LWL | Detecting Asteroids
Abstract
The growing realization of the potential for an asteroid impact has led to focus on whether current aerospace technologies are sufficient when it comes to detecting PHAs and attempting to deflect them. The extent to which current space-based and ground-based telescopes, as well as the deflection strategies are adequate means for defending against asteroids is explored in this paper. A comprehensive review of detection capabilities highlights both the strengths and limitations of current detection and deflection techniques. Substantial progress has been made to advance this knowledge, particularly with missions such as NASA's DART but current technology is inadequate ensuring that every asteroid threat can be addressed reliably and in a warning time frame. The paper concludes by identifying critical areas for enhanced deflection methods, to ensure a more robust planetary defence system in the future.
Introduction
The inevitable threat of asteroids and near-Earth objects (NEOs) hitting our planet has long been a matter of public concern and scientific research. According to the Lunar and Planetary Laboratory at the University of Arizona our beloved planet has suffered up to 3 million impact craters larger than one kilometre in diameter (Science Time, 2021). Recent advancements in aerospace technologies have increased the ability to detect and mitigate NEOs approaching our planet. Without any warning in February 2013, a meteor came towards a city in Russia and exploded in the sky releasing shockwaves which had 20-30 times more energy than a WWII atomic bomb (Johns Hopkins Applied Physics Laboratory, 2019). Such instances is what led to the conclusion that our planet requires advance detection and deflection technologies in order to avoid devastating collisions that may wipe out humanity as a whole. As we continue to gain further and deeper understanding of the NEOs surrounding us, so does our scope of analysing, detecting, deflecting and protecting mankind from a potentially hazardous collision.
Current modernised technologies almost effectively assist in asteroid detection and deflection. The ground-based telescopes and space-based observatories have significantly improved our capacity to monitor and track any NEO activity around. Moreover, the kinetic impactor and nuclear explosive device have played a pivotal role in diverting the trajectories of such asteroids, providing a strengthened defence strategy. Several missions such as the DART from NASA have successfully been implemented in the past, promising bright prospects for the future of aerospace technologies.
While promising, these mechanisms are not always reliable enough. Over the years it has been observed and established that these detection strategies only go so far due to observational limitations and varying sizes and compositions of asteroids. Moreover, deflection techniques also are constrained due to the factors of limited intervention time, and uncertainties in practical application. The current aerospace technologies offer a level of readiness for detecting and deflecting potentially hazardous asteroids, but ongoing research and development are crucial to further strengthen our defences against these celestial threats.
Literature Review
Excell, J. (2023, January 6). Detecting and deflecting the asteroid threat. The Engineer. https://www.theengineer.co.uk/content/in-depth/detecting-and-deflecting-the-asteroid-threat/
The source "Detecting and Deflecting the Asteroid Threat" by Excell (2023) from The Engineer is crucial for the research topic as it provides an up-to-date overview of technological advancements, such as space missions and ground-based systems, designed to detect and track near-Earth objects (NEOs). Moreover, it highlights emerging deflection strategies, such as kinetic impactors and gravity tractors, providing valuable insights into the real-world capabilities and limitations of these technologies. The article serves as a vital resource for understanding the current state of readiness and the gaps that need to be addressed to ensure effective asteroid threat mitigation.
The Hunt for Hazardous Asteroids: Challenges and Advancements in Planetary Defense. (2024, August 2). New Space Economy. https://newspaceeconomy.ca/2024/08/05/the-hunt-for-hazardous-asteroids-challenges-and-advancements-in-planetary-defense/#google_vignette
The source "The Hunt for Hazardous Asteroids: Challenges and Advancements in Planetary Defense" (2024) from New Space Economy is vital for the research as it offers a contemporary perspective on the latest advancements and challenges in planetary defense, focusing on space missions, international collaborations, and detection systems. This source helps contextualize the current strengths and weaknesses of aerospace technologies, providing a balanced view of where planetary defense stands and where further improvements are needed, which is the major aim of the research, to counter analyse the current technologies.
Defending Earth: Strategies for Deflecting Hazardous Asteroids. (2024, May 29). New Space Economy. https://newspaceeconomy.ca/2024/06/02/defending-earth-strategies-for-deflecting-hazardous-asteroids/#google_vignette
The source "Defending Earth: Strategies for Deflecting Hazardous Asteroids" (2024) from New Space Economy is important for research as it delves into the specific methods being developed to prevent asteroid impacts, such as kinetic impactors, nuclear deflection, and other innovative approaches. By examining these strategies, the article provides a detailed look at both the practical application and limitations of present-day technologies. This helps assess whether the current arsenal of aerospace tools is sufficient for successfully addressing the asteroid threat or if further technological advances are required.
