Space Situational Awareness (SSA): AN Essential Strategic Requirement
Pushpinder Bath

Usage of space by own forces and its denial to adversary has grown to become essential for modern militaries. Today, space is increasingly being viewed as enabler for conduct of own operations and the 'Achilles heel' which if targeted can cripple adversary's war waging efforts1. In order to preserve their rights to use space, militaries of the world need to be watchful of events inspace. Situational awareness of space is thus an increasingly felt necessity for operations in space and on ground.

Space Situational Awareness (SSA) is the knowledge/observation of activities, objects/particles and energies in space2. These activities, objects/ particles and energies in space can be natural or a part of human endeavours.

In 2007, China launched a KT-2 missile on its own FY-1C satellite thus demonstrating its Anti-satellite (ASAT) weapons capability3. The news was published in Indian newspapers two days after it was published in the US print media. So, if offensive counter space activities of an adversary were to damage or degrade the functioning of India’s space assets, India would best rely on its guess work or on foreign inputs to track the causes of malfunctioning of the targeted space asset. On the premise of India's 'blindness’ in space, the underscoring argument here is that having considerably invested in space assets, should India build its indigenous capabilities for intelligence and surveillance of activities in space. Further, militarily, if space is to be seen as the backbone of future warfare, should the knowledge of suspicious activities in space not be an operational priority? If the answer is yes, then India needs to look at SSA critically.

Constituents of Space Activities

Outer space as commonly understood is not an absolute vacuum. Energies, objects/particles and activities found in space together with their corresponding affects are as under: -

  1. Atomic Fluxes and Space Energies
  2. Solar winds and resultant atomic fluxes affect smooth station keeping and may even render a satellite non-functional.

  3. Orbiting Space Objects
  4. These consist of active, dormant and inactive satellites, space debris chipped off from defunct satellites or remnants of launch vehicles etc.

  5. Human Activities in Space

Human’s activities in space, both bona fide and belligerent including launch of ASAT weapons, satellite manoeuvres, and undeclared payloads or satellites.

Space Collision

The velocity of orbiting space objects is about 7-8 Km/sec. When objects collide, the combined speeds are comparable to 25-30 times that of sound. This causes kinetic energy carried by such particles or objects to far exceed that produced by explosion of a trinitrotoluene (TNT) particle of similar mass. Thus even small slivers of paint on collision can disrupt a satellite's functioning. A particle of the size one cm and above is potentially harmful while those with sizes 10 cm and above can cause complete disruption of the satellite functioning. The Joint Space Operations Centre (JSpOC), which is the nerve centre for USA's global SSA network is responsible for tracking and cataloguing orbiting space objects4. This catalogue is a key database and is available on internet. It enables predicting orbital paths of catalogued objects/debris and is used by majority of countries for planning their space activities. Currently, about 20,000 orbiting space objects (including more than 1000 active satellites) of the size 10 cm and above have been catalogued. In 2014 alone, the JSpoC issued 6,71,000 notifications of possible orbital collisions across the complete space domain. Hence, space collisions have now become a new reality and all space faring nations have to be alive to this problem.

Protecting Satellites from Collisions

The methodology of predicting collisions and subsequent evasion has been explained below: -

  1. Conjunction Assessment
  2. It refers to identifying objects that can potentially hit satellites and generating the necessary warning in a suitable timeframe.

  3. Collision Avoidance

The owner agency/country may then decide maneuvering the satellite based on probability of collision and cost benefit analysis.

In order to establish its need and relevance, SSA is being discussed from the civil and military perspectives in the subsequent paragraphs.

SSA: Civil Perspective

Purely from civil perspective, SSA covers space surveillance and tracking of orbiting space objects; space weather and monitoring near Earth objects like asteroids. Specific surveillance and predictive knowledge of adversary space activities that may threaten own space assets are not the focus here.

From the civil perspective, SSA provides essential information for mission support by surveillance and tracking of orbiting space objects and thus plays a major role in selecting the right window for launch operations. Hence, it is related to launch requirements and sustenance of the mission rather than being concerned with the security of space assets. This entails need for basic SSA requirements, which can be readily obtained from open source data provided by US websites. Therefore, need to have indigenous SSA may not ring the alarm of urgency from the civil perspective.

