The subject of the study are space threats – Near-Earth Objects (NEO) and Potentially Hazardous Asteroids (PHA). The research methods employed in this article included the classic theoretical methods used in security sciences and a practical method – a quantitative study of social media. At present, space threat studies aim to resolve the terminological confusion related to NEOs, to determine current and potentially hazardous space objects and estimate the potential threats from them. The research is also expected to come up with two methods for estimating NEO threats, the Palermo and Torino scales. The practical result is to evaluate the public mood regarding NEO threats. Studies have shown that certain active space objects are capable of reaching the Earth’s surface and colliding with human-made in-space objects and devices, such as communication satellites. Should this happen, it could cause substantial social damage and destabilise state security, particularly if elements of critical infrastructure of the state were to be affected. Continuous monitoring of NEOs may play a central role in the provision of security. Furthermore, the public should be kept abreast of the threats.
Outer space is a clear and present source of hazard to the Earth; the scope of dangers includes natural objects such as: asteroids, planetoids or fireballs. How serious the space threats may be was best illustrated by one of the most important and dangerous astronomical events of the last century that occurred in Chelyabinsk in the morning of 15 February 2013. A 20-meter meteor, travelling at a speed of approx. 19 km/s, flew over the Russian town generating a shock wave of kinetic energy amounting to 500 kt (
This paper combines review and research methodologies. The purpose of this study was to organise terminology related to NEOs, to provide examples of Near-Earth Objects and to present literature methods for the estimation of impact threat levels. The final aim of the research works was to study public activity and moods based on social media monitoring in a one-year timeframe.
Given that outer space has only recently begun to be considered in the context of emergence and evolution of threats, the relevant nomenclature requires clarification. Therefore, for the purpose of this and future scientific studies, this section reviews the specialist literature in order to define key terms and organise the terminology.
Asteroids are rocky remnants dated back to approx. 4.6 billion years ago – to the early formation of the solar system. Sometimes referred to as minor planets, they are orbiting the Sun in the main asteroid belt between Mars and Jupiter. Asteroids vary in size: the smallest specimens are less than 1 km in diameter, while the largest body, Ceres, is about 950 km across and is categorised as a dwarf planet. The total mass of all the asteroids combined is less than that of the Earth’s Moon (
C-type (carbonaceous) – the most common type, accounting for 75% of known asteroids. Very dark objects with an albedo of 0.03-0.09. Their composition is thought to resemble the Sun, i.e. the base material is depleted in hydrogen, helium and other volatiles. They are typically found in the outer regions of the main belt;
S-type (silicaceous) – 17% of known asteroids. Due to the metallic iron mixed with iron- and magnesium-silicates composition, they are relatively bright (albedo 0.10-0.22). Mainly in the inner asteroid belt;
M-type (metallic) – Relatively bright (albedo 0.10-0.18) on account of their main element – metallic iron. Dominate the middle region of the asteroid belt.
The differences in composition converge with the distance from the Sun. Exposure to elevated temperatures has resulted in their partial melting and caused iron to move to the centre and basaltic lava to the asteroids’ surface (
Asteroids are classified into families according to the domains of proper elements. They are either a product of collision or rotational fission. Young collisional asteroid families are particularly closely investigated as they contain information on their original expulsion velocity field and also because they may host a significant population of clusters produced by rotational fission (
Some studies trace the origins of the Earth and other inner planets to aggregation of vapour condensates and powders – planetoids – following a supernova explosion. Up to 1000 such planetoids, resembling physical fractals, have been detected (
Small solar system bodies were initially described as planetoids, only later to become known as asteroids. The shift in terminology also entailed introducing the technological limits of the time. With an increasing amount of spectral data for minor bodies, they are presently classified as asteroidal (primordial, undifferentiated surfaces) or planetoidal (showing some surface differentiation). The paragraphs that follow attempt to differentiate between a planet, a planetoid and an asteroid.
One source of confusion is that American and English-speaking sources tend to generically refer to all small, rocky bodies orbiting the Sun as asteroids (
Apart from asteroids and planetoids, the specialist literature uses other terms that require specifying such as meteoroids, fireballs and bolides.
When an asteroid or comet approaches the Earth’s orbit, it is referred to as a Near-Earth Object – NEO. The threat from NEOs is an object of ongoing debates by the international scientific institutions and governments and has not yet been clearly defined (
Asteroids exhibiting the capability of making close approaches to the Earth have come to be called Potentially Hazardous Asteroids (PHAs). To be exact, PHAs are all asteroids at a distance equal to the Earth Minimum Orbit Intersection Distance (
Particular names of NEO objects are a combination of digits and letters, which require proper clarification. A newly discovered asteroid receives a provisional name e.g. 1999 RQ36, which must conform to the guidelines of the Minor Planet Center at the Smithsonian Astrophysical Observatory. The first four digits designate the year of discovery, and further details are given by the last four characters: 1999 RQ36 was the 916th object observed in the first half of September 1999. An asteroid is issued an official sequential number when its orbit is established. Since 1999 RQ36 was the 101,955th asteroid to have been numbered, it is known as 101955. Statistics show that merely 5% of numbered asteroids are given formal names, e.g. following the proposal of their discoverers to the International Astronomical Union. In brief, proposed names must not exceed 16 characters (spaces and punctuation included), should be preferably one word that is pronounceable in some language and written using Latin characters (transliterations from non-Latin languages are acceptable); the name cannot be offensive nor similar to an existing name of a minor planet or natural planetary satellite. An additional requirement for NEOs is that their names are to be derived from any mythology, except for those associated with creation or underworld themes, which are reserved for other bodies in the Solar system. In certain cases, the definition may have to be stretched to include fictional mythological characters. These guidelines are to an extent flexible, and names that are not mythological are not automatically disqualified, yet a mythological name is more likely to receive an approval (
At present, NEOs are under constant surveillance. The Center for Near-Earth Object Studies (CNEOS) provides high-precision computations of their current orbits, projections of their future motions and assessment of their impact risk. (
Currently active major asteroids (
AsteroidNumber and Name | Diameter (km) | ~Mass 1015 kg | Rota- tion Period | Orbital (yrs) | Spec- tral Class | Semi- major Axis (au) | Orbital Eccentricity | Orbital Inclina- tion (deg) | |
---|---|---|---|---|---|---|---|---|---|
1 | Ceres | 965 x 961 x891 | 939,3 | 9.074 | 4.60 | C | 2.768 | 0.0758 | 10.59 |
2 | Pallas | 582 x 556 x500 | 205 | 7.813 | 4.61 | U | 2.772 | 0.2310 | 34.84 |
3 | Juno | 234 | 20 | 7.210 | 4.36 | S | 2.670 | 0.2563 | 12.99 |
4 | Vesta | 569 x 555 x453 | 259 | 5.342 | 3.63 | U | 2.362 | 0.0889 | 7.14 |
21 | Lutetia | 124 x 101 x 80 | 1,7 | 8.168 | 3.80 | C | 2.435 | 0.1646 | 3.06 |
45 | Eugenia | 215 | 6,1 | 5.699 | 4.49 | FC | 2.721 | 0.0835 | 6.60 |
140 | Siwa | 103 | 1,5 | 18.5 | 4.51 | C | 2.732 | 0.2161 | 3.19 |
216 | Kleopatra | 217 x 94 | 5.385 | 4.67 | M | 2.794 | 0.2504 | 13.11 | |
243 | Ida | 58 x 23 | 100 | 4.633 | 4.84 | S | 2.861 | 0.0412 | 1.13 |
253 | Mathilde | 66 x 48 x 46 | 103.3 | 417.7 | 4.31 | C | 2.647 | 0.2655 | 6.74 |
433 | Eros | 33 x 13 x 13 | cze.69 | 5.270 | 1.76 | S | 1.458 | 0.2227 | 10.83 |
1566 | Icarus | 1.4 | 0.001 | 2.273 | 1.12 | U | 1.078 | 0.8269 | 22.83 |
1620 | Geographos | 2.0 | 0.004 | 5.222 | 1.39 | S | 1.245 | 0.3354 | 13.34 |
1862 | Apollo | 1.6 | 0.002 | 3.063 | 1.81 | S | 1.470 | 0.5599 | 6.35 |
2060 | Chiron | 180 | 4 | 5.9 | 50.7 | B | 13.637 | 0.3827 | 6.94 |
2530 | Shipka | 5.25 | 3.017 | 0.1280 | 10.11 | ||||
2703 | Rodari | 5.5 | 3.25 | 2.194 | 0.0566 | 6.03 | |||
2867 | Steins | 6.8 x 5.7 x 4.4 | 6.049 | 3.64 | E | 2.363 | 0.1455 | 9.93 | |
3352 | McAuliffe | 2–5 | 2.57 | 1.879 | 0.3690 | 4.77 | |||
3840 | Mimistrobell | 3.38 | 2.250 | 0.0827 | 3.92 | ||||
4179 | Toutatis | 4.6 x 2.4 x 1.9 | 0.05 | 130 | 3.98 | S | 2.534 | 0.6294 | 0.45 |
4769 | Castalia | 1.8 x 0.8 | 0.0005 | 4.095 | 1.10 | 1.063 | 0.4831 | 8.89 | |
4979 | Otawara | 5.5 | 0.2 | 2.707 | 3.19 | 2.168 | 0.1441 | 0.91 | |
5535 | AnneFrank | 4.8 | 15.12 | 3.29 | S | 2.213 | 0.0635 | 4.25 | |
9969 | Braille | 2.2 x 1.0 | 226.4 | 3.58 | B | 2.341 | 0.4333 | 29.00 | |
25143 | Itokawa | 0.5 x 0.3 x 0.2 | 0.000035 | 12.13 | 1.52 | S | 1.324 | 0.2801 | 1.62 |
101955 | Bennu | 0.49 | 0.000073 | 4.276 | 1.20 | 1.126 | 0.2037 | 6.03 |
One of the most recently observed NEOs is (367943 Duende) 2012 DA14. At about 19:26 UTC (
The orbit of 367943 Duende as it approached the Earth (
Another potentially hazardous (PHA) near-Earth asteroid (NEO) is 25143 Itokawa (1998 SF36). This S-type object is roughly 0.5×0.3×0.2 km and weighs in approximation 0.000035×1015 kg. It is a particularly interesting subject of investigations due to its shape and internal structure evidencing a history of violent collisions, which may bring new discoveries regarding the structure and formation processes of rubble pile asteroids. The asteroid’s exceptionally rough surface is composed of boulders and in 20% of centimetre-sized gravel, constituting the flat surface. The “smooth terrain” areas are believed to indicate low areas of the gravitational potential where pebbles accumulated. According to computational models, Itokawa is composed of two dissimilar lobes – ”head” and ”body” – that should have different respective densities 2,450 kg/m3 and 1,930 kg/m3. (
Another notable NEO/PHA object is (99942) Apophis (2004 MN4), named after an Egyptian demon of destruction and the symbol of darkness. It was discovered on 19 June 2004 by researchers affiliated with the NASA-funded University of Hawaii’s asteroid detection and tracking programme. The asteroid’s average diameter is 0.325±0.015 km and mass 6.1×1010 kg, and it moves at a velocity of 30.73 km/s, which allows it to circulate the Sun in 323 days and 14 hours. According to estimates carried out using the full six-dimensional Monte Carlo method, on 13 April 2029, Apophis is expected to be at the closest distance from the Earth, 38,000 ± 580 km. (
During the atmospheric entry phase, the atmospheric friction causes such an object to decelerate and pick up temperature. It is preceded by a bow shock where atmospheric gases are concentrated and grow to extreme temperatures. The energy involved in the process tends to be exuded to the object resulting in melting and fragmentation. The breaking up increases the amount of atmosphere intercepted, further contributing to ablation and atmospheric breaking. In physical terms, the object breaks up when the forces from the unequal pressure distribution on the front and back faces exceed in aggregate its tensile strength.
Owing to their insufficient size, objects entering the atmosphere as fireballs are highly unlikely to pass intact; however, their fragments/meteorites are occasionally found on the ground. The atmospheric total radiated energy is given in Joules, a unit of energy expressed by kilograms times velocity squared, or kg x (m/s)
Given the current data, it is estimated that a space object (asteroid) sized between 1.5 and 2 km represents a threshold for a global catastrophe, which could result in the death of even a quarter of the world’s population. Various possible effects of such a collision are considered: the propagation of shock waves or tsunamis lasting several hours, fires continuing for several weeks, several months of darkness; in the longer time horizon and a wider scope, the impact would affect the entire planet, as it could inevitably lead to the greenhouse effect or the destruction of the ozone layer. The frequency of such objects’ impacting the Earth is, however, once in a million years. The probability increases with the decrease in the size of an object, e.g. an asteroid approx. 200 m in diameter is likely to impact once every 10,000 years, causing considerable damage should it hit densely populated areas. However, an asteroid that could trigger mass extinction is expected to come into contact with the Earth no more frequently than once every 100-200 million years.
One of the most spectacular impacts recorded in the relatively recent history happened in Tunguska. The composition of the object has been debated ever since, however, the hypothesis of the stony (asteroidal) nature of the object appears to prevail. In general, a low-density icy comet unleashing the energy in this range would not be expected to penetrate beyond the lower atmosphere; on the other hand, a tougher rocky object is more likely to reach the surface and produce a crater. Unless there are very few rocky objects in the small NEA population, numerous fresh kilometre-sized craters would be found. Instead, most of the relatively recent craters (such as Barringer Crater) are connected with rare metal objects. This confirms the mathematical models that provided the indication of the Tunguska explosion having been caused by a rocky asteroid rather than a comet. Considering a lower impact energy, 3 Mt, this the results from computations appear even more convincing. Numerical modelling has allowed researchers to assess the impact of such collisions, which is even more important given that the impact of this scale, by an asteroid of hundreds of metres or larger capable of causing a regional or global catastrophe, has not been observed by modern science. Mathematical models employ data from orbiting monitoring systems for small objects, which account for the low-energy end of the population distribution. Despite the inefficiency of the data, it is estimated, from 136 reported atmospheric entries between 1975 and 1992, that the annual maximum impactor has an energy of roughly 10 kt, corresponding to the Hiroshima atomic bomb and yet 1000 weaker than the Tunguska event. The strongest collision observed in the past 25 years (several tens of kilotons) (
The Center for Near-Earth Object Studies collects information about fireballs. The list published by the centre (first submission 15 April 1988, 3:03:10 am) contains information regarding the date and time of each fireball-related event reported, including its approximate Total Radiated Energy (J) and calculated Total Impact Energy (kt) – CTIE. The records also describe the geographical location, altitude and speed at peak brightness. The available data, which is filtered to exclude minor events, have been presented in the form of a graph (
Fireball velocities and Calculated Total Impact Energy
The records show that fireballs develop average speeds of several km/s as no significant changes in these values have been observed since the beginning of the records. However, CTIE (kt) is observed to have been decreasing to reach an average level of approx. 17 kt. A decrease in CTIE may indicate lower hazard levels from NEOs at present and in the near future.
The specialist literature tends to employ two formalised possibilities of estimating NEO threats – Palermo and Torino scales. The Palermo Technical Impact Hazard Scale
The Torino scale is shown in the table below (
Torino Impact Hazard Scale (
Level of hazard (colour of zone) | Value | Description |
---|---|---|
No Hazard (White Zone) | 0 | The probability of a collision is very low or zero. Includes events involving small objects that are destroyed by heat in the atmosphere and rare meteorite falls un- likely to cause damage. |
Normal (Green Zone) | 1 | A standard observation indicating a NEO’s pass with no serious threat level. A collision is highly unlikely, and the incident doe not need to be communicated to the public to worry. Following telescopic observations, events are typically down- graded to Level 0. |
Meriting Attention by As- tronomers (Yellow Zone) | 2 | An object makes a relatively close but not an excessively unusual near-Earth pass. The incident merits attention by astronomers, however, due to little chance of impact, informing the public would be excessive. On further observation, events are typically downgraded to Level 0. |
3 | A close encounter that deserves attention by astronomers or even the public or of- ficials should the encounter to occur within a decade of detection. Current math- ematical models ascribe these events a 1% or greater chance of collision capable of localised destruction. Following telescopic observations, events are typically down- graded to Level 0. | |
4 | A near pass requiring scientific analysis. As in Level 3, a potential impact event is given a 1% or greater chance of collision but is understood to be capable of re- gional rather than localised devastation. Following telescopic observations, events are typically downgraded to Level 0. Unless the event is expected to occur within 10 years, the public and authorities do not require informing. | |
5 | A near encounter that poses a serious, yet indeterminate threat of devastation on a regional level. Critical attention from astronomers necessary, in order to provide a conclusive determination of whether or not a collision will occur. Should the encounter be projected to occur within 10 year of observation, governmental plan- ning may be warranted. | |
6 | The catastrophe that would be likely to follow from the impact would have a global reach. Demand the attention from astronomers to provide conclusive indi- cation of whether an impact should be expected. Governmental planning may be warranted should the event occur within 30 years of discovery. | |
7 | An unprecedentedly close encounter by an object of big size and a potential to cause a global catastrophe. If expected within a 100-year period, the risk should trigger international emergency planning, particularly to obtain a clear communi- cation of whether or not a collision is due. | |
8 | An impact is unavoidable and likely to cause localised devastation if hitting the land or a tsunami if in the near-shore region. The events are estimated to occur at a frequency in the region between once per 50 to several 1000 years. | |
9 | Extremely rare events (between once per 10,000 years and once per 100,000 years) capable of triggering extensive regional devastation/a major tsunami. | |
10 | A collision is not to be avoided and may likely cause a global climate catastrophe, posing a serious threat to the entire civilisation, regardless of the impact site. These collisions are highly infrequent and are estimated to occur once per 100,000 years, or less often. |
A 0-10 point Torino Impact Hazard Scale serves as a communication medium between scientists and the public to provide information on threats from near-Earth objects. To an extent, a space threat carries an inherent uncertainty regarding the determination of orbits of newly discovered asteroids and comets, which results from the natural limitations of measurement precision. In the case of objects making near-Earth passes that uncertainty causes that the collision cannot be ruled out. In brief, the scale is to contextualise the level of public concern and urgency that is merited for any near pass in a 100-year timespan. The Torino Scale values describe both the chance of collision and its kinetic energy; however, the scale value may be modified in view of the new, refined data describing the probability and energy estimates. Category 1 describes a collision probability equal to the current annual chance for any given size impactor. The top categories denote an inevitable collision (probability >99%) whose consequences are increasingly serious. While Category 0 events may not require public attention, their occurrence should spur researchers to improve orbital data for such objects for improved accuracy of impact prediction. Nevertheless, due to the multi-dimensionality of these problems, it is unattainable to express them by means of a one-dimensional system such as the Torino Scale (
While Torino Scale is predominantly a communication tool with the public, accounting for the predicted impact energy of the event and the chance of occurrence, the Palermo Scale is rather dedicated for specialists to aid the assessment of an event with respect to the level of concern warranted for a potential future impact. The Palermo Scale enables a careful hazard assessment of minor Torino Scale 0 events, which in fact account for virtually all potential impacts determined so far. The priority rules for space objects considered in Palermo Scale determine the amount of due scientific observations and analysis. As noted earlier, the scale is continuous (positive and negative values) and specifies the time of the predicted potential impact, the object’s projected impact energy and probability of occurrence.
From data collected and published by NASA (
Palermo and Torino scale scores for selected NEOs (
Object Designation | Palermo Scale (cum.) | Palermo Scale (max.) | Torino Scale (max.) |
---|---|---|---|
29075 (1950 DA) | -1,42 | -1,42 | * |
101955 Bennu (1999 RQ36) | -1,71 | -2,32 | |
99942 Apophis (2004 MN4) | -2,83 | -2,93 | 0 |
(2000 SG344) | -2,86 | -3,23 | 0 |
(2007 FT3) | -3,07 | -3,73 | 0 |
(2008 JL3) | -3,27 | -3,27 | 0 |
(2009 JF1) | -3,28 | -3,28 | 0 |
(2019 DS1) | -3,29 | -3,3 | 0 |
(2010 RF12) | -3,3 | -3,31 | 0 |
(2005 QK76) | -3,55 | -3,7 | 0 |
(1994 GK) | -3,65 | -3,66 | 0 |
(2019 ND7) | -3,67 | -4,38 | 0 |
(2008 UB7) | -3,69 | -4,3 | 0 |
(2017 US) | -3,75 | -4,03 | 0 |
(2012 HG2) | -3,76 | -4,26 | 0 |
(2000 SB45) | -3,77 | -4,24 | 0 |
(2012 QD8) | -3,81 | -3,95 | 0 |
(2007 DX40) | -3,84 | -4,26 | 0 |
(2018 VP1) | -3,86 | -3,86 | 0 |
(2008 EX5) | -3,88 | -4,16 | 0 |
(2005 ED224) | -3,9 | -3,93 | 0 |
(2019 WG2) | -3,91 | -4,22 | 0 |
(2013 VW13) | -3,92 | -4,09 | 0 |
– is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future
From the survey of existing literature, it can be concluded that space objects are indeed a source of serious threat of destruction on the Earth’s surface. Consequently, opportunities to counteract them must be continually explored. One of the joint concepts developed by NASA and the US National Nuclear Security Administration is a programme Hypervelocity Asteroid Mitigation Mission for Emergency Response – HAMMER. The solution considers a nuclear charge explosion as a method to impart kinetic energy to a hazardous asteroid in order to change its trajectory and distance from the Earth. The deflector is nine metres tall and weighs more than 8,000 kg. HAMMER can be used as a kinetic impactor (a high-speed spacecraft applying the push), or as a nuclear payload carrier. The explosion planning phase will be preceded by space probe testing of a designated object using an unmanned space probe. A similar NASA mission, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is currently underway, since 8 September 2016. It is aimed at asteroid 101955 Bennua and its objectives are the possibility of a high-precision determination of the asteroid trajectory, and secondly, the analysis of its chemical composition in terms of new raw materials and organic compounds. Another mission objective is to evaluate the detonation of a nuclear charge in order to mitigate the risk of a collision with the Earth. However, given the current legislative state, there are no provisions regarding the possibility of placing nuclear charges in space, which is an issue for future studies.
The Internet and social media monitoring was performed using Unamo SEO software (
For the purpose of further numerical analyses, the following metrics were considered:
The results obtained for particular channels are presented in
Responses to NEO posts on the Internet and in social media
Category | Interac- tions | Reach | Likes | Comments | Re-posts | Popularity | Ad equiva- lent (USD) | Links | Images | Status change | Videos |
---|---|---|---|---|---|---|---|---|---|---|---|
2,614 | 2.13E+08 | 586,975 | 7,929 | 161,338 | 3,200,099 | 3,305,572 | 533 | 177 | 1,872 | 32 | |
19,138 | 6409,062 | 40,800 | 15,170 | 7,334 | 218,824 | 307,453 | 3,109 | 1,862 | 14,003 | 164 | |
4,428 | 882,890 | 49,267 | 3,952 | 0 | 65,075 | 36,069 | 0 | 293 | 4,112 | 23 | |
Blogs | 89 | 0 | 0 | 2 | 0 | 8 | 0 | 0 | 18 | 69 | 0 |
Portals | 115 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Communities | 112 | 0 | 0 | 18 | 0 | 72 | 0 | 0 | 0 | 0 | 0 |
Fora | 48 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
YouTube | 13,993 | 4,143,671 | 103,317 | 12,058 | 0 | 151,549 | 10,359 | 0 | 0 | 13,822 | 171 |
Sentiment towards statements
Sentiment | Interactions | % |
---|---|---|
Neutral | 25,923 | 63.94% |
Negative | 2,003 | 4.94% |
Positive | 12,617 | 31.12% |
The graph in
Statements and reach in the analysed timeframe
Media equivalent and popularity in the analysed timeframe
From the presented social media/Internet study, it can be seen that threat news disseminated through social media demonstrate decent popularity and thus can serve to raise public awareness. If implemented with skill and careful thought, the social media messages are capable of warning the public about threats and support potential evacuation and protection of the population in crisis. Furthermore, the results provide data for the estimation of public concern (e.g. sentiment) in the face of this type of threat.
The main conclusions that emerge from the review of international specialist literature and the results from own research reported in this study are as follows:
The definitions of NEO and related objects vary in the literature, thus contributing to the terminological confusion. One of the objectives of this work was to introduce order and precision in the relevant nomenclature, for the sake of this and future works on space security. Near-Earth Objects are capable of impacting the Earth or colliding with satellites and other equipment on the orbit of our planet, including systems critical for state security or e.g. air traffic safety (GNSS navigation systems). The safety of citizens in view of space threats can be provided by continuous monitoring of variable parameters of NEOs, e.g. by means of Palermo and Torino scale indicators. Fundamentally, the concept of protecting the Earth against NEOs comes down to discharging a nuclear missile at a hazardous object. The use of nuclear deflector should be, however, preceded by a thorough analysis of the object using a space probe. The inherent problem is the time factor. A further obstacle consists in the inadequacy of international space law provisions that in the current legislative state prohibit the placement of nuclear charges in space. Prior to resolving the outstanding legal and technological issues, the solution should be regarded merely as a potential future concept. The study of the social media has confirmed an extensive interest in Near-Earth Objects among Internet users. Furthermore, the sentiment analysis has indicated that NEO-related news and stories do not create a sense of impending danger in the general public.
The proposed work is financed through funds for scientific activity as part of the research task: Militarisation of Outer Space and Threats to State Security (task number: II.1.6.0).
au (Astronomical Unit) – is defined by the International Astronomical Union (IAU) as exactly 149,597,870,700 m.
albedo – the ratio of the light received by a body to the light reflected by that body. Albedo values range from 0 (pitch black) to 1 (perfect reflector). Examples – our Moon has a very low albedo (0.07), while Venus has a high albedo (0.60). The albedo combined with the absolute magnitude can help determine the size of an asteroid (
The Palermo Technical Impact Hazard Scale – the full name of Palermo scale.