Reitsema, H. J., & Lu, E. T. (2015b). Sentinel: A Space Telescope Program to Create a 100-Year Asteroid Impact Warning. In Springer eBooks (pp. 569–581). https://doi.org/10.1007/978-3-319-03952-7_42
The chapter "Sentinel: A Space Telescope Program to Create a 100-Year Asteroid Impact Warning" by Reitsema and Lu (2015) is crucial for the research as it focuses on the Sentinel space telescope project, designed specifically to identify potentially hazardous asteroids well in advance. It discusses how Sentinel would contribute to long-term planetary defense by creating a comprehensive catalog of near-Earth objects (NEOs) and providing early warnings of impact threats. This long-term detection capability is essential for evaluating how well current and proposed space-based technologies can meet the challenge of providing adequate lead time for effective deflection or mitigation efforts. The source offers a detailed technical background on one of the most significant detection initiatives.
TheIHMC. (2022b, April 7). Rusty Schweickart: What is the Gravity Tractor Deflection Method for Deflecting NEAs [Video]. YouTube. https://www.youtube.com/watch?v=OsRD2zU0aMY
The video "Rusty Schweickart: What is the Gravity Tractor Deflection Method for Deflecting NEAs" (2022) by TheIHMC on YouTube is a significant source for research on the effectiveness of current aerospace technologies for asteroid deflection. In this video, Rusty Schweickart, a well-known astronaut and planetary defence advocate, explains the gravity tractor method, a theoretical technique that involves using a spacecraft's gravitational pull to gradually alter an asteroid's trajectory. The source helps in understanding the potential of the gravity tractor method as a complementary or alternative solution to current deflection strategies, contributing to the broader discussion of how sufficient today's technologies are in mitigating asteroid threats. This particular source was chosen as Rusty Schweickart is the co-founder of the B612 foundation, thus, no one else would have more expertise than him on this topic, making the information more credible for the research.
Johns Hopkins Applied Physics Laboratory. (2019b, July 17). DART - The First Planetary Defense Mission [Video]. YouTube. https://www.youtube.com/watch?v=LoLH3ruxDsY
The video "DART - The First Planetary Defense Mission" (2019) by Johns Hopkins Applied Physics Laboratory on YouTube is a vital source for research as it provides an overview of NASA's Double Asteroid Redirection Test (DART), the first mission designed to test the kinetic impactor technique, a direct deflection method involving the collision of a spacecraft with an asteroid to change its trajectory. The video offers insights into the mission's objectives, technology, and expected outcomes, making it a critical example of real-world testing of deflection strategies. This source helps assess how effectively current technologies can address the asteroid threat and the readiness of such methods for planetary defense applications. This source was particularly chosen as the presenter is the main person in charge of this mission, making her more reliable and credible than anyone else on this subject.
Current detection methods
In present world we have several promising asteroid detection instruments that mainly comprises of the ground-based optical telescopes. This includes primarily the Hawaii’s PanSTARRS (Panoramic Survey Telescope and Rapid Response System) telescope and the NASA-funded Catalina Sky Survey (CSS). In fact, it has been established that these facilities are responsible for almost 90 per cent of discoveries and identify around 1,800 objects every year (Excell, 2023). These telescopes capture the extraterrestrial objects hovering the night sky using the aid of wide-field cameras. then analysing and observing any potential asteroids or NEOs.
Along with that, the space-based telescopes provide better observations given that they do not have the disadvantage of atmospheric disturbances. “One of the greatest things it does for us is allow a more accurate estimation of size,” said Lindley Johnson, who is head of planetary protection at NASA (Excell, 2023). The NEOWISE mission, which uses NASA’s Wide-field Infrared Survey Explorer (WISE) spacecraft has surpassed it’s expected lifetime however effectively helped NASA and humankind in the field of asteroid detection. In place of that, NASA is now working on developing NEOCam that will serve for similar purposes.
The B612, non-profit organisation, launched a space based observatory called Sentinel that aims to detect more near Earth asteroids than the already present space-based and ground-based telescopes. The Sentinel mission will place an infrared telescope in an orbit around the Sun’s interior to the Earth’s orbit for about 6.5 years. Sentinel is designed is such a manner that permits accurate data collection and provides us with the path of the asteroid for almost the next 100 years. This facility allows humans to easily check if there is a possibility of a collision and plan way ahead of time and deflect the asteroid off its course just within the time of impact.
Moreover, scientists have used radar observations to estimate the shape, size, orbit and more accurately detailed information about asteroid’s velocity, distance to plan ahead of time if it clashes with Earth’s orbit anytime in the future that poses any potential threat. Facilities like NASA’s Goldstone Deep Space Communications Complex have played a vital role in providing any information about any possible asteroids.
Lastly, as the world is evolving and moving further towards technological advancements including artificial intelligence and machine learning. Such advancements are also increasingly being used in asteroid detection to create more accurate understandings of them and their trajectories.
Current deflection methods
The most widely successful and accepted deflection method that has been effectively tested by the NASA’s Double Asteroid Redirection Test (DART) mission, launched in November 2021, which was humanity’s first attempt to test the Kinetic Impactor method. In laymen terms, the kinetic impactor would be described as a space rocket simply crashing into an asteroid that is on its way towards earth, which causes the asteroid to deflect and slightly change its trajectory. A tiny impact can also work wonders by changing the trajectory by miles. The DART mission was targeted towards the asteroid Dimorphos and collide with it at a velocity of 6 metres per second which caused Dimorphos’s trajectory to shorten by 32 minutes which consequently pulled Earth out of threat. The project scientist, Nancy Chabot, stated that The spacecraft is going be totally destroyed and so it’s not going to be able to measure how much of a deflection it made when this happens, instead we are going to be using existing telescopes here on Earth in order to make that crucial measurement (Johns Hopkins Applied Physics Laboratory, 2019) shows how carefully and strategically the technologies of detection and deflection are being interconnectedly used to make the project cost effective and to obtain accurate details.
Along with the Kinetic Impactor method, the Nuclear Explosive device comes to the saviour for short-notice asteroid warnings. When detonated at a accurately calculated distance from the asteroid, the x-ray radiation from the nuclear explosive device can possibly cause vaporisation of material on the asteroid, providing the asteroid with a rocket-like thrust to cause it to change trajectories. However, there has not yet been any real test carried out as this method would result to a number of legal, financial and environmental consequences for the people already on Earth.
The Gravity Tractor method is another precise and controlled technology in the run for asteroid deflection. The Gravity Tractor method has a very interesting way of methodology. A small spacecraft would simply hover over the asteroid and move along with it using ion propulsion or its engines, this would eventually exert a towing kind of force upon the asteroid which would basically be the weight of the spacecraft. This would cause a slight pull to the asteroid towards the spacecraft, forcing it to change its course, which could take weeks, months or even a year. This method would work wonders as the spacecraft never really has to touch the asteroid, eliminating the risk of breaking down the asteroid into smaller fragments.
Limitations and Challenges
Despite such advancements, the human race can’t compete with the vast and endless nature of space and the celestial bodies that surround Earth. There are several limitations and challenges that yet haven’t been resolved, making detection and deflection of asteroids not completely reliable and promising at all times.
To begin with, asteroids come in all shapes and sizes, however, even the smallest of them can cause damage to Earth in some or the other way. Unfortunately, the small asteroids, especially the ones that are distant or the ones that have dark surfaces, are difficult to detect as they do not reflect that much light, spotting them against the darkness of space make sit almost impossible. This problem requires extremely accurate and detailed instruments to detect the smallest of the small asteroids.
Without doubt, asteroids travel at extremely high velocities across the sky which makes it difficult to exactly track their motion from here down on Earth, especially because they are visible in the sky for very short periods of time. Moreover, the field of view for the ground-based telescopes is extremely limited and constricted which is suitable only for observations of already known objects, but it hinders the tracking and detection of unknown objects. In addition to their tremendously high velocities, these asteroid are also only visible during certain short time periods, this gives the researchers a short observation window. This becomes even more difficult for the ground-based telescopes due to the unpredictable weather conditions and seasonal changes.
One of the most significant challenges that astro-physicists face is the sun’s glare. This is typically a problem relating to asteroids that are farther from the Earth than the sun, which are called Atira asteroids. These asteroids go unnoticed and hide within the sun’s glare thus they remain undetected that increases the rick of collision with Earth without anyone’s knowledge. The sky in these regions and very bright which causes the sensitivity of optical equipment to reduce which may eventually also lead to damage of the optical equipment if directly pointed towards the sun. The previously stated incident at the start of the paper, of the meteor explosion above a City of Russia was the Chelyabinsk meteor. This meteor approached Earth completely uninformed which was primarily due to our blind spot in asteroid and meteor detection as a result of sun’s glare. We yet stand at the risk of further such asteroid impacts if this issue of the sun’s glare continues to persist. Further advanced equipments are required to overcome this issue such as the space-based telescopes positioned away from Earth, such as the proposed Near-Earth Object Surveillance Mission (NEOSM), could provide a better vantage point for observing sunward asteroids(The Hunt for Hazardous Asteroids: Challenges and Advancements in Planetary Defense, 2024).
Moving on to the limitations and challenges in asteroid deflection, there are various in each method. To begin with, in the Kinetic Impactor method, there are several factors that we need to take in account, which includes, the composition of the asteroid, size of asteroid, mass and velocity of the spacecraft, etc. Moreover, executing this method is tricky as in order for maximum deflection to occur, the spacecraft must collide with the asteroid in direction of the motion of the asteroid, however, the rotation and shape can cause complications.
For Nuclear Explosive Devices, the main challenge would be the political and legal challenges. The Outer Space Treaty of 1967 prohibits placing nuclear weapons in orbit or on celestial bodies.(Defending Earth: Strategies for Deflecting Hazardous Asteroids, 2024). Thus even before we think about any technical difficulties, it would be difficult to even plan a NED mission. Howsoever, looking at the technical difficulties, the detonation of the bomb too close to the asteroid could lead to the asteroid disseminating into several tiny pieces that could eventually put Earth at a higher risk than before as controlling several pieces of asteroid would be more difficult and could lead to collisions all around the planet.
Lastly, the Gravity Tractor method also has its limitations and challenges even though it is the most safest and most precise out of all. This method is not suitable for short-warning asteroids given that it requires a huge spacecraft and it must be implemented for a long period of time. The spacecraft must remain in a position parallel to the movement of the asteroid, however, given to irregularities in the shapes, sizes and rotation of asteroids, this is extremely difficult to maintain.
Conclusion
It can be safely concluded that our current asteroid detection and deflection technologies aren’t a 100% reliable enough to ensure the safety of our planet, however, the astro-physicists and aerospace engineers are working day in and day out to come up with alternatives or solutions to the present issues. There have already been progresses. For instance, Lawrence Livermore National Laboratory has developed sophisticated simulation tools to model the effects of a nuclear detonation on an asteroid’s surface. These models consider factors such as the asteroid’s porosity, the device’s yield and detonation altitude, and the angle of incidence of the radiation (Defending Earth: Strategies for Deflecting Hazardous Asteroids, 2024). Moreover, there are ways to minimise difficulties of the kinetic impactor method using an observatory spacecraft that accurately tracks the motion of the asteroid, or using several different spacecrafts one after another to keep of deflecting it further. However, to guarantee the best efficiency and outcomes, a combination of these strategies could also be applied. For instance, the asteroid's trajectory may be generally altered by a kinetic impactor and then fine-tuned by a gravity tractor.
References
Excell, J. (2023, January 6). Detecting and deflecting the asteroid threat. The Engineer. https://www.theengineer.co.uk/content/in-depth/detecting-and-deflecting-the-asteroid-threat/
The Hunt for Hazardous Asteroids: Challenges and Advancements in Planetary Defense. (2024, August 2). New Space Economy. https://newspaceeconomy.ca/2024/08/05/the-hunt-for-hazardous-asteroids-challenges-and-advancements-in-planetary-defense/#google_vignette
Defending Earth: Strategies for Deflecting Hazardous Asteroids. (2024, May 29). New Space Economy. https://newspaceeconomy.ca/2024/06/02/defending-earth-strategies-for-deflecting-hazardous-asteroids/#google_vignette
Science Time. (2021, December 4). Can We Prevent an Asteroid From Hitting Earth? [Video]. YouTube. https://www.youtube.com/watch?v=JMb6e3g3diM
Reitsema, H. J., & Lu, E. T. (2015b). Sentinel: A Space Telescope Program to Create a 100-Year Asteroid Impact Warning. In Springer eBooks (pp. 569–581). https://doi.org/10.1007/978-3-319-03952-7_42
TheIHMC. (2022b, April 7). Rusty Schweickart: What is the Gravity Tractor Deflection Method for Deflecting NEAs [Video]. YouTube. https://www.youtube.com/watch?v=OsRD2zU0aMY
Johns Hopkins Applied Physics Laboratory. (2019b, July 17). DART - The First Planetary Defense Mission [Video]. YouTube. https://www.youtube.com/watch?v=LoLH3ruxDsY