SSA: Military Perspective

From the military perspective, SSA is related to the predictive knowledge about space threats from hostile space faring nations to enable decision makers to gain and maintain space superiority. As is evident, in military minds, SSA relates not only to 'security of space assets' but also to superiority in space. Information that military planners seek from SSA are as under: -

  1. Observation of adversary's activities in space to include undeclared satellite launches, parasitic satellites, orbital parameters, in-orbit intentional manoeuvres during conflict scenario, malicious tests, experiments, space robotic activities and utilisation of suspicious dormant satellites.
  2. Detection of adversary's counter space activities.
  3. Signal Intelligence (SIGINT) to include Communication Intelligence (COMINT) and Electronic Intelligence (ELINT)) of adversary's space assets.
  4. Intelligence of adversary's satellite design, payload and their employment.
  5. Monitoring adversary's missile launches and in order to augment own ballistic missile defence warning system.
  6. Identify orbiting space objects, assess their hazard, establish ownership and predict the possible intention and usage by an adversary.

It should be understood that continuity of service during critical times of war is of paramount importance and therefore, satellites providing essential services need to be provided SSA cover. It is evident that while civil SSA looks everywhere and is generic, military SSA primarily focuses on the security implications of the adversary's space activities. Therefore, military perspective of SSA is proactive unlike the civil perspective, which is reactive and largely driven by cost benefit analysis.

Global Capabilities in SSA

Development of indigenous SSA capabilities entails creation of an elaborate space surveillance network comprising satellites, radars, telescopes and ground stations. Presently very few countries have ventured in this domain as it is a very cost prohibitive project. US is the world leader in SSA, hence their capabilities can be taken as a benchmark for assessment of capabilities of other countries. Therefore, current standings of China and India in the domain of SSA should be viewed in reference to USA.


US spends a huge amount on SSA, which is largely financed by the Department of Defence. US operateshundreds ofgeographically dispersed sensors owned by military, civil or intelligence community. Various segments of US Space Surveillance Network (SSN) have been discussed below:-

  1. Space Segment
  2. Space segment of SSN includes deployment of sensors in space for generating SSA. Current US projects providing SSA from space are asunder:-

    1. Space Based Space Surveillance (SBSS)5
    2. This project includes theUS Satellite 'Block-10 Pathfinder'launched in 2010 to observe orbiting space objectsin Low Earth Orbit (LEO), Medium Earth Orbit (MEO) as well as Geostationary Earth Orbit (GEO). The satellite can observe objects of the size of one meter cube up to the altitude of 36,000 Km from Earth.

    3. Geosynchronous Space Situational Awareness Programme (GSSAP)6
    4. Placed in GEO and operated by US Air Force (USAF), the GSSAP satellites GSSAP 1 and 2 were launched in 2014 and GSSAP 3 and 4 were launched in 2016. These satellites provide surveillance cover to other US critical constellations like Space Based Infra Red System (SBIRS) employed for missile defence and the Advanced Extremely High Frequency (AEHF) constellation, which provides jam-proof communications for the US President even during a nuclear event.

    5. Satellite Inspector Prowler
    6. As part of its STS-38 Space Shuttle mission, US has used the 'Prowler Satellite' which can approach as close as one foot to the target satellite to observe its payloads, radar signatures, size, frequency etc.

    7. Cooperation with Canada
    8. Canada's Near Earth Object Surveillance Satellite (NEOSS) and ‘Sapphire’ satellites use optical telescopes for tracking objects in space. These systems also provide necessary inputs to the SSN of USA.

    9. Missile Defence

Assets involved in missile defence form a major subset of US space based SSN. These include the Space Tracking and Surveillance System Advanced Technology Risk Reduction Satellite (STSS-ATRR) and the Space Based Infra Red System (SBIRS).

  1. Ground Segment
  2. Components of ground based SSN infrastructure of USA are given below: -

    1. Space Fence7
    2. Located at Kwajalein islands the space fence is a three km long transmitter array producing a powerful radiated beam. It can track objects in space with a capability to execute thousands of observations per day. It can detect orbiting space objectsas small as five cm.

