There has been an exponential growth of space objects, including orbital debris that has increased the in-orbit collision risk. In the year 2019 alone, 385 smallsats were launched reaching a value close to 2900 in mid-2020 and still rapidly increasing. Moreover, taking into account all the applications filed by satellite operators to the relevant licensing authorities, more than 100,000 new spacecraft might be launched in orbit by 2030. And even if only 10% of these plans were realized, taking into account financial and market constraints, another 10,000 operational satellites could still be added to those currently in service,
In addition to polluting space, space junk poses risks for safely navigating spacecraft. In the year 2010 alone, space debris increased by over 75%, posing huge collision risks for spacecraft operating in the low earth atmosphere. NASA estimates there are 21,000 objects orbiting Earth that are larger than 10 cm, 500,000 between 1 and 10 cm, and more than 100 million that are less than 1 cm.
The large number of debris around Earth is a risk for the safety of operational satellites. Orbital debris of even 1cm size, traveling at an average speed of about 11 km/sec can cause partial or complete destruction of the satellite. Any of the debris objects can cause harm to an operational spacecraft, where a collision with a 10-cm object could entail a catastrophic fragmentation, a 1-cm object will most likely disable a spacecraft and penetrate the satellite shields, and a 1-mm object could destroy sub-systems onboard a spacecraft.
Space situational awareness (SSA)
Space situational awareness (SSA) is the foundational element of space security, and it entails keeping track of all natural and artificial space objects, energy and particle fluxes and understanding how the space picture is changing over time. SSA is a system of systems dealing with space surveillance, space weather and NEOs.
The overall objective of space situational awareness (SSA) is to identify the location of every object orbiting the Earth, why it is there, what it is doing, and to predict what it will be doing in the future. Its aim is to track and understand what exactly is in orbit from either space or from the ground. This knowledge enables the management of space assets and the exercise of a level of control over the space environment.
SSA holds crucial importance for space safety owing to continuous monitoring of the presence of natural or man-made hazards like debris. SSA services document real-time information of space components while alerting satellite operators of potential accidents. It carries out Conjunction Assessment or identifying objects that can potentially hit satellites and generating the necessary warning in a suitable timeframe. In addition, SSA tracks space bodies that may interfere with a particular orbit while predicting their positions in advance for preventing collisions with satellites. The owner agency/country may then perform Collision Avoidance by maneuvering the satellite-based on the probability of collision and cost benefit analysis.
Militarization of Space and SSA
Space is also becoming increasingly militarized many countries are developing killer microsatellites and other antisatellite weapons (ASAT) that could be used to damage other satellites. There is also thrust on space robots that can perform the repair of satellites and could provide complete awareness of the adversary’s activities in space so that one can take counteractions. They could also be employed to deorbit adversary’s satellites.
There is an international effort to regulate debris and space warfare regulations. UK’s Exeter Law School has joined a consortium of founding institutions, including McGill University and the University of Adelaide, for the development of rules for space warfare. The Manual on International Law Applicable to Military Uses of Outer Space (MILAMOS) will also set out rules for war crimes in space and for the development of space-based weaponry, including lasers and missile defense systems. The manual will also look into the issue of who will be responsible for cleaning up space debris caused by military action.
However, militaries are going ahead to protect their space assets and formed space commands and space forces. The US Strategic Command defines SSA as “The requisite current and predictive knowledge of space events, threats, activities, conditions and space system (space, ground, link) status capabilities, constraints and employment — to current and future, friendly and hostile– to enable commanders, decision-makers, planners and operators to gain and maintain space superiority across the spectrum of conflict.”
SSA encompasses surveillance of all space objects, activities, and terrestrial support systems (satellites & debris), more detailed reconnaissance of specific space objects assets (mission identification, capabilities, vulnerabilities, etc.), discerning the intent of others who operate in space, knowing the status of our own forces in real-time, and analysis of the space environment and its effects (solar storms, meteor showers, etc.).
