RISAT-1: ISRO's Moment of Glory

India, within a week of successful testing of a long range missile, the Agni-V launched a Radar Imaging Satellite primarily meant for civilian use such as agriculture, forestry and to facilitate disaster management. Indian space program has certainly come of age.

India's Polar Satellite Launch Vehicle (PSLV) proved its might for the 20th time in a row on 26^th April 2012, with PSLV – C19 injecting India's first indigenous microwave all-weather Radar Imaging Satellite RISAT into orbit nearly 18 minutes after a perfect lift off at 5.47 am from Satish Dhawan Space Centre at Sriharikota. At 1858 kg, RISAT I is the heaviest payload carried by PSLV so far. Soon after the satellite separated from the rocket, the solar panel was deployed and the 6m synthetic radar antenna panel weighing 230kg opened. It will start sending images from 1^st May 2012. The images will facilitate agriculture and disaster management. 

RISAT-1 would be parked at its final orbit of 536 km altitude, has a mission life of five years and would make 14 orbits per day. 

India had in April 2009 launched a Radar Imaging Satellite (RISAT-2) with all weather capability but it was bought from Israel for $110 million largely for surveillance purposes. The launch of RISAT-1 came several years after that of RISAT-2, which carried an Israeli-built x-band radar. The RISAT-2 mission was prioritized over RISAT-1 following the attacks in Mumbai in November 2008, resulting in RISAT-1 being delayed by several years.

What is a Radar Satellite?

Optical remote sensing satellites rely on sunlight to illuminate the ground below, working much like an ordinary camera. They do not work in darkness and their view can be obstructed by clouds. Radar satellites send out radio signals and record the echoes that return. They can image the ground even at night and are unaffected by cloud cover.

 

The Indian Space Research Organisation (ISRO) has long been aware of the advantages of deploying radar in space, remarked Y.S. Rajan, who was its Scientific Secretary for many years from the late 1970s and participated in the decision-making process that shaped the remote sensing programme. 

The engineering challenges of putting a radar on a satellite are “enormous” and considerably greater than for building optical imaging satellites, he told The Hindu. The processing of radar data and interpretation of images are also vastly more complicated. In addition, there was pressure from the launch vehicle team to hold down the weight of satellites, a factor that again worked in favour of optical satellites. 

So while ISRO opted to go the optical route for India's early remote sensing satellites, it was also very clear that the technological capability to build and use space-based radars needed to be developed, he said. Led by O.P.N. Calla, a group at ISRO's Space Applications Centre at Ahmedabad built a “Side-Looking Airborne Radar” that was installed on a Dakota aircraft in 1980. It subsequently built a more sophisticated “Airborne Synthetic Aperture Radar.” The National Remote Sensing Centre at Hyderabad operates two aircraft that can carry such radars. 

Apart from learning to build the hardware, the space agency sought to develop the necessary expertise in using radar imageries for various applications. It did so by taking data from foreign radar satellites, starting with Europe's ERS-1 that was launched in 1991. 

Military use

 

Radar satellites, popularly, have a swashbuckling image that is often associated with covertly watching over other countries and tracking their military hardware. These satellites can certainly serve that sort of function. But such spacecraft also support a range of more humdrum but vital operations.

A radar satellite opens up avenues for watching over another country's military operations. Such satellites can pick out military vehicles, aircraft and ships. 

A radar satellite is “a very powerful instrument” for detecting naval movements, remarked Bhupendra Jasani of the Department of War Studies at King's College London. They could even pick up submarines moving below the surface.

Radar imageries could also aid in examining if a nuclear reactor was being used for plutonium production. In that case, there would be signs that the reactor was being shut down more frequently, he told this correspondent. 

Though RISAT-1 is not a spy satellite, it is likely to be used to keep a vigil on border areas irrespective of hostile weather conditions, which is often the case in the Indian subcontinent and will add to the ability of Indian monitors to track movements on the ground in areas considered sensitive from a defence and security viewpoint. ISRO officials said this satellite would not be used for defence applications. RISAT-2, primarily a spy spacecraft, is already doing that job.

One view which merits consideration is that “Radar satellites can look through clouds and work in darkness. However, Radar signals are highly attenuated by moisture and hence would not be effective during monsoon or in regions with high rainfall. Radar images are usually noisy and hence can easily miss smart targets. Radar images are vulnerable to terrain effects and the like, that can be used to the advantage by adversaries. Identifying missile launches are also difficult in Radar images. Camouflaging is difficult with optical satellites that use hyperspectral/multispectral images. However, that is not the case with Radar images. There are advantages and disadvantages of both the type of sensors.”

RISAT-I will be followed by a geo-imaging satellite (GISAT) that will provide "near real-time pictures of large areas". Risat I will transmit pictures only during passage over India, while GISAT will deliver data on "areas of interest...sector wise imaging every five minutes and entire Indian land surface every 30 minutes at a 50 metre resolution".

AGNI-V: Strengthening India’s Nuclear Deterrence

On 19^th April 2012, at about 8.07 a.m. (IST) India for the first time successfully test fired the nuclear-capable Agni-V from launch complex-4 of Integrated Test Range (ITR) in Wheeler Island off the Odisha coast. The test was originally scheduled for 7 p.m. (IST) on 18^th April 2012, but was put off due to inclement weather. With this, India joined an elite missile club of the US, Russia, France and China, which produce Inter Continental Ballistic Missiles (ICBMs). France used to deploy land-based ICBMs but has decommissioned them due to high costs.