    3. Ground Electro Optical Deep Space Surveillance (GEODSS)8
    4. The GEODSS is a terrestrial network of telescopes situated at Socorro, Diego Garcia and Hawaii. It also constitutes an additional mobile site at Moron, Spain. Data from GEODSS is transmitted to JSpOC, Colorado.

    5. Orbit Outlook: DARPA9
    6. The ‘Orbit Outlook’ programme of Defence Advanced Research Projects Agency (DARPA) is a global network of scores of space surveillance radars and telescopes that observe and catalogue space objects. The programme also integrates data from amateur observers and major academic institutions.

    7. Falcon Telescope Network

The US Air Force has also built a network of 12 observatories in US, Chile, Germany, Australia and South Africa. Data collation is done centrally to create a fused picture.

  1. Command and Control Structure

The nerve centre of the space vertical of US Joint Forces Component Command (JFCC) is the Joint Space Operations Centre (JSpOC). Manned by USAF, the JSpOC is responsible for space surveillance, collision analysis, launch support and maintaining the satellite catalogue. It receives inputs from the US Space Surveillance Network (SSN). US shares its SSA inputs with global space community through its SSA sharing programme. However, the sharing of such information is selective. The official website of US Strategic Command (STRATCOM) i.e. ‘’ shares only the basic information related to SSA. Advanced information is provided to only those agencies/nations with which US has a SSA sharing agreement. The SSA programme of USA is primarily funded out of their defence budget. This clearly reflects the military orientation and nature of their SSA programme.

European Space Agency (ESA)

Bitter experiences with US over sharing of SSA information, formed the basis of the ESA's forays in the SSA domain, commencing from January 2009. ESA satellites Proba-2 and 3, SOHO, Gain and Swarm are tasked with SSA. It has at least a dozen ground facilities located in Europe and South America. The SSA activities undertaken by ESA are as under:-

  1. SSA data collection and coordination.
  2. Development of applications and user interfaces for sharing.
  3. Asteroid attack mitigation techniques.
  4. Testing and validation of radar detection technologies.
  5. Research in satellite laser ranging.
  6. Development of optical surveillance technologies.

Russia has its own space surveillance network. Russian radars are spread over the complete landmass of the erstwhile USSR. However, with bilateral agreements, Russia continues to operate them even today. Russian sensors are primarily ground based and augmented by ship based sensors. Ship based sensors provide them flexibility and redundancy. Apart from the Russian mainland, their SSA sensors are deployed in Azerbaijan, Belarus, Kazakhstan and Tajikistan. There are also a few trans-continental telescopes deployed in Asia, Africa and South America.


China has a network of phased array radars for tracking objects in LEO till 3000 Km of altitude at Jiangxi, Hainan, Xuanhua, Changchun, Henan, Kunming and Kashi. China also operates Yuanwang tracking ships for increasing its surveillance coverage10. In addition, it has four telescopes at the Purple Mountain Observatory in Nanjing. In 2013, China commissioned a tracking station at Ngari, in the Tibetan Autonomous Region (TAR), which is can enable China to track all Indian satellites11. A similar facility has also been commissioned by China in Patagonia, Argentina, which is believed to be utilised for tracking US military satellites. Nicknamed as 'Heavenly Eye' or 'Tinyan,' China has also built the world's largest radio telescope here with an aperture of 500 m.


Japan is at a nascent stage of developing its space surveillance network. It has commenced installing radars for scanning space objects in the range of 200 to 1000 Km from Earth. However, optical telescopes are being designed to observe up to 36,000 Km. With the development of its SSA capabilities, Japan would be able to detect space objects of the size of up to 10 cm in a near timeframe.