SSA is segregated into three service segments including space surveillance & tracking of various objects within the Earth’s orbit, space weather, and near-Earth objects. The near-Earth space extends to the Earth-radius of more than 100,000km to cover all man-made objects in the orbit. Space Situational Awareness (SSA) concept revolves around monitoring and understanding the near-Earth environment, encompassing existing and predictive knowledge regarding natural and man-made objects within the Earth’s orbit. The ability holds a pivotal role in understanding space conditions, events, activities, threats, natural or man-made debris, and intentional or unintentional attacks on space assets such as satellites. It encompasses Signal Intelligence (SIGINT) to include Communication Intelligence (COMINT) and Electronic Intelligence (ELINT)) of adversary’s space assets
It also entails determining the various threats to space assets such as the growing number of debris, space weather, meteorites, orbital collisions and intentional attacks including directed energy attack, direct ascent and orbital ASAT, HAND events, etc. It also includes observation of adversary’s activities in space to include undeclared satellite launches, parasitic satellites, orbital parameters, in-orbit intentional maneuvers during conflict scenarios, malicious tests, experiments, space robotic activities and utilization of suspicious dormant satellites.
It involves the collection, processing, fusion, and assessment of data and information from many different sources and the dissemination of information to decision-makers and various users. Comprehensive SSA requires a networked system of radars and electro-optical sensors. Low altitude debris is usually observed by radar ground stations while high altitude debris is observed by optical ground stations. Bistatic, multistatic, and phased array radars are widely used. The optical telescopes have some disadvantages as they can only track objects that are illuminated while the telescopes are in darkness. Recently the trend is to use space-based sensors to provide timely detection, collection, identification, and tracking of man-made space objects from deep space to LEO orbits.
The information assists planners, operators, decision-makers, and commanders in gaining and maintaining space superiority through conflicts while thwarting attacks and potential collisions. SSA encompasses knowledge pertaining the space and ground-based capabilities. SSA covers space traffic management and space safety programs that include services intended to assist satellite operators in preventing physical or operational conflicts.
The scenario presents huge incentives for sophisticated SSA for solid deterrence. SSA holds a pivotal role in achieving space deterrence while enabling the US to maintain strategic stability. Sophisticated SSA capabilities along with enhanced attribution techniques are capable of reducing the overall vulnerability of spacecraft.
US Air Force Space Command has proposed Space Domain Awareness, SDA as the new term for what used to be SSA, or Space Situational Awareness. “The implication of space as a warfighting domain demands we shift our focus beyond the Space Situational Awareness mindset of a benign environment to achieve a more effective and comprehensive SDA, much the way the Navy works to achieve maritime domain awareness in support of naval operations and the Air Force strives for maximum air domain awareness to achieve air superiority,” Air Force Space Command’s deputy commander Maj. Gen. John Shaw stated in a memo.
The memo defines SDA as the “identification, characterization and understanding of any factor, passive or active, associated with the space domain that could affect space operations and thereby impact the security, safety, economy or environment of our nation.” SDA will require the “integration of legacy SSA-based metric observations and intelligence” needed to identify, locate and track potential threats to on-orbit space systems, the memo said. SDA must be “predictive and current,” the memo stated. That will require the integration of intelligence, metric observations and environmental monitoring to “execute space battle management” in support of military plans and operations.
Recent events such as moon race and asteroid mining have made the cislunar space, the entire space extending beyond Earth to the moon next “high ground” a position of advantage or superiority that needs to be monitored and controlled. The cis-lunar domain is defined as that area of deep space under the gravitational influence of the earth-moon system. This includes a set of earth-centered orbital locations in low earth orbit (LEO), geosynchronous earth orbit (GEO), highly elliptical and high earth orbits (HEO), earth-moon libration or “Lagrange” points (E-ML1 through E-ML5, and in particular, E-ML1 and E-ML2), and low lunar orbit (LLO). Now with space competition and future militarization has reached to Cislunar Space, militaries are extending the Space situational awareness (SSA) to this entire space between earth and moon.
Dean Cheng, a senior research fellow at the Heritage Foundation, noted that visibility into cislunar space will become an area of greater interest soon. The cislunar domain “is going to become a more intense area of competition,” he said. There are areas there where the Earth and the sun’s gravitational fields cancel each other out, allowing satellites to stay there with minimal amounts of fuel, he added.
SSA also entails monitoring adversary’s missile launches and in order to augment own ballistic missile defence warning system. The emergence of hypersonic weapons over the last few years poses a problem to America’s missile warning systems. When viewed from space, the weapons appear 10 to 20 times dimmer than traditional ballistic missiles, making it harder for satellites in geosynchronous orbit to pick them up. Because the weapons are maneuverable, they can theoretically move to avoid ground-based sensors. It became clear that the U.S. needed a new constellation of space-based sensors that could detect and track the new threat. Therefore SSA has now getting integrated with hypersonic missile defense.
