Asteroid Exploration: A Key to Earth's Future Safety
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Asteroid exploration is now underway with five missions aimed at uncovering the mysteries of our ancient Solar System, potentially aiding in the preservation of humanity.
Approximately 66 million years ago, a colossal asteroid struck Earth near the Yucatan Peninsula, leading to the extinction of the dinosaurs. The catastrophic event caused massive fires globally and resulted in a prolonged period of darkness.
On October 17, Asteroid 2021 TG14, roughly the size of a bus, came within 250,000 km (155,000 miles) of Earth. While this distance might seem secure, it's notably less than two-thirds the distance to the Moon, which averages 385,000 km (239,000 miles).
Despite its close approach, 2021 TG14 orbits the Sun every 470 days and poses no threat of collision with Earth in the foreseeable future. Even in the unlikely event of a strike, it would likely result in limited damage.
Unlocking the Secrets of Asteroids
Asteroids are fascinating remnants of the early Solar System, often regarded as "fossils" from a time before planets formed. Investigating these celestial bodies offers astronomers unique insights into our cosmic history.
A collection of spacecraft is poised to answer many questions about these ancient rocks. While meteorites, which are fragments that land on Earth, can provide information, they don't reflect the original conditions of their source.
As meteors enter our atmosphere, they undergo extreme heating, altering their chemical composition. Additionally, once they land, weathering and oxidation further change these ancient materials.
The ongoing missions to asteroids are expected to pose new questions and unravel mysteries about the early formation of our solar system. Such explorations could eventually play a pivotal role in protecting cities and nations from potential disasters.
OSIRIS-REx
The Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx) was launched in 2016 to study the asteroid Bennu. After reaching Bennu more than two years later, it successfully collected samples from its surface, set to arrive on Earth on September 24, 2023, landing in Utah's desert.
This solar-powered spacecraft, equipped with five scientific instruments, will not only advance our understanding of the Solar System but also help protect Earth from potential threats. It aims to gather knowledge that could enable humanity to extend its reach beyond our planet, safeguarding future generations from global disasters.
“OSIRIS-REx will assess Bennu’s physical and chemical characteristics, crucial for any future impact mitigation efforts. Furthermore, asteroids like Bennu may contain valuable resources such as water and metals, which could support future space exploration,” states the OSIRIS-REx team.
Recent data indicates a slight chance of Bennu colliding with Earth on September 24, 2182, with a probability of about one in 2,700. Current estimates suggest a one-in-1,700 likelihood of impact before the year 2300. A close approach in 2135 will provide astronomers with more clarity regarding Bennu's trajectory.
Hayabusa2
The asteroid Ryugu is now being analyzed in laboratories on Earth for the first time. Upon its arrival, the Hayabusa2 spacecraft executed a swift touch-and-go maneuver to gather samples, which returned to Earth on December 6, 2020.
Led by the Japanese space agency JAXA, Hayabusa2 follows the earlier Hayabusa mission that collected around 1,500 grains from the asteroid Itokawa a decade ago. Only a limited number of institutions worldwide possess samples from Ryugu, with Argonne National Laboratory being the sole facility in the U.S. that has examined these rare materials.
> On our Asteroid Close-Up on November 9, we will feature Dr. Esen Ercan Alp from Argonne National Laboratory, one of the few individuals to have analyzed these samples firsthand.
The insights gained from Ryugu are expected to yield significant scientific advancements in asteroid research.
The Psyche Mission
Scheduled for launch in August 2022, the Psyche mission aims to explore the asteroid Psyche, notable for its metallic composition. Initial assessments suggested that Psyche could be composed of up to 90% metal, though recent findings indicate it might contain only 30 to 60% metal.
“It may represent the iron-rich core of an early planet, stripped of its rocky exterior due to impacts during the Solar System's formation. Alternatively, it could be a remnant of a different iron-rich body that formed from metal-rich materials,” explains NASA.
> Our Asteroid Close-Up on November 9 will provide an in-depth look at the Psyche mission, with guest speakers to be announced.