India is due to undertake Aditya-L1 mission towards the end of 2020, aboard PSLV XL with the aim of observing solar corona activities. Hence, it will assist in predicting hazardous space weather. This project marks the beginning of India’s forays in space in the direction of SSA, albeit in a limited manner. India’s ground segment of SSA is also at a nascent stage. ISRO has commissioned a Multi-Object Tracking Radar (MOTR)12 with a capability of tracking objects of the size of 30x30 cm at an altitude of 800 Km and 50x50 cm up to 1000 Km. The radar located at Sriharikota can track up to 10 objects simultaneously. The radar may have dual usage in the field of air defence for tracking ballistic missiles. In addition, DRDO's has developed the ‘Super Swordfish’ radar13 capable of detecting objects in space at an altitude of 1500 Km. In 2018, ISRO commissioned the SSA control centre at Bengaluru to plan and coordinate all research and development in the domain of space. India also has a few space observatories spread across Indian landmass. These are as under: -

  1. Indian Astronomical Observatory consisting of a 2.01 meter optical-infrared Himalayan Chandra Telescope (HCT) and a High Altitude Gamma Ray (HAGAR) Telescope at Hanle near Leh.
  2. Devstahal optical telescope built in collaboration with Belgium, is situated at Nainital and was dedicated to the nation by Prime Minister Narendra Modi in March 2016.
  3. Gauribidanur radio observatory is a radar-based observatory located in Karnataka.
  4. Giant meter wave radio telescope observatory is located in Pune and it is the largest interferometry observatory in the country. It consists of about three dozen radio telescopes of diameter 45m each thus providing a base diameter of 25 Km.

India has taken some initiatives in international cooperation to develop SSA capabilities. The US-India Joint Statement of September 2014 identified collaboration in SSA and collision avoidance as one of the potential areas of cooperation. By February 2016, a bilateral arrangement for sharing of information had been setup between US and India for tracking movement of satellites and collision avoidance. During his visit in 2018, French President Emanuel Macron signed a SSA cooperation agreement with India. Recently in March 2019, India-Japan space dialogue resulted in an understanding between the two countries on need to share SSA information.

International SSA Exchange

Information sharing regarding SSA has remained a sore point of contention among the space faring nations. The United Nations Resolutions namely UN GA 1721 B (xvi), 1472 (xiv) and 62/101 and the Outer Space Treaty 196714 encourage sharing of space related information amongst the member countries. However, there is much ambiguity on the type of data to be shared and the way it is to be shared. USA, which is the dominant power in the domain of SSA may therefore selectively provide data to other space faring nations as and when it deems necessary. Current model of sharing SSA data by US STRATCOM has been categorised under firstly advanced data sharing based on bilateral agreements with strategic allies, secondly on emergency basis to warn the concerned countries about likelihood of a potential collision and thirdly basic information sharing through open source media over the website

China leads the Asia Pacific Ground Based Optical Space Objects Observation System (APOSOS)15 having a network of observatories spread all over Asia. Its objective is to track and share information about objects and debris in space. Member states include China, Pakistan, Thailand, Bangladesh, Indonesia, Iran, Mongolia, Peru and Turkey.

Private space faring companies have congregated to from a non-profit association for controlled and reliable data sharing. Formed in 2009 by three private space companies (INMARSAT, INTELSAT and SES), it is known as Space Data Association (SDA). It operates a high-tech centre, which automates SSA and reduces risks of in-orbit collisions.

A closed user group has been formed by freelance astronomers across the world through emails. This group known as SEESAT-L exchanges information of satellites not listed in the internationally registered/ declared list of satellites. Till date, SEESAT-L has disclosed information about 200 such satellites. Apart from, a number of satellite tracking websites are available in the open source. These include,, Celestrak, Heavens at etc.