SSA capability of different nations
Space Situational Awareness (or SSA for short) is a multi-million dollar effort undertaken by various agencies, governments, and organizations around the world many times combined with Space Weather and Near-Earth Objects tracking. Most (if not all) of those efforts are deeply rooted in their defense-related past.
The military branches of their countries directly oversee many of them. For example, in the US, SSA services are operated by the 18th Space Control Squadron, a unit of the US Air Force, while in Russia, the 821st Main Centre for Reconnaissance of Situation in Space is operated under the Russian Space Forces. Inherently, running such services under a military branch imposes heavy restrictions with regards to data openness and transparency to operational capabilities of the Networks of radio and optical tracking equipment used by them.
Various militaries around the world maintain a particular SSA capability, and in some cases, we do have public data around their existence. For example, the French military operates the GRAVES radar to track objects in predominantly LEO, while Germany operates GESTRA under GSSAC with multiple locations. Eight EU Member States (France, Germany, Italy, Poland, Portugal, Romania, Spain and UK), with representatives from National Designated Entities and Ministries of Defence and EU SatCen participate in the EUSST Cooperation, joining SST efforts. No data or orbital elements are made public.
United states operates the largest network of sensors and maintains the most complete catalog of space objects.”As the space domain has become more congested, the potential for intentional and unintentional threats to space system assets has increased. To mitigate these threats, the Department of Defense (DOD) has undertaken a variety of initiatives to enhance its network of sensors and systems to provide space situational awareness (SSA)—the current and predictive knowledge and characterization of space objects and the operational environment upon which space operations depend” , according to Budgets Information.
The latest SPACETRACK programme represents a worldwide Space Surveillance Network (SSN) of dedicated, collateral and electro-optical, passive radio frequency (RF) and Radar sensors. The SSN has also developed the system interfaces necessary for the command and control, targeting and damage assessment of a potential future USA anti-satellite weapon (ASAT) system.
According to DOD, a potential of 375 sensors for SSA are available across the civil, military, commercial and intelligence communities. The US Space Surveillance Network (SSN) is the principal system used to detect, track and identify objects orbiting earth. It has the best set of SSA capabilities, operating a global network of 30+ ground based radars and optical telescopes and 2 satellites in orbit. It maintains the most complete tracking database of 23,000+ space objects bigger than 10 cm. SSN largely relies on phased array radars that are also used for early missile warning sensors.
US has two space based sensors to detect space objects- the Space Based Visible (SBV) sensor on the Midcourse Space Experiment (MSX) and Space Based Space Surveillance (SBSS) Pathfinder satellite.
The SSN has fewer telescopes, but they are better distributed geographically. The ground based Electro-optical Deep Space Surveillance System (GEODSS) consists of three separate sensor sites located in New Mexico Hawaii and Diego Garcia in the Indian Ocean. Each site operates a cluster of three telescopes, each of which can be operated independently of each other. Along with these sites there is a mobile site with one telescope located in spain. Together they provide global coverage of the GEO belt, although weather can cause gaps. The data is fed to the Joint Space Operations Center (JSpOC) in California that provides a range of data and services for US government, satellite operators, and public.
The SSN system is not ideal and has limitations like outdated hardware and software and provides very little coverage in the Southern Hemisphere like in Asia, Africa, and South America. Space Fence program is the upgrading of current VHF-based radar system to an S-band radar system that will allow the Air Force to track microsatellites or debris, as far out as 1,900 kilometers in space. Lockheed Martin in 2020, delivered its Space Fence radar to the military. The system — which is based on the Kwajalein Atoll in the Marshall Islands — detects, tracks and measures space objects, primarily in LEO, though it also has visibility into medium-Earth orbit and GEO. Space Force Maj. Bryan Sanchez, director of operations, cyber and exercises at Space Delta 2 for space domain awareness, said the system has been performing well.
The new system has a maximum coverage area of 40,000 kilometers compared to 22,000 kilometers maximum of earlier system. It would track about 200,000 orbital objects and make 1.5 million observations per day, about 10 times the number made by previous the earlier Air Force Space Surveillance System (AFSSS). Later in 2021, the system’s program office will deliver a “coherent integration upgrade” to the platform, which will enable greater positional accuracy at geostationary orbit, he said.
