<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Had the shuttle not been visible (i.e. due to cloud cover) the range safety officer would have had a much more difficult job. I would expect a man-rated launch vehicle to be reliable enough not to require a self-destruct system. We obviously don't have them on aircraft although they occasionally crash into the ground and kill people. The inability of a solid fuel rocket to shut down (Challenger) and the potential for sudden and catastrophic failure (1997 Delta II explosion) are two factors that lead me to question its appropriateness in human spaceflight. <br /> Posted by vulture4</DIV></p><p>Well, they are pretty reliable -- more so than aircraft, which as you point out, lack range-safety features. So far, there have only been a handful of launches gone horribly wrong on a manned launch.</p><p>Soyuz 18A (officially, no designation, but it would have been Soyuz 18) -- the second and third stage failed to separate properly, seriously altering the rocket's trajectory. The escape system recognized the situation was not correct and separated the spacecraft in time. Because the rocket was pointing slightly downwards at the time, the net acceleration was a punishing 21 Gs. The crew survived, though one cosmonaut was so seriously injured that he was never able to return to spaceflight.</p><p>Soyuz T-10A (again, would've been Soyuz T-10; the designations only went out to flights which made orbit) -- launch vehicle did not actually leave the pad, but exploded moments after the launch escape system fired and pulled the capsule to safety. The explosion severely damaged the pad.</p><p>STS-51L: Challenger. We all know that one, far too well.</p><p>So, with only three catastrophic launch vehicle accidents, and the rest being basically nominal as far as the booster goes, the reliability seems to be very good for manned launch vehicles worldwide. In the case of Soyuz T-10A, range safety would not have been af actor; the vehicle had not even left the ground, and in any case, destroyed itself quite efficiently as it is. In the case of Challenger, range safety systems were used to destroy the wayward SRBs. Soyuz 18A is a bit more of a mystery, as far as I can tell; what became of that still-thrusting third stage when the Soyuz separated? Did the Russians destroy it before it could crash into some inhabited area, and/or give technological secrets to the Chinese? Or did they let it go? If so, where did it end up? Does anybody know?</p> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>