (because it takes so long for the sound to arrive) and how big it is (because it's still a massive KABOOM even at that distance).
the KABOOM is impressive, shock wave at that distance is more telling
A rocket going far off the designated trajectory. It would be a catastrophe for a space launch rocket to fall into a civilian area.
probably isn't such a difficult system to add when you're adding that capability to a massive tank of pressurized fuel.
One can imagine all sorts of instances where it'd be preferable to litter the area with debris rather than missle-ing the rocket into a densely populated area.
Alien on board comes to mind.