bruce19@ihuxi.UUCP (Bruce Whiteside) (06/25/84)
The Sunday Chicago Tribune (June 25th) carried a short article about the launch of Discovery. The article went on to say: "One of Discovery's computer memory banks was replaced Thursday when it failed a test; an explosive cable used by the orbiter's self-destruct system also was replaced." Question - What is the "self-destruct system?" Is this just part of the explosive bolt system for shedding the boosters and tank? Is it maybe intended to destroy military payloads if the shuttle is forced to land in unfriendly territory? Or is the entire shuttle considered "military" and really designed to blow-up on command? Reply by mail to nwuxc!bruce or to ihuxi!bruce19. Bruce Whiteside AT&T-NS 11NW561240 (312)510-6744
ajaym@ihu1h.UUCP (Jay Mitchell) (06/26/84)
If someone knows the anwer to this, posting it to the net would be appropriate. I am certainly curious. -- ------------------------- Jay Mitchell ihnp4!ihu1h!ajaym -------------------------
djmolny@wnuxb.UUCP (Molny) (06/26/84)
In light of Tuesday's fizzled launch, who needs a self-destruct!? Today's Chicago Tribune (Tues., 6/26) has an article about the replacement of Discovery's backup computer, described as costing $1.2 million, and weighing 57 tons. No wonder it won't fly. Regards, DJ Molny, ccom consultants, inc at AT&T Technologies ihnp4!mgnetp!hw3b!wnuxb!djmolny
alb@alice.UUCP (Adam L. Buchsbaum) (06/26/84)
The self destruct system is of similar idea to that used on all American rockets, manned and unmanned. Explosvie charges are positioned in the shuttle and on the ET and SRB's. At the command of the range safety officer, these charges are set off, destroying the orbiter and its tank and boosters. It would be used if, for example, the shuttle veered off course and headed for a populated area.
eder@ssc-vax.UUCP (Dani Eder) (06/26/84)
[26 June 1984]
It is officially called the 'range safety system'. Following are
quotes from the "Space Shuttle News Reference". That is what NASA gives
reporters to use in writing feature articles., and the Rockwell International
STS Press Information book, which is much more technical.
"Each Solid Rocket Booster has a systems tunnel that provides protection
and mechanical support for the cables associated with the electrical and
instrumentation subsystem and the linear-shaped explosive charge of the
range safety system. The tunnel extends along almost the entire length of
the booster." [page 2-25]
"RANGE SAFETY SYSTEM
The Shuttle vehicle has three range safety systems (RSS's). One is
located in each SRB and one in the external tank. Any one, or all three
is capable of receiving two command messages (arm and fire) transmitted
from the ground station. The RSS is used only when the Shuttle vehicle
violates a launch trajectory red line [comment: that means it is heading
for Cocoa Beach or Disney World instead of where it should be going].
An RSS consists of two antenna couplers, command receivers and command
decoders, a dual distributor, a safe and arm device with two NSI's [NSI=
NASA Standard Initiator=a standard electrically fired pyrotechnic charge
used for all kind of things on the Shuttle, like igniting motors and
cutting restraining bolts], two confined detonator fuse (CDF) manifolds,
and two linear shaped charges(LSC's).
The antenna couplers provide the proper impedance for radio frequency
(RF) and ground support equipment commands. The command decoders use a
coded plug to prevent any RF signal other than the proper RF signal from
getting into the distributors. The distributors contain the logic to
supply valid destruct commands to the RSS pyrotechnics.
The NSI's provide the spark to ignite the CDF, which, in turn, ignites
the LSC for Shuttle vehicle destruction. The safe and arm device provides
mechanical isolation between the NSI's and the CDF before launch and
during SRB separation.
The first message, arm, allows the onboard logic to enable a destruct
an illuminates a light on the flight deck diplay and control panel
at the Commander and Pilot stations [astronauts proceed to wet pants].