As outer space becomes more congested due to the proliferation of satellites and orbital debris, the US Space Force is investing in powerful radars and sensors for better situational awareness. The service is currently pursuing a deep-space advanced radar concept program, also known as DARC. According to the service, the platform is a ground-based radar system designed to detect, track and maintain custody of deep space objects 24/7. It will primarily track objects at geosynchronous-Earth orbit, though it could also track objects in low-Earth orbit, according to officials. President Joe Biden’s fiscal year 2022 budget request included $123 million for research, development, testing and evaluation for the program.
As the effort moves forward, the Space Force is still mulling over where it wants all three of the sites to be located. “We’re looking at three geographically dispersed sites around the globe, approximately 120 degrees separated for global coverage,” Greiner said. “We are in talks with some partner nations.” There will be locations within the continental United States, European Command and Indo-Pacific Command regions, he added. Additionally, it would be preferred if they were near the equator, but that is not a requirement.
Canada’s Near Earth Object Surveillance Satellite (NEOSS) orbits around 800 km above the earth to monitor space objects. It is the first micro satellite that is used for this purpose. Canada contributes to Us’s Space Surveillance Network.
Russian Military Space Surveillance Network (SKKP)
Russia operates the second-largest network of sensors and also maintains a relatively complete catalog of space objects. The SKKP is part of the Russian Space Forces (Космические войска России). The Network of multiple radars and ground stations across Russia was initially part of the missile early warning system of the Soviet Union and gradually gained its independence and specialization to detect satellites, identify them, and to discern their orbits. It maintains the Russian catalog of space objects, and provides data that could be used to support space launches, feed an anti-satellite program, and provides intelligence on hostile military satellites. It is the Russian equivalent of the United States Space Surveillance Network. No public data is available from SKKP.
The Russian system also known as the Space Surveillance System (SSS), consists of phased array radars used primarily for missile warning, along with some dedicated radars and optical telescopes. Several of the SSS sensors are located in former Soviet republics and are operated by Russia under a series of bilateral agreements with the host countries. Russia is also in the process of upgrading and modernizing its SSA capabilities with the Automated Space Danger Warning System (ASPOS) to track space debris and support national security.
Russia has two bistatic phased array radars in Pechora (Russia) and Gabala (Azerbaijan). There is another Bistatic phased array radar in Belarus, operating near 3GHz. The Don-2N radar, known as Pill Box, is a four faced phased array radar which is a part of the ABM system protecting Moscow. Russia also maintains older radars in Kazakastan. Russia also operates an optical tracking facility in Tajikistan, which gives coverage of the GEO belt only over Russia. Similarly, Russian sensors offer less accuracy in LEO due to lack of geographical distribution. The Russian government does not routinely share data from these facilities with other entities.
Russian Academy of Sciences manages a network of optical telescopes known as International Scientific Optical Network (ISON) which is partnership between many academics and scientific institutions and consists of about 30 telescopes of 20 observatories in 10 countries. ISON as a network can track a wide range of objects through deep space with its facilities located mostly in Europe and Asia along with one being located in South America and off the coast of Africa.
People’s Republic of China (PRC)
A variety of open evidence shows that China is making significant investments in SSA to support both its civilian and military space programs. China is now number 1 country in number of satellite launches, but the more satellites China puts into orbit, the more it needs to keep track of objects that might threaten them.
PRC has radar sensors that could be or are used for SSA purposes, but this information is not publicly known. Reportedly China has network of phased array radars with estimated range of 3000 km and 120 degree of azimuth coverage. It laos has long range precision mechanical tracking radar. China operates two Yuanwang tracking ships which can be deployed to broaden its coverage for SSA. PRC does operate four optical observatory locations from its Purple Mountain Observatory. Again, due to sensors being located only in China, global coverage of the GEO belt is not possible with this optical network, even as objects can be tracked through all orbital regimes.It is postulated that seven radar sites exist inside China which contribute to tracking of objects in LEO
China is using its growing space program to achieve a range of geopolitical and economic goals, including attracting partners for its Belt and Road Initiative (BRI), improving economic and political ties with other countries, and deepening others’ reliance on its space systems and data services. In 2015, Beijing secured a deal for a much larger and more capable satellite and space mission control center in Patagonia, Argentina,” the report said. China has said the Patagonia tracking station is part of its deep space network for communicating with scientific spacecraft. However, the Argentine government has little insight into the actual functions of the station, which is under the control of an arm of the Chinese People’s Liberation Army that is in charge of “telemetry, tracking, and command of Chinese military space missions as well as counterspace activities.
