The maiden and successful flight-test of the indigenous anti-missile missile
(PAD project) in the exo-atmosphere at 47km altitude on 27 November 2006 took
the nation by surprise. Dr V.K. Saraswat, the director for Defence Research and
Development Organisation’s strategic systems division said that with the test
all mission objectives had been met. This included the integrated functioning of
air defence system elements, target launch, acquisition and tracking by ground
radar, mid-course guidance performance, stage separation, target acquisition by
seeker, and satisfactory terminal guidance. While the media went overboard in
declaring that India had built a world class Ballistic Missile Defence, Dr
Saraswat tempered the mood by announcing that soon the DRDO would conduct a
missile interception in the endo-atmospheric zone followed by at least half a
dozen tests over the next four years to validate the system as a credible
defence against incoming ballistic missiles. The endo-atmospheric interceptor
(AAD project) test at a range of 15km altitude was successfully done on 6
December 2007 and validated the Long Range Tracking Radar (LRTR), the
Multi-Functional Fire Control Radar (MFFCR), mission control centre, launch
control centre, mobile launcher, and mobile and multi-layer communication system
and data links. Speaking recently to FORCE about what these technologies would
accomplish and the roadmap for planned technical advances, Dr Saraswat is
optimistic that Phase I interceptors, to include PAD (exo-atmospheric
interceptor) and AAD (endo-atmospheric interceptor), will be operationally
deployed by 2011. (Dr Saraswat said that PAD and AAD are not acronyms but just
codenames that he gave to the projects). Before we delve into these
technologies, it would be interesting to appreciate the genesis of the
indigenous anti-ballistic missile (ABM) system or the Indian BMD.
Two events at the turn of the century got the DRDO thinking about building an
indigenous BMD. On assuming office, the US President George W. Bush announced
his BMD plans, and India became the first country, even before the US’ closest
allies like Japan and South Korea, to endorse it wholeheartedly. To demonstrate
Washington’s pleasure with New Delhi’s fast endorsement, the then US deputy
secretary of state, Richard Armitage travelled to New Delhi in April 2001 to
explain the Bush initiative, a gesture that US does with a few valued countries
to explain important decisions. The Bush BMD was in two parts: National Missile
Defence (NMD) and Theatre Missile Defence (TMD); and deeper nuclear cuts, even
unilateral if Russia did not agree. With the proliferation of short and medium
range ballistic missiles with China and Pakistan, the TMD caught New Delhi’s
interest. Moreover, it was argued that years of US’ pressure on India to slow
its indigenous ballistic missile programme had taken its toll where it was felt
that Pakistan had acquired a lead in ballistic missiles, clandestinely acquired
from China and North Korea. The answer for India lay in concentrating instead on
the BMD, where the US had even offered its improved Patriot (PAC-3) system to
New Delhi. While the PAC-3 is a state-of-the-art system, it had two drawbacks:
it was too expensive for the numbers of vulnerable areas (VA) and vulnerable
points (VP) to be guarded. Moreover, the system is endo-atmospheric, implying it
can intercept a hostile missile within the atmosphere in the terminal phase.
Given its sub-continental size, what India needs is a large number of
anti-missile missiles that could intercept both inside and outside the
atmosphere. It is known that ballistic missiles can be intercepted and shot down
at three points on its flight: in the early boost phase, in mid-course when most
of the missiles are outside the atmosphere, and in the terminal phase where they
hit the target. The ideal point, and also the most difficult, is to kill the
missile in the boost phase as it would require space-based sensors and directed
energy weapons like jet-based lasers to destroy the missiles. The achievable
objective for India was to attempt to kill the missile in exo and
endo-atmosphere during mid-course and terminal phases. Just when the DRDO was
mulling over how to do this, Israel sold two EL/M Green Pine ground-based
phased-array L-band 600km long-range tracking radars to India in late 2001.
This was the beginning of the Indian BMD that ideally should have the essential
five components: One, an early warning system that signals the launch of enemy
ballistic missiles; two, long-range, long-wavelength radar to spot the re-entry
vehicle; three, short-range, short-wavelength radar that can determine the
position of the attacking re-entry vehicle with precision and guides the
interceptor missile towards it; four, many long-range (exo-atmospheric) and
short-range (endo-atmospheric) interceptor missiles; and five, a launch control
centre or the battle management and command, control, communication and
intelligence centre (BM/C3I). The BMD is conceived on two established operating
principles. First, the trajectory of a re-entry vehicle after it is released by
the missile is entirely pre-determined and therefore, if one can observe an
early portion of it, the rest of the trajectory can be calculated. And second,
the exo and endo-atmosphere have their unique characteristics. For example, in
space, a bullet and a feather released at the same point with the same speed and
in the same direction would continue to travel together indefinitely. This
characteristic is employed in space where re-entry vehicle is mixed amongst very
light decoys called balloons, that have a thin, metallic coating on the outside
that reflects radar waves. These balloons appear as re-entry vehicles to the
ground-based radar used for detection purposes. The endo-atmospheric
interception, on the other hand, is extremely difficult as the re-entry vehicle
is too close to its target.