The Agni-V is a three-stage, solid-fuel missile with a range of 5,000 kilometers. Though Agni-V is referred to as an Inter-Continental Ballistic Missile (ICBM), Agni-V is technically an intermediate range ballistic missile (IRBM) because ICBM’s have ranges greater than 5,500 kilometers. This test however demonstrates that New Delhi has cleared all the significant technological hurdles on the pathway to an ICBM. Zachary Keck in his article "India Fires Agni-V Missile" in The Diplomat states "The most difficult of these is the missile’s ability to re-enter the earth’s atmosphere.  Because ICBM’s re-enter the atmosphere at a much higher velocity than other ballistic missiles, the re-entry vehicle’s (RV) nose tip must be able to withstand an enormous amount of heat, around 2,000 degrees Celsius. The Agni-V uses high ballistic coefficient strategy during reentry, which is the technologically more difficult option, but also the most accurate."

The Agni-V is capable of delivering an atomic warhead anywhere in China, even when positioned deep inside India’s own territory. It was developed by India’s Defense Research and Development Organization (DRDO) and is modeled on the Agni-III, a two-stage missile with a range of 3,500 kilometers that India first tested successfully in April 2007. According to DRDO officials, the two missiles share the same size, shape, and height. It is also said that Agni-III can go as much as 6000 km with decreased payloads. The Agni-V is about 17-metres-long and two-metres-wide with launch weight of around 50 tonnes. The missile can carry a nuclear warhead of more than one tonne. Agni-V will feature Multiple Independently Targetable Re-Entry Vehicles (MIRVs) with each missile being capable of carrying 3–10 separate nuclear warheads. Each warhead can be assigned to a different target, separated by hundreds of kilometres; alternatively, two or more warheads can be assigned to one target. MIRVs ensure a credible second strike capability even with few missiles.

This is the first time India has produced a missile that has brought China within its range and it is being considered to possess deterrent capability vis-à-vis China.

India has at present in its arsenal of Agni series, Agni 1 with 700 km range, Agni 2 with 2,000 km range, Agni 3 and Agni 4 with 2,500 km to more than 3,500 km range.

Agni-V

 

According to the chief of DRDO, V.K. Saraswat, the missile launch was a major milestone in the strategic defence preparedness of the country. He said that DRDO would conduct about two more tests before production of the system commences. He expected the missile to be inducted into the armed forces in the next two years. 

China’s reaction

China reacted in strong terms and very negatively to the successful launch of the Agni-V. In the state-run Chinese newspaper Global Times, China denounced India's advancement in missile technology, calling it a "missile delusion" and stated that India was still poor and lagged behind in infrastructure construction, but its society was highly supportive of developing nuclear power and the West has chosen to overlook India’s disregard for nuclear and missile control treaties. China claimed that India viewed China as a benchmark for military development, and further stated: "China understands the Indian desire to catch up with China. China, as the most appropriate strategic target for India, is willing to take India as a peaceful competitor." China issued threats and warnings in the report as well, "advising" India not to "over-estimate its strength", and insisted that China's nuclear power was "stronger and more reliable". China subsequently claimed that, "For the foreseeable future, India would stand no chance in an overall arms race with China, hinting about the possibility of an arms race between the two countries. The newspaper further added that if it [India] equated long range strategic missiles with deterrence of China, and stirred up further hostility, it could be sorely mistaken." From the report it is apparent that China was not happy with India’s successful advances in missile technology. It must be pointed out that China failed to appreciate the fact that India was forced to embark on advanced long range nuclear capable missiles in response to Chinese deployment of ballistic missiles in Delingha missile base, located 1,900 km northeast of New Delhi in the central province of Qinghai. The base, complete with extensive underground storage facilities, houses China’s DF 21 Medium Range Ballistic Missiles (MRBM) that have a range of over 2,200 km and can target most cities in northern India. China ought to have realised the fact that India would have responded to this threat at some point of time.

Completing the nuclear triad

Having successfully tested a potential ICBM, India must expedite the development of Submarine Launched Ballistic Missiles (SLBMs) to complete the nuclear triad and give India an effective second strike capability. India is reportedly working on the K Missile family; K-4 was reported to have been tested covertly off the Visakhapatnam coast in the beginning of 2010. However, DRDO sources neither acknowledge nor deny the existence of this project, sometimes referred to as “Black Project”. While there are some reports that claim that K-4 is a submarine launched version of AGNI-V, other reports state that it is actually a SLBM Version of the Agni-III missile that is being worked on. The goal of this project is to expand the second-strike options for the country. The missile is said to have two variants. One with a range of 3,500 km that is 10 m long and the other with a range of 5,000 km will be 12 m long to arm future nuclear submarines of the Arihant class. INS Arihant will be able to carry 4 (10m long) K-4s or 12 K-15s (Sagarika). K-5 missile is the SLBM version of Agni-IV is purportedly under development by DRDO. It will arm the future variants of Arihant class submarines of the Indian Navy. DRDO also disclosed in 2011 that it is also in the process of developing a variant of Agni missiles which would be a submarine launched solid fuel missile with a maximum range of 6,000 kilometers and a payload of one tone (probably the Agni-V’s naval version??). However, there is no clarity regarding the existence of such a project.