MIRV: India’s technological solution for Minimum Nuclear Deterrence

 

Author: Parveen Bhardwaj (Author is an Aerospace Engineer and currently working with Institute of Defense Studies and Analyses)

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With second successful test of Agni-V in a row on September 14, 2013, Scientific Advisor to Defence Minister and Director General of Defence Research and Development Organisation (DRDO), Avinash Chander, asserted that, “The country has established ICMB capability with the successful second test”[1]. After a series of technical difficulties and considerable delays in Integrated Guided Missile Development Program (IGMDP), successfully test of Agni-5 is a milestone in India’s missile development program. With Agni-5’s successful test last year India joined the elite club of ICBM capable countries.

Programme Director V. K. Saraswat discussing about technical aspects and capability of missile many times quoted about having Multiple Independently targetable Re-entry Vehicle (MIRVs) capability but lacks ability in current scenario, which indeed shall be DRDO’s next vision for Agni-5 as well as its generation of missile Agni-6. Agni-VI which will have a strike range of 8,000 km to 10,000 km[2] and will be MIRV capable and is the next vision of DRDO. This article comprehensively discusses about vital importance of having this technology and the challenges and opportunities India possess to transform MIRV technology from capability to ability.

Minimum Nuclear Deterrence?

After successful nuclear test at Pokhran on May 11, 1998, India was considered as an emerging nuclear threat by many western and neighboring countries especially Pakistan and China. Defending country’s stand on issue the then Prime Minister Atal Bihari Vajpayee declared India’s nuclear doctrine of “minimum nuclear deterrence” in United Nation. According to this doctrine, India will posse minimum nuclear warheads which it deems necessary to defend its boundaries against any nuclear  attack by any country.

Multiple Re-entry vehicle

(pic courtesy: Wikipedia)

Prominence of MIRV:

The most vital component of missile technology in recent years is the deployment of Multiple Independently targetable Re-entry Vehicle (MIRVs). The fundamental characteristic of deploying MIRVs is its ability to deliver several warheads along separate trajectories, which confers it flexibility of multiple targeting. The independent targeting capability enhances missile’s ability by exhausting the missile defence, providing deep penetration and potential of destruction of larger area, effectively and precisely. The vital advantage of MIRVs in terms of nuclear capability is very high yield, which, facilitate hitting hard targets and wide area. With same amount of nuclear warhead MIRV can increase yield upto 8 times the normal yield. With minimum nuclear warhead capability we can have exponential area damage.

Why India needs MIRVs?

It was estimated that Agni-5 is capable of launching 4-5 multiple warhead, whose yield is unknown[3]. Although head of India’s DRDO, V.K. Saraswat, noted that several Agni variants could eventually be developed with multiple independently targetable re-entry vehicles (MIRVs), or multiple nuclear warheads — while later conceding that it was not yet government’s policy to do so[4]. The three vital reasons why India should possess MIRV technology are, firstly the potential threat from hostile neighboring countries, secondly strengthen its futuristic nuclear triad and thirdly its minimum nuclear deterrence policy. Pakistan’s aggressive attitude and China’s fairly strong degree of skepticism toward India and its well tested MIRV technology necessitate India’s step toward this technology. Moreover with single missiles carrying more warheads, denigrate problem of minimum nuclear deterrence policy and constructing more missile, silos and launchers. Lastly MIRV technology can also strengthen India’s aspiration toward completing its nuclear triad.

Do we embrace the technology?

Technologically MIRVs could be designed to have separate guidance system and propulsion packages on each re-entry vehicle. The maneuvering final stage of missile, also called Post Boost Control System (PBCS) or ‘bus’, carries both missile re-entry bodies (RV) and guidance and control system[5]. This bus has ability to change orientation and trajectory. It is also estimated that most of the countries such as US (Titan III Trans stage and Minuteman), China (DF-31A) etc, followed the footprint of their space program by conceptualizing the technology of delivering multiple satellite payloads into orbit[6]. Although ISRO successfully launched PSLV C-7 multiple satellite on January 10, 2007 and used Dual launch Adapter (DLA) to dispense four satellites, this technology adaptation in India’s future MIRV program is unpredictable[7]. Final stage of PSLV C-7 has Trans-stage Post Boost Control System (PBCS) equivalent to US multiple launch technology. After the boost phase and orientation of bus suitably towards target, the minute rocket engines in each RV ignite[8]. These vernier rockets are used for precise positioning, changing orientation and moving bus away from free falling RVs. This critical technology was used in upper stage of ISRO Geosynchronous Launch Vehicle (GSLV) which placed 2 ton satellite into orbit by maneuvering using liquid propellant vernier rockets[9].