The second message transmitted is the fire command." [page 78]
Dani Eder /Boeing Aerospace Company /ssc-vax!eder /karn@mouton.UUCP (06/27/84)
A minor correction to Adam's comments about the range safety destruct system. The explosive charges are only on the external tank and on the solid rocket boosters; none are on the orbiter itself. They are actually long linear shaped charges which are designed to split the casing of the booster or tank lengthwise, dumping the propellants and disintegrating the casing. You can see these on the SRBs and ET as longitudinal 'ribs' running for most of their length. (There are other ribs as well which contain more mundane things like electrical cables and fuel lines, so not all of them contain destruct explosives.) The range safety system works by external radio command. I certainly hope that the coding is reasonably secure, but I do remember when I was on hand for the STS-9 launch that during the terminal stages of the countdown (perhaps 10-15 minutes before launch) there was an announcement that a "Range safety system test, using the actual flight codes, had been successfully conducted". This could in theory allow a terrorist to monitor the codes and retransmit them during flight. Considering all the other precautions taken, I hope that it wouldn't be quite this easy. Phil
judd@umcp-cs.UUCP (06/28/84)
OK what happens to the shuttle itself after the fire command ??
--
Spoken: Judd Rogers
Arpa: judd.umcp-cs@CSNet-relay
Uucp:...{allegra,seismo}!umcp-cs!juddpsuvm%sgl@psuvax1.UUCP (06/30/84)
Why would they use a linear-shaped charge for a destruct charge? A shape charge is designed for cutting (through armor for example) not for "blowing up" Steve Liptak sgl@psuvm liptak@psuvax1
alb@alice.UUCP (Adam L. Buchsbaum) (07/02/84)
Presumably, it will have had time to jettison away from the ET and SRB's.
giles@ucf-cs.UUCP (Bruce Giles) (07/02/84)
>> Today's Chicago Tribune (Tues., 6/26) has an article about the >> replacement of Discovery's backup computer, described as costing >> $1.2 million, and weighing 57 tons. No wonder it won't fly. Remind me to NEVER read the *Chicago Tribune*. The local news had pictures of NASA techs removing the computer and putting another one instead. One technician was able to carry the thing. So unless NASA has found a way of stuffing a box approximately 100 x 75 x 50 (cm) with 57 tons of stuff, and stuffing techs with 80 tons of wheaties, I rather distrust the paper. P.S. Perhaps they were thinking of ENIAC? I work with IBM 3082s, and I doubt they weigh more than five of tons each, including drum, hundred disks, etc.... What would a Discovery need with the equivalent of 50 IBM 3082s for? (10 mainframes/backup * 5 on-board computers). ave discordia going bump in the night ... bruce giles {decvax, duke}!ucf-cs!giles university of central florida giles.ucf-cs@Rand-Relay orlando, florida 32816
scw@cepu.UUCP (07/10/84)
In article <910@psuvm.UUCP> psuvm%sgl@psuvax1.UUCP writes: > > Why would they use a linear-shaped charge for a destruct charge? A shape >charge is designed for cutting (through armor for example) not for "blowing up" Actually a shaped charge is just a way of focusing the force of the explosive. The commonest use is in anti-tank weapons, where the shaped charge is used to generate a jet of hot gas that literally punches a small hole through the armor. Another military use is for punching a hole in very hard ground to put a larger 'cratering' charge in (for blocking roads). A linear shaped charge instead of producing a cylindrical jet produces a plainar jet, this will cut the entire surface (a knife as opposed to a rapier if you will) open. Because the skin of most space systems is also a structural member this will cause the object to collapse without having to use massive ammounts of explosive to blow it apart. -- Stephen C. Woods (VA Wadsworth Med Ctr./UCLA Dept. of Neurology) uucp: { {ihnp4, uiucdcs}!bradley, hao, trwrb, sdcsvax!bmcg}!cepu!scw ARPA: cepu!scw@ucla-cs CORRECTED location: N 34 3' 9.1" W 118 27' 4.3"
ron@brl-tgr.ARPA (Ron Natalie <ron>) (07/10/84)
Probably because they are cutting, so that it will "blow up" in an orderly fashion. -Ron
alb@alice.UUCP (Adam L. Buchsbaum) (07/10/84)
If you had read all the replies, you would know that the charges are indeed used for cutting, not blowing. They are intended to split the casings of the SRB's and ET so that the propellant will be dumped. Thanks to Phil Karn for this info.