“Experts assert the facility operates with virtually no transparency and could be used to collect intelligence on satellites, missile launches, and drone movements, and to interfere with or compromise communications, electronic networks, and electromagnetic systems in the Western Hemisphere,” the report stated.
Currently, the People’s Liberation Army relies on an extensive network of ground stations to downlink data gathered from reconnaissance, weather, and early-warning satellites and determine unit locations through the Beidou global navigation satellite system. This supporting infrastructure is largely operated by the PLA Strategic Support Force, which was established in late 2015 and consolidated many of the various organizations responsible for tracking, testing and launching space vehicles under its Space Systems Department [航天系统部]. Maintaining communication with more than 200 satellites and downlinking their data for commercial and military purposes, including a nascent space-based early warning system and a communications network, will increasingly be vital for China’s modernizing force.
The Space Situational Awareness (SSA) programme which was initially introduced by European Space Agency (ESA) in the year 2009, was an initiative designed to support Europe’s Space access and utilisation through the timely and accurate information delivery regarding the space environment and threats to orbital as well as ground-based infrastructure. The ESA’s space programme mainly consisted of three main segments viz. Space Weather (SWE) segment, Near Earth Object Segment (NEO) segment and Space Surveillance and Tracking (SST) segment.
Europe has several SSA sensors and facilities. European radar capabilities are the French GRAVES radar, the German Tracking and Imaging Radar (TIRA) system, and the European Incoherent Scatter (EISCAT) system.
The GRAVES radar owned by French military is a continuous wave bistatic fence. It is primarily developed to establish and maintain a database of satellites flying over France at altitudes of less than 1000 kilometers. German TIRA is a monostatic mechanical tracker that can track objects as small as 2 cm at an altitude of 1000 km. Germany’s fraunhofer institute for high frequency physics and radar techniques of is developing the German Experimental Space Surveillance and Tracking radar (GESTRA) to track objects in low earth orbit. Unlike TIRA, GESTRA has an electronically moving antenna and therefore can be reoriented faster as it has no heavy moving parts. The passed array system at 1.3 GHz is capable of tracking multiple objects at the same time while still supplying data of high accuracy and sensitivity.
Norway in cooperation with US government maintains GLOBUS II which is deep space mechanical tracking radar that can track and image objects in the GEO belt. Norway is also home to the European Incoherent Scatter (EISCAT) radar system which is used for space debris research. The present Optical facilities are France’s SPOC, ROSACE, and TAROT, the UK’s PIMS, and Zimlat in Switzerland.
The European Space Situational Awareness (SSA) Programme is being implemented as an optional ESA programme with financial participation by 14 Member States. It began in 2009, and the programme’s mandate was extended to 2019 at the 2012 ESA Ministerial Council. The second phase, Phase II, of the programme is currently funded at €46.5 million for 2013–16.
Some of the facilities that were developed in Phase-1 are Space Weather Coordination Centre, Space Pole, Brussels, Belgium , Space Weather Data Centre, ESA Redu Centre, Belgium, NEO Data Centre, ESA/ESRIN, Italy, Space Surveillance and Tracking Data Centre, ESA/ESAC, Madrid, Spain, SSA Tasking Centre, ESA/ESOC, Darmstadt, Germany, Development and installation of a monostatic test radar, Santorcaz, Spain, Development and installation of a bistatic test radar, France and Initial design of the SSA FlyEye automated telescope to enable full-sky NEO scan.
Australia’s contribution tio the SSA effort is primarily on ground based sensors for space surveillance. It is hosting in collaboration with US USAF C-band radar and the DARPA Space surveillance telescope at the Exmouth in WA and laser tracking by EOS on Mt Stromlo. The complementary tracking is afforded by UNSW Canberra’s new Falcon telescope, part of growing Falcon Telescope network.
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.
The Kamisaibara Spaceguard centre, KSGC has radar sensor capability and is able to detect objects 1 m in diameter at 600 km range. It has a phased array with mechanical scanning in the azimuth direction. It can observe multiple space objects simultaneously (Max 10 objects). It can also observe reentry objects.
However, optical telescopes are being designed to observe up to 36,000 Km. The Bisei Spaceguard Centre, BSGC has optical sensor capability and a longitudinal coverage of 68 deG E and an altitude of approximately 2000 km to 40,000 km. It observes space objects approaching to JAXA satellites and also facilitates NEO (Near Earth Orbit) observation.