Located in the main asteroid belt between Mars and Jupiter, Psyche resembles the core of an early planet. While remote sensing allows us to analyze Earth's core materials, geologists cannot access these directly. The Psyche mission will give scientists their first close-up view of planetary building blocks, enhancing our understanding of similar rocky worlds around other stars.
Psyche will first approach its target in 2025, three years ahead of its intended arrival, allowing for several years of scientific study before landing.
Lucy
In 1974, a partial skeleton of Australopithecus afarensis was discovered in Ethiopia, providing significant insights into our ancestral lineage. Named Lucy in honor of this find, the Lucy mission aims to explore the early solar system's asteroids.
Most asteroids reside in the belt between Mars and Jupiter, but two groups trail and lead Jupiter in its orbit. The Lucy mission will be the first to investigate these enigmatic Trojan asteroids, utilizing advanced orbital mechanics to visit at least seven of these bodies.
“Over its twelve-year mission, Lucy will explore a record number of asteroids, including one main belt asteroid and seven Trojan asteroids, with three Earth-gravity assists to reach these targets,” states NASA.
Launched on October 16, Lucy is set for an exciting journey to the Trojan asteroids. However, one of its solar arrays did not deploy fully after separation from the rocket.
“Lucy has successfully maneuvered using its thrusters and will continue with planned maneuvers to manage its momentum,” reports the Lucy team.
While the mission can proceed with the current array configuration, engineers are diligently working to resolve the issue.
DART
Despite numerous theoretical techniques to deflect asteroids, only two are currently feasible with available technology if an immediate threat is detected.
With enough lead time, a spacecraft could be sent to nudge an asteroid off its trajectory using gravitational pull. However, this method requires substantial time.
If a threat is identified with limited warning, the most viable solution may be to impact the asteroid directly. NASA's Double Asteroid Redirection Test (DART) mission represents the first large-scale test of such a kinetic impactor system.
DART is slated to launch from Vandenberg Space Force Base in California on November 23 aboard a SpaceX Falcon 9 rocket.
> On November 23, 2021, Astronomy News with The Cosmic Companion will provide an inside look at the DART mission, featuring special guests.
The spacecraft will target the double-asteroid system Didymos A and B, where the smaller asteroid orbits its larger counterpart.
“Didymos A measures approximately 780 meters, while its smaller companion is about 160 meters across, representing the size of asteroids that pose significant threats to Earth. The binary system is under intense observation to measure its properties before DART arrives,” explains the DART team.
The DART probe, comparable in size to a small storage shed, will collide with the moonlet at approximately 6.6 kilometers per second (14,750 MPH). This event will mark a significant milestone in asteroid exploration.
“The impact will alter the moonlet's speed in its orbit around its primary body by a small fraction, but enough to change its orbital period by several minutes, which can be observed with Earth-based telescopes,” states NASA’s Planetary Defense Coordination Office.
The Didymos B moonlet represents the type of asteroids that researchers believe pose the most considerable risks to Earth due to their size and the challenges in detecting them until it's too late.
Planetary Defense
The dinosaurs' downfall might be that they never developed a space program. While that may have been beyond their capabilities, humanity has the potential to address such threats.
If an asteroid threat arises tomorrow, a kinetic impactor would be our most viable option to avert disaster. However, waiting to explore asteroids until a threat is identified may be too late.
“Preparing in advance with kinetic impactors available would require a minimum of 1 to 2 years' warning for smaller asteroids. If an asteroid were detected today, it could take about 20 years to construct, launch, and impact the target to redirect it from Earth’s path,” NASA officials explain.
Through cosmic exploration, both robotic and human-led missions advance technologies to capture and store carbon dioxide, enhance renewable energy efficiency, and fundamentally reshape our understanding of humanity.
These efforts must include vigilance against asteroids and comets, as safeguarding our planet is a responsibility we owe to the brave early mammals that survived the post-dinosaur era and the beautiful world they inherited.
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