http://www.secureworldfoundation.org/index.php?id=20Below are reports written on space situational awareness.
What is the International scientific optical observation network (ISON) for the near-Earth space surveillance? An interview-style format with Dr. Vladimir Agapov helps answer the question. http://www.secureworldfoundation.org/siteadmin/images/files/file_249.pdf
More information can be found here http://lfvn.astronomer.ru/report/0000029/index.htm
. What is the ISON?When was it introduced?
The ISON is scientific project initiated by the Keldysh Institute of Applied Mathematics (KIAM) of the Russian Academy of Sciences (RAS) joined then by Pulkovo Astronomical Observatory of the Russian Academy of Sciences.
Initially it was a project aiming to establishing of regular observations of GEO region in order to obtain enough data to confirm theory of evolution of fragment clouds created in explosions of old GEO resident objects. Another goal was to support radar experiments with additional tracking data using for determination of orbit precise enough to properly point narrow radar beams on selected objects.
First experiments were conducted in 2001. Idea of the project had been presented to the public for the first time in 2003 at the conference of the ISTC (International Science and Technology Center, an intergovernmental organization dedicated to the nonproliferation of weapons and technologies of mass destruction). Since May 2004 close cooperation started with colleagues from the Great Britain (former Observatory Sciences Ltd. operated so called PIMS optical network for the UK defence ministry) and then from ESA (ESOC) and Switzerland (Astronomical Institute of the University of Bern, AIUB) (since August 2004). First results had been presented at the 4th European Conference on Space Debris at ESOC, Darmstadt in April 2005.
Initial efforts had been supported by the INTAS (International Association for the Promotion of Co-operation with Scientists from the New Independent States (NIS) of the Former Soviet Union, unfortunately not functioning anymore) grants and the special grant by the Russian Ministry of education and science.
Since the end of 2004 the project was concentrated on developing and operating of the international network of optical instruments capable to search and track faint space debris objects on higher geocentric orbits. The aim is improving of our knowledge about pollution of unique regions of the near-Earth space (first of all, GEO) due to launches, on-orbit operations, explosions, deterioration of the spacecraft outer surfaces in time etc. It is important to understand which sources of space debris exists in that orbits, how many explosion events already occurred, how the overall debris population is growing and evolutioning.
In 2007 the project was officially presented at the United Nations level at the 44th session of Scientific and Technical Subcommittee of the UN Committee on the Peaceful Use of Outer Space. In 2008 at the 45th COPUOS STSC session the further development of the ISON and obtained results are presented.
As of the beginning of 2008 the ISON joins:
18 scientific institutions in 9 states
18 observatories and observation facilities
25 optical instruments
more than 50 observers and researchers
The project principal coordinator is KIAM.
The ISON structure includes:
network of participating optical facilities consisting of
- search and survey subsystem for studying of bright objects in GEO region
- subsystem for high altitude space debris detection and tracking
- search and survey subsystem for studying bright objects on HEO, MEO and LEO orbits
center for observation planning and data processing including maintenance of the database of space objects
group of technical and programming support group of the network developmentWhat technology does the network use to observe objects in orbit?
All instruments involved into the project are representing different optical telescopes with aperture ranging from 22 cm to 2.6 m. Some of them are installed on automated mounts and automation for others is undergoing now. All telescopes are using CCD cameras (mainly produced by Finger Lakes Instrumentation, FLI, well known company developing CCD imaging systems for scientific applications) for registration of object trails on the star background. Obtained frames are processing with special software (developed within framework of the project) in order to obtain accurate timing and positions of the observed objects. Those data are using for orbit determination of each object and orbital analysis at the Ballistic Center of Keldysh Institute of Applied Mathematics (KIAM). Special software package for CCD camera control, mount control in different observation modes is also developed within framework of the project.
Using optical instruments technology is much cheaper than of radar one especially for high altitude objects which requires very high power of transmission in case of using radars for tracking and even more – for search of unknown objects.
Series of small (22 to 50 cm) aperture size instruments had been developed within the framework of the ISON project specially to meet the requirements defined by solving tasks of high altitude objects observation. Some existing classical astronomical instruments (like widely used Zeiss-600 and Zeiss-1000) had been improved by means of extending of the FOV and automation of mounts. Even some of purchased CCD cameras produced by FLI had been redesigned or specially improved to meet requirements of the ISON observation instruments or observation strategies.What kind of objects does it observe?
Each subsystem of the ISON is aiming to observe objects on different orbits. But all together they are aiming to obtain regular observations for as much number of high altitude space objects as possible in order to complete more or less complete picture.
Thus the ISON is observing operational and non-functioning spacecrafts, spent rocket bodies, operational debris (different kinds of covers, casings, adaptors etc.) releasing during normal launch and on-orbit operations and fragmentation debris from explosions and other events including spacecraft outer surfaces deterioration processes.
In terms of optical observations the ISON is capable to track objects as faint as 20th magnitude which corresponds to size of 10-15 cm at GEO distance (36000-40000 km) for object with some standard albedo (reflectivity). Due to real albedo as well as shape and attitude of space debris objects are not known real size of observed objects can vary in significant range.
Smaller survey instruments have less sensitivity than larger tracking ones. Though it should be noted that some of tracking telescopes have the size of field of view well enough in order to establish some local surveys in predetermined parts of inertial space.
The ISON is discovering and tracking the unique class of high altitude objects discovered for the first time in 2003 by the AIUB team with help of ESA Space Debris Telescope at Tenerife. These objects have enormously high area-to-mass ratio (AMR) which from 100 to tens of thousand times larger than for ‘normal objects’ – spacecraft and rocket bodies. This results in very strong orbital evolution due to perturbations caused by solar radiation pressure usually negligible for large and massive orbital objects. Due to these strong perturbations eccentricity of orbit of high AMR objects significantly varies. Depending of the AMR value, such objects initially appeared, say, on near-circular near GEO orbit very soon (in a few months) have reaching lower altitudes (in perigee of orbit) and even can at some moment to plunge into the atmosphere and to burn (been ‘born’ at the altitude of around 37000 km)! It was considered previously that such objects should be short lived and there should not be large amount of them on orbits. But results of the research made within framework of the ISON shows that we had been mistaken. More than half of newly discovered previously unknown faint high altitude space debris objects have AMR value large enough (1-10 and more sq.m/kg, compare – office paper sheet depending of quality have AMR value in range of 10-14 sq.m/kg).What danger could these objects pose to satellites and other spacecraft?
The main danger posed by the space debris and even by operational spacecrafts is unintentional collision with other operational spacecraft resulting in some cases in destruction of both bodies and creation of a large cloud of new space debris objects which in turn are raising probability of new collisions etc. Despite of the first imagination about the near-Earth space as an almost empty region in fact space debris objects are concentrating on or around the most used orbits.
In the 1970th American scientist Donald Kessler theoretically proved that there is possibility that number of space debris objects will start to grow like in a ‘chain reaction’. This can happen when number (or in other words, spatial density) of space debris objects will exceed some limit. This limit which is hard to estimate without complex mathematical model represents the boundary of space debris population stability.
Modern space debris evolution models predicts for LEO orbits constant increasing of space debris population due to collisions and around 2055 the number of collision produced space debris will exceed rate of natural ‘cleaning’ caused by upper atmosphere and will continue to grow. This result is obtained by the American scientists thanks to involvement into the model a large amount of observational data as well as data produced by sophisticated models for some space debris creation processes. But for high altitude orbits (GEO, HEO) our knowledge of the current situation is very poor so we are not able to reliably predict the future situation there especially taking into account growing interest in using GEO orbit (limited natural resource).How does ISON differ from other space surveillance systems (such as CFE data provided by the US Air Force)?
First, it should be noted that the term ‘space surveillance’ till present had been used only for military/government systems. Of course, it does not means it should not be used in more wide context, for example, with reference to scientific projects like the ISON. But we do not use this term with respect to the ISON at present to avoid some misunderstanding caused by that ‘traditional meaning’.
The ISON is an open international scientific project while existing space surveillance systems (U.S., Russian, French) are closed (and mostly classified) operational military structures working in on-duty mode. This is fundamental difference. We do not have on-duty staff, do not use special wired, optical etc. lines for communication/data transmission other than provided by the global Internet network, do not have standby or static reserves like additional CCD-camera on each facility etc. except maybe just computers etc. So, by operational nature the ISON represents just scientific community of people having joint interest and common understanding of importance of the solving scientific task while other space surveillance systems are large dedicated military units with all appropriate features.
As for the other differences, the primary one is the difference in solving tasks. We do not try to solve the problem of understanding the role each launched spacecraft plays like militaries do. We do not try to find out ‘special properties’ of operational spacecrafts and to discover their ‘soft spots’ for negation purposes. We do not using obtained data for planning of military operations on a space battlefield . We consider every orbiting object (including operational spacecraft which sooner or later are becoming a piece of dead metal) only as a potential source of danger for other objects due to possible unintentional collision or due to releasing of new space debris (including those creating in explosions of spacecrafts and rocket bodies or their parts and in other type of fragmentation events as well as during normal launch and on-orbit operations) regardless of it’s origin or ownership (all nations are equal) or purpose. And we are interested in understanding of long term global evolution of whole space objects population based on initial accurate and as complete as possible deterministic picture while military space surveillance systems are much more interested in having precise up to date deterministic picture each moment of time and in short prediction of situation based on it.
Also, despite of that fact we, similar to ‘traditional’ space surveillance systems, have developed ‘standard’ software for our hardware control and data processing which is using at every our participating facility with only few exceptions, we are not restricted, like militaries, to modify our solutions anytime trying to constantly improve our network. This does not mean our approach makes the ISON unstable system – there is some predetermined order of new ideas testing and implementation like in every large scientific project. But it makes our system more flexible than other space surveillance systems which are much more conservative.
As for the output, the ISON is comparable in this, say, with the US Air Force SSN. We also have producing orbital solutions, orbital predictions, have making analysis of the observed object’s brightness patterns, and analysis of some physical properties of observed objects like area-tomass ratio. But we have using different models for this. As a result, some of our output has quality much better than of the US SSN data provided for the public within framework of CFE initiative has.
Also, because we do not try to immediately identify each object with correspondent source (specific launch, other event or object) then we do not have restrictions on ‘creation of a new entry in official catalogue’. You probably know that the US SSN do not provide data for around of 6000 objects (mainly on LEO) they are continuously or periodically tracking but for which they are not able to determine ‘origin’ by some reason and do not keep records about such objects in ‘official catalogue’ represented for public by weekly Satellite Situation Reports (SSR). So, at every moment we have more ‘complete official records’. As for now, we definitely have much more complete database for GEO population than the U.S. Space Surveillance System (this evaluation is made by American colleagues unofficially) which is the most powerful installation of a such kind at present.
Also, we do not have strong restrictions on classification of objects from the point of view of reliability of tracking. That means we can put into our database all objects – both well tracking and have obtaining confirming measurements frequently as well as ‘rough orbits’ do not actually representing ‘real object’ (saying this I mean that this orbit can not be identified with other ‘good’ ones and can not be used for propagation and deterministic orbital analysis purposes) but rather giving just some knowledge about some orbital elements of the orbit. Of course, we have making analysis of ‘rough orbits’ in order to correlate them between each other and to construct reliable orbit for new objects. But it is very complex mathematical problem and it is not possible to solve it in any case.
Another very important difference is that there is open data exchange between the ISON partners in Russia and Europe. In 2004 for the first time in such wide international cooperation it had been established exchange not by only results but by raw observation data on GEO and high elliptical objects as well. We do regular exchange between KIAM and AIUB. AIUB, on behalf of ESA, provides also data obtained by the ESA Space Debris telescope on Tenerife. Thanks to this close and fruitful cooperation it became possible to significantly improve both quality of data and operational characteristics of the whole network especially in the field of research of the most faint space debris objects on high altitude objects. Unfortunately, there is no such exchange with American colleagues which are very restricted in distribution of their measurements and orbital data (not only with Russian scientists but even with European as well).
I am not able to compare average daily/monthly/yearly amount of measurements of the ISON and other space surveillance systems (you have these figures for the ISON on the one of viewgraphs) but I think that the numbers are comparable now.How did ISON improve space surveillance? What objects did it track that hadn’t been observed before?
The population of high altitude objects is very large though the real count of it’s members is not known yet for objects with size less approximately than 1 m (for LEO this figure is more or less reliable for objects with size larger than 10-15 cm). Moreover, this population is the most hard to study due to large distances (normally in range 25000-50000 km). If you would like to use radars then you should have very powerful ones (because received energy reflected by an object is inverse-quartic-law of a distance between the radar and the object) which will increase the cost to enormously high level. In contrast, optical instruments do not require another power to detect object in addition to that one given freely by the Sun and reflected by the object surface (so, in case of optical observations received energy reflected by an object is inverse-square-law of a distance between the telescope and the object that makes telescopes much more sensitive instruments for detection and tracking of small objects on large distances). That is why optical instruments are most common ones used to study GEO and HEO objects since 1970th. But the optics has significant constraint which radars do not have – it is the weather. Only a few places on our planet have almost absolutely dry and clear weather all the year. But these places are mostly very hard to reach and are located in very rarely populated or absolutely uninhabited regions so the cost of operating telescopes there would be very high. Moreover, even taken all together those places do not permit to cover all high altitude orbits. Due to this constraint it is very usual situation, for example, for the U.S. SSN when some particular high altitude object is becoming ‘lost’. In fact that means the object had not been obtaining confirmation measurements during long period of time and even if new measurements for it will arrive to the processing center it will be to hard if possible at all to identify them with the ‘lost’ object using only automatic software (in such cases usually only an analyst involvement capable to operate with additional ‘non-standard’ software can help to solve the problem but not always). Other hard cases are representing by maneuvering high altitude non-GEO and non half-day period MEO spacecrafts and elliptical objects with very low perigee (in range of 80-250 km). These kinds of objects require almost constant tracking. Otherwise they can be lost within short period of time (a few days). Finally, small size objects (say, 15-20 cm) at large distances are usually very faint that requires to use large aperture optical instruments or special observation/processing technique for medium-sized aperture instruments. But another problem waits around here. This time it is the Moon. It is becoming too bright in 2nd and 3rd quarters and creates very unfavorable light pollution of the star background. Weak faint object trails are also drowning by very bright moonlight. And finally, if GEO or near-GEO objects have ‘regular’ conditions of observation (though slowly and slightly periodically changing) but HEO objects have rapidly changing conditions of observations from the particular observation facility in terms of brightness, period of visibility, angular velocity (that is very important as well for the accuracy of optical observations especially in combination with brightness variability).
From explanation given above I hope it is clear (or almost clear ) that the only solution of the problem is developing worldwide distributed network of sensors of different class. First of all, this approach provides certain backup for the case of bad weather conditions. Second, it permits to cover all high altitude orbits from multiple locations that is very important from the point of view of providing acceptable observation conditions for HEO objects for as long time as possible. Wide FOV (small and average aperture size) survey class instruments can help to do the routine job on regular tracking of relatively bright objects (brighter than 16th – 16.5th magnitude) while large instruments can be effectively used for search of the most faint objects during periods of time close to the new Moon. These objects than can be tracked by medium-size aperture instruments.
You see, that the ISON implements (or is trying to implement) the strategy described above with certain level of success. Thanks to this approach the ISON is covering now entire GEO belt, capability which only the US SSN had till the recent time. Another advantage of the ISON wide cooperation is effective use of medium and large aperture size existing astronomical instruments for high altitude space debris discovering and tracking. This was never done before except maybe just a few special cases.
As a result of all efforts, the ISON scientific cooperation have discovered already 152 unknown bright GEO objects, 120 unknown bright HEO (mainly GTO) objects, more than 440 faint (fainter than 15th – 16th magnitude) high altitude (GEO and GTO) objects including ones with high AMR (nearly 200 of those 440 objects are continuously tracking).So, 2.5 years of work of the ISON have resulted in increasing of known population in GEO region more than 35 per cent (more than one third of previously known and tracked by the whole US SSN!). This is significant achievement taking into account that till now the ISON do not have (and never had) special funds for it’s development and operation provided by the government or industry. It is pure scientific project funding by scientists working in it from grants, research works etc.
Among those objects discovered by the ISON there are a lot of fragments confirming existence of clouds created in explosions of some GEO objects (old spacecrafts and upper stages). This question has initiated the project and now it is one among many others for which we have clear answer. Though this answer is still far from complete – new discoveries raised new questions.
For example, it is not clear yet how high AMR objects are definitely creating. Now it seems that creation of these strange objects has strong relation to the deterioration of multilayer insulation (MLI) covering the spacecrafts and protecting them from severe temperature conditions in space (varying from too cold to too hot). And it is possible that the process of MLI deterioration can be continuous that means high AMR objects can be creating ‘on a regular basis’. Determining the mechanism of high AMR object creation is very important from the point of view of space debris mitigation. We should not leave more and more waste in space developing more and more problems for the future generations. Instead we have to implement into the design of a new spacecrafts such solutions which would prevent creation of any kind of space debris. In order to better understand mechanisms of such kind of space debris creation it would be good to identify at least one of ‘parent’ sources of these objects. In order to do this we have to obtain solid orbital archive of space debris and to make ‘time reverse’ analysis of the evolution trying to find in the past ‘close encounters’ of those debris and suspected ‘parents’. The ISON is going by this way.
Other improvements of space surveillance thanks to the ISON work are development, testing and implementation of new standard approaches for CCD camera and mount control, new methods of CCD frame processing (including automatic processing of very large size frames covering up to 10°x10°). New approaches for correlation of short tracks spaced by days or even months had been successfully tested and implemented that in turn resulted in jump of number of faint space debris in GEO discovered by small (22 cm) aperture instruments. Are initiatives like space surveillance important for space security?
Space surveillance is a cornerstone of space security (if shorten ‘space security’ to the frame of issues concerning of artificial space debris) regardless of context in which the ‘space security’ term is using – national or international. In global context space security can be considered as a set of measures devoted to preservation of near-Earth space for the all mankind at present and in the future especially if one take into account growing dependence of humanity of technologies using in space and from space (remote sensing, navigation, communication, weather service, search and rescue, fundamental scientific tasks, space weather etc.) as well as some technologies using to keep watch over known problems of our world.
One of the main problems of space security (in wide meaning) is timely prediction of danger posed to operational satellites by other orbiting object because damage of any operational satellite results in degrading performance in solving of particular task. This problem can not be solved without very good knowledge of what is happening ‘above our heads’.
Talking about space security from the international point of view, establishing of global space surveillance which involves any nation wishing do what one can seems very important task. Of course, such system should have certain level of transparency and should be coordinated at international level.How does space surveillance need to be improved in the future?
First of all, one should reach some level at which our knowledge on situation in space would be equal for all types of orbit to at least current LEO ‘completeness’ level from the point of view of estimated objects size. This will permit to construct much more accurate picture of the evolution of whole space debris population, to identify yet unknown sources producing space debris on different orbits and thus to correctly estimate possible quantity of still undetected space debris objects. In order to do this special worldwide distributed network of optical instruments (capable
to observe objects on LEO, MEO, HEO and GEO) and maybe radars like the US Air Force Space Surveillance System (AFSSS, radar fence earlier known as NAVSPASUR) should be developed. In fact, existing astronomical facilities can be used for placement of special telescopes devoted to observation of space debris objects.
There is nothing impossible in this idea if one takes into account existing worldwide network of hundreds of telescopes (operated sometimes by amateurs and not professional astronomers) searching and tracking asteroids including those ones having close encounters with the Earth as well as dedicated project like the ISON. There is nothing absolutely new in coordination process of such network – we have at least two excellent examples of civilian coordinators represented by Minor Planet Center (MPC) and Keldysh Institute of Applied Mathematics Ballistic Center (for the ISON). It would be good if such coordination would be established under the UN aegis.
Second important direction of improvement is significant rising of quality of space surveillance data, especially orbital solutions quality. Most of the data provided by the US Air Force within the framework of the CFE initiative have average, poor or very poor quality especially for high altitude objects, objects with high AMR value of small sized objects that does not permits to use that data for precise calculations supporting decision making in case of some dangerous situation is predicted.
The next problem to be solved is creation of the world space surveillance data center supporting by and accessible to all nations. This center should collect information not only from the network discussed above but also from operators of spacecrafts.
Much more complex but very important improvement is further development of observation instruments (radar and optical) for the purpose of establishing of tracking of as many LEO objects as possible down in size to a few cm or even less. This task requires development not only of instruments but absolutely new algorithms and software for maintenance of space object catalogue containing more than 100000 actual records. This is complex and thus interesting mathematical task.Why does it need to be improved?
As it was said above, the main problem of the current space surveillance is incompleteness of knowledge of situation for different orbits, average or poor quality of produced output, rare orbital data update for many objects (low timeliness), low reliability of data in some cases. All this factors are significantly decreasing capability to make proper decision in situation of danger. In other words, current space surveillance capabilities does not meet even current (not talking about the future) space security requirements.What are the current initiatives to improve space surveillance?
In short, known (unclassified) of these initiatives can be listed as following:
- development, deployment and operation of a new optical network for the U.S. SSN within the framework of the HANDS (High Accuracy Network Determination System) program (several telescopes are already deployed)
- development of a new system of ground-based sensors to replace Air Force Space Surveillance System radar fence (AFSSS, former NAVSPASUR) within the framework of the Space Fence program (to be produced and deployed in FY2013-2014)
- development and operations of PanSTARRS (Panoramic Survey Telescope and Rapid Response System) telescope on Haleakala, Maui (initial operation is started already)
- development of space-based space surveillance capabilities within the framework of the Space-Based Space Surveillance (SBSS) project (launch of Block 10 “Pathfinder” system is expected in FY2009)
- development of own space surveillance system, final decision on funds and оperation concept should be made by the end of this year
- development of new observation facilities operated by the Ministry of Defence (there is no detailed information about this plan)
- development of the federal automated system of dangerous situations in space warning (ASPOS OKP), project initiated and funded by Russian Federal Space AgencyWhy is space traffic management becoming an increasing issue?
Despite of really huge volume of space around the Earth and apparent unlimited number of possible orbital elements combination only very limited parts of that space is using by functioning spacecrafts. This fact can be easily understood if one took into account special requirements to operational orbits for different applications namely illumination conditions on the Earth surface for the remote sensing, global or regional coverage with minimal number of spacecrafts for communication, navigation and Earth imaging, stability of the ground track position with respect to the Earth surface for various applications etc. As a result, at present we have just several heavily populated regions like sun-synchronous and other near-polar orbits of different heights, half-day near-circular and ‘Molniya’-class elliptical orbits, geostationary orbits which are unique by nature, various (but typical) geostationary transfer orbits specific for each launch site. All other space is almost not using by operational spacecrafts (though it is populated by space debris fragments, originated mainly from explosions). In other words, we have just a few space roads with constantly increasing traffic on them. And all this happens in situation when we do not have clear rules for ‘driving’ these ‘roads’ in harmony between ‘drivers’. Nobody knows what is ‘excellent driving’ and what is ‘crime on the road’. Moreover, we are leaving our tools, spare parts, empty tanks, old dead metal on the same roads do not worrying at all about possible danger which can be posed by this stuff not only to other ‘road users’ but for ourselves as well. The situation is worsening by unexpected explosions creating thousands and thousands of new space garbage pieces.
Analysis of current situation shows that the problem of unregulated space traffic already appeared at least in GEO region. Close, sometimes dangerous, proximity operations are now common in some GEO slots where spacecrafts of different operators (and even different nations) are located. Solution finding process in such situation is relying solely on goodwill of parties. But the situation can became much more complex soon due to constantly increasing number of spacecrafts and growing their lifespan.
It seems that common rules of activity in space should be widely discussed and finally developed. In general, like in case of usual roads we’ve using every day, these rules should include statements on what is prohibited, how to act properly in different situation, who is guilty (for example, if dangerous close encounter happened due a spacecraft of one operator made a maneuver and entered trajectory crossing orbital path of other spacecraft will be that operator guilty?), which punishments will follow in case of the rules violation, defines levels of responsibility etc.
Of course, development and adoption the rules will not solve the problem if there will be no effective measures to control abidance by rules, exposure of violations and means to collect solid evidentiary base. Obviously all this is possible only in case of existence of very good international space surveillance system which would serve as an arbiter whose authority is recognized and is not in doubt. In addition to improvements in space surveillance such as ISON, how else do you think space traffic management should be improved?
I think that answers on previous questions do contain at least partial answer on this question. In short, following measures should be implemented:
- world databank on orbital traffic should be created, transparent rules should be adopted on how the databank is filling, how it is accessing etc.
- as a first step (prior to the world databank) bi- or multilateral agreements on space surveillance data exchange should be implemented
- some level of coordination of the spacecraft orbital maintenance between different operators should be considered
- rules on the roads should be developed, discussed and adopted by the international community (at the UN level?)