Rocket Self-Destruct?

[Aser]

Sometimes the range safety officer has to initiate a self-destruct of a malfunctioning rocket. I'm wondering what the mechanism for the destruction is. It doesn't seem like they would place a bomb inside of the rocket, so how does it work?

[HebaruSan]

Wikipedia says they either remotely shut off the engines or, yes, put a bomb on the rocket.

[Aser]

Thank you! That page didn't show up in my initial searching (using the wrong keywords I guess).

That's an interesting read.

[wumpus]

I suspect they don't use bombs on crewed missions, but they can be terminated as well (hopefully with a crew-saving abort mode, but that was pretty iffy for the shuttle).  The areas around KSC isn't exactly unpopulated (although I think it was when chosen), and Vandenburg (the shuttle was supposed to launch from there as well, but I don't think that ever happened) launches fairly near LA and San Diego.  I really wonder how they get someone to agree to handle range safety officer on a crewed flight (you probably don't want someone clueless about how bad those abort sequences are).

[KG3]

The  space shuttle did have self destruct explosives on the SRBs and the external fuel tanks.  I remember that they ruled out the possibility of the explosives accidentally exploding as the cause of the accident.   

https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disaster#Recovery_of_debris_and_crew

It had been suggested early in the investigation that the accident was caused by inadvertent detonation of the Range Safety destruct charges on the external tank, but the charges were recovered mostly intact and a quick overview of telemetry data immediately ruled out that theory.

They also blow the rocket up when it goes off course but I'm not sure how badly off course it has to go before they blow it up.    

[radonek]

AFAIK this is usualy done by small pyrotechnic charge designed to cut open both fuel and oxidiser tanks, which then provide actual destruction. Fueled rocket is quite capable of destroying itself. There is even a video of autodestructed rocket that clearly shows how it is cut open along the length.

[DerekL1963]

6 hours ago, wumpus said:

I suspect they don't use bombs on crewed missions, but they can be terminated as well (hopefully with a crew-saving abort mode, but that was pretty iffy for the shuttle).

You suspect wrongly.  Mercury, Gemini, and Apollo all had destruct systems installed on the booster.  At one point the USAF (responsible for range safety) even wanted destruct systems on the Apollo Service Module since it was a powered stage...  (They proposed using liquid explosives, the system would have been "safed" by simply opening valves and allowing the explosives to simply drain away into space.)   I don't think the destruct and launched systems were tied together though.

Shuttle had destruct systems on the ET and SRB's, but (IIRC) the ET systems were eventually deleted.

[p1t1o]

1 hour ago, radonek said:

AFAIK this is usualy done by small pyrotechnic charge designed to cut open both fuel and oxidiser tanks, which then provide actual destruction. Fueled rocket is quite capable of destroying itself. There is even a video of autodestructed rocket that clearly shows how it is cut open along the length.

I believe that the charges are positioned in such a way as to minimise propellant/oxidiser mixing (eg: by blowing one tank a split second before the next) once the tanks are ruptured the airflow takes care of the rest.

[kerbiloid]

They call it Range Safety.

Spoiler

https://www.popularmechanics.com/space/a3232/4262479/

https://space.stackexchange.com/questions/2648/space-shuttle-range-safety-system-why-is-there-a-caution-light

https://en.wikipedia.org/wiki/Range_safety

[MaxwellsDemon]

Yup.  As above-- if a rocket, even a manned rocket, has even the smallest potential of coming down in a populated place, they blow it as high up as possible to consume/disperse all the fuel before it hits the ground.  Bad enough to have pieces of rocket coming down-- you don't want thousands of gallons of inflammable fluid coming down, complete with an ignition source.  Astronauts know this is part of what they sign up for, and I'd imagine that most, if not all, of them would willingly give their lives to prevent the loss of many other lives.   (Ideally, of course, there's an escape system to get them out of there too, but that's not always possible, as with the Shuttle.)

Most of those early movie shots you see of U.S. rockets blowing up are actually being blown by Range Safety as they veer off course.  There were entirely accidental explosions too, as with the first Vanguard launch attempt, but they were in a minority. 