 What is holding us back?

Deployment of such technology is complicated and expensive. The bus guidance system, mechanism of holding RVs, and releasing them with nuclear warhead accounts for half of the cost of each MIRV missile produce[10].  The warhead technology has evolved over the period and can sustain a very high yield-to-weight ratio[11]. The real challenge for India lies in miniaturizing the warhead and increasing the yield for integration onto MIRV platform. If India aspires to achieve high yield thermo nuclear warhead, then challenges are substantially greater. The thermonuclear test in 1998 might not have yielded desired result[12]; however the credibility of fabricating such high yield warhead is questionable.

In addition each re-entry has to sustain substantially high aerodynamic stress and heating, hence it is made of advance materials. Although ISRO and DRDO have robustly worked on aero-thermal structure and thermal protection system design over the past decade in its space and missile programs, but its effective use on MIRV platform is yet to be determined. Guidance and control computers must have enough memory and computational speed for guidance equation. Re-entry vehicle must have inertial component (Gyroscope and accelerometers) for precise and reliable targeting. This also becomes significant due to sudden change in mass distribution after disengaging from bus, which creates sudden oscillations and vibrations[13]. India has indigenously developed Redundant Strap down Inertial Guidance System (RESINS) which employ Dynamically Tuned Gyros (DTG) and Servo Accelerometer (SA)[14] for its space program. The entire attachment should be small and light enough to constitute in missile due to its weight and size constrain, created challenges for engineers.

 Way Ahead:

The history over a decade has shown close interrelation and extents of interchangeability of technology between Indian space program and its missile program. These two programs have a profound base for India’s aspirations of futuristic technology. India’s continues strive for indigenization in its missile technology has kept a profound foundation which believed is significant to materialise its MIRV dream. The bigger challenges in current scenario are the quality of nuclear arsenal, miniaturizing warhead, atmospheric reentry and expertise in military application of guidance and control in re-entry vehicle to integrate MIRV. Although for the latter part DRDO has worked substantially and its all missile tests so far are precise and accurate, but combining this accuracy with MIRV integration is a great challenge in itself.


 

[2] “Agni-VI to be ready by mid 2014”, Accessed on 24th October 2012
[3] “Inside story of Agni-5” NDTV 24X7, 18 Apr 2012.
[4] India must be clear about MIRV plans, South east Asia monitor, (www.southasiamonitor.org), accessed 24 October 2012

[5] Book on “Making the MIRV: study of defence making system” by greenwood/ Ballinger.

[7] After runaway success, a major technological task begins for ISRO” by T.S. Subramanian in Hindu , accessed on 24 October 2012
[8] “Orgin of MIRVs SIPRI research report, no.9/ August 1973.
[9] “Space Transportation” Indian space and research organization, ISRO (www.isro.org/pdf/STSBrochureFinal.pdf), accessed on 24 October 2012
[10] The Military Balance 1972-73 (IISS, 1971), pg.65
[11]  Note: EMT (Equivalent megaton)= Y2/3 where Y is in megatons. 1 bomb with a yield of 1 megaton would destroy 80 square miles. While 8 bombs, each with a yield of 125 kilotons, would destroy 160 square miles i.e higher the yield destruction level increase exponentially.
[12] Perkovich (note 8), from Kartik Bommakanti paper on MIRV and Satellite integration, Indo-US space corporation, IDSA.

[13] Ibid.

[14] Ibid. (to 13)

 

Post By Mr. Parveen Bhardwaj (6 Posts)

Author is an Aerospace Engineer and currently working with Institute of Defense Studies and Analyses.

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