Against this backdrop, India, at present, for detection of hostile missiles, has
to live with the genius of its Long Range Tracking Radar (LRTR), the Green Pine
system (peak power: 427kw, angular coverage 60 degrees, elevation is zero to 80
degrees) which can spot up to 200 targets and is equipped to provide range,
velocity and angular discrimination of the targets. This is not all. The LRTR
can identify decoys like balloons in exo-atmosphere as it has the capability to
continuously monitor the radar cross section (it can detect radar cross section
up to 0.1 sqm) and specific energy of re-entry vehicle which would be different
from decoys which in any case are not stable. An added advantage is that in
short range ballistic missiles like the Chinese M-11 (re-named Hatf-III by
Pakistan), even after complete burn-out, the propulsion motor usually does not
separate from the re-entry vehicle, thereby, provides a large cross section to
the LRTR. Thus, the LRTR is ideal against short range ballistic missiles. Dr
Saraswat told FORCE: ‘We, at present, have only ground-based surveillance radar
for detection. Over time, we plan to have an air and satellite surveillance, to
include both infra-red and synthetic aperture radar. Meanwhile, we are already
working on increasing the range of the LRTR to 1,500km from the present 600km.’
The enhancement of LRTR range implies that detection of medium range missiles
like Pakistan’s Shaheen and Ghauri missiles with ranges over 2,000km would no
longer be a problem. Needless to add that Israel’s ELTA systems group of Israel
Aerospace Industries is assisting the DRDO in this venture.
The MFFCR in use with the ABM system is a Thales made short-range,
short-wavelength radar capable of detection up to a radar cross section of
0.3sqm at 350km range. The DRDO classification for the interceptor missiles are:
AAD intercepts a 1,000km range missile up to an altitude of 20km. The altitude
between 15km to 30km is referred to as endo-atmospheric. The PAD, on the other
hand, has a kill zone up to 80km altitude for a 2,000km range ballistic missile.
PAD is the exo-atmospheric interceptor which is a two stage missile having a
miniaturised Prithvi missile liquid motor as its first stage and the second
being a solid propellant. The PAD has the capability to engage missiles with
speed of 5km/sec (the ICBMs that cover thousands of kms travel at over 7km/sec).
The PAD cruises at speed of Mach 5, however, it has the capability to attain a
peak terminal speed of up to Mach 11, which is possible by the ‘Direct Thruster’
placed on top of the second stage solid propellant. According to Dr Saraswat,
the Direct Thruster has solid propellant and generates high lateral acceleration
for the ‘end game.’ The Direct Thruster and the warhead are fired simultaneously
towards the target once they are within the seeker range of 30 to 40km. All this
happens within a span of one to two second when the hostile missile is ‘hit to
kill.’ The sequence runs as follows: once a missile is detected by the LRTR, the
interceptors on missile launcher are put on ‘hot stand’ ready to fire in 30 to
40sec. Once in range, the MFFCR takes over. The ground guidance computation
takes about 15sec and thus within 30sec, the PAD is fired. The Strap Down
Inertial Navigation System (SDINS) on the PAD provides the mid-course correction
until the seeker (an active phased array radar) finally takes over. Unlike the
platform (gimballed) INS that were used earlier on ICBMs, the SDINS use the
dry-tuned gyros strapped to the interceptor body. The SDINS has much more
reliability, is cheaper than platform INS, and is best employed against moving
targets. Unlike the endo-atmospheric interceptor that is provided by aerodynamic
control, the PAD uses a Reaction Control System that implies auxiliary motors
and flex nozzles. Once PAD is tested again, the next step will be to improve the
interceptor by increasing the missile energy. This is being done under the
codename of PDV project that essentially looks at two aspects: One, while PDV
will have the same two-stage solid motor as the PAD, the length of the
interceptor will be increased by one metre. The PDV, which has been designed and
awaits test-firing, will be able to engage at altitude of 100km suggesting that
missiles of higher velocity like Pakistan’s Shaheen and Ghauri missiles would be
the targets. The DRDO is hopefully of test firing the PDV interceptor by the end
of 2008.
The AAD endo-atmospheric interceptor has a single stage solid motor that can
engage up to 1,000km range ballistic missiles at 20km altitude. Unlike the
exo-atmospheric interceptor that has minimal manoeuvrability of 2g, the AAD
variety of interceptor has excellent manoeuvrability in the range of 25 to 30g
that makes the interceptor unstable. This coupled with the fact that the hostile
missile is in the terminal phase and close to its target, the interception
engagement becomes tricky. Plans are, however, afoot to improve the AAD to
AAD-1, a two-stage solid propellant interceptor that can engage ballistic
missiles at altitude of 30 to 45km.
Overall in phase I, the DRDO is seeking to validate the following capabilities:
to engage short range missiles with velocity vector of 3km/sec. PAD validation
for the exo-atmospheric interception, and AAD validation for the
endo-atmospheric engagement. The key validation will be to prove the overall
systems capability to engage short range ballistic missiles. In Phase-II, the
DRDO has an ambitious but achievable plan: to enhance the range of the LRTR to
1,500km, validation of PDV interception and AAD-1 interception. The DRDO hopes
to accomplish Phase-II by 2015. Given this emerging ABM capability, it can be
said that all of Pakistan’s ballistic missile will be intercepted with about 98
per cent assurance level. China, of course, is in a different league altogether.
It has vastly superior nuclear weapons and delivery systems.
An issue that the DRDO is unwilling to talk about concerns the long range
ballistic missiles which obviously would be armed with nuclear warhead. While
intercepting them in the endo-atmosphere would be dangerous as the debris of a
successful engagement would fall on own soil, the interception should
essentially be in the exo-atmosphere only. This also will be fraught with
danger. The real answer lies in attacking the ballistic missile in the boost
phase itself. |