There was a sharp debate on self-destruct systems for manned capsules too, in the early Soviet space program.  The security-minded wanted to keep "secrets" from falling into Western hands, so early (pre-manned) Vostoks were loaded with explosive charges to blow up the capsule if it was headed for a landing on anything other than Soviet territory.  At least two 'space dogs' lost their lives in this way.  When it got to Gagarin's flight and beyond, though, the explosive charges were deleted from the manned capsules (though I'm sure they were retained on the unmanned spy-satellite Zenit variants).

Edited March 2, 2018 by MaxwellsDemon
correction

[tater]

Currently, only SpaceX and ATK are using the Automated Flight Safety System (AFSS) that the AF has wanted for a while. This automates the destruction of vehicles moving outside of whatever launch corridor they program it with, with a person out of the loop. When everyone gets it installed, it will allowed increased launch cadence.

[p1t1o]

5 hours ago, p1t1o said:

I believe that the charges are positioned in such a way as to minimise propellant/oxidiser mixing (eg: by blowing one tank a split second before the next) once the tanks are ruptured the airflow takes care of the rest.

Did a little googling to back this up, and apparently both cases (for combustion or dispersion) are relevant depending on the fuels used (emphasis mine).

 

From: Eastern and Western Range (EWR) 127-1 Range Safety Requirements - published jointly by the 45th Space Wing (Cape Canaveral Air Station, FL) and the 30th Space Wing (Vandenberg Air Force Base, CA)

4.6 FLIGHT TERMINATION ACTION
REQUIREMENTS
4.6.1 Liquid Propellant Vehicles

a. For vehicles consisting of all liquid propellant
stages, both engine shutdown and destruct
capability are required for each stage of the vehicle.
b. The Range transmitted ARM command shall
be used as a preterminate logic function in the FTS
receiver and shall cause nondestructive engine
shutdown of all thrusting stages and inhibit ignition
of all other liquid stages.
c. The subsequent Range transmitted DESTRUCT
command or activation of the Automatic
Destruct System (ADS) shall cause the following
actions to occur:
1. For liquid propellant stages using toxic
propellants, the destruct charges shall cause
penetration of the propellant tanks and initiate
rapid burning of the propellants so that as much
propellant as possible is consumed or dispersed.
2. For liquid propellant stages using non-toxic
propellants, the destruct charges shall cause
penetration of the fuel and oxidizer propellant tanks
to the extent necessary for rapid dispersion of the
propellants.
d. The destruct charge shall not detonate the liquid
propellants.

 

Full documentation provided here:

https://snebulos.mit.edu/projects/reference/NASA-Generic/EWR/EWR-127-1.html

 

Heres another interesting document that refers to the one above:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770018296.pdf

 

***

PS: Oooooh OOooooh I just reached 2000 rep!

 

 

Edited March 2, 2018 by p1t1o

[kerbiloid]

2 minutes ago, tater said:

Currently, only SpaceX and ATK are using the Automated Flight Safety System (AFSS) that the AF has wanted for a while. This automates the destruction of vehicles moving outside of whatever launch corridor they program it with, with a person out of the loop. When everyone gets it installed, it will allowed increased launch cadence.

Will BFS have it?

[sevenperforce]

Liquid rocket boosters use a pyrotechnic cord which fires along one side of the tank, essentially "unzipping" the tank walls along one side, immediately dumping the contents.

35 minutes ago, kerbiloid said:

Will BFS have it?

BFR will have an AFTS but crewed BFS will not...at least, not unless they add a separate crew capsule and LES. Uncrewed BFS will have AFTS.

[tater]

Even crew vehicles have self destruct for the boosters, I’d expect BFR to have that, but no need on BFS unless it’s used alone as an ssto. 

I’m pretty uncertain about ever seeing a crew BFS minus a LES, honestly. As a Mars colonizer, it need not have that, because Earth liftoff is the least of their problems. For operational use near home, crews would be smaller, and LES makes sense.

[kerbiloid]

Spoiler

15 minutes ago, tater said:

As a Mars colonizer, it need not have that, because Earth liftoff is the least of their problems.

They should engrave this with gold on the wall of their cabin.

 

[tater]

The welcome to Mars sign at the colony should say, “Not being killed in 2 fiery explosions was the easy part. Welcome to Mars.”

[sevenperforce]

I would definitely anticipate a Mars Transit flight article without LES that launches uncrewed, and an LEO operations flight article with LES for launching crew.

[kerbiloid]

12 minutes ago, sevenperforce said:

I would definitely anticipate a Mars Transit flight article without LES that launches uncrewed, and an LEO operations flight article with LES for launching crew.

Lifting 40 crew on another vehicle?

[tater]

I think of BFS like the C-5 use. They can fill a C-5 with seats, and it could have held as many as 1000 as an airliner. Typical crew is 7, min is 4.

I expect a manned BFS to have something closer to a C-5 crew, rather than an airliner full.

[sevenperforce]

5 minutes ago, kerbiloid said:

Lifting 40 crew on another vehicle?

You'd want four different BFS variants:

• SpaceX Earth Orbit Ferry (passengers are packed into a launch capsule with its own 0-0 abort, life support, chutes, and lifeboat capabilities; operates only in LEO; includes larger hab separate from escape capsule; can be used for P2P flights as a single stage)
• SpaceX Expedition Spaceship (no LES, includes longer-term ECLSS, includes solar storm shield chamber and crane assembly for egress)
• SpaceX Cargo Spaceship (clamshell cargo bay; can be used as a tanker in a pinch)
• SpaceX Tanker (cargo spaceship without additional propellant tanks in place of cargo bay)

For flights to space stations and the like, the BFR launches the Earth Orbit Ferry, which does its thing and then returns.

Flights BLEO are a bit more complicated. Steps:

1. BFR launches the Expedition Spaceship into LEO unmanned.
2. BFR launches repeated flights of the Tanker (or Cargo Spaceship, if need be) to refuel the Expedition Spaceship.
3. BFR launches the Earth Orbit Ferry with passengers in the launch capsule. It does a rendezvous with the Expedition Spaceship and docks, and the crew transfers to the Expedition Spaceship.
4. Earth Orbit Ferry returns to earth unmanned (or with only a few crew) while the Expedition Spaceship goes on to its BLEO mission.

This way the crew has abort options at every point where abort would be possible but you don't drag unnecessary abort and lifeboat systems out beyond LEO.

[kerbiloid]

20 minutes ago, sevenperforce said:

This way the crew has abort options at every point

I'm afraid any vessel with >6..8 passengers has no another abort option except trying to land the whole ship.

[sevenperforce]

7 minutes ago, kerbiloid said:

I'm afraid any vessel with >6..8 passengers has no another abort option except trying to land the whole ship.

The BFR/BFS can put 150 tonnes into LEO, reusable.

I'm sure you can build an escape capsule big enough to hold more than 8 passengers if your mass budget is 150 tonnes.

[kerbiloid]

20 minutes ago, sevenperforce said:

I'm sure you can build an escape capsule big enough to hold more than 8 passengers if your mass budget is 150 tonnes.

Problems are:
1. Have enough powerful LES (weights up to 1/3 of the escaping mass)
2. Landing several dozen tonnes. Chutes are unlikely applicable, while rocket engines and fuel have some mass and must be ignited close to the ground, so if something went wrong there would be twin set of them. Which again means mass.
3. Heatshield. Mass.
4. If overturns on ground, the upper ones should hold their eyes with hands _(joking) due to huge turn radius.

So, anyway the capsule has to pe a lifting body equipped with engines. I.e. what they usually call a plane itself.

Edited March 2, 2018 by kerbiloid

[tater]

The LES would have chutes, it's the LES system, not the landing system for nominal use. 1/3 the escaping mass? so the crew version has a 60 ton capsule, 40 tons for crew, 20 tons for LES stuff. The vehicle can still carry the mass of an empty Space Shuttle into orbit as cargo, lol.