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’s SSA efforts
ISRO has been dependent on North America Aerospace Defense Command (NORAD) data for tracking the debris and monitoring of the active and passive satellites in the orbit. ISRO, not being a NORAD member, hasn’t been able to access the real time data. This limited access to the batch data also resulted in the lack of accuracy and precision and delay in locating the space junk. Along with other efforts of indigenisation of space technologies, ISRO’s Space Situational Awareness Control Center can be considered as a notable step in order to make India’s Space Program more sustainable, secured and independent.
ISRO has set up the Directorate of Space Situational Awareness and Management to protect high-value assets from space debris’ close approaches and collisions. The Directorate engages in evolving improved operational mechanisms to protect Indian space assets through effective coordination amongst ISRO/DOS Centres, other space agencies and international bodies, and establishment of necessary supporting infrastructures, such as additional observation facilities for space object monitoring, and a control centre for centralized SSA activities. NEtwork for space object TRacking and Analysis (NETRA) project is initiated as a first step towards meeting this goal, its main elements being a radar, an optical telescope facility, and a control centre. ISRO SSA Control Centre, “NETRA”, is now set up within the ISTRAC campus at Peenya, Bangalore.
In addition, dedicated labs will also be set up in this control centre for Space Debris mitigation and remediation, compliance verificationof UN/IADC guidelines andvarious R&D activities. The R&D activities will encompassspace object fragmentation and break up modelling, space debris population and micrometeoroid environment modeling, Space Weather studies, Near Earth Objects and planetary defence studies etc. The establishment of ISRO SSA Control Centre marks an important milestone towards enhancement and augmentation of ISRO’s SSA capabilities, paving the way for greater self-reliance under the ambit of “Atmanirbhar” Bharat.
On 14 December, 2020, the ISRO SSA Control Centre,was formally inaugurated by Dr. K. Sivan, Chairman, ISRO/Secretary, DOS, re-iterating the need for setting up a state-of-the art facility dedicated to SSA activities on par with international agencies. India’s counter-space activities organisation Defence Space Agency (DSA) has formally started scouting technologies to enhance its abilities to tackle threats in and from space.
The DSA has made proposals to several companies to avail technologies that give complete space situational awareness (SSA) solutions that can assess, recognise and track assets of the enemy, Times of India reported in Feb 2021. It will also be tasked to raise flags over any impending attacks and a request for information (RFI) regarding the same was released in January 2021. Companies have time till March 2021 to respond to the same. Moreover, the DSA is in the lookout for a system that can combine the available surveillance data from different sources into a common operating picture (COP).
This will be done to improve the evaluation of possible threat and also optimise the efficiency of Indian operations in land, sea, space and air domains. The agency is also in the search of categorising space objects and even obtaining analysis tools for predictive assessment. The central government formulated the DSA to counter China’s development and procurement of a range of space capabilities to restrict or prevent the enemy’s use of space-related assets in times of crisis or conflicts. The Defence Research and Development Organisation (DRDO) has commissioned a few projects but the DSA aims to further stimulate India’s progress in this sector.
The second two-plus-two dialogue between India and the USA concluded in December 2019 in Washington DC. The two countries made a comprehensive review of cross-cutting foreign policy and defense and security issues in bilateral ties. One of the noticeable issues discussed during this dialogue was the Space Situational Awareness (SSA). Both parties agreed to cooperate for exchange of Information regarding space debris and space traffic management. The USA has already attained expertise in the field and possesses considerable SSA data. This data will be of significant value in ensuring the navigational safety of Indian space-based assets.
Space Data Association (SDA)
SDA is an international organization of satellite operators working to, in part, enhance the “accuracy and timeliness of collision warning notifications.” The Association is driven by the member’s needs for in-time SSA information, with the members being mostly GEO satellite operators (EUTELSAT, INMARSAT, and others). The data shared amongst its members are not made public, and their source is the satellite operators themselves.
International Scientific Optical Network (ISON)
ISON is an international project, currently consisting of about 30 telescopes at about 20 observatories in about ten countries. ISON, as a civilian global space surveillance system, covers the whole GEO and is capable of searching and tracking objects both on GEO and various classes of HEO orbits (GTO, Molniya, etc.). From the published papers and reports coming from the network, it is clear that the tracking capabilities of ISON are quite capable. Unfortunately, there is limited dissemination of their data, gated, and only valid for the analysis of past observations, not for future permissions. Participation in the Network seems to be gated too since there is no clear path of joining or an established process to contribute.
References and Resources also include: