A large asteroid or comet on its way to Earth would pose a global threat. It would take national and international efforts to stop it.
When a 2-meter-wide asteroid hit Earth’s atmosphere in March, it came as no complete surprise.
Two hours before asteroid 2022 EB5 made its impact, Krisztián Sarneczky of the Hungarian Piszkéstető observatory reported the small object to the International Astronomical Union’s Minor Planet Center. It was placed and marked for additional sightings. NASA’s ‘Scout’ impact assessment system automatically took those observations and calculated the trajectory, suggesting a possible… impact location: from West Greenland to the coast of Norway.
The range was wide, but it was only based on 14 observations, over 40 minutes, from one observatory.
Tracking asteroids and comets is a global process involving people, organizations and state-funded efforts around the world. While it could be improved, it works. If only half of those with vested interests in space invested resources in developing object reduction techniques, our chances of protecting the planet from cosmic threats would improve dramatically.
Asteroids and comets often cross paths with Earth’s orbit. The big ones don’t hit the earth very often. But they do hit. And if they do, they can cause serious damage.
It is estimated that there are more than 25,000 near-Earth asteroids with a diameter of at least 140 meters. We have mapped only about 40 percent of them. Objects as small as 40 meters or larger pose a significant threat to Earth.
Finding dangerous objects near Earth is the first step in our planetary defense† The other three steps are tracking, characterizing, and reducing or eliminating the threat they pose. Global cooperation and national efforts are essential at all four stages.
Ground and space telescopes track bodies moving in the sky relative to background stars. We have found 117 near-Earth comets and 29,248 near-Earth asteroids, of which 10,098 are larger than 140 meters wide and 852 larger than 1 kilometer.
More than 95 percent of these objects were discovered through US NASA-funded studies, primarily using ground-based telescopes such as ATLAS in Hawaii and Catalina in Arizona. The European Space Agency’s FlyEye Telescope, Japan’s Kiso Schmidt Telescope, China’s Purple Mountain Observatory, and Hungary’s Piszkéstető Observatory have also contributed, as well as non-profit organizations: the B612 Foundation has discovers more than 100 asteroids.
Once an object is found near Earth, its orbit is tracked to see if it is on a collision course with Earth. Many observations have to be made over days, weeks and months using ground or space telescopes and radars when objects are closer.
Individuals, organizations, and state-funded efforts around the world are helping to track. Observations and measurements are submitted to the International Astronomical Union Minor Planet Center (IAU MPC), which hosts them on public web pages for other observers to access. NASA’s Jet Propulsion Laboratory (JPL) and Italy’s NEODyS are running simulations of submitted coordinates and modeling projected orbits to see if they will hit Earth. All results are available on the IAU MPC website†
We need to know the specifics of asteroids and comets before coming up with a method of deflection. Asteroids are rocky or metallic and come in a variety of sizes, shapes, compositions, spin rates and densities – they can be ‘fluffballs’ (dust and rock loosely held together), heaps of rubble or solid metal.
Comets are icy, dusty little bodies formed in the outer solar system far beyond Neptune’s orbit, where ice is stable. Comets strike Earth only about 1 percent as often as asteroids, which is why planetary defenses are mostly focused on asteroids.
Spectroscopy analysis, light curves, infrared telescopes and radars are some of the techniques scientists use to learn about the physical properties and chemical composition of objects. Remote Earth and space observations can also teach us a lot about the chemical and physical properties of an asteroid properties†
But the best way to learn more about an object is to send a spacecraft. In 2005, Japan’s Hayabusa 1 mission retrieved dirt samples from the asteroid Itokawa; its successor, the Hayabusa 2 mission, returned samples from asteroid Ryugu in 2020. NASA’s Osiris-Rex collected samples from the asteroid Bennu in 2020.
If an asteroid or comet turns out to be on a collision course with Earth, we can destroy or deflect it. Deflection techniques include pushing sideways with a spacecraft (kinetic impact), pulling off course using a spacecraft’s gravity, and using a laser or nuclear explosion to vaporize or destroy part of the object and to change his job.
NASAs Double Asteroid Redirect Test (DART) is the world’s first large-scale kinetic impactor mission. The DART spacecraft aims to crash into the moon Dimorphos of the twin asteroid Didymos and send it off course. For these and follow-up missions, NASA will work with several domestic agencies and international partners, including the European Space Agency, the Italian Space Agency and the Japanese space agency JAXA.
In 2013, the International Asteroid Warning Network (IAWN) and the International Advisory Group on Space Mission Planning (SMPAG) have been established. IAWN keeps records of all near-Earth observations collected by observatories around the world and facilitates the dissemination of the information to Member States. SMPAG promotes opportunities for international collaboration and research on deflection technology and techniques.
To increase its chances of success, planetary defense infrastructure needs more funding and more object detection, characterization and mitigation missions. Countries must continue to develop and test different mitigation techniques, while international entities focus on consolidating and expanding object information hosting and sharing.
The US has several projects to improve our planetary defense capabilities. As for finding and tracking NEOs, NASA plans to launch NEO Surveyor in 2026, a space-based infrared telescope which will scan the solar system for potentially dangerous objects. As for characterizing NEOs, the US is planning two asteroid missions. The first, in 2023, will launch the Osiris-Apex spacecraft to study the asteroid Apophis, which is expected to pass over Earth in 2029. A second mission to the metal rich asteroid Psyche will start in 2023 or 2024.
In 2024, NASA and international partners will launch the Hera mission to succeed DART.
China recently announced it would develop a planetary defense system. It will conduct its first asteroid deflection test in 2025 or 2026 (though it’s unclear) which method? it will use) and will use radars and ground- and space-based telescopes to improve the ability to track, monitor, and assess objects.
A variety of asteroids and comets can threaten Earth, so a variety of ideas and missions need to be tested. This can only be done at the national level for two main reasons. First, techniques can be developed and tested without the involvement of multiple actors and complex international decision-making.
Second, because they are sovereign and willing to invest resources, and have their own unique approaches, countries can develop and test new methods. Such methods are necessary because deflection missions must be tailored to the physical and chemical particulars of a threatening object.
Of the 193 UN member states, 75 have a government space agency and a dozen other satellites. Many other private organizations have vested interests in space and could invest resources in developing object limitation techniques. Space is hostile and uncertain, so the more options we have, the better our chances of success.
International institutions must ensure that all parties have access to up-to-date, transparent and comprehensive information about nearby Earth objects. This should help reduce mistrust between states regarding planetary defense. International bodies such as IAWN, SMPAG and IAU MPC are well placed to house and disseminate NEO observation and measurement data. Such information is critical to establishing a successful planetary defense, which would require a global effort. No state could do it alone.
International and national efforts contribute to planetary defense in unique ways. Together they increase our chances of survival if a near-terrestrial object were to threaten our planet.
Svetla Ben-Itzhak, PhD, is an assistant professor at West Space Seminar, Air University, US Air Force, Alabama. She can be reached at email@example.com and declares no conflict of interest with respect to the above article.
The views expressed are those of the author and do not reflect the official views of the United States Department of Defense or of any organization to which the author is affiliated, including Air University, the United States Air Force, and the United States Space Force.
Originally published under Creative Commons by means of 360 info™.
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