Way Ahead for India

The idea of utilising space for national security has recently begun to gather foothold. In the future scenario of net-centric operations, Indian military is likely to be using space-based services for satellite communications, surveillance, and navigation and targeting. The Indian Navy is reliant on GSAT-7 for its maritime communications and the Indian Air Force uses GSAT-7A. Apart from these communication satellites, the defence forces are utilising the data from nearly a dozen surveillance satellites and the IRNSS constellation. The number of defence satellites is likely to grow manifold in the years ahead. The newly raised Defence Space Agency (DSA) is expected to control the Defence Image Processing and Analysis Centre (DIPAC) and the Defence Satellite Control Centre (DSCC). It will not only be responsible for all military space projects but will also oversee the development of counter space capabilities. The conduct of ASAT test by India in 2019 shows India's new resolve in the space domain. To put it across in brief, Indian military's reliance on space assets is all set to increase in future. Further, with this increased reliance will also grow the need to secure our critical defence space assets. If the military were to base their operations on space assets, development of SSA capabilities needs to be seriously considered. It is also important to consider the emergence of China as a space power in our neighbourhood. Not only did China successfully conduct a direct ascent ASAT test in 2007, it has also been surreptitiously engaged in the development of Directed Energy Weapons (DEWs). China’s declared strategy of informationised warfare and consequent increase in space activities needs to be monitored. The point to ponder is that monitoring China's activities in space is exclusively a military/ security necessity and will not invoke concrete actions till such time the Department of Space and ISRO continue to view SSA purely from the civil perspective.

Majority of space faring nations today rely on USA for provision of SSA data. This allows US to selectively part with the data that it wishes to divulge. On 03 February 2015, the US meteorological satellite DMSP-F13 exploded in near vicinity of European Eumetsat satellite. No prior information of a possible explosion was conveyed by US to ESA, citing that it was accidental due to battery over heating. However, ESA felt that telemetry information of a spike in battery temperature would have already been available with USA. It can thus be understood that data flow on SSA from USA is not perennial even to its closest allies. In the field of navigation, it was the foreign control over GPS that led India to conceive its own indigenous satellite navigation post the Kargil war. Similarly, we need to seriously consider the need to develop our indigenous SSA capabilities to safeguard our space assets. However, the space surveillance network required for acquiring indigenous SSA capabilities entails heavy financial implications. Therefore, we need to adopt a cost effective approach towards its implementation. A national level task force headed by the National Security Advisor (NSA) needs to be created having representatives from the Department of Space, Ministry of Defence, Ministry of Finance, National Technical Research Organisation (NTRO), Defence Space Agency (DSA) and the Service Headquarters. The task force so created should be able to chalk out a roadmap for development of India's SSA capabilities. It would be ideal to nominate DSA as the executive agency towards the implementation of the project for creation of a space surveillance network. A collaborative concept could be considered with data being provided by radars and telescopes owned by ISRO, defence services and private companies. Data received from international cooperation and open source could also be be factored to generate a fused space situational picture.

While an indigenous space surveillance network is a need of the hour, it is cost prohibitive and technology sensitive. Thus it is not likely to materialise in the short term. In the interim, it would be prudent to develop customised software to incorporate open source data for predicting the orbital characteristics of adversary satellites. The software should be designed to provide early warning of incoming satellites with filters related to nationality, payload and resolution. It should facilitate customised map search for a specific geographical location and prediction should be based on multiple open source satellite parameters available from various websites. Such asoftware will not only be useful for the security of own space assets but will also be able to depict the blind periods for adversary satellites over a specific geographical location. This will be of immense value to military commanders for executing the deployment of critical equipment and for planning deception measures.


India is amongst the major space faring nations in the world. Ever since its inception, the focus of Indian space programme has been on societal applications and economic development. This was also in line with the Outer Space Treaty, which considers space as an arena of global commons. However, unlike India, some nations have kept their national security needs as their primary reason for venturing into space. Such nations have taken a clear lead in niche domains such as SSA and are on a spree to control space and deny its use to other nations. As space plays an increasing role in the domain of national security, SSA has emerged as the stepping stone towards ensuring continuity of own access to space. Concept of informationised wars demands continued availability of space assets and thus necessitates their security. To secure space assets it is essential for military planners to know what's in space. SSA therefore is the key to space based operations. While the US has a clear lead in the field, EU, Russia and China have also made appreciable progress. We are as yet at a very nascent stage in this domain with very limited assets. Under the given circumstances, India needs to adopt a considered policy that integrates both societal and national security needs in a balanced manner.

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(The paper is the author’s individual scholastic articulation. The author certifies that the article/paper is original in content, unpublished and it has not been submitted for publication/web upload elsewhere, and that the facts and figures quoted are duly referenced, as needed, and are believed to be correct). (The paper does not necessarily represent the organisational stance... More >>

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