We’ve had quite a discussion in the comments over Russia’s recent failed Bulava SLBM test and the pretty spiral it made before crashing into the ocean.
Having largely dispensed with the usual spate of extraterrestrial and paranormal hypotheses — is everyone on the internet crazy? asked one commentator — you, dear readers, have gotten down to brass tacks.
As far as I can tell, there are basically three non-insane explanations floating around, none of which are (strictly speaking) mutually exclusive:
1. Something went terribly, terribly wrong.
2. It was an energy management maneuver.
3. It is a countermeasure designed to defeat future boost phase missile defenses.
For the something went terribly, terribly wrong we have the official statement of the Russian Defense Ministry that the third stage became “unstable” and that the test failed. As we know from similar US mishaps, an unstable missile can make a couple of loopdy-loops before going kaput.
On the other hand, this is correlation not causation.
Which brings us to the second reason that solid-fueled missiles make pretty spirals — so-called “generalized energy management” manuevers or GEMS. You can’t just shut-off a solid-fueled missile in mid-burn (at least not easily), so you need to let it do a little dance to burn off some energy.
Here is a nice video of a US THAAD interceptor getting funky before getting down to business.
The Bulava was most likely aimed at the test ground in Kamchatka, so it would have needed to perform an energy management maneuver to reduce the missiles range from 8,000 km to about 3,000-4,000 km. The fact that a bunch of drunken Norwegians think that a StarGate has opened up is just a bonus, as far as the Russians are concerned.
Which, brings us to the countermeasure hypothesis. A missile in boost could use an energy management maneuver to attempt to evade a boost phase missile defenses.
It isn’t clear to me that the nice tight spiral is the optimum countermeasure, since the goal is to move unpredictably in ways that stress the kill vehicles maneuverability. One hears talks of dog-legs, lunges and jinking — not tight spirals.
Indeed, since GEMS are likely to be part of most ICBM and SLBM flight profiles, I presume our any future boost phase system would be designed against the typical array of spirals and so-forth.
Moreover, the problem with executing an energy management maneuver is that it reduces the distance that the missile flies — which is, of course, the point. With an 8,000 kilometer range, the Bulava wouldn’t want to manage too much energy on its way to North America unless Vladmir Putin has something against Pugwash, Nova Scotia.
I haven’t done any calculations, but fortunately Mosher et al discuss GEMs and other boost-phase countermeasures at some length in the Final Report of the American Physical Society Study
Group on Boost-Phase Intercept Systems for National Missile Defense. If you are interested, I recommend pp S230-236, S264-266, S271-274.